SEC Info - Quanta Services, Inc. - ‘10-K’ for 12/31/23

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Quanta Services, Inc. – ‘10-K’ for 12/31/23 – ‘EX-101.LAB’

On: Thursday, 2/22/24, at 9:56am ET · For: 12/31/23 · Accession #: 1050915-24-9 · File #: 1-13831

Previous ‘10-K’: ‘10-K’ on 2/23/23 for 12/31/22 · Latest ‘10-K’: This Filing · 34 References:

  As Of               Filer                 Filing    For·On·As Docs:Size

 2/22/24  Quanta Services, Inc.             10-K       12/31/23  128:15M

Annual Report — Form 10-K — SEA’34

Filing Table of Contents

Document/Exhibit                   Description                      Pages   Size 

 1: 10-K        Annual Report                                       HTML   2.83M 
 2: EX-4.1      Instrument Defining the Rights of Security Holders  HTML     51K 
 3: EX-21.1     Subsidiaries List                                   HTML    258K 
 4: EX-23.1     Consent of Expert or Counsel                        HTML     34K 
 8: EX-97       Clawback Policy re: Recovery of Erroneously         HTML     50K 
                Awarded Compensation                                             
 5: EX-31.1     Certification -- §302 - SOA'02                      HTML     40K 
 6: EX-31.2     Certification -- §302 - SOA'02                      HTML     40K 
 7: EX-32.1     Certification -- §906 - SOA'02                      HTML     37K 
14: R1          Cover Page                                          HTML    101K 
15: R2          Audit Information                                   HTML     40K 
16: R3          Consolidated Balance Sheets                         HTML    160K 
17: R4          Consolidated Balance Sheets (Parenthetical)         HTML     47K 
18: R5          Consolidated Statements of Operations               HTML    132K 
19: R6          Consolidated Statements of Comprehensive Income     HTML     70K 
                (Loss)                                                           
20: R7          Consolidated Statements of Cash Flows               HTML    135K 
21: R8          Consolidated Statements of Equity                   HTML    111K 
22: R9          Consolidated Statements of Equity (Parenthetical)   HTML     38K 
23: R10         Description of Business                             HTML     38K 
24: R11         Basis of Presentation and Accounting Policies       HTML     79K 
25: R12         New Accounting Pronouncements                       HTML     50K 
26: R13         Revenue Recognition and Related Balance Sheet       HTML    122K 
                Accounts                                                         
27: R14         Segment Information                                 HTML     99K 
28: R15         Acquisitions                                        HTML    118K 
29: R16         Goodwill and Other Intangible Assets                HTML    104K 
30: R17         Investments in Affiliates and Other Entities        HTML     50K 
31: R18         Per Share Information                               HTML     49K 
32: R19         Debt Obligations                                    HTML    105K 
33: R20         Leases                                              HTML    181K 
34: R21         Income Taxes                                        HTML    144K 
35: R22         Equity                                              HTML     82K 
36: R23         Stock-Based Compensation                            HTML     82K 
37: R24         Employee Benefit Plans                              HTML    135K 
38: R25         Commitments and Contingencies                       HTML     87K 
39: R26         Detail of Certain Accounts                          HTML     72K 
40: R27         Supplemental Cash Flow Information                  HTML     77K 
41: R28         Pay vs Performance Disclosure                       HTML     47K 
42: R29         Insider Trading Arrangements                        HTML     41K 
43: R30         Basis of Presentation and Accounting Policies       HTML    210K 
                (Policies)                                                       
44: R31         Revenue Recognition and Related Balance Sheet       HTML     93K 
                Accounts (Tables)                                                
45: R32         Segment Information (Tables)                        HTML     89K 
46: R33         Acquisitions (Tables)                               HTML    110K 
47: R34         Goodwill and Other Intangible Assets (Tables)       HTML    110K 
48: R35         Investments in Affiliates and Other Entities        HTML     46K 
                (Tables)                                                         
49: R36         Per Share Information (Tables)                      HTML     48K 
50: R37         Debt Obligations (Tables)                           HTML     89K 
51: R38         Leases (Tables)                                     HTML    130K 
52: R39         Income Taxes (Tables)                               HTML    147K 
53: R40         Equity (Tables)                                     HTML     74K 
54: R41         Stock-Based Compensation (Tables)                   HTML     78K 
55: R42         Employee Benefit Plans (Tables)                     HTML    129K 
56: R43         Detail of Certain Accounts (Tables)                 HTML     74K 
57: R44         Supplemental Cash Flow Information (Tables)         HTML     78K 
58: R45         Basis of Presentation and Accounting Policies -     HTML     61K 
                Stock-Based Compensation (Details)                               
59: R46         Revenue Recognition and Related Balance Sheet       HTML     48K 
                Accounts - Performance Obligation (Details)                      
60: R47         Revenue Recognition and Related Balance Sheet       HTML     86K 
                Accounts - Additional Information (Details)                      
61: R48         Revenue Recognition and Related Balance Sheet       HTML     62K 
                Accounts - Revenue Disaggregated by Geographic                   
                Location and Contract Type (Details)                             
62: R49         Revenue Recognition and Related Balance Sheet       HTML     40K 
                Accounts - Contract Assets and Liabilities                       
                (Details)                                                        
63: R50         Revenue Recognition and Related Balance Sheet       HTML     43K 
                Accounts - Composition of the Allowance for Credit               
                Losses (Details)                                                 
64: R51         Segment Information - Narrative (Details)           HTML     36K 
65: R52         Segment Information - Summarized Financial          HTML     86K 
                Information (Details)                                            
66: R53         Acquisitions - Additional Information (Details)     HTML    100K 
67: R54         Acquisitions - Aggregate Consideration Paid or      HTML    102K 
                Payable and Allocation of Net Assets (Details)                   
68: R55         Acquisitions - Estimated Fair Values of             HTML     50K 
                Identifiable Intangible Assets and Related                       
                Weighted Average Amortization (Details)                          
69: R56         Acquisitions - Significant Estimates Used by        HTML     46K 
                Management in Determining Fair Values of Customer                
                Relationships Acquired (Details)                                 
70: R57         Acquisitions - Aggregate Fair Values of             HTML     46K 
                Outstanding Contingent Consideration Liabilities                 
                (Details)                                                        
71: R58         Acquisitions - Unaudited Supplemental Pro Forma     HTML     39K 
                Results of Operations (Details)                                  
72: R59         Goodwill and Other Intangible Assets - Summary of   HTML     60K 
                Changes in Goodwill (Details)                                    
73: R60         Goodwill and Other Intangible Assets - Other        HTML     74K 
                Intangible Assets (Details)                                      
74: R61         Goodwill and Other Intangible Assets - Additional   HTML     38K 
                Information (Details)                                            
75: R62         Goodwill and Other Intangible Assets - Estimated    HTML     51K 
                Future Aggregate Amortization Expense of                         
                Intangible Assets (Details)                                      
76: R63         Investments in Affiliates and Other Entities -      HTML     55K 
                Equity Investments by Type (Details)                             
77: R64         Investments in Affiliates and Other Entities -      HTML     82K 
                Equity Method Investments (Details)                              
78: R65         Per Share Information - Basic and Diluted Earnings  HTML     55K 
                Per Share (Details)                                              
79: R66         Debt Obligations - Long-term Debt Obligations       HTML     78K 
                (Details)                                                        
80: R67         Debt Obligations - Principal Payments Required to   HTML     49K 
                be Made (Details)                                                
81: R68         Debt Obligations - Senior Notes (Details)           HTML    100K 
82: R69         Debt Obligations - Interest on Senior Notes         HTML     56K 
                (Details)                                                        
83: R70         Debt Obligations - Senior Credit Facility           HTML    163K 
                (Details)                                                        
84: R71         Debt Obligations - Information on Borrowings under  HTML     53K 
                Current and Prior Credit Facility and Commercial                 
                Paper Program (Details)                                          
85: R72         Debt Obligations - Commercial Paper Program         HTML     55K 
                (Details)                                                        
86: R73         Debt Obligations - Letters of Credit Outside the    HTML     38K 
                Credit Facility (Details)                                        
87: R74         Leases - Narrative (Details)                        HTML     55K 
88: R75         Leases - Components of Lease Costs (Details)        HTML     51K 
89: R76         Leases - Components of Leases in the Balance Sheet  HTML     66K 
                (Details)                                                        
90: R77         Leases - Future Minimum Lease Payments (Details)    HTML     93K 
91: R78         Leases - Weighted Average Remaining Lease Terms     HTML     46K 
                and Discount Rates (Details)                                     
92: R79         Income Taxes - Components of Income (Loss) Before   HTML     45K 
                Income Taxes (Details)                                           
93: R80         Income Taxes - Provision for Income Taxes           HTML     63K 
                (Details)                                                        
94: R81         Income Taxes - Narrative (Details)                  HTML     98K 
95: R82         Income Taxes - Effective Income Tax Rate            HTML     64K 
                Reconciliation (Details)                                         
96: R83         Income Taxes - Deferred Tax Assets and Liabilities  HTML     79K 
                (Details)                                                        
97: R84         Income Taxes - Net Deferred Income Tax Assets and   HTML     42K 
                Liabilities (Details)                                            
98: R85         Income Taxes - Reconciliation of Unrecognized Tax   HTML     49K 
                Benefit (Details)                                                
99: R86         Income Taxes - Balances of Unrecognized Tax         HTML     53K 
                Benefits (Details)                                               
100: R87         Equity - Treasury Stock (Details)                   HTML     51K  
101: R88         Equity - Repurchases of Common Stock Under Stock    HTML     43K  
                Repurchase Programs (Details)                                    
102: R89         Equity - Non-controlling Interests (Details)        HTML     46K  
103: R90         Equity - Dividends (Details)                        HTML     41K  
104: R91         Stock-Based Compensation - Stock Incentive Plans    HTML     46K  
                (Details)                                                        
105: R92         Stock-Based Compensation - Summary of RSUs and      HTML     68K  
                PSUs to be Settled in Common Stock Activity                      
                (Details)                                                        
106: R93         Stock-Based Compensation - Restricted Stock and     HTML     55K  
                RSUs to be Settled in Common Stock (Details)                     
107: R94         Stock-Based Compensation - PSUs to be Settled in    HTML     57K  
                Common Stock (Details)                                           
108: R95         Stock-Based Compensation - Grant Date Fair Value    HTML     54K  
                for Awards of Performance Units Inputs (Details)                 
109: R96         Employee Benefit Plans - Additional Information     HTML     67K  
                (Details)                                                        
110: R97         Employee Benefit Plans - Summary of Plan            HTML     86K  
                Information Relating to Participation in                         
                Multiemployer Pension Plans (Details)                            
111: R98         Employee Benefit Plans - Changes in FMV of COLI     HTML     39K  
                Assets and Deferred Compensation Liabilities                     
                (Details)                                                        
112: R99         Commitments and Contingencies - Legal Proceedings   HTML     84K  
                (Details)                                                        
113: R100        Commitments and Contingencies - Silverado Wildfire  HTML     41K  
                Matter (Details)                                                 
114: R101        Commitments and Contingencies - Insurance           HTML     48K  
                (Details)                                                        
115: R102        Commitments and Contingencies - Performance Bonds   HTML     43K  
                and Parent Guarantees (Details)                                  
116: R103        Commitments and Contingencies - Committed           HTML     42K  
                Expenditures (Details)                                           
117: R104        Detail of Certain Accounts - Cash and Cash          HTML     52K  
                Equivalents (Details)                                            
118: R105        Detail of Certain Accounts - Property and           HTML     81K  
                Equipment (Details)                                              
119: R106        Detail of Certain Accounts - Accounts Payable and   HTML     44K  
                Accrued Expenses (Details)                                       
120: R107        Supplemental Cash Flow Information -                HTML     49K  
                Reconciliation of Cash, Cash Equivalents, and                    
                Restricted Cash (Details)                                        
121: R108        Supplemental Cash Flow Information - Supplemental   HTML     51K  
                Cash Flow Information Related to Leases (Details)                
122: R109        Supplemental Cash Flow Information - Additional     HTML     42K  
                Supplemental Cash Flow Information (Details)                     
123: R110        Supplemental Cash Flow Information - Narrative      HTML     37K  
                (Details)                                                        
125: XML         IDEA XML File -- Filing Summary                      XML    237K  
128: XML         XBRL Instance -- pwr-20231231_htm                    XML   3.66M  
124: EXCEL       IDEA Workbook of Financial Report Info              XLSX    293K  
10: EX-101.CAL  XBRL Calculations -- pwr-20231231_cal                XML    380K 
11: EX-101.DEF  XBRL Definitions -- pwr-20231231_def                 XML   1.02M 
12: EX-101.LAB  XBRL Labels -- pwr-20231231_lab                      XML   3.04M 
13: EX-101.PRE  XBRL Presentations -- pwr-20231231_pre               XML   1.76M 
 9: EX-101.SCH  XBRL Schema -- pwr-20231231                          XSD    326K 
126: JSON        XBRL Instance as JSON Data -- MetaLinks              795±  1.20M  
127: ZIP         XBRL Zipped Folder -- 0001050915-24-000009-xbrl      Zip    884K

‘EX-101.LAB’ — XBRL Labels — pwr-20231231_lab

This Exhibit is an XBRL File.

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<link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_EquityMethodInvesteeNameDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_EquityMethodInvesteeNameDomain" xlink:to="lab_srt_EquityMethodInvesteeNameDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_428a9b2f-e5bb-4f8b-adae-a21b602a9120_terseLabel_en-US" xlink:label="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Recognition period for remaining performance obligation (in years) </link:label>

<link:label id="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_label_en-US" xlink:label="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1" xlink:to="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PaymentsToAcquireBusinessesGross_ef8b28b9-9ac6-4ba4-bff8-f75e64954462_terseLabel_en-US" xlink:label="lab_us-gaap_PaymentsToAcquireBusinessesGross" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Aggregate cash consideration paid </link:label>

<link:label id="lab_us-gaap_PaymentsToAcquireBusinessesGross_label_en-US" xlink:label="lab_us-gaap_PaymentsToAcquireBusinessesGross" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments to Acquire Businesses, Gross </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsToAcquireBusinessesGross" xlink:to="lab_us-gaap_PaymentsToAcquireBusinessesGross" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossNoncurrent_56441261-9f60-4873-bf23-0b760bbbd260_terseLabel_en-US" xlink:label="lab_us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-current retainage balances </link:label>

<link:label id="lab_us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossNoncurrent_label_en-US" xlink:label="lab_us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract with Customer, Receivable, after Allowance for Credit Loss, Noncurrent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossNoncurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossNoncurrent" xlink:to="lab_us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossNoncurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_9ba7870f-700e-40e3-91fa-465cd60253b0_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Aggregate Consideration Paid or Payable and Allocation of Net Assets </link:label>

<link:label id="lab_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfRecognizedIdentifiedAssetsAcquiredAndLiabilitiesAssumedTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DeferredTaxAssetsDeferredTaxBenefitsOnUnrecognizedTaxPositions_a7f9591e-63b1-4aeb-a5e8-6de0c6caf868_terseLabel_en-US" xlink:label="lab_pwr_DeferredTaxAssetsDeferredTaxBenefitsOnUnrecognizedTaxPositions" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred tax benefits on unrecognized tax positions </link:label>

<link:label id="lab_pwr_DeferredTaxAssetsDeferredTaxBenefitsOnUnrecognizedTaxPositions_label_en-US" xlink:label="lab_pwr_DeferredTaxAssetsDeferredTaxBenefitsOnUnrecognizedTaxPositions" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Deferred Tax Benefits On Unrecognized Tax Positions </link:label>

<link:label id="lab_pwr_DeferredTaxAssetsDeferredTaxBenefitsOnUnrecognizedTaxPositions_documentation_en-US" xlink:label="lab_pwr_DeferredTaxAssetsDeferredTaxBenefitsOnUnrecognizedTaxPositions" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Deferred Tax Benefits On Unrecognized Tax Positions </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DeferredTaxAssetsDeferredTaxBenefitsOnUnrecognizedTaxPositions" xlink:href="pwr-20231231.xsd#pwr_DeferredTaxAssetsDeferredTaxBenefitsOnUnrecognizedTaxPositions"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DeferredTaxAssetsDeferredTaxBenefitsOnUnrecognizedTaxPositions" xlink:to="lab_pwr_DeferredTaxAssetsDeferredTaxBenefitsOnUnrecognizedTaxPositions" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PerformanceGuaranteeMember_aa1733be-d109-4b84-a71c-bde9c9c825c3_terseLabel_en-US" xlink:label="lab_us-gaap_PerformanceGuaranteeMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Performance Guarantee </link:label>

<link:label id="lab_us-gaap_PerformanceGuaranteeMember_label_en-US" xlink:label="lab_us-gaap_PerformanceGuaranteeMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Performance Guarantee [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceGuaranteeMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PerformanceGuaranteeMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PerformanceGuaranteeMember" xlink:to="lab_us-gaap_PerformanceGuaranteeMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ExcessOfEuroCurrencyRateOfCreditAgreementForForeignBorrowingsMember_512fe26f-a73e-4240-b6e5-bbb687021286_terseLabel_en-US" xlink:label="lab_pwr_ExcessOfEuroCurrencyRateOfCreditAgreementForForeignBorrowingsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess of Euro Currency Rate of Credit Agreement for Foreign Borrowings </link:label>

<link:label id="lab_pwr_ExcessOfEuroCurrencyRateOfCreditAgreementForForeignBorrowingsMember_label_en-US" xlink:label="lab_pwr_ExcessOfEuroCurrencyRateOfCreditAgreementForForeignBorrowingsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess Of Euro Currency Rate Of Credit Agreement For Foreign Borrowings [Member] </link:label>

<link:label id="lab_pwr_ExcessOfEuroCurrencyRateOfCreditAgreementForForeignBorrowingsMember_documentation_en-US" xlink:label="lab_pwr_ExcessOfEuroCurrencyRateOfCreditAgreementForForeignBorrowingsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess Of Euro Currency Rate Of Credit Agreement For Foreign Borrowings [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ExcessOfEuroCurrencyRateOfCreditAgreementForForeignBorrowingsMember" xlink:href="pwr-20231231.xsd#pwr_ExcessOfEuroCurrencyRateOfCreditAgreementForForeignBorrowingsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ExcessOfEuroCurrencyRateOfCreditAgreementForForeignBorrowingsMember" xlink:to="lab_pwr_ExcessOfEuroCurrencyRateOfCreditAgreementForForeignBorrowingsMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_SecondaryPoolMember_ba56736b-966c-40dc-adcd-680dfeb1bfdc_terseLabel_en-US" xlink:label="lab_pwr_SecondaryPoolMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Secondary Pool </link:label>

<link:label id="lab_pwr_SecondaryPoolMember_label_en-US" xlink:label="lab_pwr_SecondaryPoolMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Secondary Pool [Member] </link:label>

<link:label id="lab_pwr_SecondaryPoolMember_documentation_en-US" xlink:label="lab_pwr_SecondaryPoolMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Secondary Pool </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_SecondaryPoolMember" xlink:href="pwr-20231231.xsd#pwr_SecondaryPoolMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_SecondaryPoolMember" xlink:to="lab_pwr_SecondaryPoolMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredIncomeTaxLiabilitiesNet_da6c6a01-2097-4089-8cb0-5332e1213957_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred income taxes </link:label>

<link:label id="lab_us-gaap_DeferredIncomeTaxLiabilitiesNet_a13490a7-5475-48d6-a144-0cf292e2baaf_negatedLabel_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities </link:label>

<link:label id="lab_us-gaap_DeferredIncomeTaxLiabilitiesNet_label_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Income Tax Liabilities, Net </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:to="lab_us-gaap_DeferredIncomeTaxLiabilitiesNet" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_BuildingsAndLeaseholdImprovementsMember_1ca7b6e6-2c02-4d7b-a958-476613d52fd1_terseLabel_en-US" xlink:label="lab_pwr_BuildingsAndLeaseholdImprovementsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Buildings and leasehold improvements </link:label>

<link:label id="lab_pwr_BuildingsAndLeaseholdImprovementsMember_label_en-US" xlink:label="lab_pwr_BuildingsAndLeaseholdImprovementsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Buildings And Leasehold Improvements [Member] </link:label>

<link:label id="lab_pwr_BuildingsAndLeaseholdImprovementsMember_documentation_en-US" xlink:label="lab_pwr_BuildingsAndLeaseholdImprovementsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Buildings and leasehold improvements. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_BuildingsAndLeaseholdImprovementsMember" xlink:href="pwr-20231231.xsd#pwr_BuildingsAndLeaseholdImprovementsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_BuildingsAndLeaseholdImprovementsMember" xlink:to="lab_pwr_BuildingsAndLeaseholdImprovementsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_09c4a208-3160-4fc8-98f4-57147fcb0627_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts payable and accrued liabilities </link:label>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember_0f8140f1-5eb9-4215-8746-476eef0a645c_terseLabel_en-US" xlink:label="lab_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid Expenses and Other Current Assets </link:label>

<link:label id="lab_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember_label_en-US" xlink:label="lab_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid Expenses and Other Current Assets [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember" xlink:to="lab_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax_f4bf112b-b201-4560-9688-e0a5d3460e6f_terseLabel_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign currency translation adjustment, tax </link:label>

<link:label id="lab_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax_label_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax" xlink:to="lab_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentTax" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PaymentsToAcquireInvestments_2084496d-b1d9-478c-8a68-4db19b9dcd63_negatedLabel_en-US" xlink:label="lab_us-gaap_PaymentsToAcquireInvestments" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investments in unconsolidated affiliates and other </link:label>

<link:label id="lab_us-gaap_PaymentsToAcquireInvestments_label_en-US" xlink:label="lab_us-gaap_PaymentsToAcquireInvestments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments to Acquire Investments </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireInvestments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireInvestments"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsToAcquireInvestments" xlink:to="lab_us-gaap_PaymentsToAcquireInvestments" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_EmployersLiabilityWorkersCompensationAutoLiabilityGeneralLiabilityAndGroupHealthCareClaimsMember_94ad99b5-b1bf-40d1-91c4-272b6499568f_terseLabel_en-US" xlink:label="lab_pwr_EmployersLiabilityWorkersCompensationAutoLiabilityGeneralLiabilityAndGroupHealthCareClaimsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employer's Liability, Workers' Compensation, Auto Liability, General Liability and Group Health Care Claims </link:label>

<link:label id="lab_pwr_EmployersLiabilityWorkersCompensationAutoLiabilityGeneralLiabilityAndGroupHealthCareClaimsMember_label_en-US" xlink:label="lab_pwr_EmployersLiabilityWorkersCompensationAutoLiabilityGeneralLiabilityAndGroupHealthCareClaimsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employer's Liability, Workers' Compensation, Auto Liability, General Liability And Group Health Care Claims [Member] </link:label>

<link:label id="lab_pwr_EmployersLiabilityWorkersCompensationAutoLiabilityGeneralLiabilityAndGroupHealthCareClaimsMember_documentation_en-US" xlink:label="lab_pwr_EmployersLiabilityWorkersCompensationAutoLiabilityGeneralLiabilityAndGroupHealthCareClaimsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employer's Liability, Workers' Compensation, Auto Liability, General Liability And Group Health Care Claims [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_EmployersLiabilityWorkersCompensationAutoLiabilityGeneralLiabilityAndGroupHealthCareClaimsMember" xlink:href="pwr-20231231.xsd#pwr_EmployersLiabilityWorkersCompensationAutoLiabilityGeneralLiabilityAndGroupHealthCareClaimsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_EmployersLiabilityWorkersCompensationAutoLiabilityGeneralLiabilityAndGroupHealthCareClaimsMember" xlink:to="lab_pwr_EmployersLiabilityWorkersCompensationAutoLiabilityGeneralLiabilityAndGroupHealthCareClaimsMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_BusinessCombinationAmortization_8601f498-9d3d-4d82-aa26-3f898de29782_terseLabel_en-US" xlink:label="lab_pwr_BusinessCombinationAmortization" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amortization expense </link:label>

<link:label id="lab_pwr_BusinessCombinationAmortization_label_en-US" xlink:label="lab_pwr_BusinessCombinationAmortization" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Amortization </link:label>

<link:label id="lab_pwr_BusinessCombinationAmortization_documentation_en-US" xlink:label="lab_pwr_BusinessCombinationAmortization" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Amortization </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_BusinessCombinationAmortization" xlink:href="pwr-20231231.xsd#pwr_BusinessCombinationAmortization"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_BusinessCombinationAmortization" xlink:to="lab_pwr_BusinessCombinationAmortization" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_InsiderTradingPoliciesProcLineItems_label_en-US" xlink:label="lab_ecd_InsiderTradingPoliciesProcLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insider Trading Policies and Procedures [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_InsiderTradingPoliciesProcLineItems" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_InsiderTradingPoliciesProcLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_InsiderTradingPoliciesProcLineItems" xlink:to="lab_ecd_InsiderTradingPoliciesProcLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_Rule10b51ArrTrmntdFlag_terseLabel_en-US" xlink:label="lab_ecd_Rule10b51ArrTrmntdFlag" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Rule 10b5-1 Arrangement Terminated </link:label>

<link:label id="lab_ecd_Rule10b51ArrTrmntdFlag_label_en-US" xlink:label="lab_ecd_Rule10b51ArrTrmntdFlag" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Rule 10b5-1 Arrangement Terminated [Flag] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_Rule10b51ArrTrmntdFlag" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_Rule10b51ArrTrmntdFlag"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_Rule10b51ArrTrmntdFlag" xlink:to="lab_ecd_Rule10b51ArrTrmntdFlag" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DisaggregationOfRevenueLineItems_70ab8b12-51a0-4190-bdf4-d212a1789bd2_terseLabel_en-US" xlink:label="lab_us-gaap_DisaggregationOfRevenueLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Disaggregation of Revenue [Line Items] </link:label>

<link:label id="lab_us-gaap_DisaggregationOfRevenueLineItems_label_en-US" xlink:label="lab_us-gaap_DisaggregationOfRevenueLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Disaggregation of Revenue [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems" xlink:to="lab_us-gaap_DisaggregationOfRevenueLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_07ed4af8-f48b-4952-b6f9-f6647722caaf_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2028 </link:label>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, to be Paid, Year Five </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_RestatementDoesNotRequireRecoveryTextBlock_terseLabel_en-US" xlink:label="lab_ecd_RestatementDoesNotRequireRecoveryTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restatement does not require Recovery </link:label>

<link:label id="lab_ecd_RestatementDoesNotRequireRecoveryTextBlock_label_en-US" xlink:label="lab_ecd_RestatementDoesNotRequireRecoveryTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restatement Does Not Require Recovery [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_RestatementDoesNotRequireRecoveryTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_RestatementDoesNotRequireRecoveryTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_RestatementDoesNotRequireRecoveryTextBlock" xlink:to="lab_ecd_RestatementDoesNotRequireRecoveryTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock_c47cb91f-c47b-40c3-a879-38cad993f60b_terseLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity </link:label>

<link:label id="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityNoteDisclosureTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:to="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LesseeOperatingAndFinanceLeaseAssetsAndLiabilitiesTableTextBlock_41a13c9c-8152-4093-a63f-bd0a23d38dd1_terseLabel_en-US" xlink:label="lab_pwr_LesseeOperatingAndFinanceLeaseAssetsAndLiabilitiesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Components of Leases in the Balance Sheet </link:label>

<link:label id="lab_pwr_LesseeOperatingAndFinanceLeaseAssetsAndLiabilitiesTableTextBlock_label_en-US" xlink:label="lab_pwr_LesseeOperatingAndFinanceLeaseAssetsAndLiabilitiesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating And Finance Lease Assets And Liabilities [Table Text Block] </link:label>

<link:label id="lab_pwr_LesseeOperatingAndFinanceLeaseAssetsAndLiabilitiesTableTextBlock_documentation_en-US" xlink:label="lab_pwr_LesseeOperatingAndFinanceLeaseAssetsAndLiabilitiesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating And Finance Lease Assets And Liabilities [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LesseeOperatingAndFinanceLeaseAssetsAndLiabilitiesTableTextBlock" xlink:href="pwr-20231231.xsd#pwr_LesseeOperatingAndFinanceLeaseAssetsAndLiabilitiesTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LesseeOperatingAndFinanceLeaseAssetsAndLiabilitiesTableTextBlock" xlink:to="lab_pwr_LesseeOperatingAndFinanceLeaseAssetsAndLiabilitiesTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LineOfCreditFacilityLineItems_1d36283b-eb60-49e2-b8e7-11d6289ec3c2_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility [Line Items] </link:label>

<link:label id="lab_us-gaap_LineOfCreditFacilityLineItems_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems" xlink:to="lab_us-gaap_LineOfCreditFacilityLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShortTermLeaseCommitmentAmount_09b4d8da-96b1-4317-ad10-19b363464a82_terseLabel_en-US" xlink:label="lab_us-gaap_ShortTermLeaseCommitmentAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Future minimum lease payments for short-term leases </link:label>

<link:label id="lab_us-gaap_ShortTermLeaseCommitmentAmount_label_en-US" xlink:label="lab_us-gaap_ShortTermLeaseCommitmentAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Short-Term Lease Commitment, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermLeaseCommitmentAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermLeaseCommitmentAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShortTermLeaseCommitmentAmount" xlink:to="lab_us-gaap_ShortTermLeaseCommitmentAmount" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2023And2024Member_ac716e17-1442-4180-ad73-958907c8e573_terseLabel_en-US" xlink:label="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2023And2024Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments Due First Business Day Of Quarter In 2023 And 2024 </link:label>

<link:label id="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2023And2024Member_label_en-US" xlink:label="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2023And2024Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments Due First Business Day Of Quarter In 2023 And 2024 [Member] </link:label>

<link:label id="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2023And2024Member_documentation_en-US" xlink:label="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2023And2024Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments Due First Business Day Of Quarter In 2023 And 2024 </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2023And2024Member" xlink:href="pwr-20231231.xsd#pwr_PaymentsDueFirstBusinessDayOfQuarterIn2023And2024Member"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2023And2024Member" xlink:to="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2023And2024Member" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_VariableInterestEntityLineItems_b31aa5c4-2d1b-4cf4-8580-1e9dd3a30b89_terseLabel_en-US" xlink:label="lab_us-gaap_VariableInterestEntityLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Variable Interest Entity [Line Items] </link:label>

<link:label id="lab_us-gaap_VariableInterestEntityLineItems_label_en-US" xlink:label="lab_us-gaap_VariableInterestEntityLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Variable Interest Entity [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableInterestEntityLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableInterestEntityLineItems" xlink:to="lab_us-gaap_VariableInterestEntityLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_currency_CAD_68a7cd40-5b16-40d0-8515-94a714ddf90c_terseLabel_en-US" xlink:label="lab_currency_CAD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Canadian Dollars </link:label>

<link:label id="lab_currency_CAD_label_en-US" xlink:label="lab_currency_CAD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Canada, Dollars </link:label>

<link:loc xlink:type="locator" xlink:label="loc_currency_CAD" xlink:href="https://xbrl.sec.gov/currency/2023/currency-2023.xsd#currency_CAD"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_currency_CAD" xlink:to="lab_currency_CAD" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ProjectMember_05f7abc9-607a-46ba-95d4-c511e2a08492_terseLabel_en-US" xlink:label="lab_us-gaap_ProjectMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Project [Domain] </link:label>

<link:label id="lab_us-gaap_ProjectMember_label_en-US" xlink:label="lab_us-gaap_ProjectMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Project [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProjectMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProjectMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProjectMember" xlink:to="lab_us-gaap_ProjectMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidAfterYearFive_89631c6c-b6a6-4e43-ae7d-f4a265d363dd_totalLabel_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidAfterYearFive" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Thereafter </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidAfterYearFive_label_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidAfterYearFive" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, To Be Paid After Year Five </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidAfterYearFive_documentation_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidAfterYearFive" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, To Be Paid After Year Five </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingAndFinanceLeaseLiabilityToBePaidAfterYearFive" xlink:href="pwr-20231231.xsd#pwr_OperatingAndFinanceLeaseLiabilityToBePaidAfterYearFive"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingAndFinanceLeaseLiabilityToBePaidAfterYearFive" xlink:to="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidAfterYearFive" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_016a6d5d-75a6-4bc0-97a1-56bef85cd162_terseLabel_en-US" xlink:label="lab_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-term Purchase Commitment, Category of Item Purchased [Domain] </link:label>

<link:label id="lab_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_label_en-US" xlink:label="lab_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Purchase Commitment, Category of Item Purchased [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain" xlink:to="lab_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain" xlink:type="arc" order="1"/>

<link:label id="lab_srt_MajorCustomersAxis_affc9b3d-9577-4b29-be8b-c313b6c87a21_terseLabel_en-US" xlink:label="lab_srt_MajorCustomersAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer [Axis] </link:label>

<link:label id="lab_srt_MajorCustomersAxis_label_en-US" xlink:label="lab_srt_MajorCustomersAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MajorCustomersAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_MajorCustomersAxis" xlink:to="lab_srt_MajorCustomersAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LiabilitiesCurrentAbstract_add425a4-e01d-4190-aedf-7cbd6868c4b4_terseLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesCurrentAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current Liabilities: </link:label>

<link:label id="lab_us-gaap_LiabilitiesCurrentAbstract_label_en-US" xlink:label="lab_us-gaap_LiabilitiesCurrentAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities, Current [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrentAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:to="lab_us-gaap_LiabilitiesCurrentAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_ebd3a160-8307-45ab-b1ff-6c080e649f53_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Federal </link:label>

<link:label id="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_label_en-US" xlink:label="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Federal Income Tax Expense (Benefit) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredFederalIncomeTaxExpenseBenefit"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:to="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_5d8785ea-cd6e-4562-9df5-7886a1acb157_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill, impaired, accumulated impairment loss </link:label>

<link:label id="lab_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_label_en-US" xlink:label="lab_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill, Impaired, Accumulated Impairment Loss </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xlink:to="lab_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SubsequentEventTypeDomain_f46e666d-2278-48fb-acfc-5fce9fa8fc4c_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventTypeDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event Type [Domain] </link:label>

<link:label id="lab_us-gaap_SubsequentEventTypeDomain_label_en-US" xlink:label="lab_us-gaap_SubsequentEventTypeDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event Type [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventTypeDomain" xlink:to="lab_us-gaap_SubsequentEventTypeDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DividendsCash_49f1ed33-9590-4745-91c6-8647e45a9953_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_DividendsCash" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Dividend declared </link:label>

<link:label id="lab_us-gaap_DividendsCash_label_en-US" xlink:label="lab_us-gaap_DividendsCash" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Dividends, Cash </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCash" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsCash"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DividendsCash" xlink:to="lab_us-gaap_DividendsCash" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimatePercent_1216c030-f5eb-468f-99be-a7d1c908dda8_terseLabel_en-US" xlink:label="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimatePercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Change in contract estimates, (favorable) unfavorable impact on operating results, percent </link:label>

<link:label id="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimatePercent_label_en-US" xlink:label="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimatePercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Cumulative Catch-Up Adjustment, To Gross Profit, Change In Estimate, Percent </link:label>

<link:label id="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimatePercent_documentation_en-US" xlink:label="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimatePercent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Cumulative Catch-Up Adjustment, To Gross Profit, Change In Estimate, Percent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimatePercent" xlink:href="pwr-20231231.xsd#pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimatePercent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimatePercent" xlink:to="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimatePercent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PaymentsOfDividendsCommonStock_f359f71e-42ae-457e-b452-c399af6cc8b4_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_PaymentsOfDividendsCommonStock" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments of dividends </link:label>

<link:label id="lab_us-gaap_PaymentsOfDividendsCommonStock_label_en-US" xlink:label="lab_us-gaap_PaymentsOfDividendsCommonStock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments of Ordinary Dividends, Common Stock </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividendsCommonStock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsOfDividendsCommonStock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsOfDividendsCommonStock" xlink:to="lab_us-gaap_PaymentsOfDividendsCommonStock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EarningsPerShareDiluted_317b69f1-69d1-4693-9564-c482e59c9d49_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareDiluted" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Diluted (in dollars per share) </link:label>

<link:label id="lab_us-gaap_EarningsPerShareDiluted_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareDiluted" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Earnings Per Share, Diluted </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareDiluted"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareDiluted" xlink:to="lab_us-gaap_EarningsPerShareDiluted" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UnrealizedGainLossOnInvestments_36f91602-3316-4834-a6e2-58f7e2d3aef3_terseLabel_en-US" xlink:label="lab_us-gaap_UnrealizedGainLossOnInvestments" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrealized gain (loss) on investments </link:label>

<link:label id="lab_us-gaap_UnrealizedGainLossOnInvestments_label_en-US" xlink:label="lab_us-gaap_UnrealizedGainLossOnInvestments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrealized Gain (Loss) on Investments </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnInvestments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrealizedGainLossOnInvestments"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrealizedGainLossOnInvestments" xlink:to="lab_us-gaap_UnrealizedGainLossOnInvestments" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AccountsReceivableNetCurrent_93c40f89-9481-4a28-a794-67e7e90b59a1_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsReceivableNetCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts receivable, net </link:label>

<link:label id="lab_us-gaap_AccountsReceivableNetCurrent_label_en-US" xlink:label="lab_us-gaap_AccountsReceivableNetCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable, after Allowance for Credit Loss, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivableNetCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsReceivableNetCurrent" xlink:to="lab_us-gaap_AccountsReceivableNetCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SupplementalCashFlowElementsAbstract_820fecee-204b-48ca-bdd3-71e1716cf4b6_terseLabel_en-US" xlink:label="lab_us-gaap_SupplementalCashFlowElementsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Supplemental Cash Flow Elements [Abstract] </link:label>

<link:label id="lab_us-gaap_SupplementalCashFlowElementsAbstract_label_en-US" xlink:label="lab_us-gaap_SupplementalCashFlowElementsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Supplemental Cash Flow Elements [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalCashFlowElementsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SupplementalCashFlowElementsAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SupplementalCashFlowElementsAbstract" xlink:to="lab_us-gaap_SupplementalCashFlowElementsAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CommittedCapitalPrimarilyFleetMember_74e26522-5b1d-4439-9964-9163eaf9e941_verboseLabel_en-US" xlink:label="lab_pwr_CommittedCapitalPrimarilyFleetMember" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Committed Capital Primarily Fleet </link:label>

<link:label id="lab_pwr_CommittedCapitalPrimarilyFleetMember_label_en-US" xlink:label="lab_pwr_CommittedCapitalPrimarilyFleetMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Committed Capital Primarily Fleet [Member] </link:label>

<link:label id="lab_pwr_CommittedCapitalPrimarilyFleetMember_documentation_en-US" xlink:label="lab_pwr_CommittedCapitalPrimarilyFleetMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Committed Capital Primarily Fleet </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CommittedCapitalPrimarilyFleetMember" xlink:href="pwr-20231231.xsd#pwr_CommittedCapitalPrimarilyFleetMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CommittedCapitalPrimarilyFleetMember" xlink:to="lab_pwr_CommittedCapitalPrimarilyFleetMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LineOfCreditMember_d4c901cc-7372-4735-898a-120544929a67_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit </link:label>

<link:label id="lab_us-gaap_LineOfCreditMember_label_en-US" xlink:label="lab_us-gaap_LineOfCreditMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditMember" xlink:to="lab_us-gaap_LineOfCreditMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_GoodwillAndIntangibleAssetsLineItems_b5f07d34-e34f-45ee-b85f-24ad25e2d693_terseLabel_en-US" xlink:label="lab_pwr_GoodwillAndIntangibleAssetsLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill And Intangible Assets [Line Items] </link:label>

<link:label id="lab_pwr_GoodwillAndIntangibleAssetsLineItems_label_en-US" xlink:label="lab_pwr_GoodwillAndIntangibleAssetsLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill And Intangible Assets [Line Items] </link:label>

<link:label id="lab_pwr_GoodwillAndIntangibleAssetsLineItems_documentation_en-US" xlink:label="lab_pwr_GoodwillAndIntangibleAssetsLineItems" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill and intangible assets. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_GoodwillAndIntangibleAssetsLineItems" xlink:href="pwr-20231231.xsd#pwr_GoodwillAndIntangibleAssetsLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_GoodwillAndIntangibleAssetsLineItems" xlink:to="lab_pwr_GoodwillAndIntangibleAssetsLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OfficeEquipmentFurnitureAndFixturesAndInformationTechnologySystemsMember_0ee08015-ce34-4373-8664-48171aaccaa1_terseLabel_en-US" xlink:label="lab_pwr_OfficeEquipmentFurnitureAndFixturesAndInformationTechnologySystemsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Office equipment, furniture and fixtures and information technology systems </link:label>

<link:label id="lab_pwr_OfficeEquipmentFurnitureAndFixturesAndInformationTechnologySystemsMember_label_en-US" xlink:label="lab_pwr_OfficeEquipmentFurnitureAndFixturesAndInformationTechnologySystemsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Office Equipment Furniture And Fixtures And Information Technology Systems [Member] </link:label>

<link:label id="lab_pwr_OfficeEquipmentFurnitureAndFixturesAndInformationTechnologySystemsMember_documentation_en-US" xlink:label="lab_pwr_OfficeEquipmentFurnitureAndFixturesAndInformationTechnologySystemsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Office equipment, furniture and fixtures and information technology systems. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OfficeEquipmentFurnitureAndFixturesAndInformationTechnologySystemsMember" xlink:href="pwr-20231231.xsd#pwr_OfficeEquipmentFurnitureAndFixturesAndInformationTechnologySystemsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OfficeEquipmentFurnitureAndFixturesAndInformationTechnologySystemsMember" xlink:to="lab_pwr_OfficeEquipmentFurnitureAndFixturesAndInformationTechnologySystemsMember" xlink:type="arc" order="1"/>

<link:label id="lab_srt_LitigationCaseAxis_f56ed36d-bebf-48c5-afa2-7510cfd3d5ad_terseLabel_en-US" xlink:label="lab_srt_LitigationCaseAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Litigation Case [Axis] </link:label>

<link:label id="lab_srt_LitigationCaseAxis_label_en-US" xlink:label="lab_srt_LitigationCaseAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Litigation Case [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_LitigationCaseAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_LitigationCaseAxis" xlink:to="lab_srt_LitigationCaseAxis" xlink:type="arc" order="1"/>

<link:label id="lab_dei_TradingSymbol_0ef87a84-e9b6-432e-9ec1-fac09e80402e_terseLabel_en-US" xlink:label="lab_dei_TradingSymbol" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trading Symbol </link:label>

<link:label id="lab_dei_TradingSymbol_label_en-US" xlink:label="lab_dei_TradingSymbol" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trading Symbol </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_TradingSymbol"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_TradingSymbol" xlink:to="lab_dei_TradingSymbol" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LettersOfCreditOutstandingAmount_46dc202e-9474-44bf-a812-aa1fb70d17b6_terseLabel_en-US" xlink:label="lab_us-gaap_LettersOfCreditOutstandingAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Letters of credit and bank guarantees under the credit facility </link:label>

<link:label id="lab_us-gaap_LettersOfCreditOutstandingAmount_0a34961d-c993-4298-9146-db6627c5adc9_verboseLabel_en-US" xlink:label="lab_us-gaap_LettersOfCreditOutstandingAmount" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Surety-backed letters of credit </link:label>

<link:label id="lab_us-gaap_LettersOfCreditOutstandingAmount_label_en-US" xlink:label="lab_us-gaap_LettersOfCreditOutstandingAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Letters of Credit Outstanding, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LettersOfCreditOutstandingAmount" xlink:to="lab_us-gaap_LettersOfCreditOutstandingAmount" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CashNotHeldByJointVenturesMember_62cd61b6-3de9-49f3-b6e6-7b4569fa45d7_terseLabel_en-US" xlink:label="lab_pwr_CashNotHeldByJointVenturesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Not Held by Joint Ventures </link:label>

<link:label id="lab_pwr_CashNotHeldByJointVenturesMember_label_en-US" xlink:label="lab_pwr_CashNotHeldByJointVenturesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash Not Held By Joint Ventures [Member] </link:label>

<link:label id="lab_pwr_CashNotHeldByJointVenturesMember_documentation_en-US" xlink:label="lab_pwr_CashNotHeldByJointVenturesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash Not Held By Joint Ventures [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CashNotHeldByJointVenturesMember" xlink:href="pwr-20231231.xsd#pwr_CashNotHeldByJointVenturesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CashNotHeldByJointVenturesMember" xlink:to="lab_pwr_CashNotHeldByJointVenturesMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingEngineersLocal324PensionFundMember_ec646110-aa1b-4dc6-8f07-1b695dba0fb3_terseLabel_en-US" xlink:label="lab_pwr_OperatingEngineersLocal324PensionFundMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Engineers Local 324 Pension Fund </link:label>

<link:label id="lab_pwr_OperatingEngineersLocal324PensionFundMember_label_en-US" xlink:label="lab_pwr_OperatingEngineersLocal324PensionFundMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Engineers Local 324 Pension Fund [Member] </link:label>

<link:label id="lab_pwr_OperatingEngineersLocal324PensionFundMember_documentation_en-US" xlink:label="lab_pwr_OperatingEngineersLocal324PensionFundMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Engineers Local 324 Pension Fund [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingEngineersLocal324PensionFundMember" xlink:href="pwr-20231231.xsd#pwr_OperatingEngineersLocal324PensionFundMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingEngineersLocal324PensionFundMember" xlink:to="lab_pwr_OperatingEngineersLocal324PensionFundMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NoncompeteAgreementsMember_86844f26-1538-4f3c-b2dd-aaa956f946e3_terseLabel_en-US" xlink:label="lab_us-gaap_NoncompeteAgreementsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-compete agreements </link:label>

<link:label id="lab_us-gaap_NoncompeteAgreementsMember_label_en-US" xlink:label="lab_us-gaap_NoncompeteAgreementsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Noncompete Agreements [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncompeteAgreementsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncompeteAgreementsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NoncompeteAgreementsMember" xlink:to="lab_us-gaap_NoncompeteAgreementsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_GuaranteeObligationsNatureDomain_3407b85d-605a-49f2-9233-3caa42eb05b2_terseLabel_en-US" xlink:label="lab_us-gaap_GuaranteeObligationsNatureDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Guarantor Obligations, Nature [Domain] </link:label>

<link:label id="lab_us-gaap_GuaranteeObligationsNatureDomain_label_en-US" xlink:label="lab_us-gaap_GuaranteeObligationsNatureDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Guarantor Obligations, Nature [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain" xlink:to="lab_us-gaap_GuaranteeObligationsNatureDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_611f69e7-e45a-40e7-a91c-79a47f83d03c_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Thereafter </link:label>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Asset, Expected Amortization, after Year Five </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_2d2a23a9-acb1-41d6-aa38-16704abdfff1_terseLabel_en-US" xlink:label="lab_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Indefinite-lived Intangible Assets, Major Class Name [Domain] </link:label>

<link:label id="lab_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_label_en-US" xlink:label="lab_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Indefinite-Lived Intangible Assets, Major Class Name [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="lab_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfCashAndCashEquivalentsTableTextBlock_112b4dfa-c2af-4344-b2d4-7b70b90c2851_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfCashAndCashEquivalentsTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and Cash Equivalents </link:label>

<link:label id="lab_us-gaap_ScheduleOfCashAndCashEquivalentsTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfCashAndCashEquivalentsTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Cash and Cash Equivalents [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfCashAndCashEquivalentsTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfCashAndCashEquivalentsTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IntangibleAssetsGrossExcludingGoodwill_d143e27b-c9bf-4009-bdbe-0554570091d0_totalLabel_en-US" xlink:label="lab_us-gaap_IntangibleAssetsGrossExcludingGoodwill" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Intangible Assets </link:label>

<link:label id="lab_us-gaap_IntangibleAssetsGrossExcludingGoodwill_label_en-US" xlink:label="lab_us-gaap_IntangibleAssetsGrossExcludingGoodwill" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Intangible Assets, Gross (Excluding Goodwill) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill" xlink:to="lab_us-gaap_IntangibleAssetsGrossExcludingGoodwill" xlink:type="arc" order="1"/>

<link:label id="lab_currency_AllCurrenciesDomain_3d1e6971-301e-4426-ae12-37df06226612_terseLabel_en-US" xlink:label="lab_currency_AllCurrenciesDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Currencies [Domain] </link:label>

<link:label id="lab_currency_AllCurrenciesDomain_label_en-US" xlink:label="lab_currency_AllCurrenciesDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Currencies [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_currency_AllCurrenciesDomain" xlink:href="https://xbrl.sec.gov/currency/2023/currency-2023.xsd#currency_AllCurrenciesDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_currency_AllCurrenciesDomain" xlink:to="lab_currency_AllCurrenciesDomain" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_BusinessAcquisitionsProFormaNetIncomeLossAttributableToCommonStockNetOfTax_74af403a-eba0-4aba-8cf6-71a943132d6c_terseLabel_en-US" xlink:label="lab_pwr_BusinessAcquisitionsProFormaNetIncomeLossAttributableToCommonStockNetOfTax" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net income attributable to common stock </link:label>

<link:label id="lab_pwr_BusinessAcquisitionsProFormaNetIncomeLossAttributableToCommonStockNetOfTax_label_en-US" xlink:label="lab_pwr_BusinessAcquisitionsProFormaNetIncomeLossAttributableToCommonStockNetOfTax" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisitions Pro Forma, Net Income (Loss) Attributable To Common Stock, Net Of Tax </link:label>

<link:label id="lab_pwr_BusinessAcquisitionsProFormaNetIncomeLossAttributableToCommonStockNetOfTax_documentation_en-US" xlink:label="lab_pwr_BusinessAcquisitionsProFormaNetIncomeLossAttributableToCommonStockNetOfTax" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisitions Pro Forma, Net Income (Loss) Attributable To Common Stock, Net Of Tax </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_BusinessAcquisitionsProFormaNetIncomeLossAttributableToCommonStockNetOfTax" xlink:href="pwr-20231231.xsd#pwr_BusinessAcquisitionsProFormaNetIncomeLossAttributableToCommonStockNetOfTax"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_BusinessAcquisitionsProFormaNetIncomeLossAttributableToCommonStockNetOfTax" xlink:to="lab_pwr_BusinessAcquisitionsProFormaNetIncomeLossAttributableToCommonStockNetOfTax" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_IncomeTaxesLineItems_b069c53f-dc2f-4df6-823e-e89b4ac92bef_terseLabel_en-US" xlink:label="lab_pwr_IncomeTaxesLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Taxes [Line Items] </link:label>

<link:label id="lab_pwr_IncomeTaxesLineItems_label_en-US" xlink:label="lab_pwr_IncomeTaxesLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Taxes [Line Items] </link:label>

<link:label id="lab_pwr_IncomeTaxesLineItems_documentation_en-US" xlink:label="lab_pwr_IncomeTaxesLineItems" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income taxes. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_IncomeTaxesLineItems" xlink:href="pwr-20231231.xsd#pwr_IncomeTaxesLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_IncomeTaxesLineItems" xlink:to="lab_pwr_IncomeTaxesLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfEquityMethodInvestmentsTable_4658cf67-cbeb-4e08-a71c-908f7d02b572_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfEquityMethodInvestmentsTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Equity Method Investments [Table] </link:label>

<link:label id="lab_us-gaap_ScheduleOfEquityMethodInvestmentsTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfEquityMethodInvestmentsTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Equity Method Investments [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsTable" xlink:to="lab_us-gaap_ScheduleOfEquityMethodInvestmentsTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_10605346-071f-4355-888b-74ff2a3c15fe_terseLabel_en-US" xlink:label="lab_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and Cash Equivalents [Domain] </link:label>

<link:label id="lab_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_label_en-US" xlink:label="lab_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and Cash Equivalents [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:to="lab_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StockholdersEquityAbstract_1fec770a-784a-4579-bed8-7fd6d1ebaa0b_terseLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquityAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity: </link:label>

<link:label id="lab_us-gaap_StockholdersEquityAbstract_label_en-US" xlink:label="lab_us-gaap_StockholdersEquityAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity, Attributable to Parent [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquityAbstract" xlink:to="lab_us-gaap_StockholdersEquityAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_e1750f16-c61a-4fa0-8d03-3e04c245fc6c_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Basic and Diluted Earnings Per Share Attributable to Common Stock </link:label>

<link:label id="lab_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RevenueFromContractWithCustomerSegmentBenchmarkMember_2abf7193-7ce1-4d79-bf33-14fd6e2a62c3_terseLabel_en-US" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerSegmentBenchmarkMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue from Contract with Customer, Segment Benchmark </link:label>

<link:label id="lab_us-gaap_RevenueFromContractWithCustomerSegmentBenchmarkMember_label_en-US" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerSegmentBenchmarkMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue from Contract with Customer, Segment Benchmark [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerSegmentBenchmarkMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerSegmentBenchmarkMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenueFromContractWithCustomerSegmentBenchmarkMember" xlink:to="lab_us-gaap_RevenueFromContractWithCustomerSegmentBenchmarkMember" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_ExecutiveCategoryAxis_terseLabel_en-US" xlink:label="lab_ecd_ExecutiveCategoryAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Executive Category: </link:label>

<link:label id="lab_ecd_ExecutiveCategoryAxis_label_en-US" xlink:label="lab_ecd_ExecutiveCategoryAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Executive Category [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_ExecutiveCategoryAxis" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_ExecutiveCategoryAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_ExecutiveCategoryAxis" xlink:to="lab_ecd_ExecutiveCategoryAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations_0cdb4e59-c4b1-4069-aa9d-3621fe32b3fc_terseLabel_en-US" xlink:label="lab_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash </link:label>

<link:label id="lab_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations_label_en-US" xlink:label="lab_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" xlink:to="lab_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_bd1e879c-7989-46c7-8a5d-4ebba16f68aa_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> RSUs </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DefinedContributionPlanEmployerMatchingContributionPercentofMatchByEmployerOfEachEmployeeWhoContributesToPlan_372ff4df-b5bc-483f-ab77-b858124fb30d_terseLabel_en-US" xlink:label="lab_pwr_DefinedContributionPlanEmployerMatchingContributionPercentofMatchByEmployerOfEachEmployeeWhoContributesToPlan" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Percentage of contribution by employer of each employee who contributes between 3% and 6% </link:label>

<link:label id="lab_pwr_DefinedContributionPlanEmployerMatchingContributionPercentofMatchByEmployerOfEachEmployeeWhoContributesToPlan_label_en-US" xlink:label="lab_pwr_DefinedContributionPlanEmployerMatchingContributionPercentofMatchByEmployerOfEachEmployeeWhoContributesToPlan" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Defined Contribution Plan, Employer Matching Contribution, Percent of Match By Employer Of Each Employee Who Contributes To Plan </link:label>

<link:label id="lab_pwr_DefinedContributionPlanEmployerMatchingContributionPercentofMatchByEmployerOfEachEmployeeWhoContributesToPlan_documentation_en-US" xlink:label="lab_pwr_DefinedContributionPlanEmployerMatchingContributionPercentofMatchByEmployerOfEachEmployeeWhoContributesToPlan" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Defined Contribution Plan, Employer Matching Contribution, Percent of Match By Employer Of Each Employee Who Contributes To Plan </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DefinedContributionPlanEmployerMatchingContributionPercentofMatchByEmployerOfEachEmployeeWhoContributesToPlan" xlink:href="pwr-20231231.xsd#pwr_DefinedContributionPlanEmployerMatchingContributionPercentofMatchByEmployerOfEachEmployeeWhoContributesToPlan"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DefinedContributionPlanEmployerMatchingContributionPercentofMatchByEmployerOfEachEmployeeWhoContributesToPlan" xlink:to="lab_pwr_DefinedContributionPlanEmployerMatchingContributionPercentofMatchByEmployerOfEachEmployeeWhoContributesToPlan" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SignificantAccountingPoliciesTextBlock_c084a311-9fd8-44bf-8608-8f05a4e3b6a6_terseLabel_en-US" xlink:label="lab_us-gaap_SignificantAccountingPoliciesTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Basis of Presentation and Accounting Policies </link:label>

<link:label id="lab_us-gaap_SignificantAccountingPoliciesTextBlock_label_en-US" xlink:label="lab_us-gaap_SignificantAccountingPoliciesTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Significant Accounting Policies [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SignificantAccountingPoliciesTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SignificantAccountingPoliciesTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SignificantAccountingPoliciesTextBlock" xlink:to="lab_us-gaap_SignificantAccountingPoliciesTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxAssetsNet_46386dcf-79e5-4898-a521-465605adcc40_totalLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsNet" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total deferred income tax assets </link:label>

<link:label id="lab_us-gaap_DeferredTaxAssetsNet_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Net of Valuation Allowance </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsNet"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsNet" xlink:to="lab_us-gaap_DeferredTaxAssetsNet" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LesseeLeasesOtherInformationTableTextBlock_de981862-bfe2-4b2a-b6f4-fc0c9234090b_terseLabel_en-US" xlink:label="lab_pwr_LesseeLeasesOtherInformationTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Information Related to Leases </link:label>

<link:label id="lab_pwr_LesseeLeasesOtherInformationTableTextBlock_label_en-US" xlink:label="lab_pwr_LesseeLeasesOtherInformationTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Leases, Other Information [Table Text Block] </link:label>

<link:label id="lab_pwr_LesseeLeasesOtherInformationTableTextBlock_documentation_en-US" xlink:label="lab_pwr_LesseeLeasesOtherInformationTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Leases, Other Information [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LesseeLeasesOtherInformationTableTextBlock" xlink:href="pwr-20231231.xsd#pwr_LesseeLeasesOtherInformationTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LesseeLeasesOtherInformationTableTextBlock" xlink:to="lab_pwr_LesseeLeasesOtherInformationTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_GuaranteeObligationsMaximumExposure_2369e83a-a8dd-4870-a2b2-8bc117097aca_verboseLabel_en-US" xlink:label="lab_us-gaap_GuaranteeObligationsMaximumExposure" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total amount of outstanding performance bonds </link:label>

<link:label id="lab_us-gaap_GuaranteeObligationsMaximumExposure_label_en-US" xlink:label="lab_us-gaap_GuaranteeObligationsMaximumExposure" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Guarantor Obligations, Maximum Exposure, Undiscounted </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsMaximumExposure" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsMaximumExposure"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GuaranteeObligationsMaximumExposure" xlink:to="lab_us-gaap_GuaranteeObligationsMaximumExposure" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OmnibusPlanMember_4e55d572-4135-4486-a4c1-089a381026ef_terseLabel_en-US" xlink:label="lab_pwr_OmnibusPlanMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Omnibus Plan </link:label>

<link:label id="lab_pwr_OmnibusPlanMember_label_en-US" xlink:label="lab_pwr_OmnibusPlanMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Omnibus Plan [Member] </link:label>

<link:label id="lab_pwr_OmnibusPlanMember_documentation_en-US" xlink:label="lab_pwr_OmnibusPlanMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Omnibus Plan </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OmnibusPlanMember" xlink:href="pwr-20231231.xsd#pwr_OmnibusPlanMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OmnibusPlanMember" xlink:to="lab_pwr_OmnibusPlanMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentTextBlock_cb24bcdd-f9fe-4704-a98f-44eec410507f_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and Equipment </link:label>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentTextBlock_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StatementEquityComponentsAxis_655b8cd0-6e8b-4e81-baa1-a251ca9e81b4_terseLabel_en-US" xlink:label="lab_us-gaap_StatementEquityComponentsAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Components [Axis] </link:label>

<link:label id="lab_us-gaap_StatementEquityComponentsAxis_label_en-US" xlink:label="lab_us-gaap_StatementEquityComponentsAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Components [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementEquityComponentsAxis" xlink:to="lab_us-gaap_StatementEquityComponentsAxis" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_Additional402vDisclosureTextBlock_terseLabel_en-US" xlink:label="lab_ecd_Additional402vDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Additional 402(v) Disclosure </link:label>

<link:label id="lab_ecd_Additional402vDisclosureTextBlock_label_en-US" xlink:label="lab_ecd_Additional402vDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Additional 402(v) Disclosure [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_Additional402vDisclosureTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_Additional402vDisclosureTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_Additional402vDisclosureTextBlock" xlink:to="lab_ecd_Additional402vDisclosureTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_973194c3-3757-4acb-a837-b88c18714855_terseLabel_en-US" xlink:label="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2025 </link:label>

<link:label id="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_label_en-US" xlink:label="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Debt, Maturity, Year Two </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo" xlink:to="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_d6ff8acb-cb34-4950-a052-0175232ebb63_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid expenses and other current assets </link:label>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTextBlock_71a1f440-d4da-49d1-8fd5-855b6d83bcf9_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Deferred Compensation Arrangement with Individual, Excluding Share-Based Payments and Postretirement Benefits by Title of Individual and Type of Deferred Compensation </link:label>

<link:label id="lab_us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Deferred Compensation Arrangement with Individual, Excluding Share-Based Payments and Postretirement Benefits by Title of Individual and Type of Deferred Compensation [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTextBlock" xlink:to="lab_us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntitySmallBusiness_b37104ed-4997-4e3c-bc56-37bf2b7ca702_terseLabel_en-US" xlink:label="lab_dei_EntitySmallBusiness" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Small Business </link:label>

<link:label id="lab_dei_EntitySmallBusiness_label_en-US" xlink:label="lab_dei_EntitySmallBusiness" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Small Business </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntitySmallBusiness"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntitySmallBusiness" xlink:to="lab_dei_EntitySmallBusiness" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_071f6034-cfcb-4e4c-8a66-721323b2cfc6_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2027 </link:label>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Asset, Expected Amortization, Year Four </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:type="arc" order="1"/>

<link:label id="lab_dei_LocalPhoneNumber_bd27dab3-e303-4a84-ab61-e3fda4a18ffa_terseLabel_en-US" xlink:label="lab_dei_LocalPhoneNumber" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Local Phone Number </link:label>

<link:label id="lab_dei_LocalPhoneNumber_label_en-US" xlink:label="lab_dei_LocalPhoneNumber" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Local Phone Number </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LocalPhoneNumber"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_LocalPhoneNumber" xlink:to="lab_dei_LocalPhoneNumber" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_RecoveryOfErrCompDisclosureLineItems_label_en-US" xlink:label="lab_ecd_RecoveryOfErrCompDisclosureLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Recovery of Erroneously Awarded Compensation Disclosure [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_RecoveryOfErrCompDisclosureLineItems" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_RecoveryOfErrCompDisclosureLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_RecoveryOfErrCompDisclosureLineItems" xlink:to="lab_ecd_RecoveryOfErrCompDisclosureLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_a6b25cd3-c9b4-42f4-b30f-77ccc7bf65e9_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2028 </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, to be Paid, Year Five </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LetterOfCreditMember_0955b013-3914-428b-8d4b-7d5cfea746ed_terseLabel_en-US" xlink:label="lab_us-gaap_LetterOfCreditMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Letters of Credit </link:label>

<link:label id="lab_us-gaap_LetterOfCreditMember_label_en-US" xlink:label="lab_us-gaap_LetterOfCreditMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Letter of Credit [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LetterOfCreditMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LetterOfCreditMember" xlink:to="lab_us-gaap_LetterOfCreditMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable_55b65bd5-37e8-4f86-9837-2569006ef434_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Finite-Lived Intangible Assets [Table] </link:label>

<link:label id="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Business Acquisitions by Acquisition, Contingent Consideration [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable" xlink:to="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxAssetDomain_124f4f92-c0a1-456c-8f42-f9b081f1d9c7_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Asset [Domain] </link:label>

<link:label id="lab_us-gaap_DeferredTaxAssetDomain_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Asset [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetDomain" xlink:to="lab_us-gaap_DeferredTaxAssetDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AccountsReceivableMember_c4c82c5b-f1da-40a2-ab52-5c08060a53a5_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsReceivableMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable </link:label>

<link:label id="lab_us-gaap_AccountsReceivableMember_label_en-US" xlink:label="lab_us-gaap_AccountsReceivableMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivableMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsReceivableMember" xlink:to="lab_us-gaap_AccountsReceivableMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractLiabilities_108fec5f-c1b2-4150-8555-6ad6c95b434f_negatedTerseLabel_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractLiabilities" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract liabilities </link:label>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractLiabilities_label_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractLiabilities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Contract Liabilities </link:label>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractLiabilities_documentation_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractLiabilities" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Contract Liabilities </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractLiabilities" xlink:href="pwr-20231231.xsd#pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractLiabilities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractLiabilities" xlink:to="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractLiabilities" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_ForgoneRecoveryDueToViolationOfHomeCountryLawAmt_terseLabel_en-US" xlink:label="lab_ecd_ForgoneRecoveryDueToViolationOfHomeCountryLawAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Forgone Recovery due to Violation of Home Country Law, Amount </link:label>

<link:label id="lab_ecd_ForgoneRecoveryDueToViolationOfHomeCountryLawAmt_label_en-US" xlink:label="lab_ecd_ForgoneRecoveryDueToViolationOfHomeCountryLawAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Forgone Recovery due to Violation of Home Country Law, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_ForgoneRecoveryDueToViolationOfHomeCountryLawAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_ForgoneRecoveryDueToViolationOfHomeCountryLawAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_ForgoneRecoveryDueToViolationOfHomeCountryLawAmt" xlink:to="lab_ecd_ForgoneRecoveryDueToViolationOfHomeCountryLawAmt" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_EighthDistrictElectricalPensionFundMember_6fb449f3-279e-4fc0-a94e-88be3a00138c_terseLabel_en-US" xlink:label="lab_pwr_EighthDistrictElectricalPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Eighth District Electrical Pension Fund </link:label>

<link:label id="lab_pwr_EighthDistrictElectricalPensionFundMember_label_en-US" xlink:label="lab_pwr_EighthDistrictElectricalPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Eighth District Electrical Pension Fund [Member] </link:label>

<link:label id="lab_pwr_EighthDistrictElectricalPensionFundMember_documentation_en-US" xlink:label="lab_pwr_EighthDistrictElectricalPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Eighth District Electrical Pension Fund [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_EighthDistrictElectricalPensionFundMember" xlink:href="pwr-20231231.xsd#pwr_EighthDistrictElectricalPensionFundMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_EighthDistrictElectricalPensionFundMember" xlink:to="lab_pwr_EighthDistrictElectricalPensionFundMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_Depreciation_e9af0058-55ec-419b-926a-3e1d8cd41310_terseLabel_en-US" xlink:label="lab_us-gaap_Depreciation" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Depreciation </link:label>

<link:label id="lab_us-gaap_Depreciation_label_en-US" xlink:label="lab_us-gaap_Depreciation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Depreciation </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Depreciation"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Depreciation" xlink:to="lab_us-gaap_Depreciation" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_fad6091c-e81e-4e43-bed3-307d55bce72a_terseLabel_en-US" xlink:label="lab_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] </link:label>

<link:label id="lab_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems_label_en-US" xlink:label="lab_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems" xlink:to="lab_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CompensationAndRetirementDisclosureAbstract_ac9e7413-29cc-4f7f-9a53-603785f3e232_terseLabel_en-US" xlink:label="lab_us-gaap_CompensationAndRetirementDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Retirement Benefits [Abstract] </link:label>

<link:label id="lab_us-gaap_CompensationAndRetirementDisclosureAbstract_label_en-US" xlink:label="lab_us-gaap_CompensationAndRetirementDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Retirement Benefits [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CompensationAndRetirementDisclosureAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CompensationAndRetirementDisclosureAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CompensationAndRetirementDisclosureAbstract" xlink:to="lab_us-gaap_CompensationAndRetirementDisclosureAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AccountsReceivableBilledForLongTermContractsOrPrograms_94f4415a-abfb-4ff8-b42d-fb6e989b76ac_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsReceivableBilledForLongTermContractsOrPrograms" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net receivable position on projects </link:label>

<link:label id="lab_us-gaap_AccountsReceivableBilledForLongTermContractsOrPrograms_label_en-US" xlink:label="lab_us-gaap_AccountsReceivableBilledForLongTermContractsOrPrograms" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Construction Contractor, Receivable, Excluding Contract Retainage </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableBilledForLongTermContractsOrPrograms" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivableBilledForLongTermContractsOrPrograms"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsReceivableBilledForLongTermContractsOrPrograms" xlink:to="lab_us-gaap_AccountsReceivableBilledForLongTermContractsOrPrograms" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LineOfCreditFacilityTable_f5797332-0f3d-40b2-89c4-44e115e5108a_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility [Table] </link:label>

<link:label id="lab_us-gaap_LineOfCreditFacilityTable_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityTable" xlink:to="lab_us-gaap_LineOfCreditFacilityTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfDebtInstrumentsTextBlock_01a41fdc-094d-44f4-9f48-5bae186a7a1f_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfDebtInstrumentsTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Long-term Debt Instruments </link:label>

<link:label id="lab_us-gaap_ScheduleOfDebtInstrumentsTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfDebtInstrumentsTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Long-Term Debt Instruments [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDebtInstrumentsTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDebtInstrumentsTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfDebtInstrumentsTextBlock" xlink:to="lab_us-gaap_ScheduleOfDebtInstrumentsTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ArrangementsAndNonarrangementTransactionsMember_7a4bd996-7467-47fc-b717-af3373d1014b_terseLabel_en-US" xlink:label="lab_us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Collaborative Arrangement and Arrangement Other than Collaborative [Domain] </link:label>

<link:label id="lab_us-gaap_ArrangementsAndNonarrangementTransactionsMember_label_en-US" xlink:label="lab_us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Collaborative Arrangement and Arrangement Other than Collaborative [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="lab_us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_RevenueRecognitionTable_06b69062-78e1-43d2-ba4d-b21311952fdf_terseLabel_en-US" xlink:label="lab_pwr_RevenueRecognitionTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue Recognition [Table] </link:label>

<link:label id="lab_pwr_RevenueRecognitionTable_label_en-US" xlink:label="lab_pwr_RevenueRecognitionTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue Recognition [Table] </link:label>

<link:label id="lab_pwr_RevenueRecognitionTable_documentation_en-US" xlink:label="lab_pwr_RevenueRecognitionTable" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue Recognition [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_RevenueRecognitionTable" xlink:href="pwr-20231231.xsd#pwr_RevenueRecognitionTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_RevenueRecognitionTable" xlink:to="lab_pwr_RevenueRecognitionTable" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearThree_63ee998e-9573-4c7a-9d4a-2915159d2f14_totalLabel_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearThree" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2026 </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearThree_label_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearThree" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, To Be Paid, Year Three </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearThree_documentation_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearThree" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, To Be Paid, Year Three </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearThree" xlink:href="pwr-20231231.xsd#pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearThree"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearThree" xlink:to="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearThree" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_GainLossOnSaleOfInvestments_e347bce8-0545-4a15-aeae-de3b28ee0c6f_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_GainLossOnSaleOfInvestments" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Gains on sales of investments </link:label>

<link:label id="lab_us-gaap_GainLossOnSaleOfInvestments_label_en-US" xlink:label="lab_us-gaap_GainLossOnSaleOfInvestments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Gain (Loss) on Sale of Investments </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfInvestments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSaleOfInvestments"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GainLossOnSaleOfInvestments" xlink:to="lab_us-gaap_GainLossOnSaleOfInvestments" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock_b6a1c301-5235-4df4-8270-0f655bc30496_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Payable and Accrued Expenses </link:label>

<link:label id="lab_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_TrdArrSecuritiesAggAvailAmt_terseLabel_en-US" xlink:label="lab_ecd_TrdArrSecuritiesAggAvailAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Aggregate Available </link:label>

<link:label id="lab_ecd_TrdArrSecuritiesAggAvailAmt_label_en-US" xlink:label="lab_ecd_TrdArrSecuritiesAggAvailAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trading Arrangement, Securities Aggregate Available Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_TrdArrSecuritiesAggAvailAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_TrdArrSecuritiesAggAvailAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_TrdArrSecuritiesAggAvailAmt" xlink:to="lab_ecd_TrdArrSecuritiesAggAvailAmt" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities_ccf3eacd-321d-4274-a543-2a4f486412f8_terseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts payable and accrued expenses and other non-current liabilities </link:label>

<link:label id="lab_us-gaap_IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Other Accounts Payable and Accrued Liabilities </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities" xlink:to="lab_us-gaap_IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_TermLoanMember_91567853-5004-44ab-a008-bffb00263ede_terseLabel_en-US" xlink:label="lab_pwr_TermLoanMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Term Loan </link:label>

<link:label id="lab_pwr_TermLoanMember_label_en-US" xlink:label="lab_pwr_TermLoanMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Term Loan [Member] </link:label>

<link:label id="lab_pwr_TermLoanMember_documentation_en-US" xlink:label="lab_pwr_TermLoanMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Term Loan [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_TermLoanMember" xlink:href="pwr-20231231.xsd#pwr_TermLoanMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_TermLoanMember" xlink:to="lab_pwr_TermLoanMember" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_InsiderTrdPoliciesProcNotAdoptedTextBlock_terseLabel_en-US" xlink:label="lab_ecd_InsiderTrdPoliciesProcNotAdoptedTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insider Trading Policies and Procedures Not Adopted </link:label>

<link:label id="lab_ecd_InsiderTrdPoliciesProcNotAdoptedTextBlock_label_en-US" xlink:label="lab_ecd_InsiderTrdPoliciesProcNotAdoptedTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insider Trading Policies and Procedures Not Adopted [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_InsiderTrdPoliciesProcNotAdoptedTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_InsiderTrdPoliciesProcNotAdoptedTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_InsiderTrdPoliciesProcNotAdoptedTextBlock" xlink:to="lab_ecd_InsiderTrdPoliciesProcNotAdoptedTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationAcquisitionRelatedCosts_9b138179-b1ab-4625-a0fe-7c197088d6cf_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationAcquisitionRelatedCosts" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisition-related costs </link:label>

<link:label id="lab_us-gaap_BusinessCombinationAcquisitionRelatedCosts_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationAcquisitionRelatedCosts" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Acquisition Related Costs </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts" xlink:to="lab_us-gaap_BusinessCombinationAcquisitionRelatedCosts" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AwardTypeAxis_30227550-9f94-4c1a-a94e-bf85ab7bc62b_terseLabel_en-US" xlink:label="lab_us-gaap_AwardTypeAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Type [Axis] </link:label>

<link:label id="lab_us-gaap_AwardTypeAxis_label_en-US" xlink:label="lab_us-gaap_AwardTypeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Type [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AwardTypeAxis" xlink:to="lab_us-gaap_AwardTypeAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_bb2bb3b3-5d8d-4c93-a8fb-2ebff5b5a1a3_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Granted (in shares) </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CaptiveInsuranceCompanyMember_8ec63b62-960c-4068-a31d-342138fedec8_terseLabel_en-US" xlink:label="lab_pwr_CaptiveInsuranceCompanyMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Captive Insurance Company </link:label>

<link:label id="lab_pwr_CaptiveInsuranceCompanyMember_label_en-US" xlink:label="lab_pwr_CaptiveInsuranceCompanyMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Captive Insurance Company [Member] </link:label>

<link:label id="lab_pwr_CaptiveInsuranceCompanyMember_documentation_en-US" xlink:label="lab_pwr_CaptiveInsuranceCompanyMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Captive Insurance Company </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CaptiveInsuranceCompanyMember" xlink:href="pwr-20231231.xsd#pwr_CaptiveInsuranceCompanyMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CaptiveInsuranceCompanyMember" xlink:to="lab_pwr_CaptiveInsuranceCompanyMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_931ebf70-7bca-4bfe-b97a-d68edb9269aa_terseLabel_en-US" xlink:label="lab_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reconciliation of Unrecognized Tax Benefits </link:label>

<link:label id="lab_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_label_en-US" xlink:label="lab_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:to="lab_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_TelecommunicationNetworksConstructionAndOperationMember_54bd33ba-5f63-49bb-a44a-3e7540749fdc_terseLabel_en-US" xlink:label="lab_pwr_TelecommunicationNetworksConstructionAndOperationMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Telecommunication Networks Construction and Operation </link:label>

<link:label id="lab_pwr_TelecommunicationNetworksConstructionAndOperationMember_label_en-US" xlink:label="lab_pwr_TelecommunicationNetworksConstructionAndOperationMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Telecommunication Networks Construction And Operation [Member] </link:label>

<link:label id="lab_pwr_TelecommunicationNetworksConstructionAndOperationMember_documentation_en-US" xlink:label="lab_pwr_TelecommunicationNetworksConstructionAndOperationMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Telecommunication Networks Construction And Operation [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_TelecommunicationNetworksConstructionAndOperationMember" xlink:href="pwr-20231231.xsd#pwr_TelecommunicationNetworksConstructionAndOperationMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_TelecommunicationNetworksConstructionAndOperationMember" xlink:to="lab_pwr_TelecommunicationNetworksConstructionAndOperationMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CommitmentAndContingenciesLineItems_c15957a7-cea0-4e20-941c-decad62a1f67_terseLabel_en-US" xlink:label="lab_pwr_CommitmentAndContingenciesLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitment And Contingencies [Line Items] </link:label>

<link:label id="lab_pwr_CommitmentAndContingenciesLineItems_label_en-US" xlink:label="lab_pwr_CommitmentAndContingenciesLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitment And Contingencies [Line Items] </link:label>

<link:label id="lab_pwr_CommitmentAndContingenciesLineItems_documentation_en-US" xlink:label="lab_pwr_CommitmentAndContingenciesLineItems" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitment And Contingencies [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CommitmentAndContingenciesLineItems" xlink:href="pwr-20231231.xsd#pwr_CommitmentAndContingenciesLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CommitmentAndContingenciesLineItems" xlink:to="lab_pwr_CommitmentAndContingenciesLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_dei_IcfrAuditorAttestationFlag_9f8ad7e5-ffcf-4b61-be71-b8b7eaf6d2c5_terseLabel_en-US" xlink:label="lab_dei_IcfrAuditorAttestationFlag" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> ICFR Auditor Attestation Flag </link:label>

<link:label id="lab_dei_IcfrAuditorAttestationFlag_label_en-US" xlink:label="lab_dei_IcfrAuditorAttestationFlag" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> ICFR Auditor Attestation Flag </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_IcfrAuditorAttestationFlag" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_IcfrAuditorAttestationFlag"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_IcfrAuditorAttestationFlag" xlink:to="lab_dei_IcfrAuditorAttestationFlag" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentGross_61791599-f07d-47e0-9ad7-2543891aead1_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentGross" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and equipment, gross </link:label>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentGross_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentGross" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment, Gross </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentGross" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentGross" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_GoodwillLineItems_8a660ae8-0ce7-4db7-b7d5-dd13a89ad93b_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill [Line Items] </link:label>

<link:label id="lab_us-gaap_GoodwillLineItems_label_en-US" xlink:label="lab_us-gaap_GoodwillLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillLineItems" xlink:to="lab_us-gaap_GoodwillLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_976a9f47-c8e4-47a8-9a73-47047b05a629_terseLabel_en-US" xlink:label="lab_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating leases </link:label>

<link:label id="lab_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_label_en-US" xlink:label="lab_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Right-of-Use Asset Obtained in Exchange for Operating Lease Liability </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability" xlink:to="lab_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaid_0d76147d-f47a-4ebc-8d0e-b83e241f643d_totalLabel_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaid" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total future minimum payments related to operating leases, finance leases and lease financing transactions </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaid_label_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaid" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, To Be Paid </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaid_documentation_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaid" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, To Be Paid </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingAndFinanceLeaseLiabilityToBePaid" xlink:href="pwr-20231231.xsd#pwr_OperatingAndFinanceLeaseLiabilityToBePaid"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingAndFinanceLeaseLiabilityToBePaid" xlink:to="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaid" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_3efa82e6-b321-47af-a1df-ab62c893a646_terseLabel_en-US" xlink:label="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable, Allowance for Credit Loss [Roll Forward] </link:label>

<link:label id="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward_label_en-US" xlink:label="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable, Allowance for Credit Loss [Roll Forward] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward" xlink:to="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableRollforward" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DividendsDeclaredTableTextBlock_ae1c9ac1-1272-45fb-9ff0-b6d2cc2a60b3_terseLabel_en-US" xlink:label="lab_us-gaap_DividendsDeclaredTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Dividends </link:label>

<link:label id="lab_us-gaap_DividendsDeclaredTableTextBlock_label_en-US" xlink:label="lab_us-gaap_DividendsDeclaredTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Dividends Declared [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsDeclaredTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsDeclaredTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DividendsDeclaredTableTextBlock" xlink:to="lab_us-gaap_DividendsDeclaredTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_ac141852-d3b3-4d31-aa6d-13e1a7396136_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Less imputed interest </link:label>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, Undiscounted Excess Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_PeoActuallyPaidCompAmt_terseLabel_en-US" xlink:label="lab_ecd_PeoActuallyPaidCompAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> PEO Actually Paid Compensation Amount </link:label>

<link:label id="lab_ecd_PeoActuallyPaidCompAmt_label_en-US" xlink:label="lab_ecd_PeoActuallyPaidCompAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> PEO Actually Paid Compensation Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_PeoActuallyPaidCompAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_PeoActuallyPaidCompAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_PeoActuallyPaidCompAmt" xlink:to="lab_ecd_PeoActuallyPaidCompAmt" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeFinanceLeasesTextBlock_ff430d7a-2d80-462b-a350-ddf91b340667_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeFinanceLeasesTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Leases </link:label>

<link:label id="lab_us-gaap_LesseeFinanceLeasesTextBlock_label_en-US" xlink:label="lab_us-gaap_LesseeFinanceLeasesTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Finance Leases [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeFinanceLeasesTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeFinanceLeasesTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeFinanceLeasesTextBlock" xlink:to="lab_us-gaap_LesseeFinanceLeasesTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock_7147621a-a0ca-4e37-977a-504d8553e693_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Provision for Income Taxes </link:label>

<link:label id="lab_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfComponentsOfIncomeTaxExpenseBenefitTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LossContingencyLossInPeriod_2585935a-f89b-4b8a-a853-a39ad71a8562_verboseLabel_en-US" xlink:label="lab_us-gaap_LossContingencyLossInPeriod" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Recorded charges </link:label>

<link:label id="lab_us-gaap_LossContingencyLossInPeriod_label_en-US" xlink:label="lab_us-gaap_LossContingencyLossInPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss Contingency, Loss in Period </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyLossInPeriod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyLossInPeriod"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LossContingencyLossInPeriod" xlink:to="lab_us-gaap_LossContingencyLossInPeriod" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OperatingLeaseLiabilityCurrent_6de9f7bc-e4ef-4aeb-86e6-c525643e9042_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current portion of operating lease liabilities </link:label>

<link:label id="lab_us-gaap_OperatingLeaseLiabilityCurrent_baeb5fa8-14be-49de-9744-495cde873a8a_verboseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating </link:label>

<link:label id="lab_us-gaap_OperatingLeaseLiabilityCurrent_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Liability, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseLiabilityCurrent" xlink:to="lab_us-gaap_OperatingLeaseLiabilityCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_IncomeTaxesTable_cc653f98-f116-44e2-b0ac-5a5f170d0c71_terseLabel_en-US" xlink:label="lab_pwr_IncomeTaxesTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Taxes [Table] </link:label>

<link:label id="lab_pwr_IncomeTaxesTable_label_en-US" xlink:label="lab_pwr_IncomeTaxesTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Taxes [Table] </link:label>

<link:label id="lab_pwr_IncomeTaxesTable_documentation_en-US" xlink:label="lab_pwr_IncomeTaxesTable" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income taxes. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_IncomeTaxesTable" xlink:href="pwr-20231231.xsd#pwr_IncomeTaxesTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_IncomeTaxesTable" xlink:to="lab_pwr_IncomeTaxesTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseInterestExpense_17f21d05-c0ca-4dbe-b841-46f67d40f7b8_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseInterestExpense" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest on lease liabilities </link:label>

<link:label id="lab_us-gaap_FinanceLeaseInterestExpense_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseInterestExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Interest Expense </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseInterestExpense"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseInterestExpense" xlink:to="lab_us-gaap_FinanceLeaseInterestExpense" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LifeInsuranceCorporateOrBankOwnedChangeInValue_35bce6e3-80f7-4cf6-b55b-ff65917536fb_terseLabel_en-US" xlink:label="lab_us-gaap_LifeInsuranceCorporateOrBankOwnedChangeInValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other income (expense), net </link:label>

<link:label id="lab_us-gaap_LifeInsuranceCorporateOrBankOwnedChangeInValue_label_en-US" xlink:label="lab_us-gaap_LifeInsuranceCorporateOrBankOwnedChangeInValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Life Insurance, Corporate or Bank Owned, Change in Value </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LifeInsuranceCorporateOrBankOwnedChangeInValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LifeInsuranceCorporateOrBankOwnedChangeInValue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LifeInsuranceCorporateOrBankOwnedChangeInValue" xlink:to="lab_us-gaap_LifeInsuranceCorporateOrBankOwnedChangeInValue" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_f49b0c76-7843-4838-90d5-a4f83a7e516f_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2026 </link:label>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, to be Paid, Year Three </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentLineItems_b520cc60-fbef-43a9-962e-d01a8f7df085_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment [Line Items] </link:label>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentLineItems_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsNet_1a7660a8-553e-438d-855f-6f3150c0a57a_totalLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsNet" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total </link:label>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsNet_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Assets, Net </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsNet" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_b6cbd550-b7ab-4742-a03a-71d34550034d_terseLabel_en-US" xlink:label="lab_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> New Accounting Pronouncements Not Yet Adopted </link:label>

<link:label id="lab_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> New Accounting Pronouncements, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xlink:to="lab_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_country_AU_91051fe1-4f5a-4777-b96a-ccb7cdf2d971_terseLabel_en-US" xlink:label="lab_country_AU" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Australia </link:label>

<link:label id="lab_country_AU_label_en-US" xlink:label="lab_country_AU" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> AUSTRALIA </link:label>

<link:loc xlink:type="locator" xlink:label="loc_country_AU" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_AU"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_country_AU" xlink:to="lab_country_AU" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsThereafter_375d3dc4-1f34-46bd-b0d4-dd7334e7bdbf_terseLabel_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsThereafter" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Tax carryforwards expiring thereafter </link:label>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsThereafter_label_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsThereafter" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expiration Amount Of State And Foreign Net Operating Loss Carryforwards Thereafter </link:label>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsThereafter_documentation_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsThereafter" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expiration amount of state and foreign net operating loss carryforwards thereafter. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsThereafter" xlink:href="pwr-20231231.xsd#pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsThereafter"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsThereafter" xlink:to="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsThereafter" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CashFlowLesseeAbstract_53b792dc-68e8-4d76-92ef-5859e97558bf_terseLabel_en-US" xlink:label="lab_pwr_CashFlowLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash paid for amounts included in the measurement of lease liabilities: </link:label>

<link:label id="lab_pwr_CashFlowLesseeAbstract_label_en-US" xlink:label="lab_pwr_CashFlowLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash Flow, Lessee [Abstract] </link:label>

<link:label id="lab_pwr_CashFlowLesseeAbstract_documentation_en-US" xlink:label="lab_pwr_CashFlowLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash Flow, Lessee [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CashFlowLesseeAbstract" xlink:href="pwr-20231231.xsd#pwr_CashFlowLesseeAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CashFlowLesseeAbstract" xlink:to="lab_pwr_CashFlowLesseeAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1_72c4da5b-5220-456f-9b16-09cbe3884e68_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease terms of operating leases not yet commenced (in years) </link:label>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1" xlink:to="lab_us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DefinedContributionPlanEmployerMatchingContributionPercentOfMatchByEmployerUpToSpecificPercentage_c5903d4a-bafb-4795-8205-d6fbca35b4a3_terseLabel_en-US" xlink:label="lab_pwr_DefinedContributionPlanEmployerMatchingContributionPercentOfMatchByEmployerUpToSpecificPercentage" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Percentage of contribution by employer of each employee's contribution up to 3% </link:label>

<link:label id="lab_pwr_DefinedContributionPlanEmployerMatchingContributionPercentOfMatchByEmployerUpToSpecificPercentage_label_en-US" xlink:label="lab_pwr_DefinedContributionPlanEmployerMatchingContributionPercentOfMatchByEmployerUpToSpecificPercentage" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Defined Contribution Plan, Employer Matching Contribution, Percent Of Match By Employer Up To Specific Percentage </link:label>

<link:label id="lab_pwr_DefinedContributionPlanEmployerMatchingContributionPercentOfMatchByEmployerUpToSpecificPercentage_documentation_en-US" xlink:label="lab_pwr_DefinedContributionPlanEmployerMatchingContributionPercentOfMatchByEmployerUpToSpecificPercentage" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Defined Contribution Plan, Employer Matching Contribution, Percent of Match By Employer Up To Specific Percentage </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DefinedContributionPlanEmployerMatchingContributionPercentOfMatchByEmployerUpToSpecificPercentage" xlink:href="pwr-20231231.xsd#pwr_DefinedContributionPlanEmployerMatchingContributionPercentOfMatchByEmployerUpToSpecificPercentage"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DefinedContributionPlanEmployerMatchingContributionPercentOfMatchByEmployerUpToSpecificPercentage" xlink:to="lab_pwr_DefinedContributionPlanEmployerMatchingContributionPercentOfMatchByEmployerUpToSpecificPercentage" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_33edc2ab-955c-4a19-9fb9-06311e630713_negatedLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accumulated Amortization </link:label>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Assets, Accumulated Amortization </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_7cbc7d26-981f-4778-bdac-e042c4c0a74b_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2025 </link:label>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, to be Paid, Year Two </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_SeniorNotesDue20242032And2041Member_f4388630-231e-42d9-9a13-331a498ad1be_terseLabel_en-US" xlink:label="lab_pwr_SeniorNotesDue20242032And2041Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Notes Due 2024, 2032 And 2041 </link:label>

<link:label id="lab_pwr_SeniorNotesDue20242032And2041Member_label_en-US" xlink:label="lab_pwr_SeniorNotesDue20242032And2041Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Notes Due 2024, 2032 And 2041 [Member] </link:label>

<link:label id="lab_pwr_SeniorNotesDue20242032And2041Member_documentation_en-US" xlink:label="lab_pwr_SeniorNotesDue20242032And2041Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Notes Due 2024, 2032 And 2041 </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_SeniorNotesDue20242032And2041Member" xlink:href="pwr-20231231.xsd#pwr_SeniorNotesDue20242032And2041Member"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_SeniorNotesDue20242032And2041Member" xlink:to="lab_pwr_SeniorNotesDue20242032And2041Member" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ConstructionLaborersPensionTrustFundForSouthernCaliforniaMember_6df533f7-a5b7-44e4-af29-7cf30443c208_terseLabel_en-US" xlink:label="lab_pwr_ConstructionLaborersPensionTrustFundForSouthernCaliforniaMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Construction Laborers Pension Trust Fund for Southern California </link:label>

<link:label id="lab_pwr_ConstructionLaborersPensionTrustFundForSouthernCaliforniaMember_label_en-US" xlink:label="lab_pwr_ConstructionLaborersPensionTrustFundForSouthernCaliforniaMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Construction Laborers Pension Trust Fund for Southern California [Member] </link:label>

<link:label id="lab_pwr_ConstructionLaborersPensionTrustFundForSouthernCaliforniaMember_documentation_en-US" xlink:label="lab_pwr_ConstructionLaborersPensionTrustFundForSouthernCaliforniaMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Construction Laborers Pension Trust Fund for Southern California </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ConstructionLaborersPensionTrustFundForSouthernCaliforniaMember" xlink:href="pwr-20231231.xsd#pwr_ConstructionLaborersPensionTrustFundForSouthernCaliforniaMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ConstructionLaborersPensionTrustFundForSouthernCaliforniaMember" xlink:to="lab_pwr_ConstructionLaborersPensionTrustFundForSouthernCaliforniaMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock_5f7d48be-96bd-4128-9e15-d8686b117aa9_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Components of Income (Loss) Before Income Taxes </link:label>

<link:label id="lab_us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfIncomeBeforeIncomeTaxDomesticAndForeignTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DeferredTaxAssetsNoLongerAvailableAndCurrencyTranslationAdjustmentsMember_2b49f274-3a16-4436-a6ed-10e7e7075ec3_terseLabel_en-US" xlink:label="lab_pwr_DeferredTaxAssetsNoLongerAvailableAndCurrencyTranslationAdjustmentsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets No Longer Available And Currency Translation Adjustments </link:label>

<link:label id="lab_pwr_DeferredTaxAssetsNoLongerAvailableAndCurrencyTranslationAdjustmentsMember_label_en-US" xlink:label="lab_pwr_DeferredTaxAssetsNoLongerAvailableAndCurrencyTranslationAdjustmentsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets No Longer Available And Currency Translation Adjustments [Member] </link:label>

<link:label id="lab_pwr_DeferredTaxAssetsNoLongerAvailableAndCurrencyTranslationAdjustmentsMember_documentation_en-US" xlink:label="lab_pwr_DeferredTaxAssetsNoLongerAvailableAndCurrencyTranslationAdjustmentsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets No Longer Available And Currency Translation Adjustments </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DeferredTaxAssetsNoLongerAvailableAndCurrencyTranslationAdjustmentsMember" xlink:href="pwr-20231231.xsd#pwr_DeferredTaxAssetsNoLongerAvailableAndCurrencyTranslationAdjustmentsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DeferredTaxAssetsNoLongerAvailableAndCurrencyTranslationAdjustmentsMember" xlink:to="lab_pwr_DeferredTaxAssetsNoLongerAvailableAndCurrencyTranslationAdjustmentsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_InvestmentIncomeInterest_c9b249c8-4e0b-4d45-bd5c-cd2ea87af826_terseLabel_en-US" xlink:label="lab_us-gaap_InvestmentIncomeInterest" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest income </link:label>

<link:label id="lab_us-gaap_InvestmentIncomeInterest_label_en-US" xlink:label="lab_us-gaap_InvestmentIncomeInterest" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investment Income, Interest </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterest" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentIncomeInterest"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InvestmentIncomeInterest" xlink:to="lab_us-gaap_InvestmentIncomeInterest" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_StkPrcOrTsrEstimationMethodTextBlock_terseLabel_en-US" xlink:label="lab_ecd_StkPrcOrTsrEstimationMethodTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Price or TSR Estimation Method </link:label>

<link:label id="lab_ecd_StkPrcOrTsrEstimationMethodTextBlock_label_en-US" xlink:label="lab_ecd_StkPrcOrTsrEstimationMethodTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Price or TSR Estimation Method [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_StkPrcOrTsrEstimationMethodTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_StkPrcOrTsrEstimationMethodTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_StkPrcOrTsrEstimationMethodTextBlock" xlink:to="lab_ecd_StkPrcOrTsrEstimationMethodTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_efb06755-c17e-44ed-a946-24e33fca0ebb_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign </link:label>

<link:label id="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_label_en-US" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income (Loss) from Continuing Operations before Income Taxes, Foreign </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign" xlink:to="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationConsiderationTransferred1_840d2249-607d-44ec-b65c-50f2aaf31bf1_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationConsiderationTransferred1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair value of total consideration transferred or estimated to be transferred </link:label>

<link:label id="lab_us-gaap_BusinessCombinationConsiderationTransferred1_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationConsiderationTransferred1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Consideration Transferred </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferred1" xlink:to="lab_us-gaap_BusinessCombinationConsiderationTransferred1" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_GrossProfit_e0d31f63-549f-4510-b27c-a33c125e8dc6_totalLabel_en-US" xlink:label="lab_us-gaap_GrossProfit" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Gross profit </link:label>

<link:label id="lab_us-gaap_GrossProfit_label_en-US" xlink:label="lab_us-gaap_GrossProfit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Gross Profit </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GrossProfit"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GrossProfit" xlink:to="lab_us-gaap_GrossProfit" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ContractWithCustomerLiabilityCurrent_00ba92cb-2233-46a8-837e-e73499404a49_terseLabel_en-US" xlink:label="lab_us-gaap_ContractWithCustomerLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract liabilities </link:label>

<link:label id="lab_us-gaap_ContractWithCustomerLiabilityCurrent_50d87303-049f-4ffc-b01c-32d7c82ace6f_verboseLabel_en-US" xlink:label="lab_us-gaap_ContractWithCustomerLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract liabilities </link:label>

<link:label id="lab_us-gaap_ContractWithCustomerLiabilityCurrent_label_en-US" xlink:label="lab_us-gaap_ContractWithCustomerLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract with Customer, Liability, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ContractWithCustomerLiabilityCurrent" xlink:to="lab_us-gaap_ContractWithCustomerLiabilityCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_dei_SecurityExchangeName_74c37b96-e3a2-43ed-bb9c-a0c26d060e14_terseLabel_en-US" xlink:label="lab_dei_SecurityExchangeName" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Security Exchange Name </link:label>

<link:label id="lab_dei_SecurityExchangeName_label_en-US" xlink:label="lab_dei_SecurityExchangeName" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Security Exchange Name </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_SecurityExchangeName"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_SecurityExchangeName" xlink:to="lab_dei_SecurityExchangeName" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SellingGeneralAndAdministrativeExpense_c3d92dc5-dc6c-4b20-a0bb-24a7f63d67d0_negatedLabel_en-US" xlink:label="lab_us-gaap_SellingGeneralAndAdministrativeExpense" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Selling, general and administrative expenses </link:label>

<link:label id="lab_us-gaap_SellingGeneralAndAdministrativeExpense_label_en-US" xlink:label="lab_us-gaap_SellingGeneralAndAdministrativeExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Selling, General and Administrative Expense </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SellingGeneralAndAdministrativeExpense" xlink:to="lab_us-gaap_SellingGeneralAndAdministrativeExpense" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_8e370c5c-c629-4d21-879e-e35ba704370f_terseLabel_en-US" xlink:label="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accumulated other comprehensive loss </link:label>

<link:label id="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_label_en-US" xlink:label="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accumulated Other Comprehensive Income (Loss), Net of Tax </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:to="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_RedesAndinasDeComunicacionesS.R.L.RedesMember_d9ce3e1f-1d2a-4b4d-8103-4d2ee9106e3e_terseLabel_en-US" xlink:label="lab_pwr_RedesAndinasDeComunicacionesS.R.L.RedesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Redes </link:label>

<link:label id="lab_pwr_RedesAndinasDeComunicacionesS.R.L.RedesMember_label_en-US" xlink:label="lab_pwr_RedesAndinasDeComunicacionesS.R.L.RedesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Redes Andinas De Comunicaciones S.R.L. (Redes) [Member] </link:label>

<link:label id="lab_pwr_RedesAndinasDeComunicacionesS.R.L.RedesMember_documentation_en-US" xlink:label="lab_pwr_RedesAndinasDeComunicacionesS.R.L.RedesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Redes Andinas De Comunicaciones S.R.L. (Redes) [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_RedesAndinasDeComunicacionesS.R.L.RedesMember" xlink:href="pwr-20231231.xsd#pwr_RedesAndinasDeComunicacionesS.R.L.RedesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_RedesAndinasDeComunicacionesS.R.L.RedesMember" xlink:to="lab_pwr_RedesAndinasDeComunicacionesS.R.L.RedesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EmployeeStockOptionMember_terseLabel_en-US" xlink:label="lab_us-gaap_EmployeeStockOptionMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employee Stock Option </link:label>

<link:label id="lab_us-gaap_EmployeeStockOptionMember_label_en-US" xlink:label="lab_us-gaap_EmployeeStockOptionMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employee Stock Option [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockOptionMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EmployeeStockOptionMember" xlink:to="lab_us-gaap_EmployeeStockOptionMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_InvestmentPolicyTextBlock_e7ccdf06-d09c-4ca1-bd2e-a2e9b07ca332_terseLabel_en-US" xlink:label="lab_us-gaap_InvestmentPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investments in Affiliates and Other </link:label>

<link:label id="lab_us-gaap_InvestmentPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_InvestmentPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investment, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InvestmentPolicyTextBlock" xlink:to="lab_us-gaap_InvestmentPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_srt_MaximumMember_e1910a1f-c1d6-4134-b0a4-a6b052170c36_terseLabel_en-US" xlink:label="lab_srt_MaximumMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Maximum </link:label>

<link:label id="lab_srt_MaximumMember_label_en-US" xlink:label="lab_srt_MaximumMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Maximum [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_MaximumMember" xlink:to="lab_srt_MaximumMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation_dcf1d9a7-58c1-4ff6-8b3b-b6064e2c5349_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock and incentive compensation </link:label>

<link:label id="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Compensation </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation" xlink:to="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CashEquivalentsAtCarryingValue_e031ede6-4b95-439d-ba92-925f1650e8e1_terseLabel_en-US" xlink:label="lab_us-gaap_CashEquivalentsAtCarryingValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash equivalents </link:label>

<link:label id="lab_us-gaap_CashEquivalentsAtCarryingValue_label_en-US" xlink:label="lab_us-gaap_CashEquivalentsAtCarryingValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash Equivalents, at Carrying Value </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashEquivalentsAtCarryingValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashEquivalentsAtCarryingValue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashEquivalentsAtCarryingValue" xlink:to="lab_us-gaap_CashEquivalentsAtCarryingValue" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_1a89793d-34a0-4716-a019-b6cf2633c041_terseLabel_en-US" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecognized compensation cost, related to unvested restricted stock, total </link:label>

<link:label id="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_label_en-US" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:to="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:type="arc" order="1"/>

<link:label id="lab_dei_DocumentType_16a23541-1bda-462f-962e-22880272f21f_terseLabel_en-US" xlink:label="lab_dei_DocumentType" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Type </link:label>

<link:label id="lab_dei_DocumentType_label_en-US" xlink:label="lab_dei_DocumentType" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Type </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentType"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_DocumentType" xlink:to="lab_dei_DocumentType" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_AllSeniorNotesMember_0056f0dc-7f9a-4f59-97ab-babdd9459ed4_terseLabel_en-US" xlink:label="lab_pwr_AllSeniorNotesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Senior Notes </link:label>

<link:label id="lab_pwr_AllSeniorNotesMember_label_en-US" xlink:label="lab_pwr_AllSeniorNotesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Senior Notes [Member] </link:label>

<link:label id="lab_pwr_AllSeniorNotesMember_documentation_en-US" xlink:label="lab_pwr_AllSeniorNotesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Senior Notes </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_AllSeniorNotesMember" xlink:href="pwr-20231231.xsd#pwr_AllSeniorNotesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_AllSeniorNotesMember" xlink:to="lab_pwr_AllSeniorNotesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_GoodwillAcquiredDuringPeriod_59861d76-0254-430a-a48a-8c3bf9dbf8bb_verboseLabel_en-US" xlink:label="lab_us-gaap_GoodwillAcquiredDuringPeriod" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill acquired </link:label>

<link:label id="lab_us-gaap_GoodwillAcquiredDuringPeriod_label_en-US" xlink:label="lab_us-gaap_GoodwillAcquiredDuringPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill, Acquired During Period </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillAcquiredDuringPeriod"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillAcquiredDuringPeriod" xlink:to="lab_us-gaap_GoodwillAcquiredDuringPeriod" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_FairValueInputsDiscountRate_7984c126-0329-47c1-a663-cdf312837c72_terseLabel_en-US" xlink:label="lab_pwr_FairValueInputsDiscountRate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Discount rates </link:label>

<link:label id="lab_pwr_FairValueInputsDiscountRate_label_en-US" xlink:label="lab_pwr_FairValueInputsDiscountRate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair Value Inputs, Discount Rate </link:label>

<link:label id="lab_pwr_FairValueInputsDiscountRate_documentation_en-US" xlink:label="lab_pwr_FairValueInputsDiscountRate" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair Value Inputs, Discount Rate </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_FairValueInputsDiscountRate" xlink:href="pwr-20231231.xsd#pwr_FairValueInputsDiscountRate"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_FairValueInputsDiscountRate" xlink:to="lab_pwr_FairValueInputsDiscountRate" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_TabularListTableTextBlock_terseLabel_en-US" xlink:label="lab_ecd_TabularListTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Tabular List, Table </link:label>

<link:label id="lab_ecd_TabularListTableTextBlock_label_en-US" xlink:label="lab_ecd_TabularListTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Tabular List [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_TabularListTableTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_TabularListTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_TabularListTableTextBlock" xlink:to="lab_ecd_TabularListTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_TreasuryStockValueAcquiredCostMethod_71872a22-59bf-43a4-8688-9adf049c0ddd_negatedLabel_en-US" xlink:label="lab_us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock repurchases </link:label>

<link:label id="lab_us-gaap_TreasuryStockValueAcquiredCostMethod_49d88a43-6051-44ad-9c81-d167d3502701_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Value of treasury stock acquired, cost method </link:label>

<link:label id="lab_us-gaap_TreasuryStockValueAcquiredCostMethod_label_en-US" xlink:label="lab_us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Treasury Stock, Value, Acquired, Cost Method </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:to="lab_us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_InventoryPolicyTextBlock_b8ed7650-115f-4726-b5b3-6d5c5a77f435_terseLabel_en-US" xlink:label="lab_us-gaap_InventoryPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventories </link:label>

<link:label id="lab_us-gaap_InventoryPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_InventoryPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InventoryPolicyTextBlock" xlink:to="lab_us-gaap_InventoryPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_1c35f206-6502-4e47-a447-a9f54bdc2e5b_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2026 </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, to be Paid, Year Three </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_213a4319-646a-49eb-a1d0-cdf8223880bc_terseLabel_en-US" xlink:label="lab_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock-Based Compensation </link:label>

<link:label id="lab_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_label_en-US" xlink:label="lab_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Payment Arrangement [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:to="lab_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CurrentFederalTaxExpenseBenefit_8f43bf33-78ee-4c68-9782-5b37504570f3_terseLabel_en-US" xlink:label="lab_us-gaap_CurrentFederalTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Federal </link:label>

<link:label id="lab_us-gaap_CurrentFederalTaxExpenseBenefit_label_en-US" xlink:label="lab_us-gaap_CurrentFederalTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current Federal Tax Expense (Benefit) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentFederalTaxExpenseBenefit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CurrentFederalTaxExpenseBenefit"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CurrentFederalTaxExpenseBenefit" xlink:to="lab_us-gaap_CurrentFederalTaxExpenseBenefit" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal_f27e890a-2fd5-4043-a8b4-5c97937ab458_terseLabel_en-US" xlink:label="lab_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Realized gain (loss) on disposal </link:label>

<link:label id="lab_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal_label_en-US" xlink:label="lab_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Method Investment, Realized Gain (Loss) on Disposal </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal" xlink:to="lab_us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LimetreeBayRefiningLLCMember_60cca5b4-a163-4f9c-b0c4-070b639237a3_terseLabel_en-US" xlink:label="lab_pwr_LimetreeBayRefiningLLCMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Limetree Bay Refining, LLC </link:label>

<link:label id="lab_pwr_LimetreeBayRefiningLLCMember_label_en-US" xlink:label="lab_pwr_LimetreeBayRefiningLLCMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Limetree Bay Refining, LLC [Member] </link:label>

<link:label id="lab_pwr_LimetreeBayRefiningLLCMember_documentation_en-US" xlink:label="lab_pwr_LimetreeBayRefiningLLCMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Limetree Bay Refining, LLC </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LimetreeBayRefiningLLCMember" xlink:href="pwr-20231231.xsd#pwr_LimetreeBayRefiningLLCMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LimetreeBayRefiningLLCMember" xlink:to="lab_pwr_LimetreeBayRefiningLLCMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessAcquisitionAxis_882bc2e9-ac63-4179-8e74-b9c03754cd84_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisition [Axis] </link:label>

<link:label id="lab_us-gaap_BusinessAcquisitionAxis_label_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisition [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessAcquisitionAxis" xlink:to="lab_us-gaap_BusinessAcquisitionAxis" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_StarryGroupHoldingsIncMember_b8c7ec23-b100-48a3-a09b-30afed702224_terseLabel_en-US" xlink:label="lab_pwr_StarryGroupHoldingsIncMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Starry Group Holdings, Inc. </link:label>

<link:label id="lab_pwr_StarryGroupHoldingsIncMember_label_en-US" xlink:label="lab_pwr_StarryGroupHoldingsIncMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Starry Group Holdings, Inc. [Member] </link:label>

<link:label id="lab_pwr_StarryGroupHoldingsIncMember_documentation_en-US" xlink:label="lab_pwr_StarryGroupHoldingsIncMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Starry Group Holdings, Inc. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_StarryGroupHoldingsIncMember" xlink:href="pwr-20231231.xsd#pwr_StarryGroupHoldingsIncMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_StarryGroupHoldingsIncMember" xlink:to="lab_pwr_StarryGroupHoldingsIncMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfLineOfCreditFacilitiesTextBlock_2cbbbd6b-02e5-46ae-ad61-a06950a9dcce_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfLineOfCreditFacilitiesTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Borrowings under Credit Facility and Applicable Interest Rates </link:label>

<link:label id="lab_us-gaap_ScheduleOfLineOfCreditFacilitiesTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfLineOfCreditFacilitiesTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Line of Credit Facilities [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfLineOfCreditFacilitiesTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfLineOfCreditFacilitiesTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfLineOfCreditFacilitiesTextBlock" xlink:to="lab_us-gaap_ScheduleOfLineOfCreditFacilitiesTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_EstimatedCostsToCompleteBondedProjects_496909ef-4b9d-4ca1-aec5-c58c2250e1f2_terseLabel_en-US" xlink:label="lab_pwr_EstimatedCostsToCompleteBondedProjects" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Estimated cost to complete bonded projects </link:label>

<link:label id="lab_pwr_EstimatedCostsToCompleteBondedProjects_label_en-US" xlink:label="lab_pwr_EstimatedCostsToCompleteBondedProjects" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Estimated Costs To Complete Bonded Projects </link:label>

<link:label id="lab_pwr_EstimatedCostsToCompleteBondedProjects_documentation_en-US" xlink:label="lab_pwr_EstimatedCostsToCompleteBondedProjects" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Estimated Costs To Complete Bonded Projects </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_EstimatedCostsToCompleteBondedProjects" xlink:href="pwr-20231231.xsd#pwr_EstimatedCostsToCompleteBondedProjects"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_EstimatedCostsToCompleteBondedProjects" xlink:to="lab_pwr_EstimatedCostsToCompleteBondedProjects" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CustomerConcentrationRiskMember_ab07b2bc-d395-422e-8fef-3484236cbaff_terseLabel_en-US" xlink:label="lab_us-gaap_CustomerConcentrationRiskMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer Concentration Risk </link:label>

<link:label id="lab_us-gaap_CustomerConcentrationRiskMember_label_en-US" xlink:label="lab_us-gaap_CustomerConcentrationRiskMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer Concentration Risk [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerConcentrationRiskMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CustomerConcentrationRiskMember" xlink:to="lab_us-gaap_CustomerConcentrationRiskMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SelfInsuranceReservePolicyTextBlock_1854b668-ddbb-4556-89bf-77c1ed64c950_terseLabel_en-US" xlink:label="lab_us-gaap_SelfInsuranceReservePolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insurance </link:label>

<link:label id="lab_us-gaap_SelfInsuranceReservePolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_SelfInsuranceReservePolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Self Insurance Reserve [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SelfInsuranceReservePolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SelfInsuranceReservePolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SelfInsuranceReservePolicyTextBlock" xlink:to="lab_us-gaap_SelfInsuranceReservePolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_aad27190-8050-4978-8007-cc4e6b1319c7_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> State </link:label>

<link:label id="lab_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_label_en-US" xlink:label="lab_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred State and Local Income Tax Expense (Benefit) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xlink:to="lab_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_VariableRateAxis_a439391b-0755-4a4f-a2f4-008c5c3b6207_terseLabel_en-US" xlink:label="lab_us-gaap_VariableRateAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Variable Rate [Axis] </link:label>

<link:label id="lab_us-gaap_VariableRateAxis_label_en-US" xlink:label="lab_us-gaap_VariableRateAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Variable Rate [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableRateAxis" xlink:to="lab_us-gaap_VariableRateAxis" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToUpdatedAcquisitionRatio_6bca77e5-7c79-4fe0-b3af-1052e46ba082_terseLabel_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToUpdatedAcquisitionRatio" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of fiscal quarters applicable to updated acquisition ratio </link:label>

<link:label id="lab_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToUpdatedAcquisitionRatio_label_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToUpdatedAcquisitionRatio" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Covenant, Number Of Fiscal Quarters Applicable To Updated Acquisition Ratio </link:label>

<link:label id="lab_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToUpdatedAcquisitionRatio_documentation_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToUpdatedAcquisitionRatio" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Covenant, Number Of Fiscal Quarters Applicable To Updated Acquisition Ratio </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToUpdatedAcquisitionRatio" xlink:href="pwr-20231231.xsd#pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToUpdatedAcquisitionRatio"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToUpdatedAcquisitionRatio" xlink:to="lab_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToUpdatedAcquisitionRatio" xlink:type="arc" order="1"/>

<link:label id="lab_dei_Security12bTitle_524f3474-435e-4468-87bf-46154ad427b8_terseLabel_en-US" xlink:label="lab_dei_Security12bTitle" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Title of 12(b) Security </link:label>

<link:label id="lab_dei_Security12bTitle_label_en-US" xlink:label="lab_dei_Security12bTitle" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Title of 12(b) Security </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_Security12bTitle"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_Security12bTitle" xlink:to="lab_dei_Security12bTitle" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LitigationSettlementAmountAwardedFromOtherParty_7f6f0350-213f-4609-b30c-72ceba08045c_terseLabel_en-US" xlink:label="lab_us-gaap_LitigationSettlementAmountAwardedFromOtherParty" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amount awarded in arbitration </link:label>

<link:label id="lab_us-gaap_LitigationSettlementAmountAwardedFromOtherParty_label_en-US" xlink:label="lab_us-gaap_LitigationSettlementAmountAwardedFromOtherParty" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Litigation Settlement, Amount Awarded from Other Party </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedFromOtherParty" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LitigationSettlementAmountAwardedFromOtherParty"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LitigationSettlementAmountAwardedFromOtherParty" xlink:to="lab_us-gaap_LitigationSettlementAmountAwardedFromOtherParty" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_8e7a8e10-5afc-42ad-b20f-c702aac28f5b_negatedLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other long-term liabilities </link:label>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LossContingencyNatureDomain_705db642-3f05-459e-a919-d3bff2c1fdea_terseLabel_en-US" xlink:label="lab_us-gaap_LossContingencyNatureDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss Contingency, Nature [Domain] </link:label>

<link:label id="lab_us-gaap_LossContingencyNatureDomain_label_en-US" xlink:label="lab_us-gaap_LossContingencyNatureDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss Contingency, Nature [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyNatureDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LossContingencyNatureDomain" xlink:to="lab_us-gaap_LossContingencyNatureDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RelatedPartyDomain_6375a654-00cb-4b6e-ace6-bb4d1520710e_terseLabel_en-US" xlink:label="lab_us-gaap_RelatedPartyDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party [Domain] </link:label>

<link:label id="lab_us-gaap_RelatedPartyDomain_label_en-US" xlink:label="lab_us-gaap_RelatedPartyDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party, Type [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RelatedPartyDomain" xlink:to="lab_us-gaap_RelatedPartyDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationDisclosureTextBlock_5fce7e22-fbe0-4be6-926e-444a3862406a_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions </link:label>

<link:label id="lab_us-gaap_BusinessCombinationDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination Disclosure [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationDisclosureTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationDisclosureTextBlock" xlink:to="lab_us-gaap_BusinessCombinationDisclosureTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_0e3f9011-f9d2-4d27-b804-e749e5bf08cb_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] </link:label>

<link:label id="lab_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:to="lab_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StockholdersEquityPolicyTextBlock_f4fbba03-7cb3-46e3-9f1f-8a0549d7c34b_terseLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquityPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity </link:label>

<link:label id="lab_us-gaap_StockholdersEquityPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_StockholdersEquityPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stockholders' Equity, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquityPolicyTextBlock" xlink:to="lab_us-gaap_StockholdersEquityPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod_25695abe-58a0-4382-82aa-c82ec2a14379_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Maximum amount outstanding </link:label>

<link:label id="lab_us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Maximum Amount Outstanding During Period </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod" xlink:to="lab_us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_e13abad8-f8f8-46c2-bdd9-e2cd77f830a3_terseLabel_en-US" xlink:label="lab_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Intangible Assets </link:label>

<link:label id="lab_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_label_en-US" xlink:label="lab_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Indefinite-Lived Intangible Assets (Excluding Goodwill) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" xlink:to="lab_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AggtErrCompNotYetDeterminedTextBlock_terseLabel_en-US" xlink:label="lab_ecd_AggtErrCompNotYetDeterminedTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Aggregate Erroneous Compensation Not Yet Determined </link:label>

<link:label id="lab_ecd_AggtErrCompNotYetDeterminedTextBlock_label_en-US" xlink:label="lab_ecd_AggtErrCompNotYetDeterminedTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Aggregate Erroneous Compensation Not Yet Determined [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AggtErrCompNotYetDeterminedTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AggtErrCompNotYetDeterminedTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AggtErrCompNotYetDeterminedTextBlock" xlink:to="lab_ecd_AggtErrCompNotYetDeterminedTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LaborersPensionTrustFundForNorthernCaliforniaMember_0018f7c1-86e6-4f0b-8267-d766eeda0330_terseLabel_en-US" xlink:label="lab_pwr_LaborersPensionTrustFundForNorthernCaliforniaMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Laborers Pension Trust Fund for Northern California </link:label>

<link:label id="lab_pwr_LaborersPensionTrustFundForNorthernCaliforniaMember_label_en-US" xlink:label="lab_pwr_LaborersPensionTrustFundForNorthernCaliforniaMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Laborers Pension Trust Fund for Northern California [Member] </link:label>

<link:label id="lab_pwr_LaborersPensionTrustFundForNorthernCaliforniaMember_documentation_en-US" xlink:label="lab_pwr_LaborersPensionTrustFundForNorthernCaliforniaMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Laborers Pension Trust Fund for Northern California [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LaborersPensionTrustFundForNorthernCaliforniaMember" xlink:href="pwr-20231231.xsd#pwr_LaborersPensionTrustFundForNorthernCaliforniaMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LaborersPensionTrustFundForNorthernCaliforniaMember" xlink:to="lab_pwr_LaborersPensionTrustFundForNorthernCaliforniaMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfMultiemployerPlansTable_eb92dc66-f133-4393-aeb6-52e9653ca0e1_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfMultiemployerPlansTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Multiemployer Plans [Table] </link:label>

<link:label id="lab_us-gaap_ScheduleOfMultiemployerPlansTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfMultiemployerPlansTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Multiemployer Plan [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfMultiemployerPlansTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfMultiemployerPlansTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfMultiemployerPlansTable" xlink:to="lab_us-gaap_ScheduleOfMultiemployerPlansTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OperatingSegmentsMember_4008bd33-daf0-4db2-a823-9188ad611846_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingSegmentsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Segments </link:label>

<link:label id="lab_us-gaap_OperatingSegmentsMember_label_en-US" xlink:label="lab_us-gaap_OperatingSegmentsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Segments [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingSegmentsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingSegmentsMember" xlink:to="lab_us-gaap_OperatingSegmentsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_dd21ee42-4a90-4b43-aad8-d83cc0c03f61_periodStartLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unvested, weighted average grant date fair value, beginning of period (in usd per share) </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_679a16c5-0f60-45ba-83c2-36f929aff2a4_periodEndLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unvested, weighted average grant date fair value, end of period (in usd per share) </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxDisclosureAbstract_1124661e-9a2b-411b-9474-78a988f8b920_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Disclosure [Abstract] </link:label>

<link:label id="lab_us-gaap_IncomeTaxDisclosureAbstract_label_en-US" xlink:label="lab_us-gaap_IncomeTaxDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Disclosure [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxDisclosureAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxDisclosureAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract" xlink:to="lab_us-gaap_IncomeTaxDisclosureAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_IncomeTaxExaminationPenaltiesAndInterestExpenseIncome_9af5df6b-f820-4c63-bac5-55a469112bb5_terseLabel_en-US" xlink:label="lab_pwr_IncomeTaxExaminationPenaltiesAndInterestExpenseIncome" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest and penalties expense (income) in the provision for income taxes </link:label>

<link:label id="lab_pwr_IncomeTaxExaminationPenaltiesAndInterestExpenseIncome_label_en-US" xlink:label="lab_pwr_IncomeTaxExaminationPenaltiesAndInterestExpenseIncome" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Examination, Penalties And Interest Expense (Income) </link:label>

<link:label id="lab_pwr_IncomeTaxExaminationPenaltiesAndInterestExpenseIncome_documentation_en-US" xlink:label="lab_pwr_IncomeTaxExaminationPenaltiesAndInterestExpenseIncome" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Examination, Penalties And Interest Expense (Income) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_IncomeTaxExaminationPenaltiesAndInterestExpenseIncome" xlink:href="pwr-20231231.xsd#pwr_IncomeTaxExaminationPenaltiesAndInterestExpenseIncome"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_IncomeTaxExaminationPenaltiesAndInterestExpenseIncome" xlink:to="lab_pwr_IncomeTaxExaminationPenaltiesAndInterestExpenseIncome" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_ForgoneRecoveryDueToExpenseOfEnforcementAmt_terseLabel_en-US" xlink:label="lab_ecd_ForgoneRecoveryDueToExpenseOfEnforcementAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Forgone Recovery due to Expense of Enforcement, Amount </link:label>

<link:label id="lab_ecd_ForgoneRecoveryDueToExpenseOfEnforcementAmt_label_en-US" xlink:label="lab_ecd_ForgoneRecoveryDueToExpenseOfEnforcementAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Forgone Recovery due to Expense of Enforcement, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_ForgoneRecoveryDueToExpenseOfEnforcementAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_ForgoneRecoveryDueToExpenseOfEnforcementAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_ForgoneRecoveryDueToExpenseOfEnforcementAmt" xlink:to="lab_ecd_ForgoneRecoveryDueToExpenseOfEnforcementAmt" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ExcessOfEurocurrencyRateApplicableToDomesticBorrowingsOnlyMember_b8d2fcdf-bfd0-4300-bc1d-3244880f1859_terseLabel_en-US" xlink:label="lab_pwr_ExcessOfEurocurrencyRateApplicableToDomesticBorrowingsOnlyMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess of Eurocurrency Rate Applicable to Domestic Borrowings Only </link:label>

<link:label id="lab_pwr_ExcessOfEurocurrencyRateApplicableToDomesticBorrowingsOnlyMember_label_en-US" xlink:label="lab_pwr_ExcessOfEurocurrencyRateApplicableToDomesticBorrowingsOnlyMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess Of Eurocurrency Rate Applicable To Domestic Borrowings Only [Member] </link:label>

<link:label id="lab_pwr_ExcessOfEurocurrencyRateApplicableToDomesticBorrowingsOnlyMember_documentation_en-US" xlink:label="lab_pwr_ExcessOfEurocurrencyRateApplicableToDomesticBorrowingsOnlyMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess Of Eurocurrency Rate Applicable To Domestic Borrowings Only [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ExcessOfEurocurrencyRateApplicableToDomesticBorrowingsOnlyMember" xlink:href="pwr-20231231.xsd#pwr_ExcessOfEurocurrencyRateApplicableToDomesticBorrowingsOnlyMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ExcessOfEurocurrencyRateApplicableToDomesticBorrowingsOnlyMember" xlink:to="lab_pwr_ExcessOfEurocurrencyRateApplicableToDomesticBorrowingsOnlyMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_b28a1f19-7d6c-4e01-a9df-cd2f3ce8b5fd_terseLabel_en-US" xlink:label="lab_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Payment Arrangement [Abstract] </link:label>

<link:label id="lab_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_label_en-US" xlink:label="lab_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Payment Arrangement [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:to="lab_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityTaxIdentificationNumber_cd444d62-8efc-407a-8284-7b1ba4d02293_terseLabel_en-US" xlink:label="lab_dei_EntityTaxIdentificationNumber" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Tax Identification Number </link:label>

<link:label id="lab_dei_EntityTaxIdentificationNumber_label_en-US" xlink:label="lab_dei_EntityTaxIdentificationNumber" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Tax Identification Number </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityTaxIdentificationNumber"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityTaxIdentificationNumber" xlink:to="lab_dei_EntityTaxIdentificationNumber" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_ae4ce1e1-814b-48c9-aec6-e833ca811cc6_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillForeignCurrencyTranslationGainLoss" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign currency translation adjustments </link:label>

<link:label id="lab_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_label_en-US" xlink:label="lab_us-gaap_GoodwillForeignCurrencyTranslationGainLoss" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill, Foreign Currency Translation Gain (Loss) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss" xlink:to="lab_us-gaap_GoodwillForeignCurrencyTranslationGainLoss" xlink:type="arc" order="1"/>

<link:label id="lab_srt_RangeAxis_b90ad77c-4da6-4751-a6cd-cd009aa8a71b_terseLabel_en-US" xlink:label="lab_srt_RangeAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statistical Measurement [Axis] </link:label>

<link:label id="lab_srt_RangeAxis_label_en-US" xlink:label="lab_srt_RangeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statistical Measurement [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_RangeAxis" xlink:to="lab_srt_RangeAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_InsuranceRecoveries_f4c9d28c-dadc-4967-ba9f-2b995c2c0f4d_terseLabel_en-US" xlink:label="lab_us-gaap_InsuranceRecoveries" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insurance recoveries </link:label>

<link:label id="lab_us-gaap_InsuranceRecoveries_label_en-US" xlink:label="lab_us-gaap_InsuranceRecoveries" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insurance Recoveries </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InsuranceRecoveries" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InsuranceRecoveries"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InsuranceRecoveries" xlink:to="lab_us-gaap_InsuranceRecoveries" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BalanceSheetLocationDomain_77f92029-b39c-495a-be79-7a8fd88a2859_terseLabel_en-US" xlink:label="lab_us-gaap_BalanceSheetLocationDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Balance Sheet Location [Domain] </link:label>

<link:label id="lab_us-gaap_BalanceSheetLocationDomain_label_en-US" xlink:label="lab_us-gaap_BalanceSheetLocationDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Balance Sheet Location [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BalanceSheetLocationDomain" xlink:to="lab_us-gaap_BalanceSheetLocationDomain" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityInteractiveDataCurrent_f4f56e33-1a64-4210-8067-62630e0ef68a_terseLabel_en-US" xlink:label="lab_dei_EntityInteractiveDataCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Interactive Data Current </link:label>

<link:label id="lab_dei_EntityInteractiveDataCurrent_label_en-US" xlink:label="lab_dei_EntityInteractiveDataCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Interactive Data Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityInteractiveDataCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityInteractiveDataCurrent" xlink:to="lab_dei_EntityInteractiveDataCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DisaggregationOfRevenueTable_fc27d7cd-fe90-40fd-8c65-869c1dbc99e2_terseLabel_en-US" xlink:label="lab_us-gaap_DisaggregationOfRevenueTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Disaggregation of Revenue [Table] </link:label>

<link:label id="lab_us-gaap_DisaggregationOfRevenueTable_label_en-US" xlink:label="lab_us-gaap_DisaggregationOfRevenueTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Disaggregation of Revenue [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable" xlink:to="lab_us-gaap_DisaggregationOfRevenueTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_3a26aa4e-4c37-4ea1-a09b-8b06155205cb_terseLabel_en-US" xlink:label="lab_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustments to reconcile net income to net cash provided by operating activities: </link:label>

<link:label id="lab_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_label_en-US" xlink:label="lab_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="lab_us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock_a086772a-1d56-45cc-a45d-638fb1037cc6_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill and Other Intangible Assets </link:label>

<link:label id="lab_us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill and Intangible Assets, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" xlink:to="lab_us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityWellKnownSeasonedIssuer_f39aa8e5-11ee-4432-b04d-567bc827ce60_terseLabel_en-US" xlink:label="lab_dei_EntityWellKnownSeasonedIssuer" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Well-known Seasoned Issuer </link:label>

<link:label id="lab_dei_EntityWellKnownSeasonedIssuer_label_en-US" xlink:label="lab_dei_EntityWellKnownSeasonedIssuer" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Well-known Seasoned Issuer </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityWellKnownSeasonedIssuer" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityWellKnownSeasonedIssuer"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityWellKnownSeasonedIssuer" xlink:to="lab_dei_EntityWellKnownSeasonedIssuer" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DebtInstrumentVariableRateFloor_c32cc7b5-87c2-4853-87b2-31d80c138c5f_terseLabel_en-US" xlink:label="lab_pwr_DebtInstrumentVariableRateFloor" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest rate floor </link:label>

<link:label id="lab_pwr_DebtInstrumentVariableRateFloor_label_en-US" xlink:label="lab_pwr_DebtInstrumentVariableRateFloor" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Variable Rate Floor </link:label>

<link:label id="lab_pwr_DebtInstrumentVariableRateFloor_documentation_en-US" xlink:label="lab_pwr_DebtInstrumentVariableRateFloor" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Variable Rate Floor </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DebtInstrumentVariableRateFloor" xlink:href="pwr-20231231.xsd#pwr_DebtInstrumentVariableRateFloor"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DebtInstrumentVariableRateFloor" xlink:to="lab_pwr_DebtInstrumentVariableRateFloor" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OtherAssetsMember_7e839026-0a32-40da-9c8c-f0ec3e805654_terseLabel_en-US" xlink:label="lab_us-gaap_OtherAssetsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Assets, Net </link:label>

<link:label id="lab_us-gaap_OtherAssetsMember_label_en-US" xlink:label="lab_us-gaap_OtherAssetsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Assets [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherAssetsMember" xlink:to="lab_us-gaap_OtherAssetsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_861b9cfd-3271-45b6-9c72-ee43a448558c_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award [Line Items] </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_MeasureAxis_terseLabel_en-US" xlink:label="lab_ecd_MeasureAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Measure: </link:label>

<link:label id="lab_ecd_MeasureAxis_label_en-US" xlink:label="lab_ecd_MeasureAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Measure [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_MeasureAxis" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_MeasureAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_MeasureAxis" xlink:to="lab_ecd_MeasureAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_71996d0a-89de-4bea-bded-797aa64e0347_terseLabel_en-US" xlink:label="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitments and Contingencies Disclosure [Abstract] </link:label>

<link:label id="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_label_en-US" xlink:label="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitments and Contingencies Disclosure [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommitmentsAndContingenciesDisclosureAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:to="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_OutstandingRecoveryIndName_terseLabel_en-US" xlink:label="lab_ecd_OutstandingRecoveryIndName" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Name </link:label>

<link:label id="lab_ecd_OutstandingRecoveryIndName_label_en-US" xlink:label="lab_ecd_OutstandingRecoveryIndName" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Outstanding Recovery, Individual Name </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_OutstandingRecoveryIndName" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_OutstandingRecoveryIndName"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_OutstandingRecoveryIndName" xlink:to="lab_ecd_OutstandingRecoveryIndName" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RevenueFromContractWithCustomerPolicyTextBlock_488f5224-9368-4b52-b1b0-2492c86bba6e_terseLabel_en-US" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue Recognition </link:label>

<link:label id="lab_us-gaap_RevenueFromContractWithCustomerPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue from Contract with Customer [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" xlink:to="lab_us-gaap_RevenueFromContractWithCustomerPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ContractWithCustomerContractValue_5f2b21c2-443e-43b6-832e-06064a52160f_verboseLabel_en-US" xlink:label="lab_pwr_ContractWithCustomerContractValue" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Aggregate consideration for projects </link:label>

<link:label id="lab_pwr_ContractWithCustomerContractValue_label_en-US" xlink:label="lab_pwr_ContractWithCustomerContractValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Contract Value </link:label>

<link:label id="lab_pwr_ContractWithCustomerContractValue_documentation_en-US" xlink:label="lab_pwr_ContractWithCustomerContractValue" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Contract Value </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ContractWithCustomerContractValue" xlink:href="pwr-20231231.xsd#pwr_ContractWithCustomerContractValue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ContractWithCustomerContractValue" xlink:to="lab_pwr_ContractWithCustomerContractValue" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityIncorporationStateCountryCode_2f549795-fe08-4d09-9e20-fd40f4d9430c_terseLabel_en-US" xlink:label="lab_dei_EntityIncorporationStateCountryCode" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Incorporation, State or Country Code </link:label>

<link:label id="lab_dei_EntityIncorporationStateCountryCode_label_en-US" xlink:label="lab_dei_EntityIncorporationStateCountryCode" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Incorporation, State or Country Code </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityIncorporationStateCountryCode"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityIncorporationStateCountryCode" xlink:to="lab_dei_EntityIncorporationStateCountryCode" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_A2023RepurchaseProgramMember_430bf687-e0de-4b44-8cac-8c0f4f0876ad_terseLabel_en-US" xlink:label="lab_pwr_A2023RepurchaseProgramMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2023 Repurchase Program </link:label>

<link:label id="lab_pwr_A2023RepurchaseProgramMember_label_en-US" xlink:label="lab_pwr_A2023RepurchaseProgramMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2023 Repurchase Program [Member] </link:label>

<link:label id="lab_pwr_A2023RepurchaseProgramMember_documentation_en-US" xlink:label="lab_pwr_A2023RepurchaseProgramMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2023 Repurchase Program </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_A2023RepurchaseProgramMember" xlink:href="pwr-20231231.xsd#pwr_A2023RepurchaseProgramMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_A2023RepurchaseProgramMember" xlink:to="lab_pwr_A2023RepurchaseProgramMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OtherLongTermDebt_5032cc37-8d56-4127-8a74-15220611447d_terseLabel_en-US" xlink:label="lab_us-gaap_OtherLongTermDebt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other long-term debt </link:label>

<link:label id="lab_us-gaap_OtherLongTermDebt_label_en-US" xlink:label="lab_us-gaap_OtherLongTermDebt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Long-Term Debt </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLongTermDebt" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLongTermDebt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherLongTermDebt" xlink:to="lab_us-gaap_OtherLongTermDebt" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent_5ad69f0d-2794-49b2-be54-f549234512af_verboseLabel_en-US" xlink:label="lab_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Marketable equity securities </link:label>

<link:label id="lab_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent_label_en-US" xlink:label="lab_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Securities, FV-NI </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent" xlink:to="lab_us-gaap_EquitySecuritiesFvNiCurrentAndNoncurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessAcquisitionContingentConsiderationLineItems_5856c186-0e01-4bf8-8d3b-d5dec150dbf7_verboseLabel_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionContingentConsiderationLineItems" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisition, Contingent Consideration [Line Items] </link:label>

<link:label id="lab_us-gaap_BusinessAcquisitionContingentConsiderationLineItems_label_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionContingentConsiderationLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisition, Contingent Consideration [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionContingentConsiderationLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionContingentConsiderationLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessAcquisitionContingentConsiderationLineItems" xlink:to="lab_us-gaap_BusinessAcquisitionContingentConsiderationLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_df21df55-64fa-4a9c-888e-2eeb95f67f0e_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets and Liabilities and Net Deferred Income Tax Assets and Liabilities </link:label>

<link:label id="lab_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Deferred Tax Assets and Liabilities [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfDeferredTaxAssetsAndLiabilitiesTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ReductionInCompanyMaximumFundedDebtAndMaximumSeniorDebtByAllCashAndCashEquivalentsInExcessOfAmount_bfd161f5-cc3d-4bba-a1ef-d3049fce8c7c_terseLabel_en-US" xlink:label="lab_pwr_ReductionInCompanyMaximumFundedDebtAndMaximumSeniorDebtByAllCashAndCashEquivalentsInExcessOfAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reduction in Quanta's funded indebtedness reduced by cash and cash equivalents in excess of this amount </link:label>

<link:label id="lab_pwr_ReductionInCompanyMaximumFundedDebtAndMaximumSeniorDebtByAllCashAndCashEquivalentsInExcessOfAmount_label_en-US" xlink:label="lab_pwr_ReductionInCompanyMaximumFundedDebtAndMaximumSeniorDebtByAllCashAndCashEquivalentsInExcessOfAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reduction In Company Maximum Funded Debt And Maximum Senior Debt By All Cash And Cash Equivalents In Excess Of Amount </link:label>

<link:label id="lab_pwr_ReductionInCompanyMaximumFundedDebtAndMaximumSeniorDebtByAllCashAndCashEquivalentsInExcessOfAmount_documentation_en-US" xlink:label="lab_pwr_ReductionInCompanyMaximumFundedDebtAndMaximumSeniorDebtByAllCashAndCashEquivalentsInExcessOfAmount" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reduction in Quanta's maximum funded debt and maximum senior debt by all cash and cash equivalents in excess of amount. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ReductionInCompanyMaximumFundedDebtAndMaximumSeniorDebtByAllCashAndCashEquivalentsInExcessOfAmount" xlink:href="pwr-20231231.xsd#pwr_ReductionInCompanyMaximumFundedDebtAndMaximumSeniorDebtByAllCashAndCashEquivalentsInExcessOfAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ReductionInCompanyMaximumFundedDebtAndMaximumSeniorDebtByAllCashAndCashEquivalentsInExcessOfAmount" xlink:to="lab_pwr_ReductionInCompanyMaximumFundedDebtAndMaximumSeniorDebtByAllCashAndCashEquivalentsInExcessOfAmount" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_a196225e-ab2f-48e0-aead-64dbc3a0ee4d_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2024 </link:label>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Asset, Expected Amortization, Year One </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OperatingLeasePayments_161991fe-b6b4-4ffe-94ae-c306c2f6c4cc_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasePayments" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating cash flows used by operating leases </link:label>

<link:label id="lab_us-gaap_OperatingLeasePayments_label_en-US" xlink:label="lab_us-gaap_OperatingLeasePayments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Payments </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePayments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeasePayments"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasePayments" xlink:to="lab_us-gaap_OperatingLeasePayments" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CommonStockSharesOutstanding_0a598502-5d39-4e0e-9b77-dfc319fb832d_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock, shares outstanding (in shares) </link:label>

<link:label id="lab_us-gaap_CommonStockSharesOutstanding_c2340e79-6d31-4501-bb5e-9f3d053cd82f_periodStartLabel_en-US" xlink:label="lab_us-gaap_CommonStockSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Beginning Balance (in shares) </link:label>

<link:label id="lab_us-gaap_CommonStockSharesOutstanding_f96b7805-a01b-49f8-bd17-503c026dc29c_periodEndLabel_en-US" xlink:label="lab_us-gaap_CommonStockSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Ending Balance (in shares) </link:label>

<link:label id="lab_us-gaap_CommonStockSharesOutstanding_label_en-US" xlink:label="lab_us-gaap_CommonStockSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock, Shares, Outstanding </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesOutstanding"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockSharesOutstanding" xlink:to="lab_us-gaap_CommonStockSharesOutstanding" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract_1fd093d4-304a-4073-a523-129bdebc0667_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current: </link:label>

<link:label id="lab_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract_label_en-US" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Expense (Benefit), Continuing Operations [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:to="lab_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DebtInstrumentPaymentDueDateAxis_2a79549e-9328-4137-b22a-bbc2d93a037d_terseLabel_en-US" xlink:label="lab_pwr_DebtInstrumentPaymentDueDateAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Payment Due Date [Axis] </link:label>

<link:label id="lab_pwr_DebtInstrumentPaymentDueDateAxis_label_en-US" xlink:label="lab_pwr_DebtInstrumentPaymentDueDateAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Payment Due Date [Axis] </link:label>

<link:label id="lab_pwr_DebtInstrumentPaymentDueDateAxis_documentation_en-US" xlink:label="lab_pwr_DebtInstrumentPaymentDueDateAxis" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Payment Due Date </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DebtInstrumentPaymentDueDateAxis" xlink:href="pwr-20231231.xsd#pwr_DebtInstrumentPaymentDueDateAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DebtInstrumentPaymentDueDateAxis" xlink:to="lab_pwr_DebtInstrumentPaymentDueDateAxis" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_SeniorNotesDueOctober2024Member_709d8aa5-7477-4747-8053-8eb39b34e594_terseLabel_en-US" xlink:label="lab_pwr_SeniorNotesDueOctober2024Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 0.950% Senior Notes due October 2024 </link:label>

<link:label id="lab_pwr_SeniorNotesDueOctober2024Member_label_en-US" xlink:label="lab_pwr_SeniorNotesDueOctober2024Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Notes Due October 2024 [Member] </link:label>

<link:label id="lab_pwr_SeniorNotesDueOctober2024Member_documentation_en-US" xlink:label="lab_pwr_SeniorNotesDueOctober2024Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Notes Due October 2024 </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_SeniorNotesDueOctober2024Member" xlink:href="pwr-20231231.xsd#pwr_SeniorNotesDueOctober2024Member"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_SeniorNotesDueOctober2024Member" xlink:to="lab_pwr_SeniorNotesDueOctober2024Member" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_PeoMember_terseLabel_en-US" xlink:label="lab_ecd_PeoMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> PEO </link:label>

<link:label id="lab_ecd_PeoMember_label_en-US" xlink:label="lab_ecd_PeoMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> PEO [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_PeoMember" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_PeoMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_PeoMember" xlink:to="lab_ecd_PeoMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LeaseFinancingTransactionsAbstract_1d64eba8-2b96-4a9a-adaf-70b2211a0b1d_terseLabel_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transactions [Abstract] </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionsAbstract_label_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transactions [Abstract] </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionsAbstract_documentation_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionsAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transactions </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LeaseFinancingTransactionsAbstract" xlink:href="pwr-20231231.xsd#pwr_LeaseFinancingTransactionsAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LeaseFinancingTransactionsAbstract" xlink:to="lab_pwr_LeaseFinancingTransactionsAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StockholdersEquityOther_c75792cb-c0e3-4e45-b0fd-e2b986eae27c_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquityOther" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other </link:label>

<link:label id="lab_us-gaap_StockholdersEquityOther_label_en-US" xlink:label="lab_us-gaap_StockholdersEquityOther" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stockholders' Equity, Other </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityOther" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityOther"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquityOther" xlink:to="lab_us-gaap_StockholdersEquityOther" xlink:type="arc" order="1"/>

<link:label id="lab_dei_AuditorLocation_b8c2cf2a-6e21-4305-9acd-53d2146e52b4_terseLabel_en-US" xlink:label="lab_dei_AuditorLocation" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Auditor Location </link:label>

<link:label id="lab_dei_AuditorLocation_label_en-US" xlink:label="lab_dei_AuditorLocation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Auditor Location </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_AuditorLocation" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_AuditorLocation"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_AuditorLocation" xlink:to="lab_dei_AuditorLocation" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock_84a501bf-7af1-47f9-9cb8-92b41687a9cb_terseLabel_en-US" xlink:label="lab_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employee Benefit Plans </link:label>

<link:label id="lab_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Retirement Benefits [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock" xlink:to="lab_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OtherOperatingActivitiesCashFlowStatement_d54dc41c-c4d7-40ed-a8a8-5875e9bbe48e_terseLabel_en-US" xlink:label="lab_us-gaap_OtherOperatingActivitiesCashFlowStatement" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other non-cash adjustments, net </link:label>

<link:label id="lab_us-gaap_OtherOperatingActivitiesCashFlowStatement_label_en-US" xlink:label="lab_us-gaap_OtherOperatingActivitiesCashFlowStatement" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Operating Activities, Cash Flow Statement </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherOperatingActivitiesCashFlowStatement"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement" xlink:to="lab_us-gaap_OtherOperatingActivitiesCashFlowStatement" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_RightOfUseAssetObtainedInExchangeForFinanceAndOperatingLeaseLiabilitiesAbstract_929e3bc6-09af-4630-9bfb-3635b4157011_terseLabel_en-US" xlink:label="lab_pwr_RightOfUseAssetObtainedInExchangeForFinanceAndOperatingLeaseLiabilitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease assets obtained in exchange for lease liabilities: </link:label>

<link:label id="lab_pwr_RightOfUseAssetObtainedInExchangeForFinanceAndOperatingLeaseLiabilitiesAbstract_label_en-US" xlink:label="lab_pwr_RightOfUseAssetObtainedInExchangeForFinanceAndOperatingLeaseLiabilitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Right-Of-Use Asset Obtained In Exchange For Finance And Operating Lease Liabilities [Abstract] </link:label>

<link:label id="lab_pwr_RightOfUseAssetObtainedInExchangeForFinanceAndOperatingLeaseLiabilitiesAbstract_documentation_en-US" xlink:label="lab_pwr_RightOfUseAssetObtainedInExchangeForFinanceAndOperatingLeaseLiabilitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Right-Of-Use Asset Obtained In Exchange For Finance And Operating Lease Liabilities [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_RightOfUseAssetObtainedInExchangeForFinanceAndOperatingLeaseLiabilitiesAbstract" xlink:href="pwr-20231231.xsd#pwr_RightOfUseAssetObtainedInExchangeForFinanceAndOperatingLeaseLiabilitiesAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_RightOfUseAssetObtainedInExchangeForFinanceAndOperatingLeaseLiabilitiesAbstract" xlink:to="lab_pwr_RightOfUseAssetObtainedInExchangeForFinanceAndOperatingLeaseLiabilitiesAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfVariableInterestEntitiesTable_c1460fd1-cde9-4eb1-a18d-66f19764832d_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfVariableInterestEntitiesTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Variable Interest Entities [Table] </link:label>

<link:label id="lab_us-gaap_ScheduleOfVariableInterestEntitiesTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfVariableInterestEntitiesTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Variable Interest Entities [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfVariableInterestEntitiesTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfVariableInterestEntitiesTable" xlink:to="lab_us-gaap_ScheduleOfVariableInterestEntitiesTable" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearTwo_0cd8170f-11db-44cc-906a-94e1a0244dc9_terseLabel_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearTwo" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Tax carryforwards expiring in year two </link:label>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearTwo_label_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearTwo" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expiration Amount Of State And Foreign Net Operating Loss Carryforwards Year Two </link:label>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearTwo_documentation_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearTwo" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expiration amount of state and foreign net operating loss carryforwards year two. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearTwo" xlink:href="pwr-20231231.xsd#pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearTwo"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearTwo" xlink:to="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearTwo" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_de7c7acc-aa89-49d4-9334-643eb3a5a0f6_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> State taxes </link:label>

<link:label id="lab_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_label_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:to="lab_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CommonStockParOrStatedValuePerShare_9e42fdb3-8b49-42f4-a17a-f3283934da69_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockParOrStatedValuePerShare" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock, par value (in dollars per share) </link:label>

<link:label id="lab_us-gaap_CommonStockParOrStatedValuePerShare_label_en-US" xlink:label="lab_us-gaap_CommonStockParOrStatedValuePerShare" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock, Par or Stated Value Per Share </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockParOrStatedValuePerShare" xlink:to="lab_us-gaap_CommonStockParOrStatedValuePerShare" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_NumberOfPools_5e66e37d-b7c8-4617-a5d4-820d642d2142_terseLabel_en-US" xlink:label="lab_pwr_NumberOfPools" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of pools </link:label>

<link:label id="lab_pwr_NumberOfPools_label_en-US" xlink:label="lab_pwr_NumberOfPools" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number Of Pools </link:label>

<link:label id="lab_pwr_NumberOfPools_documentation_en-US" xlink:label="lab_pwr_NumberOfPools" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number Of Pools </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_NumberOfPools" xlink:href="pwr-20231231.xsd#pwr_NumberOfPools"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_NumberOfPools" xlink:to="lab_pwr_NumberOfPools" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities_a28b0a68-3453-47df-a8ff-fe5eaccf2762_totalLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net cash used in investing activities </link:label>

<link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Cash Provided by (Used in) Investing Activities </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingIncomeLossMarginPercentage_1d769f82-55a1-4d2c-9f9c-c7ef31247f9c_terseLabel_en-US" xlink:label="lab_pwr_OperatingIncomeLossMarginPercentage" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating income (loss) margin (in percent) </link:label>

<link:label id="lab_pwr_OperatingIncomeLossMarginPercentage_label_en-US" xlink:label="lab_pwr_OperatingIncomeLossMarginPercentage" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Income (Loss) Margin, Percentage </link:label>

<link:label id="lab_pwr_OperatingIncomeLossMarginPercentage_documentation_en-US" xlink:label="lab_pwr_OperatingIncomeLossMarginPercentage" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Income (Loss) Margin, Percentage </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingIncomeLossMarginPercentage" xlink:href="pwr-20231231.xsd#pwr_OperatingIncomeLossMarginPercentage"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingIncomeLossMarginPercentage" xlink:to="lab_pwr_OperatingIncomeLossMarginPercentage" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxReconciliationNondeductibleExpenseMealsAndEntertainment_787f3af1-9791-4907-ab45-51f80fdd0117_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationNondeductibleExpenseMealsAndEntertainment" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employee per diems, meals and entertainment </link:label>

<link:label id="lab_us-gaap_IncomeTaxReconciliationNondeductibleExpenseMealsAndEntertainment_label_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationNondeductibleExpenseMealsAndEntertainment" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Nondeductible Expense, Meals and Entertainment, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseMealsAndEntertainment" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxReconciliationNondeductibleExpenseMealsAndEntertainment"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxReconciliationNondeductibleExpenseMealsAndEntertainment" xlink:to="lab_us-gaap_IncomeTaxReconciliationNondeductibleExpenseMealsAndEntertainment" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentAxis_723abdc9-242e-4c06-bb49-8e2b1a68a1ee_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument [Axis] </link:label>

<link:label id="lab_us-gaap_DebtInstrumentAxis_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentAxis" xlink:to="lab_us-gaap_DebtInstrumentAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_0257fefa-b465-43d7-b5c2-891a127de97d_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenues included in consolidated results of operations </link:label>

<link:label id="lab_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual" xlink:to="lab_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_OutstandingAggtErrCompAmt_terseLabel_en-US" xlink:label="lab_ecd_OutstandingAggtErrCompAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Outstanding Aggregate Erroneous Compensation Amount </link:label>

<link:label id="lab_ecd_OutstandingAggtErrCompAmt_label_en-US" xlink:label="lab_ecd_OutstandingAggtErrCompAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Outstanding Aggregate Erroneous Compensation Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_OutstandingAggtErrCompAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_OutstandingAggtErrCompAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_OutstandingAggtErrCompAmt" xlink:to="lab_ecd_OutstandingAggtErrCompAmt" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CreditFacilityAxis_d8d84a59-ecec-4c93-8a5f-5f678d35573f_terseLabel_en-US" xlink:label="lab_us-gaap_CreditFacilityAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Facility [Axis] </link:label>

<link:label id="lab_us-gaap_CreditFacilityAxis_label_en-US" xlink:label="lab_us-gaap_CreditFacilityAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Facility [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CreditFacilityAxis" xlink:to="lab_us-gaap_CreditFacilityAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock_e9fb74cc-17d0-4af9-9253-3a19f000c2b2_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Maturities of Long-term Debt </link:label>

<link:label id="lab_us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Maturities of Long-Term Debt [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfMaturitiesOfLongTermDebtTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_Liabilities_848bd681-ee23-4b9f-91d3-1fc78ac8c5d8_totalLabel_en-US" xlink:label="lab_us-gaap_Liabilities" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total liabilities </link:label>

<link:label id="lab_us-gaap_Liabilities_label_en-US" xlink:label="lab_us-gaap_Liabilities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Liabilities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Liabilities" xlink:to="lab_us-gaap_Liabilities" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CurrentIncomeTaxExpenseBenefit_fde7a4a6-59f5-43fd-8801-3ec92e638db8_totalLabel_en-US" xlink:label="lab_us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total current tax provision </link:label>

<link:label id="lab_us-gaap_CurrentIncomeTaxExpenseBenefit_label_en-US" xlink:label="lab_us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current Income Tax Expense (Benefit) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:to="lab_us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_f2e50fd8-9a99-4d95-a28e-afdab5b45a08_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expected volatility </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LesseeSupplementalCashFlowsFromLeasesTableTextBlock_d40c0684-917a-47c6-a6c1-cea39663f222_terseLabel_en-US" xlink:label="lab_pwr_LesseeSupplementalCashFlowsFromLeasesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Supplemental Cash Flow Information Related to Leases </link:label>

<link:label id="lab_pwr_LesseeSupplementalCashFlowsFromLeasesTableTextBlock_label_en-US" xlink:label="lab_pwr_LesseeSupplementalCashFlowsFromLeasesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Supplemental Cash Flows From Leases [Table Text Block] </link:label>

<link:label id="lab_pwr_LesseeSupplementalCashFlowsFromLeasesTableTextBlock_documentation_en-US" xlink:label="lab_pwr_LesseeSupplementalCashFlowsFromLeasesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Supplemental Cash Flows From Leases [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LesseeSupplementalCashFlowsFromLeasesTableTextBlock" xlink:href="pwr-20231231.xsd#pwr_LesseeSupplementalCashFlowsFromLeasesTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LesseeSupplementalCashFlowsFromLeasesTableTextBlock" xlink:to="lab_pwr_LesseeSupplementalCashFlowsFromLeasesTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ProjectsInProgressMember_c27e2528-3734-49e6-83ef-aabcf8e33e2f_terseLabel_en-US" xlink:label="lab_pwr_ProjectsInProgressMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Projects In Progress </link:label>

<link:label id="lab_pwr_ProjectsInProgressMember_label_en-US" xlink:label="lab_pwr_ProjectsInProgressMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Projects In Progress [Member] </link:label>

<link:label id="lab_pwr_ProjectsInProgressMember_documentation_en-US" xlink:label="lab_pwr_ProjectsInProgressMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Projects In Progress </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ProjectsInProgressMember" xlink:href="pwr-20231231.xsd#pwr_ProjectsInProgressMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ProjectsInProgressMember" xlink:to="lab_pwr_ProjectsInProgressMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CrossDefaultProvisions_58267e2c-e73f-41ab-8490-a1f2694f74cf_terseLabel_en-US" xlink:label="lab_pwr_CrossDefaultProvisions" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cross default provisions with debt instruments exceeding this amount </link:label>

<link:label id="lab_pwr_CrossDefaultProvisions_label_en-US" xlink:label="lab_pwr_CrossDefaultProvisions" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cross Default Provisions </link:label>

<link:label id="lab_pwr_CrossDefaultProvisions_documentation_en-US" xlink:label="lab_pwr_CrossDefaultProvisions" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cross-default provisions. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CrossDefaultProvisions" xlink:href="pwr-20231231.xsd#pwr_CrossDefaultProvisions"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CrossDefaultProvisions" xlink:to="lab_pwr_CrossDefaultProvisions" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RepaymentsOfLongTermLinesOfCredit_67ac2659-1d1d-4d36-ac34-d7036e0ddfb0_negatedLabel_en-US" xlink:label="lab_us-gaap_RepaymentsOfLongTermLinesOfCredit" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments under credit facility and commercial paper program </link:label>

<link:label id="lab_us-gaap_RepaymentsOfLongTermLinesOfCredit_6e9ad182-b3ee-4073-8cb7-2cedab079f07_terseLabel_en-US" xlink:label="lab_us-gaap_RepaymentsOfLongTermLinesOfCredit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments under credit facility </link:label>

<link:label id="lab_us-gaap_RepaymentsOfLongTermLinesOfCredit_label_en-US" xlink:label="lab_us-gaap_RepaymentsOfLongTermLinesOfCredit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Repayments of Long-Term Lines of Credit </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfLongTermLinesOfCredit"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit" xlink:to="lab_us-gaap_RepaymentsOfLongTermLinesOfCredit" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary_92713947-1c03-42be-a9fb-dc007721bdc8_terseLabel_en-US" xlink:label="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Estimated committed capital in next fiscal year </link:label>

<link:label id="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary_label_en-US" xlink:label="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecorded Unconditional Purchase Obligation, to be Paid, Year One </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary" xlink:to="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LeaseFinancingTransactionAssets_369a97ef-eef4-413d-a536-0c281e4dac41_terseLabel_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionAssets" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease financing transaction assets </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionAssets_label_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionAssets" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transaction, Assets </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionAssets_documentation_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionAssets" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transaction, Assets </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LeaseFinancingTransactionAssets" xlink:href="pwr-20231231.xsd#pwr_LeaseFinancingTransactionAssets"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LeaseFinancingTransactionAssets" xlink:to="lab_pwr_LeaseFinancingTransactionAssets" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_NonRule10b51ArrAdoptedFlag_terseLabel_en-US" xlink:label="lab_ecd_NonRule10b51ArrAdoptedFlag" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-Rule 10b5-1 Arrangement Adopted </link:label>

<link:label id="lab_ecd_NonRule10b51ArrAdoptedFlag_label_en-US" xlink:label="lab_ecd_NonRule10b51ArrAdoptedFlag" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-Rule 10b5-1 Arrangement Adopted [Flag] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_NonRule10b51ArrAdoptedFlag" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_NonRule10b51ArrAdoptedFlag"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_NonRule10b51ArrAdoptedFlag" xlink:to="lab_ecd_NonRule10b51ArrAdoptedFlag" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_BusinessesThatProvideVariousServicesInTheUnitedStatesMember_3bc9fd4d-185b-47a8-9ce5-503bf705e47f_terseLabel_en-US" xlink:label="lab_pwr_BusinessesThatProvideVariousServicesInTheUnitedStatesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Businesses That Provide Various Services In The United States </link:label>

<link:label id="lab_pwr_BusinessesThatProvideVariousServicesInTheUnitedStatesMember_label_en-US" xlink:label="lab_pwr_BusinessesThatProvideVariousServicesInTheUnitedStatesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Businesses That Provide Various Services In The United States [Member] </link:label>

<link:label id="lab_pwr_BusinessesThatProvideVariousServicesInTheUnitedStatesMember_documentation_en-US" xlink:label="lab_pwr_BusinessesThatProvideVariousServicesInTheUnitedStatesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Businesses That Provide Various Services In The United States </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_BusinessesThatProvideVariousServicesInTheUnitedStatesMember" xlink:href="pwr-20231231.xsd#pwr_BusinessesThatProvideVariousServicesInTheUnitedStatesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_BusinessesThatProvideVariousServicesInTheUnitedStatesMember" xlink:to="lab_pwr_BusinessesThatProvideVariousServicesInTheUnitedStatesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain_68a86256-3394-45f6-8bcf-3b1697bdb926_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment, Type [Domain] </link:label>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Lived Tangible Asset [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:type="arc" order="1"/>

<link:label id="lab_country_CA_e5ea2b01-903d-4b41-8545-1d7a5dfce39f_terseLabel_en-US" xlink:label="lab_country_CA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Canada </link:label>

<link:label id="lab_country_CA_label_en-US" xlink:label="lab_country_CA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> CANADA </link:label>

<link:loc xlink:type="locator" xlink:label="loc_country_CA" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_CA"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_country_CA" xlink:to="lab_country_CA" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_SuretyBackedLettersOfCreditMember_b4e63c96-a5be-4481-883f-9a73616ad1fa_terseLabel_en-US" xlink:label="lab_pwr_SuretyBackedLettersOfCreditMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Surety-Backed Letters Of Credit </link:label>

<link:label id="lab_pwr_SuretyBackedLettersOfCreditMember_label_en-US" xlink:label="lab_pwr_SuretyBackedLettersOfCreditMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Surety-Backed Letters Of Credit [Member] </link:label>

<link:label id="lab_pwr_SuretyBackedLettersOfCreditMember_documentation_en-US" xlink:label="lab_pwr_SuretyBackedLettersOfCreditMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Surety-Backed Letters Of Credit </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_SuretyBackedLettersOfCreditMember" xlink:href="pwr-20231231.xsd#pwr_SuretyBackedLettersOfCreditMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_SuretyBackedLettersOfCreditMember" xlink:to="lab_pwr_SuretyBackedLettersOfCreditMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible_e6201f72-0324-4598-861c-fa26b792b821_verboseLabel_en-US" xlink:label="lab_us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reasonably possible reduction to the balance of unrecognized tax benefits in succeeding 12 months </link:label>

<link:label id="lab_us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible_label_en-US" xlink:label="lab_us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Decrease in Unrecognized Tax Benefits is Reasonably Possible </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible" xlink:to="lab_us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingAndFinanceLeasesWeightedAverageRemainingLeaseTermAbstract_6c66994a-a183-45cc-ab64-bb4c9d5cebf7_terseLabel_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeasesWeightedAverageRemainingLeaseTermAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted average remaining lease term (in years): </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeasesWeightedAverageRemainingLeaseTermAbstract_label_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeasesWeightedAverageRemainingLeaseTermAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Leases, Weighted Average Remaining Lease Term [Abstract] </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeasesWeightedAverageRemainingLeaseTermAbstract_documentation_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeasesWeightedAverageRemainingLeaseTermAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Leases, Weighted Average Remaining Lease Term [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingAndFinanceLeasesWeightedAverageRemainingLeaseTermAbstract" xlink:href="pwr-20231231.xsd#pwr_OperatingAndFinanceLeasesWeightedAverageRemainingLeaseTermAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingAndFinanceLeasesWeightedAverageRemainingLeaseTermAbstract" xlink:to="lab_pwr_OperatingAndFinanceLeasesWeightedAverageRemainingLeaseTermAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_PerformanceBasedAwardPerformancePercentage_401e2bc4-beef-4914-8889-f3c254cd423e_terseLabel_en-US" xlink:label="lab_pwr_PerformanceBasedAwardPerformancePercentage" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Performance units performance percentage </link:label>

<link:label id="lab_pwr_PerformanceBasedAwardPerformancePercentage_label_en-US" xlink:label="lab_pwr_PerformanceBasedAwardPerformancePercentage" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Performance Based Award Performance Percentage </link:label>

<link:label id="lab_pwr_PerformanceBasedAwardPerformancePercentage_documentation_en-US" xlink:label="lab_pwr_PerformanceBasedAwardPerformancePercentage" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Performance Based Award Performance Percentage </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_PerformanceBasedAwardPerformancePercentage" xlink:href="pwr-20231231.xsd#pwr_PerformanceBasedAwardPerformancePercentage"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_PerformanceBasedAwardPerformancePercentage" xlink:to="lab_pwr_PerformanceBasedAwardPerformancePercentage" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAsset_f0d36ea0-367f-4980-a259-0a22d4cc5afe_terseLabel_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease assets </link:label>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAsset_label_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Operating Lease, Right-Of-Use Asset </link:label>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAsset_documentation_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Operating Lease, Right-Of-Use Asset </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAsset" xlink:href="pwr-20231231.xsd#pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAsset"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAsset" xlink:to="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAsset" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LifeInsuranceCorporateOrBankOwnedAmount_1c0a93ac-00a5-4f78-8b88-7d4701e77790_terseLabel_en-US" xlink:label="lab_us-gaap_LifeInsuranceCorporateOrBankOwnedAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investments in company-owned life insurance policies </link:label>

<link:label id="lab_us-gaap_LifeInsuranceCorporateOrBankOwnedAmount_label_en-US" xlink:label="lab_us-gaap_LifeInsuranceCorporateOrBankOwnedAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Life Insurance, Corporate or Bank Owned, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LifeInsuranceCorporateOrBankOwnedAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LifeInsuranceCorporateOrBankOwnedAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LifeInsuranceCorporateOrBankOwnedAmount" xlink:to="lab_us-gaap_LifeInsuranceCorporateOrBankOwnedAmount" xlink:type="arc" order="1"/>

<link:label id="lab_currency_USD_6d38c7cc-e52a-4f0b-abd1-ff236b23ab50_terseLabel_en-US" xlink:label="lab_currency_USD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> U.S. Dollars </link:label>

<link:label id="lab_currency_USD_label_en-US" xlink:label="lab_currency_USD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> United States of America, Dollars </link:label>

<link:loc xlink:type="locator" xlink:label="loc_currency_USD" xlink:href="https://xbrl.sec.gov/currency/2023/currency-2023.xsd#currency_USD"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_currency_USD" xlink:to="lab_currency_USD" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AwardsCloseToMnpiDiscTableTextBlock_terseLabel_en-US" xlink:label="lab_ecd_AwardsCloseToMnpiDiscTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Awards Close in Time to MNPI Disclosures, Table </link:label>

<link:label id="lab_ecd_AwardsCloseToMnpiDiscTableTextBlock_label_en-US" xlink:label="lab_ecd_AwardsCloseToMnpiDiscTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Awards Close in Time to MNPI Disclosures [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AwardsCloseToMnpiDiscTableTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AwardsCloseToMnpiDiscTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AwardsCloseToMnpiDiscTableTextBlock" xlink:to="lab_ecd_AwardsCloseToMnpiDiscTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_e57e1211-b154-425e-a39a-f16aeae74ecb_terseLabel_en-US" xlink:label="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> State </link:label>

<link:label id="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_label_en-US" xlink:label="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current State and Local Tax Expense (Benefit) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CurrentStateAndLocalTaxExpenseBenefit"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:to="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SegmentReportingPolicyPolicyTextBlock_b72cdc77-7b44-4912-ab84-9087512b344d_terseLabel_en-US" xlink:label="lab_us-gaap_SegmentReportingPolicyPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Information </link:label>

<link:label id="lab_us-gaap_SegmentReportingPolicyPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_SegmentReportingPolicyPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Reporting, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingPolicyPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingPolicyPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SegmentReportingPolicyPolicyTextBlock" xlink:to="lab_us-gaap_SegmentReportingPolicyPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AssetsCurrent_642b650d-9594-47e8-b7bb-794b8461ca04_totalLabel_en-US" xlink:label="lab_us-gaap_AssetsCurrent" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total current assets </link:label>

<link:label id="lab_us-gaap_AssetsCurrent_label_en-US" xlink:label="lab_us-gaap_AssetsCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Assets, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsCurrent" xlink:to="lab_us-gaap_AssetsCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AssetImpairmentCharges_5129ccb8-0a93-4e5c-8f71-92d6e4473661_negatedLabel_en-US" xlink:label="lab_us-gaap_AssetImpairmentCharges" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Asset impairment charges </link:label>

<link:label id="lab_us-gaap_AssetImpairmentCharges_25635b5d-0755-41ed-9049-414245d0907d_terseLabel_en-US" xlink:label="lab_us-gaap_AssetImpairmentCharges" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Asset impairment charges </link:label>

<link:label id="lab_us-gaap_AssetImpairmentCharges_label_en-US" xlink:label="lab_us-gaap_AssetImpairmentCharges" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Asset Impairment Charges </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetImpairmentCharges"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetImpairmentCharges" xlink:to="lab_us-gaap_AssetImpairmentCharges" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationLiability_d0e01fc1-edac-405c-8f9e-75b55e444c45_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair value of contingent consideration liability </link:label>

<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationLiability_bccbd878-8fe2-4c39-a419-9b759c825f24_verboseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contingent consideration </link:label>

<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationLiability_b1e4e733-4cf9-43c2-9e80-d5fb7d91505b_totalLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total contingent consideration liabilities </link:label>

<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationLiability_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Contingent Consideration, Liability </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:to="lab_us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RetirementPlanNameDomain_b5287724-b665-4773-a71d-7df46e49e3c3_terseLabel_en-US" xlink:label="lab_us-gaap_RetirementPlanNameDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Multiemployer Plan Name [Domain] </link:label>

<link:label id="lab_us-gaap_RetirementPlanNameDomain_label_en-US" xlink:label="lab_us-gaap_RetirementPlanNameDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Retirement Plan Name [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanNameDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RetirementPlanNameDomain" xlink:to="lab_us-gaap_RetirementPlanNameDomain" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToInterestCoverageRatio_86e063cb-15ed-46e2-90d6-cb5ddd118643_terseLabel_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToInterestCoverageRatio" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of fiscal quarters applicable to interest coverage ratio </link:label>

<link:label id="lab_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToInterestCoverageRatio_label_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToInterestCoverageRatio" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Covenant, Number Of Fiscal Quarters Applicable To Interest Coverage Ratio </link:label>

<link:label id="lab_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToInterestCoverageRatio_documentation_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToInterestCoverageRatio" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Covenant, Number Of Fiscal Quarters Applicable To Interest Coverage Ratio </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToInterestCoverageRatio" xlink:href="pwr-20231231.xsd#pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToInterestCoverageRatio"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToInterestCoverageRatio" xlink:to="lab_pwr_DebtInstrumentCovenantNumberOfFiscalQuartersApplicableToInterestCoverageRatio" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EarningsPerSharePolicyTextBlock_587fc627-2d3f-4c2f-93bc-c513bb29625a_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerSharePolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Earnings Per Share </link:label>

<link:label id="lab_us-gaap_EarningsPerSharePolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_EarningsPerSharePolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Earnings Per Share, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerSharePolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerSharePolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerSharePolicyTextBlock" xlink:to="lab_us-gaap_EarningsPerSharePolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities_a19dfa4a-50e4-4aa8-aa7e-0db6682c7eeb_totalLabel_en-US" xlink:label="lab_us-gaap_LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total long-term debt obligations </link:label>

<link:label id="lab_us-gaap_LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities_label_en-US" xlink:label="lab_us-gaap_LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Debt and Lease Obligation, Including Current Maturities </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities" xlink:to="lab_us-gaap_LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock_bb5b71e4-b1f1-4bb7-a2cd-28c2cfe5f24e_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill and Other Intangible Assets </link:label>

<link:label id="lab_us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill and Intangible Assets Disclosure [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock" xlink:to="lab_us-gaap_GoodwillAndIntangibleAssetsDisclosureTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StockRepurchasedDuringPeriodShares_ae045d8d-a345-4201-adbf-085282ef1c11_terseLabel_en-US" xlink:label="lab_us-gaap_StockRepurchasedDuringPeriodShares" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Shares </link:label>

<link:label id="lab_us-gaap_StockRepurchasedDuringPeriodShares_label_en-US" xlink:label="lab_us-gaap_StockRepurchasedDuringPeriodShares" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Repurchased During Period, Shares </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockRepurchasedDuringPeriodShares" xlink:to="lab_us-gaap_StockRepurchasedDuringPeriodShares" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock_4a2b7b8f-2d7f-4ebf-b606-9637b2f60549_terseLabel_en-US" xlink:label="lab_us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> New Accounting Pronouncements </link:label>

<link:label id="lab_us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock_label_en-US" xlink:label="lab_us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounting Standards Update and Change in Accounting Principle [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock" xlink:to="lab_us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount_03084327-5411-4551-8a0d-1a9148c6654c_terseLabel_en-US" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock-based compensation </link:label>

<link:label id="lab_us-gaap_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount_label_en-US" xlink:label="lab_us-gaap_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Tax Expense (Benefit), Share-Based Payment Arrangement, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount" xlink:to="lab_us-gaap_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_SeniorCreditFacilityMember_30cf9680-0bbd-454d-8726-9486b248ee23_terseLabel_en-US" xlink:label="lab_pwr_SeniorCreditFacilityMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Credit Facility </link:label>

<link:label id="lab_pwr_SeniorCreditFacilityMember_label_en-US" xlink:label="lab_pwr_SeniorCreditFacilityMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Credit Facility [Member] </link:label>

<link:label id="lab_pwr_SeniorCreditFacilityMember_documentation_en-US" xlink:label="lab_pwr_SeniorCreditFacilityMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Credit Facility [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_SeniorCreditFacilityMember" xlink:href="pwr-20231231.xsd#pwr_SeniorCreditFacilityMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_SeniorCreditFacilityMember" xlink:to="lab_pwr_SeniorCreditFacilityMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ConcentrationRiskPercentage1_9857531e-56c2-4584-83bb-94550c00328c_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskPercentage1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration risk (in percent) </link:label>

<link:label id="lab_us-gaap_ConcentrationRiskPercentage1_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskPercentage1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk, Percentage </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskPercentage1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskPercentage1" xlink:to="lab_us-gaap_ConcentrationRiskPercentage1" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentRevenueChangeInEstimatePercent_4dc0f12f-1818-46e4-bd02-c23c6f0af777_terseLabel_en-US" xlink:label="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentRevenueChangeInEstimatePercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Change in contract estimates, favorable (unfavorable) impact on revenue, percent </link:label>

<link:label id="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentRevenueChangeInEstimatePercent_label_en-US" xlink:label="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentRevenueChangeInEstimatePercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Cumulative Catch-Up Adjustment, Revenue, Change In Estimate, Percent </link:label>

<link:label id="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentRevenueChangeInEstimatePercent_documentation_en-US" xlink:label="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentRevenueChangeInEstimatePercent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Cumulative Catch-Up Adjustment, Revenue, Change In Estimate, Percent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentRevenueChangeInEstimatePercent" xlink:href="pwr-20231231.xsd#pwr_ContractWithCustomerCumulativeCatchUpAdjustmentRevenueChangeInEstimatePercent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentRevenueChangeInEstimatePercent" xlink:to="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentRevenueChangeInEstimatePercent" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OtherComprehensiveIncomeLossOtherTax_b572e14b-ebd7-4344-8c21-07ab6669fe2b_terseLabel_en-US" xlink:label="lab_pwr_OtherComprehensiveIncomeLossOtherTax" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other comprehensive income (loss) other, tax </link:label>

<link:label id="lab_pwr_OtherComprehensiveIncomeLossOtherTax_label_en-US" xlink:label="lab_pwr_OtherComprehensiveIncomeLossOtherTax" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Comprehensive Income (Loss), Other, Tax </link:label>

<link:label id="lab_pwr_OtherComprehensiveIncomeLossOtherTax_documentation_en-US" xlink:label="lab_pwr_OtherComprehensiveIncomeLossOtherTax" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other comprehensive income other tax. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OtherComprehensiveIncomeLossOtherTax" xlink:href="pwr-20231231.xsd#pwr_OtherComprehensiveIncomeLossOtherTax"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OtherComprehensiveIncomeLossOtherTax" xlink:to="lab_pwr_OtherComprehensiveIncomeLossOtherTax" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_559f39a5-b1c7-41b4-9d30-37f9e631719f_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted average grant date fair value (in dollars per share) </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_44b3aed6-4cd3-4ef5-a912-6e7c8db51bb1_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2028 </link:label>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Asset, Expected Amortization, Year Five </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_c83cd9f5-07e3-427f-8e18-52c45eee0e8b_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2027 </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, to be Paid, Year Four </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearThree_e21e1e92-af62-419c-bf6c-c4bc1c9af0d4_terseLabel_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearThree" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Tax carryforwards expiring in year three </link:label>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearThree_label_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearThree" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expiration Amount Of State And Foreign Net Operating Loss Carryforwards Year Three </link:label>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearThree_documentation_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearThree" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expiration amount of state and foreign net operating loss carryforwards year three. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearThree" xlink:href="pwr-20231231.xsd#pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearThree"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearThree" xlink:to="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearThree" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_0c203b7b-01eb-4341-b0df-f193a1928dc5_totalLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net cash provided by operating activities </link:label>

<link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Cash Provided by (Used in) Operating Activities </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock_78c8ddb6-b510-44d6-9d17-92d7c30a325b_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Estimated Future Aggregate Amortization Expense of Intangible Assets </link:label>

<link:label id="lab_us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock" xlink:to="lab_us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent_448cf4a2-996c-4427-84d7-305a47caa5b6_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts payable and accrued expenses </link:label>

<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Contingent Consideration, Liability, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent" xlink:to="lab_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StatementClassOfStockAxis_1b4dcab5-a117-4312-b6ce-6c3824ae23c9_terseLabel_en-US" xlink:label="lab_us-gaap_StatementClassOfStockAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class of Stock [Axis] </link:label>

<link:label id="lab_us-gaap_StatementClassOfStockAxis_label_en-US" xlink:label="lab_us-gaap_StatementClassOfStockAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class of Stock [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementClassOfStockAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementClassOfStockAxis" xlink:to="lab_us-gaap_StatementClassOfStockAxis" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_ErrCompRecoveryTable_terseLabel_en-US" xlink:label="lab_ecd_ErrCompRecoveryTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Erroneously Awarded Compensation Recovery </link:label>

<link:label id="lab_ecd_ErrCompRecoveryTable_label_en-US" xlink:label="lab_ecd_ErrCompRecoveryTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Erroneously Awarded Compensation Recovery [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_ErrCompRecoveryTable" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_ErrCompRecoveryTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_ErrCompRecoveryTable" xlink:to="lab_ecd_ErrCompRecoveryTable" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_SegmentConcentrationRiskMember_50e10e7c-7643-49d6-8303-2bb61d67f1cc_terseLabel_en-US" xlink:label="lab_pwr_SegmentConcentrationRiskMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Concentration Risk </link:label>

<link:label id="lab_pwr_SegmentConcentrationRiskMember_label_en-US" xlink:label="lab_pwr_SegmentConcentrationRiskMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Concentration Risk [Member] </link:label>

<link:label id="lab_pwr_SegmentConcentrationRiskMember_documentation_en-US" xlink:label="lab_pwr_SegmentConcentrationRiskMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Concentration Risk </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_SegmentConcentrationRiskMember" xlink:href="pwr-20231231.xsd#pwr_SegmentConcentrationRiskMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_SegmentConcentrationRiskMember" xlink:to="lab_pwr_SegmentConcentrationRiskMember" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AwardTmgHowMnpiCnsdrdTextBlock_terseLabel_en-US" xlink:label="lab_ecd_AwardTmgHowMnpiCnsdrdTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Timing, How MNPI Considered </link:label>

<link:label id="lab_ecd_AwardTmgHowMnpiCnsdrdTextBlock_label_en-US" xlink:label="lab_ecd_AwardTmgHowMnpiCnsdrdTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Timing, How MNPI Considered [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AwardTmgHowMnpiCnsdrdTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AwardTmgHowMnpiCnsdrdTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AwardTmgHowMnpiCnsdrdTextBlock" xlink:to="lab_ecd_AwardTmgHowMnpiCnsdrdTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationAndAssetAcquisitionAbstract_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationAndAssetAcquisitionAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination and Asset Acquisition [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAndAssetAcquisitionAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationAndAssetAcquisitionAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationAndAssetAcquisitionAbstract" xlink:to="lab_us-gaap_BusinessCombinationAndAssetAcquisitionAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CommercialPaperMember_e5a2c7e1-3ff9-4c60-bcb4-3b9fd10f8c60_terseLabel_en-US" xlink:label="lab_us-gaap_CommercialPaperMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commercial Paper </link:label>

<link:label id="lab_us-gaap_CommercialPaperMember_label_en-US" xlink:label="lab_us-gaap_CommercialPaperMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commercial Paper [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommercialPaperMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommercialPaperMember" xlink:to="lab_us-gaap_CommercialPaperMember" xlink:type="arc" order="1"/>

<link:label id="lab_srt_ConsolidationItemsAxis_6f6bc47e-0dfc-4358-8220-981b6086abdb_terseLabel_en-US" xlink:label="lab_srt_ConsolidationItemsAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Consolidation Items [Axis] </link:label>

<link:label id="lab_srt_ConsolidationItemsAxis_label_en-US" xlink:label="lab_srt_ConsolidationItemsAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Consolidation Items [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ConsolidationItemsAxis" xlink:to="lab_srt_ConsolidationItemsAxis" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LeaseFinancingTransactionLiabilitiesCurrent_be8aa2c3-59ae-4b53-816f-b37c27bc23cb_terseLabel_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionLiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease financing transaction liabilities </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionLiabilitiesCurrent_label_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionLiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transaction, Liabilities, Current </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionLiabilitiesCurrent_documentation_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionLiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transaction, Liabilities, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LeaseFinancingTransactionLiabilitiesCurrent" xlink:href="pwr-20231231.xsd#pwr_LeaseFinancingTransactionLiabilitiesCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LeaseFinancingTransactionLiabilitiesCurrent" xlink:to="lab_pwr_LeaseFinancingTransactionLiabilitiesCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessAcquisitionsProFormaRevenue_b9a7dc66-287c-4538-8ff8-d0418a9b6bdb_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionsProFormaRevenue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenues </link:label>

<link:label id="lab_us-gaap_BusinessAcquisitionsProFormaRevenue_label_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionsProFormaRevenue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisition, Pro Forma Revenue </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaRevenue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessAcquisitionsProFormaRevenue" xlink:to="lab_us-gaap_BusinessAcquisitionsProFormaRevenue" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxAssetsValuationAllowance_6e20e46e-eeec-4946-b1ea-2571908eea39_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsValuationAllowance" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Valuation allowance for deferred income tax assets </link:label>

<link:label id="lab_us-gaap_DeferredTaxAssetsValuationAllowance_409e5a79-a032-4a5b-bc55-f362a2705205_negatedLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsValuationAllowance" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Valuation allowance </link:label>

<link:label id="lab_us-gaap_DeferredTaxAssetsValuationAllowance_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsValuationAllowance" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Valuation Allowance </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsValuationAllowance" xlink:to="lab_us-gaap_DeferredTaxAssetsValuationAllowance" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_52f457e1-a38b-4eeb-9515-22c64d8987ee_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] </link:label>

<link:label id="lab_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="lab_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_222b83a6-7c8d-4e76-a80a-5b0c255433d2_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Leases </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract" xlink:to="lab_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_23501738-89fa-43c8-84b9-2f19784aaa7a_terseLabel_en-US" xlink:label="lab_us-gaap_ContractWithCustomerLiabilityRevenueRecognized" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue recognized related to amounts in contract liabilities outstanding at the beginning of period </link:label>

<link:label id="lab_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_label_en-US" xlink:label="lab_us-gaap_ContractWithCustomerLiabilityRevenueRecognized" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract with Customer, Liability, Revenue Recognized </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized" xlink:to="lab_us-gaap_ContractWithCustomerLiabilityRevenueRecognized" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RestrictedCashAndCashEquivalents_6aee3781-d078-4f95-bb06-7b4e7d560b43_terseLabel_en-US" xlink:label="lab_us-gaap_RestrictedCashAndCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted cash included in “Prepaid expenses and other current assets” </link:label>

<link:label id="lab_us-gaap_RestrictedCashAndCashEquivalents_label_en-US" xlink:label="lab_us-gaap_RestrictedCashAndCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted Cash and Cash Equivalents </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalents" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedCashAndCashEquivalents"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalents" xlink:to="lab_us-gaap_RestrictedCashAndCashEquivalents" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_8e2be1f4-ba92-45a3-890c-bf482b0e4870_terseLabel_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign currency translation adjustment income (loss) </link:label>

<link:label id="lab_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_label_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax" xlink:to="lab_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongTermDebtAndCapitalLeaseObligations_8f51f643-324d-475b-8523-491dfd5d8f8d_terseLabel_en-US" xlink:label="lab_us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-term debt, net of current maturities </link:label>

<link:label id="lab_us-gaap_LongTermDebtAndCapitalLeaseObligations_6f7e8432-dc7a-49c2-b2c7-b08b2ffb647e_verboseLabel_en-US" xlink:label="lab_us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total long-term debt obligations, net of current maturities </link:label>

<link:label id="lab_us-gaap_LongTermDebtAndCapitalLeaseObligations_label_en-US" xlink:label="lab_us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Debt and Lease Obligation </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:to="lab_us-gaap_LongTermDebtAndCapitalLeaseObligations" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingMachineryEquipmentAndVehiclesMember_e2745b61-de4a-4a62-a0e9-09257f166899_terseLabel_en-US" xlink:label="lab_pwr_OperatingMachineryEquipmentAndVehiclesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating machinery, equipment and vehicles </link:label>

<link:label id="lab_pwr_OperatingMachineryEquipmentAndVehiclesMember_label_en-US" xlink:label="lab_pwr_OperatingMachineryEquipmentAndVehiclesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Machinery, Equipment And Vehicles [Member] </link:label>

<link:label id="lab_pwr_OperatingMachineryEquipmentAndVehiclesMember_documentation_en-US" xlink:label="lab_pwr_OperatingMachineryEquipmentAndVehiclesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating equipment and vehicles. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingMachineryEquipmentAndVehiclesMember" xlink:href="pwr-20231231.xsd#pwr_OperatingMachineryEquipmentAndVehiclesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingMachineryEquipmentAndVehiclesMember" xlink:to="lab_pwr_OperatingMachineryEquipmentAndVehiclesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_b7618d9b-1762-4ea4-af04-d0f7cda64fb2_negatedLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred tax liabilities, net </link:label>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ProceedsFromConstructionContracts_eaa938a7-b496-4bfc-a10f-27aedd88cc6f_terseLabel_en-US" xlink:label="lab_pwr_ProceedsFromConstructionContracts" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments received on construction contracts </link:label>

<link:label id="lab_pwr_ProceedsFromConstructionContracts_label_en-US" xlink:label="lab_pwr_ProceedsFromConstructionContracts" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds From Construction Contracts </link:label>

<link:label id="lab_pwr_ProceedsFromConstructionContracts_documentation_en-US" xlink:label="lab_pwr_ProceedsFromConstructionContracts" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds From Construction Contracts </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ProceedsFromConstructionContracts" xlink:href="pwr-20231231.xsd#pwr_ProceedsFromConstructionContracts"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ProceedsFromConstructionContracts" xlink:to="lab_pwr_ProceedsFromConstructionContracts" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount_011efb39-5454-49c7-b7e8-234c9a5c79ca_terseLabel_en-US" xlink:label="lab_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-marketable equity securities </link:label>

<link:label id="lab_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount_label_en-US" xlink:label="lab_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Securities without Readily Determinable Fair Value, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount" xlink:to="lab_us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CreditRiskGroupDomain_31e87b59-c048-4a04-adfd-87479414222e_terseLabel_en-US" xlink:label="lab_pwr_CreditRiskGroupDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Risk Group [Domain] </link:label>

<link:label id="lab_pwr_CreditRiskGroupDomain_label_en-US" xlink:label="lab_pwr_CreditRiskGroupDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Risk Group [Domain] </link:label>

<link:label id="lab_pwr_CreditRiskGroupDomain_documentation_en-US" xlink:label="lab_pwr_CreditRiskGroupDomain" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Risk Group [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CreditRiskGroupDomain" xlink:href="pwr-20231231.xsd#pwr_CreditRiskGroupDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CreditRiskGroupDomain" xlink:to="lab_pwr_CreditRiskGroupDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RetirementPlanNameAxis_958a5243-a64e-4afa-b571-0f03e26e4993_terseLabel_en-US" xlink:label="lab_us-gaap_RetirementPlanNameAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Multiemployer Plan Name [Axis] </link:label>

<link:label id="lab_us-gaap_RetirementPlanNameAxis_label_en-US" xlink:label="lab_us-gaap_RetirementPlanNameAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Retirement Plan Name [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetirementPlanNameAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RetirementPlanNameAxis" xlink:to="lab_us-gaap_RetirementPlanNameAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentByTypeAxis_5381fd47-4ece-4b29-88d0-50f50949dd96_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment, Type [Axis] </link:label>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentByTypeAxis_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Lived Tangible Asset [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesAbstract_87db52a1-c355-4169-ad83-2cdf29689a1b_terseLabel_en-US" xlink:label="lab_us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> New Accounting Pronouncements and Changes in Accounting Principles [Abstract] </link:label>

<link:label id="lab_us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesAbstract_label_en-US" xlink:label="lab_us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounting Standards Update and Change in Accounting Principle [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesAbstract" xlink:to="lab_us-gaap_NewAccountingPronouncementsAndChangesInAccountingPrinciplesAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityEmergingGrowthCompany_0ff0a320-a777-4cc9-97dc-ebeac4d395e0_terseLabel_en-US" xlink:label="lab_dei_EntityEmergingGrowthCompany" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Emerging Growth Company </link:label>

<link:label id="lab_dei_EntityEmergingGrowthCompany_label_en-US" xlink:label="lab_dei_EntityEmergingGrowthCompany" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Emerging Growth Company </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityEmergingGrowthCompany"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityEmergingGrowthCompany" xlink:to="lab_dei_EntityEmergingGrowthCompany" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill_ce6ee0c8-1392-4f0e-93de-0fb8ae45e0ad_verboseLabel_en-US" xlink:label="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other intangible assets, net </link:label>

<link:label id="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill_2b57f9fa-188d-4410-a653-8e53ab490320_totalLabel_en-US" xlink:label="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Intangible Assets, Net </link:label>

<link:label id="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill_label_en-US" xlink:label="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Intangible Assets, Net (Excluding Goodwill) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:to="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxAssetsGross_7213199c-9785-462b-9ae6-ab67aa63c3d8_totalLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsGross" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subtotal </link:label>

<link:label id="lab_us-gaap_DeferredTaxAssetsGross_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsGross" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Gross </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsGross" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsGross"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsGross" xlink:to="lab_us-gaap_DeferredTaxAssetsGross" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OtherCountriesMember_52941712-9e06-4284-959d-f5f67a776ddd_terseLabel_en-US" xlink:label="lab_pwr_OtherCountriesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Others </link:label>

<link:label id="lab_pwr_OtherCountriesMember_label_en-US" xlink:label="lab_pwr_OtherCountriesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Countries [Member] </link:label>

<link:label id="lab_pwr_OtherCountriesMember_documentation_en-US" xlink:label="lab_pwr_OtherCountriesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Countries </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OtherCountriesMember" xlink:href="pwr-20231231.xsd#pwr_OtherCountriesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OtherCountriesMember" xlink:to="lab_pwr_OtherCountriesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_0fc774f0-3732-4a59-9941-f2071067b7a6_terseLabel_en-US" xlink:label="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] </link:label>

<link:label id="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_label_en-US" xlink:label="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems" xlink:to="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DebtInstrumentCovenantInterestCoverageRatioMinimum_f8d477cc-ed9b-4ae3-87a8-75be3c01d86f_terseLabel_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantInterestCoverageRatioMinimum" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Minimum consolidated interest coverage ratio </link:label>

<link:label id="lab_pwr_DebtInstrumentCovenantInterestCoverageRatioMinimum_label_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantInterestCoverageRatioMinimum" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Covenant, Interest Coverage Ratio, Minimum </link:label>

<link:label id="lab_pwr_DebtInstrumentCovenantInterestCoverageRatioMinimum_documentation_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantInterestCoverageRatioMinimum" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Covenant, Interest Coverage Ratio, Minimum </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DebtInstrumentCovenantInterestCoverageRatioMinimum" xlink:href="pwr-20231231.xsd#pwr_DebtInstrumentCovenantInterestCoverageRatioMinimum"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DebtInstrumentCovenantInterestCoverageRatioMinimum" xlink:to="lab_pwr_DebtInstrumentCovenantInterestCoverageRatioMinimum" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_a07c833e-6e09-42a7-a281-b07e88ed3c2f_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2024 </link:label>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, to be Paid, Year One </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DeferredTaxAssetValuationAllowanceReleased_7f6c1880-d4bf-47c9-b597-ec96de5c54fc_terseLabel_en-US" xlink:label="lab_pwr_DeferredTaxAssetValuationAllowanceReleased" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred tax asset, valuation allowance, released </link:label>

<link:label id="lab_pwr_DeferredTaxAssetValuationAllowanceReleased_label_en-US" xlink:label="lab_pwr_DeferredTaxAssetValuationAllowanceReleased" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Asset, Valuation Allowance, Released </link:label>

<link:label id="lab_pwr_DeferredTaxAssetValuationAllowanceReleased_documentation_en-US" xlink:label="lab_pwr_DeferredTaxAssetValuationAllowanceReleased" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Asset, Valuation Allowance, Released </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DeferredTaxAssetValuationAllowanceReleased" xlink:href="pwr-20231231.xsd#pwr_DeferredTaxAssetValuationAllowanceReleased"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DeferredTaxAssetValuationAllowanceReleased" xlink:to="lab_pwr_DeferredTaxAssetValuationAllowanceReleased" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_PvpTableTextBlock_terseLabel_en-US" xlink:label="lab_ecd_PvpTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Pay vs Performance Disclosure, Table </link:label>

<link:label id="lab_ecd_PvpTableTextBlock_label_en-US" xlink:label="lab_ecd_PvpTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Pay vs Performance [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_PvpTableTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_PvpTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_PvpTableTextBlock" xlink:to="lab_ecd_PvpTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_TrdArrIndTitle_terseLabel_en-US" xlink:label="lab_ecd_TrdArrIndTitle" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Title </link:label>

<link:label id="lab_ecd_TrdArrIndTitle_label_en-US" xlink:label="lab_ecd_TrdArrIndTitle" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trading Arrangement, Individual Title </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_TrdArrIndTitle" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_TrdArrIndTitle"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_TrdArrIndTitle" xlink:to="lab_ecd_TrdArrIndTitle" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DetailOfCertainBalanceSheetAccountsTextBlock_f2452e05-637c-48d9-9d2e-3141a0f56454_terseLabel_en-US" xlink:label="lab_pwr_DetailOfCertainBalanceSheetAccountsTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Detail of Certain Accounts </link:label>

<link:label id="lab_pwr_DetailOfCertainBalanceSheetAccountsTextBlock_label_en-US" xlink:label="lab_pwr_DetailOfCertainBalanceSheetAccountsTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Detail Of Certain Balance Sheet Accounts [Text Block] </link:label>

<link:label id="lab_pwr_DetailOfCertainBalanceSheetAccountsTextBlock_documentation_en-US" xlink:label="lab_pwr_DetailOfCertainBalanceSheetAccountsTextBlock" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Detail of certain balance sheet accounts. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DetailOfCertainBalanceSheetAccountsTextBlock" xlink:href="pwr-20231231.xsd#pwr_DetailOfCertainBalanceSheetAccountsTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DetailOfCertainBalanceSheetAccountsTextBlock" xlink:to="lab_pwr_DetailOfCertainBalanceSheetAccountsTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CommonStockMember_5811da52-d24a-46a7-8028-3c54b1f8b597_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock </link:label>

<link:label id="lab_us-gaap_CommonStockMember_label_en-US" xlink:label="lab_us-gaap_CommonStockMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockMember" xlink:to="lab_us-gaap_CommonStockMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ProceedsFromIncomeTaxRefunds_2408e22c-de7e-43ee-bb3e-0b75f2ee7dc3_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromIncomeTaxRefunds" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income tax refunds </link:label>

<link:label id="lab_us-gaap_ProceedsFromIncomeTaxRefunds_label_en-US" xlink:label="lab_us-gaap_ProceedsFromIncomeTaxRefunds" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Income Tax Refunds </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIncomeTaxRefunds" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromIncomeTaxRefunds"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromIncomeTaxRefunds" xlink:to="lab_us-gaap_ProceedsFromIncomeTaxRefunds" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_IndividualAxis_terseLabel_en-US" xlink:label="lab_ecd_IndividualAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Individual: </link:label>

<link:label id="lab_ecd_IndividualAxis_label_en-US" xlink:label="lab_ecd_IndividualAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Individual [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_IndividualAxis" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_IndividualAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_IndividualAxis" xlink:to="lab_ecd_IndividualAxis" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityAddressPostalZipCode_626b1fe2-da4e-4b61-a151-f46794d7b563_terseLabel_en-US" xlink:label="lab_dei_EntityAddressPostalZipCode" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, Postal Zip Code </link:label>

<link:label id="lab_dei_EntityAddressPostalZipCode_label_en-US" xlink:label="lab_dei_EntityAddressPostalZipCode" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, Postal Zip Code </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityAddressPostalZipCode"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityAddressPostalZipCode" xlink:to="lab_dei_EntityAddressPostalZipCode" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations_46771c8d-cd33-46e6-a675-0864a3a8b9a6_verboseLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reduction due to expiration of certain federal and state statutes of limitations </link:label>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations_1c722b7e-4b10-4277-865e-4521b00c2f0c_negatedLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reductions resulting from a lapse of the applicable statute of limitations periods </link:label>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations_label_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:to="lab_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_9ab42bc6-87ec-4f88-919e-299e1927a2dd_totalLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total equity </link:label>

<link:label id="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_f35236d8-8761-45e0-bf44-0970709bc0a5_periodStartLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Beginning Balance </link:label>

<link:label id="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_01f54cc1-4243-4445-bcef-8def6400f99c_periodEndLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Ending Balance </link:label>

<link:label id="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_label_en-US" xlink:label="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity, Including Portion Attributable to Noncontrolling Interest </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:to="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_ecabdfbf-3dcc-4d28-93ab-0311ba87ee5a_negatedLabel_en-US" xlink:label="lab_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Distributions to non-controlling interests, net </link:label>

<link:label id="lab_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_f51fe212-1960-405e-b34d-4b47798942f4_terseLabel_en-US" xlink:label="lab_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Distributions to non-controlling interests </link:label>

<link:label id="lab_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_label_en-US" xlink:label="lab_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:to="lab_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredIncomeTaxesAndTaxCreditsAbstract_4bf005ae-a9af-47cb-abbc-ed0b0406bd8d_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxesAndTaxCreditsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred: </link:label>

<link:label id="lab_us-gaap_DeferredIncomeTaxesAndTaxCreditsAbstract_label_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxesAndTaxCreditsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Income Taxes and Tax Credits [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxesAndTaxCreditsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxesAndTaxCreditsAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredIncomeTaxesAndTaxCreditsAbstract" xlink:to="lab_us-gaap_DeferredIncomeTaxesAndTaxCreditsAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_srt_MinimumMember_52622440-65d4-451b-8c4a-71f1463643be_terseLabel_en-US" xlink:label="lab_srt_MinimumMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Minimum </link:label>

<link:label id="lab_srt_MinimumMember_label_en-US" xlink:label="lab_srt_MinimumMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Minimum [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_MinimumMember" xlink:to="lab_srt_MinimumMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentNet_9a19d3cc-1ed5-4038-9105-cb802ac4977d_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentNet" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and equipment </link:label>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentNet_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment, Net </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentNet" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_b8e12bd2-ab3e-4627-82c8-96685742975c_terseLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Shares used in computing earnings per share: </link:label>

<link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_a33f6f11-6039-4346-a9c7-87efe404f36d_verboseLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted average shares: </link:label>

<link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_label_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average Number of Shares Outstanding, Diluted [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" xlink:to="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTax_94d593f0-9672-460b-acad-39ebdbecb2fc_totalLabel_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other comprehensive income (loss), net of taxes </link:label>

<link:label id="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTax_afd79e41-0544-442a-a4f1-3f8c1b13724c_terseLabel_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other comprehensive income (loss) </link:label>

<link:label id="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTax_label_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Comprehensive Income (Loss), Net of Tax </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:to="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTable_eb96db0f-98f4-4969-8aa3-89fd64f67a21_terseLabel_en-US" xlink:label="lab_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table] </link:label>

<link:label id="lab_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTable_label_en-US" xlink:label="lab_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTable" xlink:to="lab_us-gaap_SignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_ef493a1b-1bf3-42ac-9392-f7b9e3ded130_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contingent consideration payments (up to) </link:label>

<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh" xlink:to="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StatementOfCashFlowsAbstract_8718a45e-2dda-481d-a99f-638f96a63b72_terseLabel_en-US" xlink:label="lab_us-gaap_StatementOfCashFlowsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement of Cash Flows [Abstract] </link:label>

<link:label id="lab_us-gaap_StatementOfCashFlowsAbstract_label_en-US" xlink:label="lab_us-gaap_StatementOfCashFlowsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement of Cash Flows [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfCashFlowsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementOfCashFlowsAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract" xlink:to="lab_us-gaap_StatementOfCashFlowsAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LaborersNationalPensionFundMember_2a856667-e402-47b9-bb4a-ed7c1b57fbbe_terseLabel_en-US" xlink:label="lab_pwr_LaborersNationalPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Laborers National Pension Fund </link:label>

<link:label id="lab_pwr_LaborersNationalPensionFundMember_label_en-US" xlink:label="lab_pwr_LaborersNationalPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Laborers National Pension Fund [Member] </link:label>

<link:label id="lab_pwr_LaborersNationalPensionFundMember_documentation_en-US" xlink:label="lab_pwr_LaborersNationalPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Laborers national pension fund. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LaborersNationalPensionFundMember" xlink:href="pwr-20231231.xsd#pwr_LaborersNationalPensionFundMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LaborersNationalPensionFundMember" xlink:to="lab_pwr_LaborersNationalPensionFundMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AssetsAbstract_a867b995-b68c-453b-9c2c-57e16c3c08d7_terseLabel_en-US" xlink:label="lab_us-gaap_AssetsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> ASSETS </link:label>

<link:label id="lab_us-gaap_AssetsAbstract_label_en-US" xlink:label="lab_us-gaap_AssetsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Assets [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="lab_us-gaap_AssetsAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AwardTmgMnpiDiscTextBlock_terseLabel_en-US" xlink:label="lab_ecd_AwardTmgMnpiDiscTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Timing MNPI Disclosure </link:label>

<link:label id="lab_ecd_AwardTmgMnpiDiscTextBlock_label_en-US" xlink:label="lab_ecd_AwardTmgMnpiDiscTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Timing MNPI Disclosure [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AwardTmgMnpiDiscTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AwardTmgMnpiDiscTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AwardTmgMnpiDiscTextBlock" xlink:to="lab_ecd_AwardTmgMnpiDiscTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_3f120235-893d-4a98-a517-7893fd85f6a4_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments related to tax withholding for stock-based compensation </link:label>

<link:label id="lab_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_label_en-US" xlink:label="lab_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payment, Tax Withholding, Share-Based Payment Arrangement </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:to="lab_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxAssetsOther_6a89c973-c9f6-4d83-82a8-ecbfeffcb860_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsOther" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other </link:label>

<link:label id="lab_us-gaap_DeferredTaxAssetsOther_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsOther" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Other </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOther" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsOther"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsOther" xlink:to="lab_us-gaap_DeferredTaxAssetsOther" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredIncomeTaxAssetsNet_8d097019-962a-44c8-af00-0963dad7089c_verboseLabel_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxAssetsNet" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Assets </link:label>

<link:label id="lab_us-gaap_DeferredIncomeTaxAssetsNet_label_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxAssetsNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Income Tax Assets, Net </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxAssetsNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxAssetsNet"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredIncomeTaxAssetsNet" xlink:to="lab_us-gaap_DeferredIncomeTaxAssetsNet" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities_ec4fa6f2-325f-494f-aa9b-9fbe198dbe55_totalLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net cash provided by (used in) financing activities </link:label>

<link:label id="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Cash Provided by (Used in) Financing Activities </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeLeaseDescriptionLineItems_92cb0911-0261-4255-b27d-8f9e4747bbfa_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeLeaseDescriptionLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Lease, Description [Line Items] </link:label>

<link:label id="lab_us-gaap_LesseeLeaseDescriptionLineItems_label_en-US" xlink:label="lab_us-gaap_LesseeLeaseDescriptionLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Lease, Description [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems" xlink:to="lab_us-gaap_LesseeLeaseDescriptionLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_dcf6afd8-16c6-4601-a24a-6c9e0e097309_terseLabel_en-US" xlink:label="lab_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitments and Contingencies </link:label>

<link:label id="lab_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitments and Contingencies Disclosure [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommitmentsAndContingenciesDisclosureTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:to="lab_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_EquityMethodInvestmentsOutstandingCommitmentToBePaid_ef48af7d-d8fb-4f66-bd33-3b242cc42555_terseLabel_en-US" xlink:label="lab_pwr_EquityMethodInvestmentsOutstandingCommitmentToBePaid" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Outstanding capital commitments due after next twelve months </link:label>

<link:label id="lab_pwr_EquityMethodInvestmentsOutstandingCommitmentToBePaid_label_en-US" xlink:label="lab_pwr_EquityMethodInvestmentsOutstandingCommitmentToBePaid" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Method Investments, Outstanding Commitment, To Be Paid </link:label>

<link:label id="lab_pwr_EquityMethodInvestmentsOutstandingCommitmentToBePaid_documentation_en-US" xlink:label="lab_pwr_EquityMethodInvestmentsOutstandingCommitmentToBePaid" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Method Investments, Outstanding Commitment, To Be Paid </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_EquityMethodInvestmentsOutstandingCommitmentToBePaid" xlink:href="pwr-20231231.xsd#pwr_EquityMethodInvestmentsOutstandingCommitmentToBePaid"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_EquityMethodInvestmentsOutstandingCommitmentToBePaid" xlink:to="lab_pwr_EquityMethodInvestmentsOutstandingCommitmentToBePaid" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_b61b1961-627b-453d-b972-58d4a0a74128_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_PaymentsForProceedsFromOtherInvestingActivities" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other, net </link:label>

<link:label id="lab_us-gaap_PaymentsForProceedsFromOtherInvestingActivities_label_en-US" xlink:label="lab_us-gaap_PaymentsForProceedsFromOtherInvestingActivities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments for (Proceeds from) Other Investing Activities </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsForProceedsFromOtherInvestingActivities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsForProceedsFromOtherInvestingActivities" xlink:to="lab_us-gaap_PaymentsForProceedsFromOtherInvestingActivities" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_InsuranceSettlementsReceivableNoncurrent_8f89b0ed-580c-4fcd-bd6e-4f3b26da8d9e_terseLabel_en-US" xlink:label="lab_us-gaap_InsuranceSettlementsReceivableNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related insurance recoveries/receivables included in other assets </link:label>

<link:label id="lab_us-gaap_InsuranceSettlementsReceivableNoncurrent_label_en-US" xlink:label="lab_us-gaap_InsuranceSettlementsReceivableNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insurance Settlements Receivable, Noncurrent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InsuranceSettlementsReceivableNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InsuranceSettlementsReceivableNoncurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InsuranceSettlementsReceivableNoncurrent" xlink:to="lab_us-gaap_InsuranceSettlementsReceivableNoncurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RetainedEarningsMember_c2751566-a762-4839-be5d-e869be83e517_terseLabel_en-US" xlink:label="lab_us-gaap_RetainedEarningsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Retained Earnings </link:label>

<link:label id="lab_us-gaap_RetainedEarningsMember_label_en-US" xlink:label="lab_us-gaap_RetainedEarningsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Retained Earnings [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RetainedEarningsMember" xlink:to="lab_us-gaap_RetainedEarningsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_4cc6dd2b-e0c5-45c9-8fee-bdb18fce5616_verboseLabel_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill expected to be deductible for income tax purposes </link:label>

<link:label id="lab_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_label_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisition, Goodwill, Expected Tax Deductible Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount" xlink:to="lab_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_RenewableEnergyMember_4d89b0df-cca8-494f-a0c4-4e06ee6ff89f_terseLabel_en-US" xlink:label="lab_pwr_RenewableEnergyMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Renewable Energy </link:label>

<link:label id="lab_pwr_RenewableEnergyMember_00b0c2b5-a906-475a-9a56-71b132781687_verboseLabel_en-US" xlink:label="lab_pwr_RenewableEnergyMember" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Renewable Energy Segment </link:label>

<link:label id="lab_pwr_RenewableEnergyMember_label_en-US" xlink:label="lab_pwr_RenewableEnergyMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Renewable Energy [Member] </link:label>

<link:label id="lab_pwr_RenewableEnergyMember_documentation_en-US" xlink:label="lab_pwr_RenewableEnergyMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Renewable Energy </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_RenewableEnergyMember" xlink:href="pwr-20231231.xsd#pwr_RenewableEnergyMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_RenewableEnergyMember" xlink:to="lab_pwr_RenewableEnergyMember" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AdjToNonPeoNeoCompFnTextBlock_terseLabel_en-US" xlink:label="lab_ecd_AdjToNonPeoNeoCompFnTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustment to Non-PEO NEO Compensation Footnote </link:label>

<link:label id="lab_ecd_AdjToNonPeoNeoCompFnTextBlock_label_en-US" xlink:label="lab_ecd_AdjToNonPeoNeoCompFnTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustment to Non-PEO NEO Compensation Footnote [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AdjToNonPeoNeoCompFnTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AdjToNonPeoNeoCompFnTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AdjToNonPeoNeoCompFnTextBlock" xlink:to="lab_ecd_AdjToNonPeoNeoCompFnTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_InsuranceSettlementsReceivable_dfcbc548-d632-4d54-af50-09649c605286_terseLabel_en-US" xlink:label="lab_us-gaap_InsuranceSettlementsReceivable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related insurance recoveries/receivables </link:label>

<link:label id="lab_us-gaap_InsuranceSettlementsReceivable_label_en-US" xlink:label="lab_us-gaap_InsuranceSettlementsReceivable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insurance Settlements Receivable </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InsuranceSettlementsReceivable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InsuranceSettlementsReceivable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InsuranceSettlementsReceivable" xlink:to="lab_us-gaap_InsuranceSettlementsReceivable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EarningsPerShareBasic_c39ce45c-8b6e-4dea-ad86-ca837bed7689_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasic" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Basic (in dollars per share) </link:label>

<link:label id="lab_us-gaap_EarningsPerShareBasic_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasic" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Earnings Per Share, Basic </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareBasic"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareBasic" xlink:to="lab_us-gaap_EarningsPerShareBasic" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AccountingPoliciesAbstract_b99298e3-74d9-4440-a44c-05913edf64ae_terseLabel_en-US" xlink:label="lab_us-gaap_AccountingPoliciesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounting Policies [Abstract] </link:label>

<link:label id="lab_us-gaap_AccountingPoliciesAbstract_label_en-US" xlink:label="lab_us-gaap_AccountingPoliciesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounting Policies [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingPoliciesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountingPoliciesAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountingPoliciesAbstract" xlink:to="lab_us-gaap_AccountingPoliciesAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ClassOfTreasuryStockTable_b717650f-8c80-476a-8e8d-aff33373450f_terseLabel_en-US" xlink:label="lab_us-gaap_ClassOfTreasuryStockTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class of Treasury Stock [Table] </link:label>

<link:label id="lab_us-gaap_ClassOfTreasuryStockTable_label_en-US" xlink:label="lab_us-gaap_ClassOfTreasuryStockTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class of Treasury Stock [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfTreasuryStockTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfTreasuryStockTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable" xlink:to="lab_us-gaap_ClassOfTreasuryStockTable" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_ErrCompAnalysisTextBlock_terseLabel_en-US" xlink:label="lab_ecd_ErrCompAnalysisTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Erroneous Compensation Analysis </link:label>

<link:label id="lab_ecd_ErrCompAnalysisTextBlock_label_en-US" xlink:label="lab_ecd_ErrCompAnalysisTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Erroneous Compensation Analysis [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_ErrCompAnalysisTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_ErrCompAnalysisTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_ErrCompAnalysisTextBlock" xlink:to="lab_ecd_ErrCompAnalysisTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LiabilityNoncurrentLesseeAbstract_530e42ee-1fca-4f73-b8bf-7015c2f9b14e_terseLabel_en-US" xlink:label="lab_pwr_LiabilityNoncurrentLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-current: </link:label>

<link:label id="lab_pwr_LiabilityNoncurrentLesseeAbstract_label_en-US" xlink:label="lab_pwr_LiabilityNoncurrentLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liability, Noncurrent, Lessee [Abstract] </link:label>

<link:label id="lab_pwr_LiabilityNoncurrentLesseeAbstract_documentation_en-US" xlink:label="lab_pwr_LiabilityNoncurrentLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liability, Noncurrent, Lessee [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LiabilityNoncurrentLesseeAbstract" xlink:href="pwr-20231231.xsd#pwr_LiabilityNoncurrentLesseeAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LiabilityNoncurrentLesseeAbstract" xlink:to="lab_pwr_LiabilityNoncurrentLesseeAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingFinanceAndLeaseFinancingTransactionLeaseLiabilitiesLiability_632eded9-fdcd-4182-8c43-ec6fa35f7003_totalLabel_en-US" xlink:label="lab_pwr_OperatingFinanceAndLeaseFinancingTransactionLeaseLiabilitiesLiability" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total </link:label>

<link:label id="lab_pwr_OperatingFinanceAndLeaseFinancingTransactionLeaseLiabilitiesLiability_label_en-US" xlink:label="lab_pwr_OperatingFinanceAndLeaseFinancingTransactionLeaseLiabilitiesLiability" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating, Finance And Lease Financing Transaction Lease Liabilities, Liability </link:label>

<link:label id="lab_pwr_OperatingFinanceAndLeaseFinancingTransactionLeaseLiabilitiesLiability_documentation_en-US" xlink:label="lab_pwr_OperatingFinanceAndLeaseFinancingTransactionLeaseLiabilitiesLiability" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating, Finance Lease And Lease Financing Transaction, Liability </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingFinanceAndLeaseFinancingTransactionLeaseLiabilitiesLiability" xlink:href="pwr-20231231.xsd#pwr_OperatingFinanceAndLeaseFinancingTransactionLeaseLiabilitiesLiability"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingFinanceAndLeaseFinancingTransactionLeaseLiabilitiesLiability" xlink:to="lab_pwr_OperatingFinanceAndLeaseFinancingTransactionLeaseLiabilitiesLiability" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_UnitPriceContractsMember_ee1fbf39-add3-407d-8cce-ff4d1906b404_terseLabel_en-US" xlink:label="lab_pwr_UnitPriceContractsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unit-price contracts </link:label>

<link:label id="lab_pwr_UnitPriceContractsMember_label_en-US" xlink:label="lab_pwr_UnitPriceContractsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unit-Price Contracts [Member] </link:label>

<link:label id="lab_pwr_UnitPriceContractsMember_documentation_en-US" xlink:label="lab_pwr_UnitPriceContractsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unit-price Contracts [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_UnitPriceContractsMember" xlink:href="pwr-20231231.xsd#pwr_UnitPriceContractsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_UnitPriceContractsMember" xlink:to="lab_pwr_UnitPriceContractsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxesPaid_f5b533a8-b6a5-4789-af6c-afc1bed30a39_negatedLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxesPaid" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income taxes paid </link:label>

<link:label id="lab_us-gaap_IncomeTaxesPaid_label_en-US" xlink:label="lab_us-gaap_IncomeTaxesPaid" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Taxes Paid </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaid" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxesPaid"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxesPaid" xlink:to="lab_us-gaap_IncomeTaxesPaid" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LesseeOperatingLeaseLeaseNotYetCommencedUndiscountedAmount_e30d1200-afd7-4d70-acb6-350d6eddbfe9_terseLabel_en-US" xlink:label="lab_pwr_LesseeOperatingLeaseLeaseNotYetCommencedUndiscountedAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Future undiscounted lease payments under leases </link:label>

<link:label id="lab_pwr_LesseeOperatingLeaseLeaseNotYetCommencedUndiscountedAmount_label_en-US" xlink:label="lab_pwr_LesseeOperatingLeaseLeaseNotYetCommencedUndiscountedAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Lease Not Yet Commenced, Undiscounted Amount </link:label>

<link:label id="lab_pwr_LesseeOperatingLeaseLeaseNotYetCommencedUndiscountedAmount_documentation_en-US" xlink:label="lab_pwr_LesseeOperatingLeaseLeaseNotYetCommencedUndiscountedAmount" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Lease Not Yet Commenced, Undiscounted Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LesseeOperatingLeaseLeaseNotYetCommencedUndiscountedAmount" xlink:href="pwr-20231231.xsd#pwr_LesseeOperatingLeaseLeaseNotYetCommencedUndiscountedAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LesseeOperatingLeaseLeaseNotYetCommencedUndiscountedAmount" xlink:to="lab_pwr_LesseeOperatingLeaseLeaseNotYetCommencedUndiscountedAmount" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ConsolidationPolicyTextBlock_b956bc03-13cc-4b7f-8847-78263e5c3e60_terseLabel_en-US" xlink:label="lab_us-gaap_ConsolidationPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Principles of Consolidation </link:label>

<link:label id="lab_us-gaap_ConsolidationPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_ConsolidationPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Consolidation, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConsolidationPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConsolidationPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConsolidationPolicyTextBlock" xlink:to="lab_us-gaap_ConsolidationPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ProceedsFromIssuanceOfDebt_f14c751a-9db6-44d3-94c7-3dfedd8a35f8_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfDebt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from notes offerings </link:label>

<link:label id="lab_us-gaap_ProceedsFromIssuanceOfDebt_label_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfDebt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Issuance of Debt </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfDebt" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromIssuanceOfDebt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromIssuanceOfDebt" xlink:to="lab_us-gaap_ProceedsFromIssuanceOfDebt" xlink:type="arc" order="1"/>

<link:label id="lab_dei_DocumentTransitionReport_157833bc-5d42-4621-8cd1-b1d21af36e60_terseLabel_en-US" xlink:label="lab_dei_DocumentTransitionReport" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Transition Report </link:label>

<link:label id="lab_dei_DocumentTransitionReport_label_en-US" xlink:label="lab_dei_DocumentTransitionReport" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Transition Report </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentTransitionReport"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_DocumentTransitionReport" xlink:to="lab_dei_DocumentTransitionReport" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AwardTmgPredtrmndFlag_terseLabel_en-US" xlink:label="lab_ecd_AwardTmgPredtrmndFlag" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Timing Predetermined </link:label>

<link:label id="lab_ecd_AwardTmgPredtrmndFlag_label_en-US" xlink:label="lab_ecd_AwardTmgPredtrmndFlag" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Timing Predetermined [Flag] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AwardTmgPredtrmndFlag" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AwardTmgPredtrmndFlag"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AwardTmgPredtrmndFlag" xlink:to="lab_ecd_AwardTmgPredtrmndFlag" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_GoodwillPurchaseAccountingAdjustments_92c0e0c9-e948-4b30-9407-e85715100fe4_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillPurchaseAccountingAdjustments" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Purchase price allocation adjustments </link:label>

<link:label id="lab_us-gaap_GoodwillPurchaseAccountingAdjustments_label_en-US" xlink:label="lab_us-gaap_GoodwillPurchaseAccountingAdjustments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill, Purchase Accounting Adjustments </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillPurchaseAccountingAdjustments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillPurchaseAccountingAdjustments"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillPurchaseAccountingAdjustments" xlink:to="lab_us-gaap_GoodwillPurchaseAccountingAdjustments" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ContractWithCustomerOnDemandPerformanceBonds_e976bfc2-d484-49bd-b472-2ee3612354c3_terseLabel_en-US" xlink:label="lab_pwr_ContractWithCustomerOnDemandPerformanceBonds" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> On-demand performance bonds </link:label>

<link:label id="lab_pwr_ContractWithCustomerOnDemandPerformanceBonds_label_en-US" xlink:label="lab_pwr_ContractWithCustomerOnDemandPerformanceBonds" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, On-Demand Performance Bonds </link:label>

<link:label id="lab_pwr_ContractWithCustomerOnDemandPerformanceBonds_documentation_en-US" xlink:label="lab_pwr_ContractWithCustomerOnDemandPerformanceBonds" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, On-Demand Performance Bonds </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ContractWithCustomerOnDemandPerformanceBonds" xlink:href="pwr-20231231.xsd#pwr_ContractWithCustomerOnDemandPerformanceBonds"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ContractWithCustomerOnDemandPerformanceBonds" xlink:to="lab_pwr_ContractWithCustomerOnDemandPerformanceBonds" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_32aaf80a-2e63-468d-95b1-ff823c45e32b_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Business Acquisitions, by Acquisition [Table] </link:label>

<link:label id="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Business Acquisitions, by Acquisition [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:to="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionForfeitedInPeriodWeightedAverageGrantDateFairValue_bebefa4c-3f56-400c-b0aa-ad2a1cf424d6_terseLabel_en-US" xlink:label="lab_pwr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionForfeitedInPeriodWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Forfeited, weighted average grant date fair value (in usd per share) </link:label>

<link:label id="lab_pwr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionForfeitedInPeriodWeightedAverageGrantDateFairValue_label_en-US" xlink:label="lab_pwr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionForfeitedInPeriodWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Option Forfeited In Period Weighted Average Grant Date Fair Value </link:label>

<link:label id="lab_pwr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionForfeitedInPeriodWeightedAverageGrantDateFairValue_documentation_en-US" xlink:label="lab_pwr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionForfeitedInPeriodWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share based compensation arrangement by share based payment award equity instruments other than option forfeited in period weighted average grant date fair value. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionForfeitedInPeriodWeightedAverageGrantDateFairValue" xlink:href="pwr-20231231.xsd#pwr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionForfeitedInPeriodWeightedAverageGrantDateFairValue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionForfeitedInPeriodWeightedAverageGrantDateFairValue" xlink:to="lab_pwr_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionForfeitedInPeriodWeightedAverageGrantDateFairValue" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SummaryOfIncomeTaxContingenciesTextBlock_c4334ce6-b477-4263-8a33-1de664d4391a_terseLabel_en-US" xlink:label="lab_us-gaap_SummaryOfIncomeTaxContingenciesTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reconciliation of Unrecognized Tax Benefit </link:label>

<link:label id="lab_us-gaap_SummaryOfIncomeTaxContingenciesTextBlock_label_en-US" xlink:label="lab_us-gaap_SummaryOfIncomeTaxContingenciesTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary of Income Tax Contingencies [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SummaryOfIncomeTaxContingenciesTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SummaryOfIncomeTaxContingenciesTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SummaryOfIncomeTaxContingenciesTextBlock" xlink:to="lab_us-gaap_SummaryOfIncomeTaxContingenciesTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ValuationAllowanceByDeferredTaxAssetAxis_f9e5f790-7332-4f82-8bcd-6462d9339118_terseLabel_en-US" xlink:label="lab_us-gaap_ValuationAllowanceByDeferredTaxAssetAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Valuation Allowance by Deferred Tax Asset [Axis] </link:label>

<link:label id="lab_us-gaap_ValuationAllowanceByDeferredTaxAssetAxis_label_en-US" xlink:label="lab_us-gaap_ValuationAllowanceByDeferredTaxAssetAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Valuation Allowance by Deferred Tax Asset [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceByDeferredTaxAssetAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowanceByDeferredTaxAssetAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ValuationAllowanceByDeferredTaxAssetAxis" xlink:to="lab_us-gaap_ValuationAllowanceByDeferredTaxAssetAxis" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityPublicFloat_edda8762-bf73-4a75-aa42-5d797d24c57f_terseLabel_en-US" xlink:label="lab_dei_EntityPublicFloat" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Public Float </link:label>

<link:label id="lab_dei_EntityPublicFloat_label_en-US" xlink:label="lab_dei_EntityPublicFloat" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Public Float </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityPublicFloat" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityPublicFloat"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityPublicFloat" xlink:to="lab_dei_EntityPublicFloat" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentPeriodicPaymentInterest_33bcb7f7-84aa-4e33-9c0e-6abadaa6cac0_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentPeriodicPaymentInterest" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Semi-annual interest payable </link:label>

<link:label id="lab_us-gaap_DebtInstrumentPeriodicPaymentInterest_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentPeriodicPaymentInterest" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Periodic Payment, Interest </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPaymentInterest" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentPeriodicPaymentInterest"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentPeriodicPaymentInterest" xlink:to="lab_us-gaap_DebtInstrumentPeriodicPaymentInterest" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_62a6734e-eb9a-407f-896d-718da2c5f44d_terseLabel_en-US" xlink:label="lab_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Change in total valuation allowance, increase (decrease) </link:label>

<link:label id="lab_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_label_en-US" xlink:label="lab_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" xlink:to="lab_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LorenzoBentonvTelecomNetworkSpecialistsIncMember_0efd8f9d-b28e-452f-8d87-b6532a213353_terseLabel_en-US" xlink:label="lab_pwr_LorenzoBentonvTelecomNetworkSpecialistsIncMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lorenzo Benton v Telecom Network Specialists Inc </link:label>

<link:label id="lab_pwr_LorenzoBentonvTelecomNetworkSpecialistsIncMember_label_en-US" xlink:label="lab_pwr_LorenzoBentonvTelecomNetworkSpecialistsIncMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lorenzo Benton V Telecom Network Specialists Inc [Member] </link:label>

<link:label id="lab_pwr_LorenzoBentonvTelecomNetworkSpecialistsIncMember_documentation_en-US" xlink:label="lab_pwr_LorenzoBentonvTelecomNetworkSpecialistsIncMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lorenzo Benton v. Telecom Network Specialists Inc [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LorenzoBentonvTelecomNetworkSpecialistsIncMember" xlink:href="pwr-20231231.xsd#pwr_LorenzoBentonvTelecomNetworkSpecialistsIncMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LorenzoBentonvTelecomNetworkSpecialistsIncMember" xlink:to="lab_pwr_LorenzoBentonvTelecomNetworkSpecialistsIncMember" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AllTradingArrangementsMember_terseLabel_en-US" xlink:label="lab_ecd_AllTradingArrangementsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Trading Arrangements </link:label>

<link:label id="lab_ecd_AllTradingArrangementsMember_label_en-US" xlink:label="lab_ecd_AllTradingArrangementsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Trading Arrangements [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AllTradingArrangementsMember" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AllTradingArrangementsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AllTradingArrangementsMember" xlink:to="lab_ecd_AllTradingArrangementsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_a9a5b58a-d8a7-43cb-911a-791b0ce70af7_negatedLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Less — Accumulated depreciation and amortization </link:label>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AllAdjToCompMember_terseLabel_en-US" xlink:label="lab_ecd_AllAdjToCompMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Adjustments to Compensation </link:label>

<link:label id="lab_ecd_AllAdjToCompMember_label_en-US" xlink:label="lab_ecd_AllAdjToCompMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Adjustments to Compensation [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AllAdjToCompMember" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AllAdjToCompMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AllAdjToCompMember" xlink:to="lab_ecd_AllAdjToCompMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiability_4383068b-2950-4238-a371-35e51cb31b86_totalLabel_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiability_label_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease , Liability </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiability_documentation_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease , Liability </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingAndFinanceLeaseLiability" xlink:href="pwr-20231231.xsd#pwr_OperatingAndFinanceLeaseLiability"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingAndFinanceLeaseLiability" xlink:to="lab_pwr_OperatingAndFinanceLeaseLiability" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments_bd9226b4-c2bb-48c6-979e-9adb9b4d25ca_terseLabel_en-US" xlink:label="lab_us-gaap_MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Marketable security, realized gain (loss) </link:label>

<link:label id="lab_us-gaap_MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments_label_en-US" xlink:label="lab_us-gaap_MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Marketable Security, Realized Gain (Loss) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments" xlink:to="lab_us-gaap_MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_OutstandingRecoveryCompAmt_terseLabel_en-US" xlink:label="lab_ecd_OutstandingRecoveryCompAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Compensation Amount </link:label>

<link:label id="lab_ecd_OutstandingRecoveryCompAmt_label_en-US" xlink:label="lab_ecd_OutstandingRecoveryCompAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Outstanding Recovery Compensation Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_OutstandingRecoveryCompAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_OutstandingRecoveryCompAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_OutstandingRecoveryCompAmt" xlink:to="lab_ecd_OutstandingRecoveryCompAmt" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ContractsReceivableClaimsAndUncertainAmounts_3c44d291-425b-4533-a6f0-ed927ba847ec_terseLabel_en-US" xlink:label="lab_us-gaap_ContractsReceivableClaimsAndUncertainAmounts" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payment of arbitration </link:label>

<link:label id="lab_us-gaap_ContractsReceivableClaimsAndUncertainAmounts_label_en-US" xlink:label="lab_us-gaap_ContractsReceivableClaimsAndUncertainAmounts" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contracts Receivable, Claims and Uncertain Amounts </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractsReceivableClaimsAndUncertainAmounts" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractsReceivableClaimsAndUncertainAmounts"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ContractsReceivableClaimsAndUncertainAmounts" xlink:to="lab_us-gaap_ContractsReceivableClaimsAndUncertainAmounts" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ProvisionForDoubtfulAccounts_3a724808-5b25-4e90-ac44-2de419cf431c_verboseLabel_en-US" xlink:label="lab_us-gaap_ProvisionForDoubtfulAccounts" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase in provision for credit losses </link:label>

<link:label id="lab_us-gaap_ProvisionForDoubtfulAccounts_7da1dda7-2ade-458c-8dd8-2867a8bfd7f0_terseLabel_en-US" xlink:label="lab_us-gaap_ProvisionForDoubtfulAccounts" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase in provision for credit losses </link:label>

<link:label id="lab_us-gaap_ProvisionForDoubtfulAccounts_label_en-US" xlink:label="lab_us-gaap_ProvisionForDoubtfulAccounts" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable, Credit Loss Expense (Reversal) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProvisionForDoubtfulAccounts"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProvisionForDoubtfulAccounts" xlink:to="lab_us-gaap_ProvisionForDoubtfulAccounts" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxLiabilitiesLeasingArrangements_9d2b8724-dda8-4cfe-8b17-b1fbfb19a058_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesLeasingArrangements" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Leased assets </link:label>

<link:label id="lab_us-gaap_DeferredTaxLiabilitiesLeasingArrangements_label_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesLeasingArrangements" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Liabilities, Leasing Arrangements </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesLeasingArrangements" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilitiesLeasingArrangements"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesLeasingArrangements" xlink:to="lab_us-gaap_DeferredTaxLiabilitiesLeasingArrangements" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredIncomeTaxExpenseBenefit_2b779595-3470-4074-af87-5174ed4792f7_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred income tax expense </link:label>

<link:label id="lab_us-gaap_DeferredIncomeTaxExpenseBenefit_f10c9102-9084-48a1-9fa2-352fc08536bd_totalLabel_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total deferred tax provision (benefit) </link:label>

<link:label id="lab_us-gaap_DeferredIncomeTaxExpenseBenefit_label_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Income Tax Expense (Benefit) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:to="lab_us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SubsequentEventTypeAxis_d6df8e52-b35e-42f9-83aa-e01ede780d45_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventTypeAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event Type [Axis] </link:label>

<link:label id="lab_us-gaap_SubsequentEventTypeAxis_label_en-US" xlink:label="lab_us-gaap_SubsequentEventTypeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event Type [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventTypeAxis" xlink:to="lab_us-gaap_SubsequentEventTypeAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract_3bc34d2a-b43b-4c5f-810c-e365be644648_terseLabel_en-US" xlink:label="lab_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement of Comprehensive Income [Abstract] </link:label>

<link:label id="lab_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract_label_en-US" xlink:label="lab_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement of Comprehensive Income [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract" xlink:to="lab_us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OrderOrProductionBacklogMember_d39cf166-47d1-4bb4-86f5-51068c044262_terseLabel_en-US" xlink:label="lab_us-gaap_OrderOrProductionBacklogMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Backlog </link:label>

<link:label id="lab_us-gaap_OrderOrProductionBacklogMember_label_en-US" xlink:label="lab_us-gaap_OrderOrProductionBacklogMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Order or Production Backlog [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OrderOrProductionBacklogMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OrderOrProductionBacklogMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OrderOrProductionBacklogMember" xlink:to="lab_us-gaap_OrderOrProductionBacklogMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_MultiemployerPlanEmployerContributionCost_615700ff-17f2-4588-9c02-f9da49841e73_terseLabel_en-US" xlink:label="lab_us-gaap_MultiemployerPlanEmployerContributionCost" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contributions </link:label>

<link:label id="lab_us-gaap_MultiemployerPlanEmployerContributionCost_label_en-US" xlink:label="lab_us-gaap_MultiemployerPlanEmployerContributionCost" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Multiemployer Plan, Employer Contribution, Cost </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_MultiemployerPlanEmployerContributionCost" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MultiemployerPlanEmployerContributionCost"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MultiemployerPlanEmployerContributionCost" xlink:to="lab_us-gaap_MultiemployerPlanEmployerContributionCost" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiability_ad8f45ff-ced8-4caa-a6e5-f8d9ef1df263_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance leases </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiability_cbb9e270-93ce-4353-a549-3b557548b60f_verboseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiability_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiability"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiability" xlink:to="lab_us-gaap_FinanceLeaseLiability" xlink:type="arc" order="1"/>

<link:label id="lab_dei_DocumentFinStmtErrorCorrectionFlag_41865726-7452-4b01-92be-4980c7e96991_terseLabel_en-US" xlink:label="lab_dei_DocumentFinStmtErrorCorrectionFlag" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Financial Statement Error Correction [Flag] </link:label>

<link:label id="lab_dei_DocumentFinStmtErrorCorrectionFlag_label_en-US" xlink:label="lab_dei_DocumentFinStmtErrorCorrectionFlag" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Financial Statement Error Correction [Flag] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFinStmtErrorCorrectionFlag" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentFinStmtErrorCorrectionFlag"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_DocumentFinStmtErrorCorrectionFlag" xlink:to="lab_dei_DocumentFinStmtErrorCorrectionFlag" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LeaseFinancingTransactionLiabilityNoncurrent_9e61fc66-7e0d-400b-96ed-b290ebe0f5d7_terseLabel_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease financing transaction liabilities </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionLiabilityNoncurrent_label_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transaction, Liability, Noncurrent </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionLiabilityNoncurrent_documentation_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transaction, Liability, Noncurrent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LeaseFinancingTransactionLiabilityNoncurrent" xlink:href="pwr-20231231.xsd#pwr_LeaseFinancingTransactionLiabilityNoncurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LeaseFinancingTransactionLiabilityNoncurrent" xlink:to="lab_pwr_LeaseFinancingTransactionLiabilityNoncurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_c9318745-e059-4f8e-9824-fb4b231f64da_negatedLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Forfeited, shares (in shares) </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_5568239e-1045-41b1-8a71-84d808cc0c6b_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of shares granted for acquired companies (in shares) </link:label>

<link:label id="lab_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_label_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisition, Equity Interest Issued or Issuable, Number of Shares </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" xlink:to="lab_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_bc852056-2547-4858-baee-7129d184f446_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Percentage of employee contribution, lower range </link:label>

<link:label id="lab_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_label_en-US" xlink:label="lab_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" xlink:to="lab_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AllowanceForDoubtfulAccountsReceivable_accf988b-6a31-4bb1-a7f7-50e56edafb5b_periodStartLabel_en-US" xlink:label="lab_us-gaap_AllowanceForDoubtfulAccountsReceivable" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Balance at beginning of year </link:label>

<link:label id="lab_us-gaap_AllowanceForDoubtfulAccountsReceivable_211bfa75-4f9b-4fe1-8157-f2c00c2ad883_periodEndLabel_en-US" xlink:label="lab_us-gaap_AllowanceForDoubtfulAccountsReceivable" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Balance at end of year </link:label>

<link:label id="lab_us-gaap_AllowanceForDoubtfulAccountsReceivable_label_en-US" xlink:label="lab_us-gaap_AllowanceForDoubtfulAccountsReceivable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable, Allowance for Credit Loss </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable" xlink:to="lab_us-gaap_AllowanceForDoubtfulAccountsReceivable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_8a151c69-5e13-4cc0-91aa-8fb0c245ac75_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] </link:label>

<link:label id="lab_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable" xlink:to="lab_us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansDisclosuresTable" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ExcessOfEuroCurrencyRateMember_2ad638b4-2dd2-4a04-8327-74e743155f46_terseLabel_en-US" xlink:label="lab_pwr_ExcessOfEuroCurrencyRateMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess of Euro Currency Rate </link:label>

<link:label id="lab_pwr_ExcessOfEuroCurrencyRateMember_label_en-US" xlink:label="lab_pwr_ExcessOfEuroCurrencyRateMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess Of Euro Currency Rate [Member] </link:label>

<link:label id="lab_pwr_ExcessOfEuroCurrencyRateMember_documentation_en-US" xlink:label="lab_pwr_ExcessOfEuroCurrencyRateMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess Of Euro Currency Rate [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ExcessOfEuroCurrencyRateMember" xlink:href="pwr-20231231.xsd#pwr_ExcessOfEuroCurrencyRateMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ExcessOfEuroCurrencyRateMember" xlink:to="lab_pwr_ExcessOfEuroCurrencyRateMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_56f67fe9-2fbb-4bde-ad25-49da0261d600_terseLabel_en-US" xlink:label="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2024 </link:label>

<link:label id="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_label_en-US" xlink:label="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Debt, Maturity, Year One </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths" xlink:to="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SharePrice_df35fb20-05e9-4b84-b8a2-ad42d56bc945_terseLabel_en-US" xlink:label="lab_us-gaap_SharePrice" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Valuation date price based on March 9, 2023, March 2, 2022 and March 25, 2021 closing stock prices of Quanta common stock (in usd per share) </link:label>

<link:label id="lab_us-gaap_SharePrice_label_en-US" xlink:label="lab_us-gaap_SharePrice" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share Price </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharePrice" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharePrice"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharePrice" xlink:to="lab_us-gaap_SharePrice" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_1f2eafc2-173d-4913-8bdd-420be20de08a_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Segment Reporting Information, by Segment [Table] </link:label>

<link:label id="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Segment Reporting Information, by Segment [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentRedemptionPeriodOneMember_cfa2623c-75cb-4668-af1d-34adb1507d95_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodOneMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Redemption, Period One </link:label>

<link:label id="lab_us-gaap_DebtInstrumentRedemptionPeriodOneMember_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodOneMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Redemption, Period One [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember" xlink:to="lab_us-gaap_DebtInstrumentRedemptionPeriodOneMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearTwo_07f27b16-8ec4-4ecc-9a06-2495dd1ad863_totalLabel_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearTwo" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2025 </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearTwo_label_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearTwo" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, To Be Paid, Year Two </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearTwo_documentation_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearTwo" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, To Be Paid, Year Two </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearTwo" xlink:href="pwr-20231231.xsd#pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearTwo"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearTwo" xlink:to="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearTwo" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongtermDebtWeightedAverageInterestRate_62a5e30d-0a0e-4d50-a70d-e679afed755c_terseLabel_en-US" xlink:label="lab_us-gaap_LongtermDebtWeightedAverageInterestRate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest rate </link:label>

<link:label id="lab_us-gaap_LongtermDebtWeightedAverageInterestRate_label_en-US" xlink:label="lab_us-gaap_LongtermDebtWeightedAverageInterestRate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Debt, Weighted Average Interest Rate, at Point in Time </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtWeightedAverageInterestRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtWeightedAverageInterestRate"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongtermDebtWeightedAverageInterestRate" xlink:to="lab_us-gaap_LongtermDebtWeightedAverageInterestRate" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_141d6357-a507-4db6-bd44-b63aab0dbbf6_terseLabel_en-US" xlink:label="lab_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effect of dilutive unvested non-participating stock-based awards (in shares) </link:label>

<link:label id="lab_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_label_en-US" xlink:label="lab_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:to="lab_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_NationalElectricalBenefitFundMember_1137b7fc-dac1-4485-a562-01c5d189703c_terseLabel_en-US" xlink:label="lab_pwr_NationalElectricalBenefitFundMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> National Electrical Benefit Fund </link:label>

<link:label id="lab_pwr_NationalElectricalBenefitFundMember_label_en-US" xlink:label="lab_pwr_NationalElectricalBenefitFundMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> National Electrical Benefit Fund [Member] </link:label>

<link:label id="lab_pwr_NationalElectricalBenefitFundMember_documentation_en-US" xlink:label="lab_pwr_NationalElectricalBenefitFundMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> National electrical benefit fund. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_NationalElectricalBenefitFundMember" xlink:href="pwr-20231231.xsd#pwr_NationalElectricalBenefitFundMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_NationalElectricalBenefitFundMember" xlink:to="lab_pwr_NationalElectricalBenefitFundMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_MultiemployerPlanPensionSignificantEmployeesCoveredByCollectiveBargainingArrangementToAllParticipantsPercentage_ffecec96-cadf-44fe-81a9-ba11ac06b065_terseLabel_en-US" xlink:label="lab_us-gaap_MultiemployerPlanPensionSignificantEmployeesCoveredByCollectiveBargainingArrangementToAllParticipantsPercentage" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Percent of employees covered by collective bargaining agreements </link:label>

<link:label id="lab_us-gaap_MultiemployerPlanPensionSignificantEmployeesCoveredByCollectiveBargainingArrangementToAllParticipantsPercentage_label_en-US" xlink:label="lab_us-gaap_MultiemployerPlanPensionSignificantEmployeesCoveredByCollectiveBargainingArrangementToAllParticipantsPercentage" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Multiemployer Plan, Pension, Significant, Employees Covered by Collective-Bargaining Arrangement to All Participants, Percentage </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_MultiemployerPlanPensionSignificantEmployeesCoveredByCollectiveBargainingArrangementToAllParticipantsPercentage" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MultiemployerPlanPensionSignificantEmployeesCoveredByCollectiveBargainingArrangementToAllParticipantsPercentage"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MultiemployerPlanPensionSignificantEmployeesCoveredByCollectiveBargainingArrangementToAllParticipantsPercentage" xlink:to="lab_us-gaap_MultiemployerPlanPensionSignificantEmployeesCoveredByCollectiveBargainingArrangementToAllParticipantsPercentage" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_eac7c97a-eb01-4bf7-a54c-974dfd7fb463_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions (in shares) </link:label>

<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Issued During Period, Shares, Acquisitions </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:to="lab_us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:type="arc" order="1"/>

<link:label id="lab_dei_DocumentsIncorporatedByReferenceTextBlock_fd5d5c19-ca40-476a-b21c-046024c5c120_terseLabel_en-US" xlink:label="lab_dei_DocumentsIncorporatedByReferenceTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Documents Incorporated by Reference </link:label>

<link:label id="lab_dei_DocumentsIncorporatedByReferenceTextBlock_label_en-US" xlink:label="lab_dei_DocumentsIncorporatedByReferenceTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Documents Incorporated by Reference [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_DocumentsIncorporatedByReferenceTextBlock" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentsIncorporatedByReferenceTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_DocumentsIncorporatedByReferenceTextBlock" xlink:to="lab_dei_DocumentsIncorporatedByReferenceTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2026Member_ad543257-78c4-4b81-97fd-933ea60f9854_terseLabel_en-US" xlink:label="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2026Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments Due First Business Day Of Quarter In 2026 </link:label>

<link:label id="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2026Member_label_en-US" xlink:label="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2026Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments Due First Business Day Of Quarter In 2026 [Member] </link:label>

<link:label id="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2026Member_documentation_en-US" xlink:label="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2026Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments Due First Business Day Of Quarter In 2026 </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2026Member" xlink:href="pwr-20231231.xsd#pwr_PaymentsDueFirstBusinessDayOfQuarterIn2026Member"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2026Member" xlink:to="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2026Member" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LineOfCreditDebtCovenantMaximumAmountOutstanding_56d283cf-2248-46df-8758-ae5c7db55089_terseLabel_en-US" xlink:label="lab_pwr_LineOfCreditDebtCovenantMaximumAmountOutstanding" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Limit on surety-backed line of credit </link:label>

<link:label id="lab_pwr_LineOfCreditDebtCovenantMaximumAmountOutstanding_label_en-US" xlink:label="lab_pwr_LineOfCreditDebtCovenantMaximumAmountOutstanding" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit, Debt Covenant, Maximum Amount Outstanding </link:label>

<link:label id="lab_pwr_LineOfCreditDebtCovenantMaximumAmountOutstanding_documentation_en-US" xlink:label="lab_pwr_LineOfCreditDebtCovenantMaximumAmountOutstanding" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit, Debt Covenant, Maximum Amount Outstanding </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LineOfCreditDebtCovenantMaximumAmountOutstanding" xlink:href="pwr-20231231.xsd#pwr_LineOfCreditDebtCovenantMaximumAmountOutstanding"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LineOfCreditDebtCovenantMaximumAmountOutstanding" xlink:to="lab_pwr_LineOfCreditDebtCovenantMaximumAmountOutstanding" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_RevenueRecognizedRelatedToUnapprovedChangeOrdersAndClaims_ee5fc2f2-6e50-482a-a90f-250be171993c_terseLabel_en-US" xlink:label="lab_pwr_RevenueRecognizedRelatedToUnapprovedChangeOrdersAndClaims" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenues recognized related to change orders and claims </link:label>

<link:label id="lab_pwr_RevenueRecognizedRelatedToUnapprovedChangeOrdersAndClaims_label_en-US" xlink:label="lab_pwr_RevenueRecognizedRelatedToUnapprovedChangeOrdersAndClaims" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue Recognized, Related To Unapproved Change Orders And Claims </link:label>

<link:label id="lab_pwr_RevenueRecognizedRelatedToUnapprovedChangeOrdersAndClaims_documentation_en-US" xlink:label="lab_pwr_RevenueRecognizedRelatedToUnapprovedChangeOrdersAndClaims" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue Recognized, Related To Unapproved Change Orders And Claims </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_RevenueRecognizedRelatedToUnapprovedChangeOrdersAndClaims" xlink:href="pwr-20231231.xsd#pwr_RevenueRecognizedRelatedToUnapprovedChangeOrdersAndClaims"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_RevenueRecognizedRelatedToUnapprovedChangeOrdersAndClaims" xlink:to="lab_pwr_RevenueRecognizedRelatedToUnapprovedChangeOrdersAndClaims" xlink:type="arc" order="1"/>

<link:label id="lab_dei_DocumentPeriodEndDate_dbf3afad-0917-4247-880b-684aa28c0253_terseLabel_en-US" xlink:label="lab_dei_DocumentPeriodEndDate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Period End Date </link:label>

<link:label id="lab_dei_DocumentPeriodEndDate_label_en-US" xlink:label="lab_dei_DocumentPeriodEndDate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Period End Date </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentPeriodEndDate"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_DocumentPeriodEndDate" xlink:to="lab_dei_DocumentPeriodEndDate" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_TrdArrAdoptionDate_terseLabel_en-US" xlink:label="lab_ecd_TrdArrAdoptionDate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adoption Date </link:label>

<link:label id="lab_ecd_TrdArrAdoptionDate_label_en-US" xlink:label="lab_ecd_TrdArrAdoptionDate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trading Arrangement Adoption Date </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_TrdArrAdoptionDate" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_TrdArrAdoptionDate"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_TrdArrAdoptionDate" xlink:to="lab_ecd_TrdArrAdoptionDate" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent_861c8093-6399-4022-ad0b-5abb207d8f39_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance leases </link:label>

<link:label id="lab_us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Weighted Average Discount Rate, Percent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent" xlink:to="lab_us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityNoncurrent_0e362b75-68bf-48af-8aa1-ba9bb4e2b224_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityNoncurrent_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Noncurrent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityNoncurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:to="lab_us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DebtInstrumentPaymentDueDateDomain_2fc7af68-8676-4a76-b006-1951f23c7950_terseLabel_en-US" xlink:label="lab_pwr_DebtInstrumentPaymentDueDateDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Payment Due Date [Domain] </link:label>

<link:label id="lab_pwr_DebtInstrumentPaymentDueDateDomain_label_en-US" xlink:label="lab_pwr_DebtInstrumentPaymentDueDateDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Payment Due Date [Domain] </link:label>

<link:label id="lab_pwr_DebtInstrumentPaymentDueDateDomain_documentation_en-US" xlink:label="lab_pwr_DebtInstrumentPaymentDueDateDomain" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Payment Due Date [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DebtInstrumentPaymentDueDateDomain" xlink:href="pwr-20231231.xsd#pwr_DebtInstrumentPaymentDueDateDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DebtInstrumentPaymentDueDateDomain" xlink:to="lab_pwr_DebtInstrumentPaymentDueDateDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessAcquisitionProFormaInformationTextBlock_b6eea502-5b34-4aa5-aada-6dec79d6b125_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionProFormaInformationTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unaudited Supplemental Pro Forma Results of Operations </link:label>

<link:label id="lab_us-gaap_BusinessAcquisitionProFormaInformationTextBlock_label_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionProFormaInformationTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisition, Pro Forma Information [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaInformationTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionProFormaInformationTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessAcquisitionProFormaInformationTextBlock" xlink:to="lab_us-gaap_BusinessAcquisitionProFormaInformationTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AccountsReceivableAllowanceForCreditLossTableTextBlock_dff752f1-4910-425d-a113-859100dbe29d_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsReceivableAllowanceForCreditLossTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Composition of the Allowance for Credit Losses </link:label>

<link:label id="lab_us-gaap_AccountsReceivableAllowanceForCreditLossTableTextBlock_label_en-US" xlink:label="lab_us-gaap_AccountsReceivableAllowanceForCreditLossTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable, Allowance for Credit Loss [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableAllowanceForCreditLossTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivableAllowanceForCreditLossTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsReceivableAllowanceForCreditLossTableTextBlock" xlink:to="lab_us-gaap_AccountsReceivableAllowanceForCreditLossTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_TreasuryStockCommonMember_42c3b099-0159-4ff9-bded-8e486f9d307a_terseLabel_en-US" xlink:label="lab_us-gaap_TreasuryStockCommonMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Treasury Stock </link:label>

<link:label id="lab_us-gaap_TreasuryStockCommonMember_label_en-US" xlink:label="lab_us-gaap_TreasuryStockCommonMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Treasury Stock, Common [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockCommonMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TreasuryStockCommonMember" xlink:to="lab_us-gaap_TreasuryStockCommonMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SegmentReportingInformationLineItems_09d37107-150a-4018-9c62-84e2fc7de071_terseLabel_en-US" xlink:label="lab_us-gaap_SegmentReportingInformationLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Reporting Information [Line Items] </link:label>

<link:label id="lab_us-gaap_SegmentReportingInformationLineItems_label_en-US" xlink:label="lab_us-gaap_SegmentReportingInformationLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Reporting Information [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingInformationLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems" xlink:to="lab_us-gaap_SegmentReportingInformationLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LossContingenciesByNatureOfContingencyAxis_b087b38c-afdb-4d48-9d03-5643c6cacb49_terseLabel_en-US" xlink:label="lab_us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss Contingency Nature [Axis] </link:label>

<link:label id="lab_us-gaap_LossContingenciesByNatureOfContingencyAxis_label_en-US" xlink:label="lab_us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss Contingency Nature [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:to="lab_us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxExpenseBenefit_276962ec-8515-4a9c-9609-9e57c0a80f21_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Provision for income taxes </link:label>

<link:label id="lab_us-gaap_IncomeTaxExpenseBenefit_99649c14-eb8c-4ddc-bf04-26d7246c10f9_totalLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total provision for income taxes </link:label>

<link:label id="lab_us-gaap_IncomeTaxExpenseBenefit_label_en-US" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Expense (Benefit) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxExpenseBenefit"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefit" xlink:to="lab_us-gaap_IncomeTaxExpenseBenefit" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NonUsMember_7ceeea4f-2ec5-43c7-9af6-4f5cc85015c4_terseLabel_en-US" xlink:label="lab_us-gaap_NonUsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-US </link:label>

<link:label id="lab_us-gaap_NonUsMember_label_en-US" xlink:label="lab_us-gaap_NonUsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-US [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonUsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NonUsMember" xlink:to="lab_us-gaap_NonUsMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_PerformanceStockUnitsPSUsMember_31d0db77-0169-4d49-83c8-98e0d0805b62_terseLabel_en-US" xlink:label="lab_pwr_PerformanceStockUnitsPSUsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> PSUs </link:label>

<link:label id="lab_pwr_PerformanceStockUnitsPSUsMember_label_en-US" xlink:label="lab_pwr_PerformanceStockUnitsPSUsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Performance Stock Units (PSUs) [Member] </link:label>

<link:label id="lab_pwr_PerformanceStockUnitsPSUsMember_documentation_en-US" xlink:label="lab_pwr_PerformanceStockUnitsPSUsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Performance units. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_PerformanceStockUnitsPSUsMember" xlink:href="pwr-20231231.xsd#pwr_PerformanceStockUnitsPSUsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_PerformanceStockUnitsPSUsMember" xlink:to="lab_pwr_PerformanceStockUnitsPSUsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_5b36d8d6-f49c-443a-a62c-851a49180ec5_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred compensation obligations included in other long-term liabilities </link:label>

<link:label id="lab_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_label_en-US" xlink:label="lab_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Compensation Liability, Classified, Noncurrent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent" xlink:to="lab_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs_436ca411-a804-4354-8109-f149fa3cdfb5_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Write-offs charged against the allowance net of recoveries of amounts previously written off </link:label>

<link:label id="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs_label_en-US" xlink:label="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable, Allowance for Credit Loss, Writeoff </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs" xlink:to="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableWriteOffs" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseRightOfUseAsset_86088141-4fb7-44fb-a5d6-14bf90693f1a_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance lease assets </link:label>

<link:label id="lab_us-gaap_FinanceLeaseRightOfUseAsset_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Right-of-Use Asset, after Accumulated Amortization </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAsset" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseRightOfUseAsset"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseRightOfUseAsset" xlink:to="lab_us-gaap_FinanceLeaseRightOfUseAsset" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_InsuranceRecoveriesMember_5e146c43-0bf6-470b-a68c-07068136aa73_terseLabel_en-US" xlink:label="lab_pwr_InsuranceRecoveriesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insurance Recoveries </link:label>

<link:label id="lab_pwr_InsuranceRecoveriesMember_label_en-US" xlink:label="lab_pwr_InsuranceRecoveriesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insurance Recoveries [Member] </link:label>

<link:label id="lab_pwr_InsuranceRecoveriesMember_documentation_en-US" xlink:label="lab_pwr_InsuranceRecoveriesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insurance Recoveries </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_InsuranceRecoveriesMember" xlink:href="pwr-20231231.xsd#pwr_InsuranceRecoveriesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_InsuranceRecoveriesMember" xlink:to="lab_pwr_InsuranceRecoveriesMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LiabilitiesCurrentLesseeAbstract_2b8da2f1-dec4-49ee-81ec-166fe0105787_terseLabel_en-US" xlink:label="lab_pwr_LiabilitiesCurrentLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current: </link:label>

<link:label id="lab_pwr_LiabilitiesCurrentLesseeAbstract_label_en-US" xlink:label="lab_pwr_LiabilitiesCurrentLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities, Current, Lessee [Abstract] </link:label>

<link:label id="lab_pwr_LiabilitiesCurrentLesseeAbstract_documentation_en-US" xlink:label="lab_pwr_LiabilitiesCurrentLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities, Current, Lessee [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LiabilitiesCurrentLesseeAbstract" xlink:href="pwr-20231231.xsd#pwr_LiabilitiesCurrentLesseeAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LiabilitiesCurrentLesseeAbstract" xlink:to="lab_pwr_LiabilitiesCurrentLesseeAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_BlattnerHoldingCompanyMember_ae729126-379b-430a-b634-b75edd10f257_terseLabel_en-US" xlink:label="lab_pwr_BlattnerHoldingCompanyMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Blattner Holding Company </link:label>

<link:label id="lab_pwr_BlattnerHoldingCompanyMember_label_en-US" xlink:label="lab_pwr_BlattnerHoldingCompanyMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Blattner Holding Company [Member] </link:label>

<link:label id="lab_pwr_BlattnerHoldingCompanyMember_documentation_en-US" xlink:label="lab_pwr_BlattnerHoldingCompanyMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Blattner Holding Company </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_BlattnerHoldingCompanyMember" xlink:href="pwr-20231231.xsd#pwr_BlattnerHoldingCompanyMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_BlattnerHoldingCompanyMember" xlink:to="lab_pwr_BlattnerHoldingCompanyMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_VestingAxis_92da475f-680f-4c67-a65a-af39d8c4e544_terseLabel_en-US" xlink:label="lab_us-gaap_VestingAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Vesting [Axis] </link:label>

<link:label id="lab_us-gaap_VestingAxis_label_en-US" xlink:label="lab_us-gaap_VestingAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Vesting [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VestingAxis" xlink:to="lab_us-gaap_VestingAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OperatingLossCarryforwardsValuationAllowance_1a2bca4d-3955-43bd-8308-28231ffcc9ce_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLossCarryforwardsValuationAllowance" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Valuation allowance foreign and state net operating loss carryforwards </link:label>

<link:label id="lab_us-gaap_OperatingLossCarryforwardsValuationAllowance_label_en-US" xlink:label="lab_us-gaap_OperatingLossCarryforwardsValuationAllowance" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Loss Carryforwards, Valuation Allowance </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsValuationAllowance" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLossCarryforwardsValuationAllowance"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLossCarryforwardsValuationAllowance" xlink:to="lab_us-gaap_OperatingLossCarryforwardsValuationAllowance" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_RevenueFromContractWithCustomerPercentageOfRevenueRecognizedOverTime_68a69203-369b-4ef3-889a-537d6d3e4d04_terseLabel_en-US" xlink:label="lab_pwr_RevenueFromContractWithCustomerPercentageOfRevenueRecognizedOverTime" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Percent of total revenues recognized associated with revenue recognition method </link:label>

<link:label id="lab_pwr_RevenueFromContractWithCustomerPercentageOfRevenueRecognizedOverTime_label_en-US" xlink:label="lab_pwr_RevenueFromContractWithCustomerPercentageOfRevenueRecognizedOverTime" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue From Contract With Customer, Percentage Of Revenue Recognized Over Time </link:label>

<link:label id="lab_pwr_RevenueFromContractWithCustomerPercentageOfRevenueRecognizedOverTime_documentation_en-US" xlink:label="lab_pwr_RevenueFromContractWithCustomerPercentageOfRevenueRecognizedOverTime" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue From Contract With Customer, Percentage Of Revenue Recognized Over Time </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_RevenueFromContractWithCustomerPercentageOfRevenueRecognizedOverTime" xlink:href="pwr-20231231.xsd#pwr_RevenueFromContractWithCustomerPercentageOfRevenueRecognizedOverTime"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_RevenueFromContractWithCustomerPercentageOfRevenueRecognizedOverTime" xlink:to="lab_pwr_RevenueFromContractWithCustomerPercentageOfRevenueRecognizedOverTime" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EquityAbstract_7084f878-2164-474c-ad37-5cead123d96c_terseLabel_en-US" xlink:label="lab_us-gaap_EquityAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity [Abstract] </link:label>

<link:label id="lab_us-gaap_EquityAbstract_label_en-US" xlink:label="lab_us-gaap_EquityAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquityAbstract" xlink:to="lab_us-gaap_EquityAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_9fc99960-6a38-4853-abf6-60d7b8731968_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating leases </link:label>

<link:label id="lab_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Weighted Average Remaining Lease Term </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:to="lab_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_9d9a9492-23ab-4303-85bc-f833e4a5bdb3_totalLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair value of net assets acquired </link:label>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_CompActuallyPaidVsCoSelectedMeasureTextBlock_terseLabel_en-US" xlink:label="lab_ecd_CompActuallyPaidVsCoSelectedMeasureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Compensation Actually Paid vs. Company Selected Measure </link:label>

<link:label id="lab_ecd_CompActuallyPaidVsCoSelectedMeasureTextBlock_label_en-US" xlink:label="lab_ecd_CompActuallyPaidVsCoSelectedMeasureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Compensation Actually Paid vs. Company Selected Measure [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_CompActuallyPaidVsCoSelectedMeasureTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_CompActuallyPaidVsCoSelectedMeasureTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_CompActuallyPaidVsCoSelectedMeasureTextBlock" xlink:to="lab_ecd_CompActuallyPaidVsCoSelectedMeasureTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ContractWithCustomerLiabilityDeferredRevenuesCurrent_10c6aa32-5110-469c-9da6-b27f0d7a8c13_terseLabel_en-US" xlink:label="lab_pwr_ContractWithCustomerLiabilityDeferredRevenuesCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unearned revenues </link:label>

<link:label id="lab_pwr_ContractWithCustomerLiabilityDeferredRevenuesCurrent_label_en-US" xlink:label="lab_pwr_ContractWithCustomerLiabilityDeferredRevenuesCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Liability, Deferred Revenues, Current </link:label>

<link:label id="lab_pwr_ContractWithCustomerLiabilityDeferredRevenuesCurrent_documentation_en-US" xlink:label="lab_pwr_ContractWithCustomerLiabilityDeferredRevenuesCurrent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Liability, Deferred Revenues, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ContractWithCustomerLiabilityDeferredRevenuesCurrent" xlink:href="pwr-20231231.xsd#pwr_ContractWithCustomerLiabilityDeferredRevenuesCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ContractWithCustomerLiabilityDeferredRevenuesCurrent" xlink:to="lab_pwr_ContractWithCustomerLiabilityDeferredRevenuesCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_12b6261f-35e9-495d-98f4-520ba6307538_terseLabel_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and cash equivalents </link:label>

<link:label id="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_label_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and Cash Equivalents, at Carrying Value </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:to="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_166162a2-fc1c-4236-9192-7a8b589d4bf8_negatedLabel_en-US" xlink:label="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash paid for acquisitions, net of cash, cash equivalents and restricted cash acquired </link:label>

<link:label id="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_label_en-US" xlink:label="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments to Acquire Businesses, Net of Cash Acquired </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:to="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_45ab8277-0d74-4588-abef-26f1274536cc_totalLabel_en-US" xlink:label="lab_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Comprehensive income </link:label>

<link:label id="lab_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest_label_en-US" xlink:label="lab_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:to="lab_us-gaap_ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentFairValueDisclosure_84ffeb8c-4eb7-4cdd-9f67-7862f9e7fde5_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentFairValueDisclosure" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair value </link:label>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentFairValueDisclosure_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentFairValueDisclosure" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant, and Equipment, Fair Value Disclosure </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentFairValueDisclosure" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentFairValueDisclosure"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentFairValueDisclosure" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentFairValueDisclosure" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CreditFacilityDomain_0efff836-b675-4ee3-ad6b-4ddf92813a8a_terseLabel_en-US" xlink:label="lab_us-gaap_CreditFacilityDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Facility [Domain] </link:label>

<link:label id="lab_us-gaap_CreditFacilityDomain_label_en-US" xlink:label="lab_us-gaap_CreditFacilityDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Facility [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CreditFacilityDomain" xlink:to="lab_us-gaap_CreditFacilityDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_TreasuryStockSharesAcquired_3e0a25f9-64b3-499b-b570-202d803f223d_negatedLabel_en-US" xlink:label="lab_us-gaap_TreasuryStockSharesAcquired" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock repurchases (in shares) </link:label>

<link:label id="lab_us-gaap_TreasuryStockSharesAcquired_286bea0a-95ba-453c-a5ca-d01811979c9b_terseLabel_en-US" xlink:label="lab_us-gaap_TreasuryStockSharesAcquired" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Treasury stock acquired (in shares) </link:label>

<link:label id="lab_us-gaap_TreasuryStockSharesAcquired_label_en-US" xlink:label="lab_us-gaap_TreasuryStockSharesAcquired" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Treasury Stock, Shares, Acquired </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockSharesAcquired"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TreasuryStockSharesAcquired" xlink:to="lab_us-gaap_TreasuryStockSharesAcquired" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife_fbb21d52-1781-47ea-b70f-1bb540da793f_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Estimated useful lives </link:label>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment, Useful Life </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_0fbea93e-5f9c-42ed-a1ed-677b53feff8a_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt instrument basis spread on variable rate </link:label>

<link:label id="lab_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Basis Spread on Variable Rate </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:to="lab_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_CompActuallyPaidVsOtherMeasureTextBlock_terseLabel_en-US" xlink:label="lab_ecd_CompActuallyPaidVsOtherMeasureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Compensation Actually Paid vs. Other Measure </link:label>

<link:label id="lab_ecd_CompActuallyPaidVsOtherMeasureTextBlock_label_en-US" xlink:label="lab_ecd_CompActuallyPaidVsOtherMeasureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Compensation Actually Paid vs. Other Measure [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_CompActuallyPaidVsOtherMeasureTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_CompActuallyPaidVsOtherMeasureTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_CompActuallyPaidVsOtherMeasureTextBlock" xlink:to="lab_ecd_CompActuallyPaidVsOtherMeasureTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_9b510695-34e7-4994-8135-4b47e5d5f4c9_terseLabel_en-US" xlink:label="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amounts attributable to common stock: </link:label>

<link:label id="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_label_en-US" xlink:label="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Income (Loss) Available to Common Stockholders, Basic [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract" xlink:to="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ProceedsFromSaleOfEquityMethodInvestments_23f2e509-2a21-4513-b88b-689151d3fa35_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromSaleOfEquityMethodInvestments" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total consideration </link:label>

<link:label id="lab_us-gaap_ProceedsFromSaleOfEquityMethodInvestments_label_en-US" xlink:label="lab_us-gaap_ProceedsFromSaleOfEquityMethodInvestments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Sale of Equity Method Investments </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfEquityMethodInvestments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromSaleOfEquityMethodInvestments"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromSaleOfEquityMethodInvestments" xlink:to="lab_us-gaap_ProceedsFromSaleOfEquityMethodInvestments" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_dba2436c-8401-481c-bcb1-1d9d6b17c7a9_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Identifiable intangible assets </link:label>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock_866c4f25-f03f-4b75-a2c5-0de9af6abb8d_terseLabel_en-US" xlink:label="lab_us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract Assets and Liabilities </link:label>

<link:label id="lab_us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock" xlink:to="lab_us-gaap_ContractWithCustomerAssetAndLiabilityTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_e4950dbb-e8da-4a62-ae07-0251c5d34da0_terseLabel_en-US" xlink:label="lab_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance leases </link:label>

<link:label id="lab_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_label_en-US" xlink:label="lab_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Right-of-Use Asset Obtained in Exchange for Finance Lease Liability </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability" xlink:to="lab_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_4652615f-c2cb-4df9-b268-1895837af272_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Less imputed interest </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Undiscounted Excess Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" xlink:to="lab_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RevenueFromContractWithCustomerTextBlock_9054e647-a194-4df4-b2ef-903012b7be6e_terseLabel_en-US" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue Recognition and Related Balance Sheet Accounts </link:label>

<link:label id="lab_us-gaap_RevenueFromContractWithCustomerTextBlock_label_en-US" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue from Contract with Customer [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenueFromContractWithCustomerTextBlock" xlink:to="lab_us-gaap_RevenueFromContractWithCustomerTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities_64c5a092-3f4c-4c30-8f41-43a84f9bb13b_terseLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reduction related to settlement of audits </link:label>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities_9e0dfe0f-b22d-426b-a744-7d66f11ec830_negatedLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reductions for audit settlements </link:label>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities_label_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities" xlink:to="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncreaseDecreaseInAccountsAndNotesReceivable_592a0ac9-7975-4448-8d04-d6e6155c6e1f_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsAndNotesReceivable" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts and notes receivable </link:label>

<link:label id="lab_us-gaap_IncreaseDecreaseInAccountsAndNotesReceivable_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsAndNotesReceivable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Accounts and Notes Receivable </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsAndNotesReceivable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInAccountsAndNotesReceivable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInAccountsAndNotesReceivable" xlink:to="lab_us-gaap_IncreaseDecreaseInAccountsAndNotesReceivable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AdditionalPaidInCapitalCommonStock_0a8669f0-35d6-4b4b-9bb5-ca0e00591877_terseLabel_en-US" xlink:label="lab_us-gaap_AdditionalPaidInCapitalCommonStock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Additional paid-in capital </link:label>

<link:label id="lab_us-gaap_AdditionalPaidInCapitalCommonStock_label_en-US" xlink:label="lab_us-gaap_AdditionalPaidInCapitalCommonStock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Additional Paid in Capital, Common Stock </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalCommonStock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdditionalPaidInCapitalCommonStock" xlink:to="lab_us-gaap_AdditionalPaidInCapitalCommonStock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AdditionalPaidInCapitalMember_956d208d-b0e5-41d3-8fac-747e0aba5fc3_terseLabel_en-US" xlink:label="lab_us-gaap_AdditionalPaidInCapitalMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Additional Paid-in Capital </link:label>

<link:label id="lab_us-gaap_AdditionalPaidInCapitalMember_label_en-US" xlink:label="lab_us-gaap_AdditionalPaidInCapitalMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Additional Paid-in Capital [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdditionalPaidInCapitalMember" xlink:to="lab_us-gaap_AdditionalPaidInCapitalMember" xlink:type="arc" order="1"/>

<link:label id="lab_dei_DocumentAnnualReport_12c526f2-a3c7-42da-a618-04d575c6ff24_terseLabel_en-US" xlink:label="lab_dei_DocumentAnnualReport" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Annual Report </link:label>

<link:label id="lab_dei_DocumentAnnualReport_label_en-US" xlink:label="lab_dei_DocumentAnnualReport" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Annual Report </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_DocumentAnnualReport" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentAnnualReport"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_DocumentAnnualReport" xlink:to="lab_dei_DocumentAnnualReport" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BalanceSheetLocationAxis_762bb88b-af4a-440d-b5e7-9113a9e3f9e7_terseLabel_en-US" xlink:label="lab_us-gaap_BalanceSheetLocationAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Balance Sheet Location [Axis] </link:label>

<link:label id="lab_us-gaap_BalanceSheetLocationAxis_label_en-US" xlink:label="lab_us-gaap_BalanceSheetLocationAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Balance Sheet Location [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BalanceSheetLocationAxis" xlink:to="lab_us-gaap_BalanceSheetLocationAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LossContingenciesLineItems_4514629c-da1a-4580-a3c6-1bfb92e3ff86_terseLabel_en-US" xlink:label="lab_us-gaap_LossContingenciesLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss Contingencies [Line Items] </link:label>

<link:label id="lab_us-gaap_LossContingenciesLineItems_label_en-US" xlink:label="lab_us-gaap_LossContingenciesLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss Contingencies [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LossContingenciesLineItems" xlink:to="lab_us-gaap_LossContingenciesLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_dei_CoverAbstract_39524374-4715-47f0-94d4-dcd8afc679bd_terseLabel_en-US" xlink:label="lab_dei_CoverAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cover [Abstract] </link:label>

<link:label id="lab_dei_CoverAbstract_label_en-US" xlink:label="lab_dei_CoverAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cover [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_CoverAbstract" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_CoverAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_CoverAbstract" xlink:to="lab_dei_CoverAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CreditConcentrationRiskMember_ac9030f0-8c27-4294-86fe-a1c92aae324a_terseLabel_en-US" xlink:label="lab_us-gaap_CreditConcentrationRiskMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Concentration Risk </link:label>

<link:label id="lab_us-gaap_CreditConcentrationRiskMember_label_en-US" xlink:label="lab_us-gaap_CreditConcentrationRiskMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Concentration Risk [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditConcentrationRiskMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditConcentrationRiskMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CreditConcentrationRiskMember" xlink:to="lab_us-gaap_CreditConcentrationRiskMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_3458645b-c820-4b5c-a3d3-e31f4e76b96f_terseLabel_en-US" xlink:label="lab_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Category of Item Purchased [Axis] </link:label>

<link:label id="lab_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_label_en-US" xlink:label="lab_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Category of Item Purchased [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis" xlink:to="lab_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LeaseFinancingTransactionLiability_debcf05b-0bbc-4939-bcd8-235413ce1090_terseLabel_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionLiability" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease financing transactions </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionLiability_label_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionLiability" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transaction, Liability </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionLiability_documentation_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionLiability" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transaction, Liability </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LeaseFinancingTransactionLiability" xlink:href="pwr-20231231.xsd#pwr_LeaseFinancingTransactionLiability"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LeaseFinancingTransactionLiability" xlink:to="lab_pwr_LeaseFinancingTransactionLiability" xlink:type="arc" order="1"/>

<link:label id="lab_country_US_d75ef922-8483-4d16-a33b-18f2a8fd2188_terseLabel_en-US" xlink:label="lab_country_US" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> United States </link:label>

<link:label id="lab_country_US_label_en-US" xlink:label="lab_country_US" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> UNITED STATES </link:label>

<link:loc xlink:type="locator" xlink:label="loc_country_US" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_country_US" xlink:to="lab_country_US" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NumberOfBusinessesAcquired_94ee5503-6f0d-4f2f-87c4-94115b191336_terseLabel_en-US" xlink:label="lab_us-gaap_NumberOfBusinessesAcquired" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of businesses acquired </link:label>

<link:label id="lab_us-gaap_NumberOfBusinessesAcquired_label_en-US" xlink:label="lab_us-gaap_NumberOfBusinessesAcquired" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of Businesses Acquired </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfBusinessesAcquired" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NumberOfBusinessesAcquired"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NumberOfBusinessesAcquired" xlink:to="lab_us-gaap_NumberOfBusinessesAcquired" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OtherLiabilitiesNoncurrent_954f30d2-0c3b-4abb-8647-2108fe0d4af7_terseLabel_en-US" xlink:label="lab_us-gaap_OtherLiabilitiesNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insurance and other non-current liabilities </link:label>

<link:label id="lab_us-gaap_OtherLiabilitiesNoncurrent_label_en-US" xlink:label="lab_us-gaap_OtherLiabilitiesNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Liabilities, Noncurrent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherLiabilitiesNoncurrent" xlink:to="lab_us-gaap_OtherLiabilitiesNoncurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_37356fcc-1401-472b-851c-6f9c4c56e2d1_totalLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total future minimum lease payments </link:label>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, to be Paid </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfCashFlowSupplementalDisclosuresTableTextBlock_f61e8763-fdd5-4bc5-8317-5d5359b5e93f_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfCashFlowSupplementalDisclosuresTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reconciliation of Cash, Cash Equivalents, and Restricted Cash and Additional Supplemental Cash Flow Information </link:label>

<link:label id="lab_us-gaap_ScheduleOfCashFlowSupplementalDisclosuresTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfCashFlowSupplementalDisclosuresTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCashFlowSupplementalDisclosuresTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfCashFlowSupplementalDisclosuresTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfCashFlowSupplementalDisclosuresTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfCashFlowSupplementalDisclosuresTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RevenueRemainingPerformanceObligation_2abe650c-55f2-4406-a618-1f4454f4747a_terseLabel_en-US" xlink:label="lab_us-gaap_RevenueRemainingPerformanceObligation" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Remaining performance obligation </link:label>

<link:label id="lab_us-gaap_RevenueRemainingPerformanceObligation_label_en-US" xlink:label="lab_us-gaap_RevenueRemainingPerformanceObligation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue, Remaining Performance Obligation, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligation" xlink:to="lab_us-gaap_RevenueRemainingPerformanceObligation" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ForeignOperatingLossCarryforwardsMember_2961bb85-2b47-48c9-99f0-fb0c5068f181_terseLabel_en-US" xlink:label="lab_pwr_ForeignOperatingLossCarryforwardsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign Operating Loss Carryforwards </link:label>

<link:label id="lab_pwr_ForeignOperatingLossCarryforwardsMember_label_en-US" xlink:label="lab_pwr_ForeignOperatingLossCarryforwardsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign Operating Loss Carryforwards [Member] </link:label>

<link:label id="lab_pwr_ForeignOperatingLossCarryforwardsMember_documentation_en-US" xlink:label="lab_pwr_ForeignOperatingLossCarryforwardsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign Operating Loss Carryforwards </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ForeignOperatingLossCarryforwardsMember" xlink:href="pwr-20231231.xsd#pwr_ForeignOperatingLossCarryforwardsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ForeignOperatingLossCarryforwardsMember" xlink:to="lab_pwr_ForeignOperatingLossCarryforwardsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseRightOfUseAssetAmortization_2d4e6782-b002-446d-9eea-f68b826b4a92_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseRightOfUseAssetAmortization" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amortization of lease assets </link:label>

<link:label id="lab_us-gaap_FinanceLeaseRightOfUseAssetAmortization_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseRightOfUseAssetAmortization" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Right-of-Use Asset, Amortization </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseRightOfUseAssetAmortization"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseRightOfUseAssetAmortization" xlink:to="lab_us-gaap_FinanceLeaseRightOfUseAssetAmortization" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SegmentReportingDisclosureTextBlock_e6cde62d-d9a5-4175-94d8-d281e8e5ef32_terseLabel_en-US" xlink:label="lab_us-gaap_SegmentReportingDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Information </link:label>

<link:label id="lab_us-gaap_SegmentReportingDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_SegmentReportingDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Reporting Disclosure [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingDisclosureTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SegmentReportingDisclosureTextBlock" xlink:to="lab_us-gaap_SegmentReportingDisclosureTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_4222210f-4b29-4e95-ab8f-baa19207588a_totalLabel_en-US" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net increase in cash, cash equivalents and restricted cash </link:label>

<link:label id="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_label_en-US" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CurriculumMember_0f8d357b-4292-47f4-8e27-a52da7f15fe3_terseLabel_en-US" xlink:label="lab_pwr_CurriculumMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Curriculum </link:label>

<link:label id="lab_pwr_CurriculumMember_label_en-US" xlink:label="lab_pwr_CurriculumMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Curriculum [Member] </link:label>

<link:label id="lab_pwr_CurriculumMember_documentation_en-US" xlink:label="lab_pwr_CurriculumMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Curriculum [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CurriculumMember" xlink:href="pwr-20231231.xsd#pwr_CurriculumMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CurriculumMember" xlink:to="lab_pwr_CurriculumMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_GoodwillAndIntangibleAssetsTable_b145c6ad-d6bc-4803-9735-601322040413_terseLabel_en-US" xlink:label="lab_pwr_GoodwillAndIntangibleAssetsTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill And Intangible Assets [Table] </link:label>

<link:label id="lab_pwr_GoodwillAndIntangibleAssetsTable_label_en-US" xlink:label="lab_pwr_GoodwillAndIntangibleAssetsTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill And Intangible Assets [Table] </link:label>

<link:label id="lab_pwr_GoodwillAndIntangibleAssetsTable_documentation_en-US" xlink:label="lab_pwr_GoodwillAndIntangibleAssetsTable" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill And Intangible Assets [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_GoodwillAndIntangibleAssetsTable" xlink:href="pwr-20231231.xsd#pwr_GoodwillAndIntangibleAssetsTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_GoodwillAndIntangibleAssetsTable" xlink:to="lab_pwr_GoodwillAndIntangibleAssetsTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeOperatingLeaseRenewalTerm_ff470139-4bf4-438a-b2e9-b22c91c755d4_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseRenewalTerm" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Option to extend the leases (up to) </link:label>

<link:label id="lab_us-gaap_LesseeOperatingLeaseRenewalTerm_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseRenewalTerm" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Renewal Term </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRenewalTerm" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseRenewalTerm"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseRenewalTerm" xlink:to="lab_us-gaap_LesseeOperatingLeaseRenewalTerm" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EquityComponentDomain_05e3337c-ec00-46f4-9ab6-ea6da9f3a42b_terseLabel_en-US" xlink:label="lab_us-gaap_EquityComponentDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Component [Domain] </link:label>

<link:label id="lab_us-gaap_EquityComponentDomain_label_en-US" xlink:label="lab_us-gaap_EquityComponentDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Component [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquityComponentDomain" xlink:to="lab_us-gaap_EquityComponentDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityCurrent_2aa86279-f187-409a-b4ba-2d5acb0a82dc_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityCurrent_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityCurrent" xlink:to="lab_us-gaap_FinanceLeaseLiabilityCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_PercentageOfTotalRevenues_5e6c207e-8202-443e-a6da-8dc49d55087a_terseLabel_en-US" xlink:label="lab_pwr_PercentageOfTotalRevenues" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Percentage of total revenues </link:label>

<link:label id="lab_pwr_PercentageOfTotalRevenues_label_en-US" xlink:label="lab_pwr_PercentageOfTotalRevenues" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Percentage Of Total Revenues </link:label>

<link:label id="lab_pwr_PercentageOfTotalRevenues_documentation_en-US" xlink:label="lab_pwr_PercentageOfTotalRevenues" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Percentage Of Total Revenues </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_PercentageOfTotalRevenues" xlink:href="pwr-20231231.xsd#pwr_PercentageOfTotalRevenues"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_PercentageOfTotalRevenues" xlink:to="lab_pwr_PercentageOfTotalRevenues" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis_866af3ab-50d8-49e1-80c1-33bb2aacc29d_terseLabel_en-US" xlink:label="lab_us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Project [Axis] </link:label>

<link:label id="lab_us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis_label_en-US" xlink:label="lab_us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Project [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis" xlink:to="lab_us-gaap_CapitalizedCostsOfUnprovedPropertiesExcludedFromAmortizationByPropertyOrProjectAxis" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_NonGaapMeasureDescriptionTextBlock_terseLabel_en-US" xlink:label="lab_ecd_NonGaapMeasureDescriptionTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-GAAP Measure Description </link:label>

<link:label id="lab_ecd_NonGaapMeasureDescriptionTextBlock_label_en-US" xlink:label="lab_ecd_NonGaapMeasureDescriptionTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-GAAP Measure Description [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_NonGaapMeasureDescriptionTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_NonGaapMeasureDescriptionTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_NonGaapMeasureDescriptionTextBlock" xlink:to="lab_ecd_NonGaapMeasureDescriptionTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_AllOtherPlansUSMember_9bff62b6-2975-4930-b033-72d334e1c1be_terseLabel_en-US" xlink:label="lab_pwr_AllOtherPlansUSMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All other plans - U.S. </link:label>

<link:label id="lab_pwr_AllOtherPlansUSMember_label_en-US" xlink:label="lab_pwr_AllOtherPlansUSMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Other Plans, US [Member] </link:label>

<link:label id="lab_pwr_AllOtherPlansUSMember_documentation_en-US" xlink:label="lab_pwr_AllOtherPlansUSMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Other Plans, US [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_AllOtherPlansUSMember" xlink:href="pwr-20231231.xsd#pwr_AllOtherPlansUSMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_AllOtherPlansUSMember" xlink:to="lab_pwr_AllOtherPlansUSMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxLiabilitiesOther_6155d217-9057-4576-b878-db0ef2dd16aa_negatedLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesOther" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other </link:label>

<link:label id="lab_us-gaap_DeferredTaxLiabilitiesOther_label_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesOther" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Liabilities, Other </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesOther" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilitiesOther"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesOther" xlink:to="lab_us-gaap_DeferredTaxLiabilitiesOther" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityCurrentReportingStatus_f017ee15-b589-4d1e-9679-c5928e91a2f8_terseLabel_en-US" xlink:label="lab_dei_EntityCurrentReportingStatus" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Current Reporting Status </link:label>

<link:label id="lab_dei_EntityCurrentReportingStatus_label_en-US" xlink:label="lab_dei_EntityCurrentReportingStatus" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Current Reporting Status </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityCurrentReportingStatus"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityCurrentReportingStatus" xlink:to="lab_dei_EntityCurrentReportingStatus" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ConcentrationRiskTypeDomain_64062723-b8db-4b35-898a-1cc695e1b048_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskTypeDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Type [Domain] </link:label>

<link:label id="lab_us-gaap_ConcentrationRiskTypeDomain_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskTypeDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Type [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain" xlink:to="lab_us-gaap_ConcentrationRiskTypeDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FixedPriceContractMember_f850a822-9356-4f9c-8d64-430ccd148540_terseLabel_en-US" xlink:label="lab_us-gaap_FixedPriceContractMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fixed price contracts </link:label>

<link:label id="lab_us-gaap_FixedPriceContractMember_label_en-US" xlink:label="lab_us-gaap_FixedPriceContractMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fixed-Price Contract [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FixedPriceContractMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FixedPriceContractMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FixedPriceContractMember" xlink:to="lab_us-gaap_FixedPriceContractMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_MarketableSecuritiesUnrealizedGainLoss_501955e1-2520-4dbc-94d9-03579cad46ef_terseLabel_en-US" xlink:label="lab_us-gaap_MarketableSecuritiesUnrealizedGainLoss" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Marketable security, unrealized gain (loss) </link:label>

<link:label id="lab_us-gaap_MarketableSecuritiesUnrealizedGainLoss_label_en-US" xlink:label="lab_us-gaap_MarketableSecuritiesUnrealizedGainLoss" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Marketable Security, Unrealized Gain (Loss) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_MarketableSecuritiesUnrealizedGainLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MarketableSecuritiesUnrealizedGainLoss"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MarketableSecuritiesUnrealizedGainLoss" xlink:to="lab_us-gaap_MarketableSecuritiesUnrealizedGainLoss" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OperatingIncomeLoss_cc923036-4e1b-4920-b64c-1f28604f1a60_totalLabel_en-US" xlink:label="lab_us-gaap_OperatingIncomeLoss" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating income </link:label>

<link:label id="lab_us-gaap_OperatingIncomeLoss_2a2844bf-1c2d-4f5c-a029-8a1669f68361_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingIncomeLoss" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating income (loss) </link:label>

<link:label id="lab_us-gaap_OperatingIncomeLoss_label_en-US" xlink:label="lab_us-gaap_OperatingIncomeLoss" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Income (Loss) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingIncomeLoss"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingIncomeLoss" xlink:to="lab_us-gaap_OperatingIncomeLoss" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_BusinessCombinationCashConsiderationTransferredOrToBeTransferred_891ea12f-9890-4d77-ae5f-68a3f43df372_terseLabel_en-US" xlink:label="lab_pwr_BusinessCombinationCashConsiderationTransferredOrToBeTransferred" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash consideration </link:label>

<link:label id="lab_pwr_BusinessCombinationCashConsiderationTransferredOrToBeTransferred_dd6e6e40-ba7e-4812-a06a-608a44a62778_verboseLabel_en-US" xlink:label="lab_pwr_BusinessCombinationCashConsiderationTransferredOrToBeTransferred" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash paid or payable </link:label>

<link:label id="lab_pwr_BusinessCombinationCashConsiderationTransferredOrToBeTransferred_label_en-US" xlink:label="lab_pwr_BusinessCombinationCashConsiderationTransferredOrToBeTransferred" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination Cash Consideration Transferred Or To Be Transferred </link:label>

<link:label id="lab_pwr_BusinessCombinationCashConsiderationTransferredOrToBeTransferred_documentation_en-US" xlink:label="lab_pwr_BusinessCombinationCashConsiderationTransferredOrToBeTransferred" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash consideration transferred or to be transferred in cash except for contingent consideration. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_BusinessCombinationCashConsiderationTransferredOrToBeTransferred" xlink:href="pwr-20231231.xsd#pwr_BusinessCombinationCashConsiderationTransferredOrToBeTransferred"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_BusinessCombinationCashConsiderationTransferredOrToBeTransferred" xlink:to="lab_pwr_BusinessCombinationCashConsiderationTransferredOrToBeTransferred" xlink:type="arc" order="1"/>

<link:label id="lab_srt_ConsolidatedEntitiesDomain_5334a258-d19e-42ef-868f-1c9e62dd5d4e_terseLabel_en-US" xlink:label="lab_srt_ConsolidatedEntitiesDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Consolidated Entities [Domain] </link:label>

<link:label id="lab_srt_ConsolidatedEntitiesDomain_label_en-US" xlink:label="lab_srt_ConsolidatedEntitiesDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Consolidated Entities [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesDomain" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ConsolidatedEntitiesDomain" xlink:to="lab_srt_ConsolidatedEntitiesDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredIncomeTaxLiabilities_9af900f2-0b59-45b9-b653-56022c5274d5_negatedTotalLabel_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxLiabilities" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total deferred income tax liabilities </link:label>

<link:label id="lab_us-gaap_DeferredIncomeTaxLiabilities_label_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxLiabilities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Liabilities, Gross </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxLiabilities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredIncomeTaxLiabilities" xlink:to="lab_us-gaap_DeferredIncomeTaxLiabilities" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StatementBusinessSegmentsAxis_1f84740b-4cce-4676-a678-ba055aaee4fe_terseLabel_en-US" xlink:label="lab_us-gaap_StatementBusinessSegmentsAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segments [Axis] </link:label>

<link:label id="lab_us-gaap_StatementBusinessSegmentsAxis_label_en-US" xlink:label="lab_us-gaap_StatementBusinessSegmentsAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segments [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis" xlink:to="lab_us-gaap_StatementBusinessSegmentsAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock_0a13f4ef-2c44-4936-9c93-db6a6175d613_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and Equipment </link:label>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_db36e1ca-a36b-4749-9bb5-c4a993225e61_terseLabel_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other comprehensive income (loss), net of taxes: </link:label>

<link:label id="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_label_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Comprehensive Income (Loss), Net of Tax [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract" xlink:to="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_ForgoneRecoveryDueToDisqualificationOfTaxBenefitsAmt_terseLabel_en-US" xlink:label="lab_ecd_ForgoneRecoveryDueToDisqualificationOfTaxBenefitsAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Forgone Recovery due to Disqualification of Tax Benefits, Amount </link:label>

<link:label id="lab_ecd_ForgoneRecoveryDueToDisqualificationOfTaxBenefitsAmt_label_en-US" xlink:label="lab_ecd_ForgoneRecoveryDueToDisqualificationOfTaxBenefitsAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Forgone Recovery due to Disqualification of Tax Benefits, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_ForgoneRecoveryDueToDisqualificationOfTaxBenefitsAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_ForgoneRecoveryDueToDisqualificationOfTaxBenefitsAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_ForgoneRecoveryDueToDisqualificationOfTaxBenefitsAmt" xlink:to="lab_ecd_ForgoneRecoveryDueToDisqualificationOfTaxBenefitsAmt" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AwardsCloseToMnpiDiscTable_terseLabel_en-US" xlink:label="lab_ecd_AwardsCloseToMnpiDiscTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Awards Close in Time to MNPI Disclosures </link:label>

<link:label id="lab_ecd_AwardsCloseToMnpiDiscTable_label_en-US" xlink:label="lab_ecd_AwardsCloseToMnpiDiscTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Awards Close in Time to MNPI Disclosures [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AwardsCloseToMnpiDiscTable" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AwardsCloseToMnpiDiscTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AwardsCloseToMnpiDiscTable" xlink:to="lab_ecd_AwardsCloseToMnpiDiscTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LineOfCredit_b0c1639b-47d0-414a-9281-0645cdd41c31_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCredit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Borrowings under line of credit </link:label>

<link:label id="lab_us-gaap_LineOfCredit_label_en-US" xlink:label="lab_us-gaap_LineOfCredit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Line of Credit </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCredit"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCredit" xlink:to="lab_us-gaap_LineOfCredit" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CustomerRelationshipsMember_258ac6a4-4f7d-4ec8-9db2-99692adb315c_verboseLabel_en-US" xlink:label="lab_us-gaap_CustomerRelationshipsMember" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer relationships </link:label>

<link:label id="lab_us-gaap_CustomerRelationshipsMember_label_en-US" xlink:label="lab_us-gaap_CustomerRelationshipsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer Relationships [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CustomerRelationshipsMember" xlink:to="lab_us-gaap_CustomerRelationshipsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationAwardTrancheOneMember_50844d63-acc2-489e-b77e-862f485ede62_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationAwardTrancheOneMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equal Installments </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationAwardTrancheOneMember_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationAwardTrancheOneMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Payment Arrangement, Tranche One [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember" xlink:to="lab_us-gaap_ShareBasedCompensationAwardTrancheOneMember" xlink:type="arc" order="1"/>

<link:label id="lab_srt_ConsolidatedEntitiesAxis_058111f0-5bcd-482b-ac2b-813c4851ec67_terseLabel_en-US" xlink:label="lab_srt_ConsolidatedEntitiesAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Consolidated Entities [Axis] </link:label>

<link:label id="lab_srt_ConsolidatedEntitiesAxis_label_en-US" xlink:label="lab_srt_ConsolidatedEntitiesAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Consolidated Entities [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidatedEntitiesAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidatedEntitiesAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ConsolidatedEntitiesAxis" xlink:to="lab_srt_ConsolidatedEntitiesAxis" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFive_a40cb62b-232c-48dc-9254-ca25212a2fe1_totalLabel_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFive" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2028 </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFive_label_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFive" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, To Be Paid, Year Five </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFive_documentation_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFive" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, To Be Paid, Year Five </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFive" xlink:href="pwr-20231231.xsd#pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFive"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFive" xlink:to="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFive" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_VariableRateDomain_823aaa92-811c-4e03-9564-1ad6e5c31bc7_terseLabel_en-US" xlink:label="lab_us-gaap_VariableRateDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Variable Rate [Domain] </link:label>

<link:label id="lab_us-gaap_VariableRateDomain_label_en-US" xlink:label="lab_us-gaap_VariableRateDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Variable Rate [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableRateDomain" xlink:to="lab_us-gaap_VariableRateDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_cc36db24-86f4-4c26-babc-c76944bb85c3_terseLabel_en-US" xlink:label="lab_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Less: Net income attributable to non-controlling interests </link:label>

<link:label id="lab_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_label_en-US" xlink:label="lab_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Income (Loss) Attributable to Noncontrolling Interest </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:to="lab_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_PayVsPerformanceDisclosureLineItems_label_en-US" xlink:label="lab_ecd_PayVsPerformanceDisclosureLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Pay vs Performance Disclosure [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_PayVsPerformanceDisclosureLineItems" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_PayVsPerformanceDisclosureLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_PayVsPerformanceDisclosureLineItems" xlink:to="lab_ecd_PayVsPerformanceDisclosureLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityVoluntaryFilers_134a33a0-2801-45c1-9b25-b1a3718c8338_terseLabel_en-US" xlink:label="lab_dei_EntityVoluntaryFilers" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Voluntary Filers </link:label>

<link:label id="lab_dei_EntityVoluntaryFilers_label_en-US" xlink:label="lab_dei_EntityVoluntaryFilers" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Voluntary Filers </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityVoluntaryFilers" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityVoluntaryFilers"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityVoluntaryFilers" xlink:to="lab_dei_EntityVoluntaryFilers" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_SummaryOfSignificantAccountingPoliciesTable_95e15d5a-cfac-4947-ad73-ecd906afb21f_terseLabel_en-US" xlink:label="lab_pwr_SummaryOfSignificantAccountingPoliciesTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary Of Significant Accounting Policies [Table] </link:label>

<link:label id="lab_pwr_SummaryOfSignificantAccountingPoliciesTable_label_en-US" xlink:label="lab_pwr_SummaryOfSignificantAccountingPoliciesTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary Of Significant Accounting Policies [Table] </link:label>

<link:label id="lab_pwr_SummaryOfSignificantAccountingPoliciesTable_documentation_en-US" xlink:label="lab_pwr_SummaryOfSignificantAccountingPoliciesTable" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary Of Significant Accounting Policies [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_SummaryOfSignificantAccountingPoliciesTable" xlink:href="pwr-20231231.xsd#pwr_SummaryOfSignificantAccountingPoliciesTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_SummaryOfSignificantAccountingPoliciesTable" xlink:to="lab_pwr_SummaryOfSignificantAccountingPoliciesTable" xlink:type="arc" order="1"/>

<link:label id="lab_srt_RangeMember_38d41fa0-775b-45c0-92a4-3de767593a77_terseLabel_en-US" xlink:label="lab_srt_RangeMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statistical Measurement [Domain] </link:label>

<link:label id="lab_srt_RangeMember_label_en-US" xlink:label="lab_srt_RangeMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statistical Measurement [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_RangeMember" xlink:to="lab_srt_RangeMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LeaseFinancingTransactionsInterestOnLeaseLiabilities_d0652da7-d3c5-4671-9f62-c4fe8ed14b25_terseLabel_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionsInterestOnLeaseLiabilities" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionsInterestOnLeaseLiabilities_label_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionsInterestOnLeaseLiabilities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transactions, Interest On Lease Liabilities </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionsInterestOnLeaseLiabilities_documentation_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionsInterestOnLeaseLiabilities" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transactions, Interest On Lease Liabilities </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LeaseFinancingTransactionsInterestOnLeaseLiabilities" xlink:href="pwr-20231231.xsd#pwr_LeaseFinancingTransactionsInterestOnLeaseLiabilities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LeaseFinancingTransactionsInterestOnLeaseLiabilities" xlink:to="lab_pwr_LeaseFinancingTransactionsInterestOnLeaseLiabilities" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_SummaryOfSignificantAccountingPoliciesLineItems_da68cf21-dbd0-4595-8bfb-822cc3bc2f9a_terseLabel_en-US" xlink:label="lab_pwr_SummaryOfSignificantAccountingPoliciesLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary Of Significant Accounting Policies [Line Items] </link:label>

<link:label id="lab_pwr_SummaryOfSignificantAccountingPoliciesLineItems_label_en-US" xlink:label="lab_pwr_SummaryOfSignificantAccountingPoliciesLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary Of Significant Accounting Policies [Line Items] </link:label>

<link:label id="lab_pwr_SummaryOfSignificantAccountingPoliciesLineItems_documentation_en-US" xlink:label="lab_pwr_SummaryOfSignificantAccountingPoliciesLineItems" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary Of Significant Accounting Policies [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_SummaryOfSignificantAccountingPoliciesLineItems" xlink:href="pwr-20231231.xsd#pwr_SummaryOfSignificantAccountingPoliciesLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_SummaryOfSignificantAccountingPoliciesLineItems" xlink:to="lab_pwr_SummaryOfSignificantAccountingPoliciesLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_UndrlygSecurityMktPriceChngPct_terseLabel_en-US" xlink:label="lab_ecd_UndrlygSecurityMktPriceChngPct" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Underlying Security Market Price Change </link:label>

<link:label id="lab_ecd_UndrlygSecurityMktPriceChngPct_label_en-US" xlink:label="lab_ecd_UndrlygSecurityMktPriceChngPct" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Underlying Security Market Price Change, Percent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_UndrlygSecurityMktPriceChngPct" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_UndrlygSecurityMktPriceChngPct"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_UndrlygSecurityMktPriceChngPct" xlink:to="lab_ecd_UndrlygSecurityMktPriceChngPct" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_cc58ba0e-11a6-438b-9a64-208198a017bc_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and cash equivalents </link:label>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_14831381-6a01-4426-989b-4f89a41d38cb_periodStartLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unvested, shares, beginning of period (in shares) </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_ec85b075-d239-474a-ab41-edb6ddf88702_periodEndLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unvested, shares, end of period (in shares) </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_IntegralAndNonIntegralUnconsolidatedAffiliatesMember_3afc1d6a-aeb6-4966-b5ff-f3c3efc7adc9_terseLabel_en-US" xlink:label="lab_pwr_IntegralAndNonIntegralUnconsolidatedAffiliatesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Integral and Non-Integral Unconsolidated Affiliates </link:label>

<link:label id="lab_pwr_IntegralAndNonIntegralUnconsolidatedAffiliatesMember_label_en-US" xlink:label="lab_pwr_IntegralAndNonIntegralUnconsolidatedAffiliatesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Integral and Non-Integral Unconsolidated Affiliates [Member] </link:label>

<link:label id="lab_pwr_IntegralAndNonIntegralUnconsolidatedAffiliatesMember_documentation_en-US" xlink:label="lab_pwr_IntegralAndNonIntegralUnconsolidatedAffiliatesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Integral and Non-Integral Unconsolidated Affiliates </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_IntegralAndNonIntegralUnconsolidatedAffiliatesMember" xlink:href="pwr-20231231.xsd#pwr_IntegralAndNonIntegralUnconsolidatedAffiliatesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_IntegralAndNonIntegralUnconsolidatedAffiliatesMember" xlink:to="lab_pwr_IntegralAndNonIntegralUnconsolidatedAffiliatesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtDisclosureTextBlock_e9828c2e-7564-419c-82ce-944bffedef5b_terseLabel_en-US" xlink:label="lab_us-gaap_DebtDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Obligations </link:label>

<link:label id="lab_us-gaap_DebtDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_DebtDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Disclosure [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtDisclosureTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtDisclosureTextBlock" xlink:to="lab_us-gaap_DebtDisclosureTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StatementOfStockholdersEquityAbstract_b7757f73-9a5f-41a3-814b-ed05f854fd50_terseLabel_en-US" xlink:label="lab_us-gaap_StatementOfStockholdersEquityAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement of Stockholders' Equity [Abstract] </link:label>

<link:label id="lab_us-gaap_StatementOfStockholdersEquityAbstract_label_en-US" xlink:label="lab_us-gaap_StatementOfStockholdersEquityAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement of Stockholders' Equity [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfStockholdersEquityAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementOfStockholdersEquityAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementOfStockholdersEquityAbstract" xlink:to="lab_us-gaap_StatementOfStockholdersEquityAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_f48d33bc-e3a1-4ccf-a410-9cb4d1f206b7_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Discretionary contributions </link:label>

<link:label id="lab_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_label_en-US" xlink:label="lab_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Defined Contribution Plan, Employer Discretionary Contribution Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount" xlink:to="lab_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_ff9d74b2-8c2b-48d6-943f-379657c52877_terseLabel_en-US" xlink:label="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> VIE </link:label>

<link:label id="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember_label_en-US" xlink:label="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Variable Interest Entity, Primary Beneficiary [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableInterestEntityPrimaryBeneficiaryMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:to="lab_us-gaap_VariableInterestEntityPrimaryBeneficiaryMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RevolvingCreditFacilityMember_34e1de08-7035-44f8-9155-8378661165df_terseLabel_en-US" xlink:label="lab_us-gaap_RevolvingCreditFacilityMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revolving Credit Facility </link:label>

<link:label id="lab_us-gaap_RevolvingCreditFacilityMember_label_en-US" xlink:label="lab_us-gaap_RevolvingCreditFacilityMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revolving Credit Facility [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevolvingCreditFacilityMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevolvingCreditFacilityMember" xlink:to="lab_us-gaap_RevolvingCreditFacilityMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EquityMethodInvestmentsAndJointVenturesAbstract_label_en-US" xlink:label="lab_us-gaap_EquityMethodInvestmentsAndJointVenturesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Method Investments and Joint Ventures [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentsAndJointVenturesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentsAndJointVenturesAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquityMethodInvestmentsAndJointVenturesAbstract" xlink:to="lab_us-gaap_EquityMethodInvestmentsAndJointVenturesAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_MnpiDiscTimedForCompValFlag_terseLabel_en-US" xlink:label="lab_ecd_MnpiDiscTimedForCompValFlag" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> MNPI Disclosure Timed for Compensation Value </link:label>

<link:label id="lab_ecd_MnpiDiscTimedForCompValFlag_label_en-US" xlink:label="lab_ecd_MnpiDiscTimedForCompValFlag" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> MNPI Disclosure Timed for Compensation Value [Flag] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_MnpiDiscTimedForCompValFlag" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_MnpiDiscTimedForCompValFlag"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_MnpiDiscTimedForCompValFlag" xlink:to="lab_ecd_MnpiDiscTimedForCompValFlag" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SegmentReportingAbstract_c43ee455-5f63-4ee8-837e-e972a08cdac8_terseLabel_en-US" xlink:label="lab_us-gaap_SegmentReportingAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Reporting [Abstract] </link:label>

<link:label id="lab_us-gaap_SegmentReportingAbstract_label_en-US" xlink:label="lab_us-gaap_SegmentReportingAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segment Reporting [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SegmentReportingAbstract" xlink:to="lab_us-gaap_SegmentReportingAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LeaseFinancingTransactionDepreciation_963eeb9a-16d8-42fc-97aa-9e07de180b69_terseLabel_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionDepreciation" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Depreciation </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionDepreciation_label_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionDepreciation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transaction, Depreciation </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionDepreciation_documentation_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionDepreciation" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transaction, Depreciation </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LeaseFinancingTransactionDepreciation" xlink:href="pwr-20231231.xsd#pwr_LeaseFinancingTransactionDepreciation"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LeaseFinancingTransactionDepreciation" xlink:to="lab_pwr_LeaseFinancingTransactionDepreciation" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_2b773447-4c16-4e6c-b917-6c59bd2a58b7_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income from continuing operations before income taxes included in consolidated results of operations </link:label>

<link:label id="lab_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual" xlink:to="lab_us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_RestatementDateAxis_terseLabel_en-US" xlink:label="lab_ecd_RestatementDateAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restatement Determination Date: </link:label>

<link:label id="lab_ecd_RestatementDateAxis_label_en-US" xlink:label="lab_ecd_RestatementDateAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restatement Determination Date [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_RestatementDateAxis" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_RestatementDateAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_RestatementDateAxis" xlink:to="lab_ecd_RestatementDateAxis" xlink:type="arc" order="1"/>

<link:label id="lab_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_c07d21d3-bc6a-4028-82ca-64f9fc987f14_terseLabel_en-US" xlink:label="lab_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investment, Name [Axis] </link:label>

<link:label id="lab_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_label_en-US" xlink:label="lab_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investment, Name [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="lab_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CommitmentsAndContingencies_d0ee2ccc-d8a7-4533-bdcd-86be2f491e55_terseLabel_en-US" xlink:label="lab_us-gaap_CommitmentsAndContingencies" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitments and Contingencies </link:label>

<link:label id="lab_us-gaap_CommitmentsAndContingencies_label_en-US" xlink:label="lab_us-gaap_CommitmentsAndContingencies" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitments and Contingencies </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommitmentsAndContingencies"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommitmentsAndContingencies" xlink:to="lab_us-gaap_CommitmentsAndContingencies" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_feba933e-ba7b-4234-a5dd-728e37951bdd_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Leases </link:label>

<link:label id="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract" xlink:to="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfGoodwillTable_c0e30d88-ac96-4a64-9518-3ca4833ea339_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfGoodwillTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Goodwill [Table] </link:label>

<link:label id="lab_us-gaap_ScheduleOfGoodwillTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfGoodwillTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Goodwill [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfGoodwillTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable" xlink:to="lab_us-gaap_ScheduleOfGoodwillTable" xlink:type="arc" order="1"/>

<link:label id="lab_srt_StatementGeographicalAxis_308eed5d-d3ad-4ad9-bf8c-9abae363f5b1_terseLabel_en-US" xlink:label="lab_srt_StatementGeographicalAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Geographical [Axis] </link:label>

<link:label id="lab_srt_StatementGeographicalAxis_label_en-US" xlink:label="lab_srt_StatementGeographicalAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Geographical [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_StatementGeographicalAxis" xlink:to="lab_srt_StatementGeographicalAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_b055bfb4-a767-4a96-a29c-0fab1b52a674_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Required performance period </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Award Requisite Service Period </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_TypeOfArrangementAxis_69a75df8-51bc-42e2-a883-6c48e77bad0e_terseLabel_en-US" xlink:label="lab_us-gaap_TypeOfArrangementAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Collaborative Arrangement and Arrangement Other than Collaborative [Axis] </link:label>

<link:label id="lab_us-gaap_TypeOfArrangementAxis_label_en-US" xlink:label="lab_us-gaap_TypeOfArrangementAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Collaborative Arrangement and Arrangement Other than Collaborative [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfArrangementAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TypeOfArrangementAxis" xlink:to="lab_us-gaap_TypeOfArrangementAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_2640219f-4cdb-4ab2-a764-43439ae4eedc_terseLabel_en-US" xlink:label="lab_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Gross amount accrued for insurance claims </link:label>

<link:label id="lab_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_label_en-US" xlink:label="lab_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liability for Claims and Claims Adjustment Expense </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense" xlink:to="lab_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxDisclosureTextBlock_d400524b-198b-4a6a-92f3-c39672bde4d9_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Taxes </link:label>

<link:label id="lab_us-gaap_IncomeTaxDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_IncomeTaxDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Disclosure [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxDisclosureTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxDisclosureTextBlock" xlink:to="lab_us-gaap_IncomeTaxDisclosureTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncreaseDecreaseInContractWithCustomerLiability_3e442d4c-d77b-41cd-a7e8-5bfafea28f4f_terseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInContractWithCustomerLiability" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract liabilities </link:label>

<link:label id="lab_us-gaap_IncreaseDecreaseInContractWithCustomerLiability_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInContractWithCustomerLiability" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Contract with Customer, Liability </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInContractWithCustomerLiability" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInContractWithCustomerLiability"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInContractWithCustomerLiability" xlink:to="lab_us-gaap_IncreaseDecreaseInContractWithCustomerLiability" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_85e321fc-dccd-41ad-93f0-cc35c61a6c5a_totalLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and equipment, gross </link:label>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, before Accumulated Depreciation and Amortization </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeLeasesPolicyTextBlock_0bd364cd-d80d-4338-a130-f9314e57b2fa_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeLeasesPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Leases </link:label>

<link:label id="lab_us-gaap_LesseeLeasesPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_LesseeLeasesPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Leases [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeasesPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeLeasesPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeLeasesPolicyTextBlock" xlink:to="lab_us-gaap_LesseeLeasesPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_fb7b3643-e29e-478d-89f3-b3953b89c70c_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and equipment </link:label>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterestAbstract_6aef60f8-dae1-4143-9b6c-9854bf47e9e5_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterestAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income before income taxes: </link:label>

<link:label id="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterestAbstract_label_en-US" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterestAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterestAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterestAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterestAbstract" xlink:to="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterestAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_GuaranteeObligationsByNatureAxis_ed79f734-c58b-4242-8e1a-f8700b93a972_terseLabel_en-US" xlink:label="lab_us-gaap_GuaranteeObligationsByNatureAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Guarantor Obligations, Nature [Axis] </link:label>

<link:label id="lab_us-gaap_GuaranteeObligationsByNatureAxis_label_en-US" xlink:label="lab_us-gaap_GuaranteeObligationsByNatureAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Guarantor Obligations, Nature [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsByNatureAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GuaranteeObligationsByNatureAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis" xlink:to="lab_us-gaap_GuaranteeObligationsByNatureAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_749486b4-2aa2-4cf5-918d-63a5be94559c_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Valuation allowance on deferred tax assets </link:label>

<link:label id="lab_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance_label_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:to="lab_us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessAcquisitionLineItems_5ee1d46b-7c34-479f-b573-5fdfc11ae501_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisition [Line Items] </link:label>

<link:label id="lab_us-gaap_BusinessAcquisitionLineItems_label_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisition [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems" xlink:to="lab_us-gaap_BusinessAcquisitionLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_4b9c1890-2c28-4fca-a967-a5fc83d4e064_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average Grant Date Fair Value (Per Unit) </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_PeoTotalCompAmt_terseLabel_en-US" xlink:label="lab_ecd_PeoTotalCompAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> PEO Total Compensation Amount </link:label>

<link:label id="lab_ecd_PeoTotalCompAmt_label_en-US" xlink:label="lab_ecd_PeoTotalCompAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> PEO Total Compensation Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_PeoTotalCompAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_PeoTotalCompAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_PeoTotalCompAmt" xlink:to="lab_ecd_PeoTotalCompAmt" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_daaa49ea-7fc7-4ebf-b666-a782434a9b51_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment [Table] </link:label>

<link:label id="lab_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant and Equipment [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="lab_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_GoodwillRollForward_f2c93fd2-c9b5-41d7-9e67-c6ef67c63854_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillRollForward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill [Roll Forward] </link:label>

<link:label id="lab_us-gaap_GoodwillRollForward_label_en-US" xlink:label="lab_us-gaap_GoodwillRollForward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill [Roll Forward] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillRollForward" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillRollForward"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillRollForward" xlink:to="lab_us-gaap_GoodwillRollForward" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_TradingArrByIndTable_terseLabel_en-US" xlink:label="lab_ecd_TradingArrByIndTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trading Arrangements, by Individual </link:label>

<link:label id="lab_ecd_TradingArrByIndTable_label_en-US" xlink:label="lab_ecd_TradingArrByIndTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trading Arrangements, by Individual [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_TradingArrByIndTable" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_TradingArrByIndTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_TradingArrByIndTable" xlink:to="lab_ecd_TradingArrByIndTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_TreasuryStockCommonShares_37077018-62db-4f89-bce2-441ba79d9faf_terseLabel_en-US" xlink:label="lab_us-gaap_TreasuryStockCommonShares" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Treasury stock, common, shares (in shares) </link:label>

<link:label id="lab_us-gaap_TreasuryStockCommonShares_label_en-US" xlink:label="lab_us-gaap_TreasuryStockCommonShares" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Treasury Stock, Common, Shares </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockCommonShares"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TreasuryStockCommonShares" xlink:to="lab_us-gaap_TreasuryStockCommonShares" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_Acquisitions2023Member_99f77497-2f86-4e40-9035-6af49effdec2_terseLabel_en-US" xlink:label="lab_pwr_Acquisitions2023Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions 2023 </link:label>

<link:label id="lab_pwr_Acquisitions2023Member_label_en-US" xlink:label="lab_pwr_Acquisitions2023Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions 2023 [Member] </link:label>

<link:label id="lab_pwr_Acquisitions2023Member_documentation_en-US" xlink:label="lab_pwr_Acquisitions2023Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions 2023 </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_Acquisitions2023Member" xlink:href="pwr-20231231.xsd#pwr_Acquisitions2023Member"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_Acquisitions2023Member" xlink:to="lab_pwr_Acquisitions2023Member" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingAndFinanceLeasesWeightedAverageDiscountRateAbstract_d40fe670-9956-4b4a-9ba6-14bc3d6949fc_terseLabel_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeasesWeightedAverageDiscountRateAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted average discount rate: </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeasesWeightedAverageDiscountRateAbstract_label_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeasesWeightedAverageDiscountRateAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Leases, Weighted Average Discount Rate [Abstract] </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeasesWeightedAverageDiscountRateAbstract_documentation_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeasesWeightedAverageDiscountRateAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Leases, Weighted Average Discount Rate [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingAndFinanceLeasesWeightedAverageDiscountRateAbstract" xlink:href="pwr-20231231.xsd#pwr_OperatingAndFinanceLeasesWeightedAverageDiscountRateAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingAndFinanceLeasesWeightedAverageDiscountRateAbstract" xlink:to="lab_pwr_OperatingAndFinanceLeasesWeightedAverageDiscountRateAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_NonPeoNeoAvgCompActuallyPaidAmt_terseLabel_en-US" xlink:label="lab_ecd_NonPeoNeoAvgCompActuallyPaidAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-PEO NEO Average Compensation Actually Paid Amount </link:label>

<link:label id="lab_ecd_NonPeoNeoAvgCompActuallyPaidAmt_label_en-US" xlink:label="lab_ecd_NonPeoNeoAvgCompActuallyPaidAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-PEO NEO Average Compensation Actually Paid Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_NonPeoNeoAvgCompActuallyPaidAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_NonPeoNeoAvgCompActuallyPaidAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_NonPeoNeoAvgCompActuallyPaidAmt" xlink:to="lab_ecd_NonPeoNeoAvgCompActuallyPaidAmt" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LineOfCreditAvailabilityAmountToAllowDividendsAndStockRepurchases_83170945-5703-41c7-88fa-6292248f0d3e_terseLabel_en-US" xlink:label="lab_pwr_LineOfCreditAvailabilityAmountToAllowDividendsAndStockRepurchases" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amount of availability under the credit agreement and/or cash and cash equivalents on hand that must be present to allow for cash payments of dividends and stock repurchases </link:label>

<link:label id="lab_pwr_LineOfCreditAvailabilityAmountToAllowDividendsAndStockRepurchases_label_en-US" xlink:label="lab_pwr_LineOfCreditAvailabilityAmountToAllowDividendsAndStockRepurchases" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit, Availability Amount To Allow Dividends And Stock Repurchases </link:label>

<link:label id="lab_pwr_LineOfCreditAvailabilityAmountToAllowDividendsAndStockRepurchases_documentation_en-US" xlink:label="lab_pwr_LineOfCreditAvailabilityAmountToAllowDividendsAndStockRepurchases" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amount of availability under the credit agreement and/or cash and cash equivalents on hand that must be present to allow for cash payments of dividends and stock repurchases. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LineOfCreditAvailabilityAmountToAllowDividendsAndStockRepurchases" xlink:href="pwr-20231231.xsd#pwr_LineOfCreditAvailabilityAmountToAllowDividendsAndStockRepurchases"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LineOfCreditAvailabilityAmountToAllowDividendsAndStockRepurchases" xlink:to="lab_pwr_LineOfCreditAvailabilityAmountToAllowDividendsAndStockRepurchases" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongTermDebtFairValue_4e496995-0a16-4fe8-a8d1-765a827242b2_terseLabel_en-US" xlink:label="lab_us-gaap_LongTermDebtFairValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair value of notes </link:label>

<link:label id="lab_us-gaap_LongTermDebtFairValue_label_en-US" xlink:label="lab_us-gaap_LongTermDebtFairValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Debt, Fair Value </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtFairValue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermDebtFairValue" xlink:to="lab_us-gaap_LongTermDebtFairValue" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NetIncomeLoss_cc53d71f-0a41-4a97-8e9c-fc38d8ef1bd5_totalLabel_en-US" xlink:label="lab_us-gaap_NetIncomeLoss" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net income attributable to common stock </link:label>

<link:label id="lab_us-gaap_NetIncomeLoss_2f43962f-f131-4529-8f72-f85856d35655_terseLabel_en-US" xlink:label="lab_us-gaap_NetIncomeLoss" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Income (Loss) Attributable to Parent </link:label>

<link:label id="lab_us-gaap_NetIncomeLoss_label_en-US" xlink:label="lab_us-gaap_NetIncomeLoss" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Income (Loss) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetIncomeLoss" xlink:to="lab_us-gaap_NetIncomeLoss" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearFour_5b4c5216-1705-44e7-9e5c-16410c2c2d9b_terseLabel_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearFour" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Tax carryforwards expiring in year four </link:label>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearFour_label_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearFour" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expiration Amount Of State And Foreign Net Operating Loss Carryforwards Year Four </link:label>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearFour_documentation_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearFour" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expiration amount of state and foreign net operating loss carryforwards year four. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearFour" xlink:href="pwr-20231231.xsd#pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearFour"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearFour" xlink:to="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearFour" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LiabilitiesCurrent_583a7c6a-f820-4f3f-b4cf-59a9ebbe844e_totalLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total current liabilities </link:label>

<link:label id="lab_us-gaap_LiabilitiesCurrent_label_en-US" xlink:label="lab_us-gaap_LiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesCurrent" xlink:to="lab_us-gaap_LiabilitiesCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationLineItems_869ac1de-fd67-4bce-a6fb-16e53d8ec7cf_terseLabel_en-US" xlink:label="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecorded Unconditional Purchase Obligation [Line Items] </link:label>

<link:label id="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationLineItems_label_en-US" xlink:label="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecorded Unconditional Purchase Obligation [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationLineItems" xlink:to="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_06f1aeba-4aa6-4003-85c0-92d952a098ba_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2025 </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, to be Paid, Year Two </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_NonIntegralUnconsolidatedAffiliatesMember_0fe7ef5c-fce0-4987-b42a-bc8bc340391e_terseLabel_en-US" xlink:label="lab_pwr_NonIntegralUnconsolidatedAffiliatesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-Integral Unconsolidated Affiliates </link:label>

<link:label id="lab_pwr_NonIntegralUnconsolidatedAffiliatesMember_label_en-US" xlink:label="lab_pwr_NonIntegralUnconsolidatedAffiliatesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-Integral Unconsolidated Affiliates [Member] </link:label>

<link:label id="lab_pwr_NonIntegralUnconsolidatedAffiliatesMember_documentation_en-US" xlink:label="lab_pwr_NonIntegralUnconsolidatedAffiliatesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-Integral Unconsolidated Affiliates </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_NonIntegralUnconsolidatedAffiliatesMember" xlink:href="pwr-20231231.xsd#pwr_NonIntegralUnconsolidatedAffiliatesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_NonIntegralUnconsolidatedAffiliatesMember" xlink:to="lab_pwr_NonIntegralUnconsolidatedAffiliatesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock_d4f2935f-5b87-4f5c-83f8-f054231a08e2_terseLabel_en-US" xlink:label="lab_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Functional Currency and Translation of Financial Statements </link:label>

<link:label id="lab_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign Currency Transactions and Translations Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock" xlink:to="lab_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_ChangedPeerGroupFnTextBlock_terseLabel_en-US" xlink:label="lab_ecd_ChangedPeerGroupFnTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Changed Peer Group, Footnote </link:label>

<link:label id="lab_ecd_ChangedPeerGroupFnTextBlock_label_en-US" xlink:label="lab_ecd_ChangedPeerGroupFnTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Changed Peer Group, Footnote [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_ChangedPeerGroupFnTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_ChangedPeerGroupFnTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_ChangedPeerGroupFnTextBlock" xlink:to="lab_ecd_ChangedPeerGroupFnTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_CoSelectedMeasureName_terseLabel_en-US" xlink:label="lab_ecd_CoSelectedMeasureName" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Company Selected Measure Name </link:label>

<link:label id="lab_ecd_CoSelectedMeasureName_label_en-US" xlink:label="lab_ecd_CoSelectedMeasureName" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Company Selected Measure Name </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_CoSelectedMeasureName" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_CoSelectedMeasureName"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_CoSelectedMeasureName" xlink:to="lab_ecd_CoSelectedMeasureName" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeOperatingLeasesTextBlock_9bb2bbf5-5630-43a8-8be9-5128103b3dde_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeasesTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Leases </link:label>

<link:label id="lab_us-gaap_LesseeOperatingLeasesTextBlock_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeasesTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Leases [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeasesTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeasesTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeasesTextBlock" xlink:to="lab_us-gaap_LesseeOperatingLeasesTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_08fd3301-2418-4bf4-b95f-cbc614737c60_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and equipment, net </link:label>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_0a6bdecb-1e60-4a0d-9eda-0fca64717d5b_totalLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and equipment, net of accumulated depreciation </link:label>

<link:label id="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2025Member_3f4c41d1-b2c8-4988-bea1-132cf2ee3f78_terseLabel_en-US" xlink:label="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2025Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments Due First Business Day Of Quarter In 2025 </link:label>

<link:label id="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2025Member_label_en-US" xlink:label="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2025Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments Due First Business Day Of Quarter In 2025 [Member] </link:label>

<link:label id="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2025Member_documentation_en-US" xlink:label="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2025Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments Due First Business Day Of Quarter In 2025 </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2025Member" xlink:href="pwr-20231231.xsd#pwr_PaymentsDueFirstBusinessDayOfQuarterIn2025Member"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2025Member" xlink:to="lab_pwr_PaymentsDueFirstBusinessDayOfQuarterIn2025Member" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_ac5bd60b-88be-4553-afae-b82fc9638b6f_terseLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> LIABILITIES AND EQUITY </link:label>

<link:label id="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_label_en-US" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities and Equity [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsLineItems_8e3130d7-18ac-4523-9281-8067c8a6b883_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Assets [Line Items] </link:label>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsLineItems_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Assets [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StockRepurchasedDuringPeriodValue_88689483-4018-4332-80bc-23a6aba203ba_terseLabel_en-US" xlink:label="lab_us-gaap_StockRepurchasedDuringPeriodValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amount </link:label>

<link:label id="lab_us-gaap_StockRepurchasedDuringPeriodValue_label_en-US" xlink:label="lab_us-gaap_StockRepurchasedDuringPeriodValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Repurchased During Period, Value </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockRepurchasedDuringPeriodValue" xlink:to="lab_us-gaap_StockRepurchasedDuringPeriodValue" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FederalFundsEffectiveSwapRateMember_84dadf47-73b7-46c3-87fe-f3e701c13817_terseLabel_en-US" xlink:label="lab_us-gaap_FederalFundsEffectiveSwapRateMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fed Funds Effective Rate Overnight Index Swap Rate </link:label>

<link:label id="lab_us-gaap_FederalFundsEffectiveSwapRateMember_label_en-US" xlink:label="lab_us-gaap_FederalFundsEffectiveSwapRateMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fed Funds Effective Rate Overnight Index Swap Rate [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalFundsEffectiveSwapRateMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FederalFundsEffectiveSwapRateMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FederalFundsEffectiveSwapRateMember" xlink:to="lab_us-gaap_FederalFundsEffectiveSwapRateMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentRedemptionPeriodAxis_4fae316b-2e29-4d04-8322-8fd5912b92b4_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Redemption, Period [Axis] </link:label>

<link:label id="lab_us-gaap_DebtInstrumentRedemptionPeriodAxis_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Redemption, Period [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:to="lab_us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ConcentrationRiskBenchmarkDomain_3f723b10-f9db-4e2c-b098-7e9614b1c942_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Benchmark [Domain] </link:label>

<link:label id="lab_us-gaap_ConcentrationRiskBenchmarkDomain_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Benchmark [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:to="lab_us-gaap_ConcentrationRiskBenchmarkDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_a6a42693-c2c9-4fc6-83c7-1cd267e2108c_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Domestic </link:label>

<link:label id="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_label_en-US" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income (Loss) from Continuing Operations before Income Taxes, Domestic </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic" xlink:to="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossCurrent_d1655912-be86-41f4-81b9-ac3b6e157605_terseLabel_en-US" xlink:label="lab_us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current retainage balances </link:label>

<link:label id="lab_us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossCurrent_label_en-US" xlink:label="lab_us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract with Customer, Receivable, after Allowance for Credit Loss, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossCurrent" xlink:to="lab_us-gaap_ContractWithCustomerReceivableAfterAllowanceForCreditLossCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CostOfGoodsAndServicesSold_5a94dba3-e4bf-42bb-be8d-20bfad750831_terseLabel_en-US" xlink:label="lab_us-gaap_CostOfGoodsAndServicesSold" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cost of services </link:label>

<link:label id="lab_us-gaap_CostOfGoodsAndServicesSold_label_en-US" xlink:label="lab_us-gaap_CostOfGoodsAndServicesSold" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cost of Goods and Services Sold </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfGoodsAndServicesSold"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CostOfGoodsAndServicesSold" xlink:to="lab_us-gaap_CostOfGoodsAndServicesSold" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_59546ede-b7c5-485b-9295-a867454dc82a_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award vesting period </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_b09c9b01-c819-45d6-89e9-51b759a9630d_terseLabel_en-US" xlink:label="lab_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average Amortization Period in Years </link:label>

<link:label id="lab_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_label_en-US" xlink:label="lab_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:to="lab_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ScheduleOfShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock_a84d6047-91b2-404e-ab1d-7ef2bb5ac115_terseLabel_en-US" xlink:label="lab_pwr_ScheduleOfShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Grant Date Fair Value for Awards of Performance Units Inputs </link:label>

<link:label id="lab_pwr_ScheduleOfShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock_label_en-US" xlink:label="lab_pwr_ScheduleOfShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule Of Share Based Payment Award, Equity Instruments Other Than Options, Valuation Assumptions [Table Text Block] </link:label>

<link:label id="lab_pwr_ScheduleOfShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock_documentation_en-US" xlink:label="lab_pwr_ScheduleOfShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule Of Share Based Payment Award, Equity Instruments Other Than Options, Valuation Assumptions [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ScheduleOfShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock" xlink:href="pwr-20231231.xsd#pwr_ScheduleOfShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ScheduleOfShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock" xlink:to="lab_pwr_ScheduleOfShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_MeasureName_terseLabel_en-US" xlink:label="lab_ecd_MeasureName" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Name </link:label>

<link:label id="lab_ecd_MeasureName_label_en-US" xlink:label="lab_ecd_MeasureName" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Measure Name </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_MeasureName" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_MeasureName"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_MeasureName" xlink:to="lab_ecd_MeasureName" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_ForgoneRecoveryIndName_terseLabel_en-US" xlink:label="lab_ecd_ForgoneRecoveryIndName" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Name </link:label>

<link:label id="lab_ecd_ForgoneRecoveryIndName_label_en-US" xlink:label="lab_ecd_ForgoneRecoveryIndName" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Forgone Recovery, Individual Name </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_ForgoneRecoveryIndName" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_ForgoneRecoveryIndName"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_ForgoneRecoveryIndName" xlink:to="lab_ecd_ForgoneRecoveryIndName" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_RestrictedStockUnitsToBeSettledInCommonStockMember_d766b170-96ae-45bc-a952-8f407d8c07d9_terseLabel_en-US" xlink:label="lab_pwr_RestrictedStockUnitsToBeSettledInCommonStockMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted Stock Units to be Settled in Common Stock </link:label>

<link:label id="lab_pwr_RestrictedStockUnitsToBeSettledInCommonStockMember_c14a804b-987b-43dd-ae6e-a9989c522c84_verboseLabel_en-US" xlink:label="lab_pwr_RestrictedStockUnitsToBeSettledInCommonStockMember" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted Stock and RSUs to be Settled in Common Stock </link:label>

<link:label id="lab_pwr_RestrictedStockUnitsToBeSettledInCommonStockMember_label_en-US" xlink:label="lab_pwr_RestrictedStockUnitsToBeSettledInCommonStockMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted Stock Units To Be Settled In Common Stock [Member] </link:label>

<link:label id="lab_pwr_RestrictedStockUnitsToBeSettledInCommonStockMember_documentation_en-US" xlink:label="lab_pwr_RestrictedStockUnitsToBeSettledInCommonStockMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restricted stock units to be settled in common stock. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_RestrictedStockUnitsToBeSettledInCommonStockMember" xlink:href="pwr-20231231.xsd#pwr_RestrictedStockUnitsToBeSettledInCommonStockMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_RestrictedStockUnitsToBeSettledInCommonStockMember" xlink:to="lab_pwr_RestrictedStockUnitsToBeSettledInCommonStockMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_Goodwill_b14417b4-7a53-4b6c-a16d-2f842a2fd2d1_terseLabel_en-US" xlink:label="lab_us-gaap_Goodwill" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill </link:label>

<link:label id="lab_us-gaap_Goodwill_3cadc26a-cb99-43e6-b495-9d5a628a8a7e_periodStartLabel_en-US" xlink:label="lab_us-gaap_Goodwill" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill net, beginning balance </link:label>

<link:label id="lab_us-gaap_Goodwill_b03b6be6-0794-4e3e-8ae2-547e66cc142a_periodEndLabel_en-US" xlink:label="lab_us-gaap_Goodwill" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill net, ending balance </link:label>

<link:label id="lab_us-gaap_Goodwill_label_en-US" xlink:label="lab_us-gaap_Goodwill" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Goodwill" xlink:to="lab_us-gaap_Goodwill" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_41610a56-8e36-451c-af36-da02a38b6d58_terseLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Additions for tax positions of prior years </link:label>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_label_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:to="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeLeaseDescriptionTable_0006c2a3-5480-41b9-a38c-a6cd4f91d143_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeLeaseDescriptionTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Lease, Description [Table] </link:label>

<link:label id="lab_us-gaap_LesseeLeaseDescriptionTable_label_en-US" xlink:label="lab_us-gaap_LesseeLeaseDescriptionTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Lease, Description [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeLeaseDescriptionTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable" xlink:to="lab_us-gaap_LesseeLeaseDescriptionTable" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AwardUndrlygSecuritiesAmt_terseLabel_en-US" xlink:label="lab_ecd_AwardUndrlygSecuritiesAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Underlying Securities </link:label>

<link:label id="lab_ecd_AwardUndrlygSecuritiesAmt_label_en-US" xlink:label="lab_ecd_AwardUndrlygSecuritiesAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Underlying Securities Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AwardUndrlygSecuritiesAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AwardUndrlygSecuritiesAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AwardUndrlygSecuritiesAmt" xlink:to="lab_ecd_AwardUndrlygSecuritiesAmt" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringConstruction_e0f6c614-2402-4adb-8142-2d6228cd9aef_terseLabel_en-US" xlink:label="lab_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringConstruction" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Aggregate consideration to be paid during the construction period </link:label>

<link:label id="lab_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringConstruction_label_en-US" xlink:label="lab_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringConstruction" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Contract Value, Consideration To Be Transferred During Construction </link:label>

<link:label id="lab_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringConstruction_documentation_en-US" xlink:label="lab_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringConstruction" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Contract Value, Consideration To Be Transferred During Construction </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringConstruction" xlink:href="pwr-20231231.xsd#pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringConstruction"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringConstruction" xlink:to="lab_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringConstruction" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_InvestmentsInJointVenturesMember_a2c384aa-971b-4815-bba7-eed73bab65a3_terseLabel_en-US" xlink:label="lab_pwr_InvestmentsInJointVenturesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Held by Joint Ventures </link:label>

<link:label id="lab_pwr_InvestmentsInJointVenturesMember_label_en-US" xlink:label="lab_pwr_InvestmentsInJointVenturesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investments In Joint Ventures [Member] </link:label>

<link:label id="lab_pwr_InvestmentsInJointVenturesMember_documentation_en-US" xlink:label="lab_pwr_InvestmentsInJointVenturesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investments In Joint Ventures [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_InvestmentsInJointVenturesMember" xlink:href="pwr-20231231.xsd#pwr_InvestmentsInJointVenturesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_InvestmentsInJointVenturesMember" xlink:to="lab_pwr_InvestmentsInJointVenturesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CommonStockDividendsPerShareDeclared_5869762c-c539-44bf-be43-9875b2f21a25_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockDividendsPerShareDeclared" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Dividends declared per share (in dollars per share) </link:label>

<link:label id="lab_us-gaap_CommonStockDividendsPerShareDeclared_label_en-US" xlink:label="lab_us-gaap_CommonStockDividendsPerShareDeclared" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock, Dividends, Per Share, Declared </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockDividendsPerShareDeclared" xlink:to="lab_us-gaap_CommonStockDividendsPerShareDeclared" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_f8e516e9-18c7-4259-ace1-acb94e2aa692_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash payment for contingent consideration liabilities </link:label>

<link:label id="lab_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_label_en-US" xlink:label="lab_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements" xlink:to="lab_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OperatingLeaseLiabilityNoncurrent_0b002432-a51d-4c28-9e20-198707c8bc0c_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease liabilities, net of current portion </link:label>

<link:label id="lab_us-gaap_OperatingLeaseLiabilityNoncurrent_1440b241-b3c5-48ed-98d9-3c982fdccdc0_verboseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating </link:label>

<link:label id="lab_us-gaap_OperatingLeaseLiabilityNoncurrent_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Liability, Noncurrent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:to="lab_us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfMultiemployerPlansTableTextBlock_b5b14878-4443-4876-a400-c4d87c010d7b_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfMultiemployerPlansTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary of Plan Information Relating to Participation in Multiemployer Pension Plans </link:label>

<link:label id="lab_us-gaap_ScheduleOfMultiemployerPlansTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfMultiemployerPlansTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Multiemployer Plan [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfMultiemployerPlansTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfMultiemployerPlansTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfMultiemployerPlansTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfMultiemployerPlansTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_MultiemployerPlansLineItems_2bcda2cc-4fe4-4786-9c6d-ec9c3ebb1071_terseLabel_en-US" xlink:label="lab_us-gaap_MultiemployerPlansLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Multiemployer Plans [Line Items] </link:label>

<link:label id="lab_us-gaap_MultiemployerPlansLineItems_label_en-US" xlink:label="lab_us-gaap_MultiemployerPlansLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Multiemployer Plan [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_MultiemployerPlansLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MultiemployerPlansLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MultiemployerPlansLineItems" xlink:to="lab_us-gaap_MultiemployerPlansLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentTerm_e3ad9157-ea5e-4066-8f12-24d635bd219f_verboseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentTerm" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Renewal term </link:label>

<link:label id="lab_us-gaap_DebtInstrumentTerm_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentTerm" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Term </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTerm"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentTerm" xlink:to="lab_us-gaap_DebtInstrumentTerm" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentNameDomain_a3c5c834-9512-464e-9d99-c3b8f397b4e6_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentNameDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Name [Domain] </link:label>

<link:label id="lab_us-gaap_DebtInstrumentNameDomain_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentNameDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Name [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentNameDomain" xlink:to="lab_us-gaap_DebtInstrumentNameDomain" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LeaseFinancingTransactionAssetsObtainedInExchangeForLeaseFinancingTransactionLiabilities_8e2cd040-e192-4d2c-8002-13167f570f00_terseLabel_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionAssetsObtainedInExchangeForLeaseFinancingTransactionLiabilities" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease financing transaction assets obtained in exchange for lease financing transaction liabilities </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionAssetsObtainedInExchangeForLeaseFinancingTransactionLiabilities_label_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionAssetsObtainedInExchangeForLeaseFinancingTransactionLiabilities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transaction Assets Obtained In Exchange For Lease Financing Transaction Liabilities </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionAssetsObtainedInExchangeForLeaseFinancingTransactionLiabilities_documentation_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionAssetsObtainedInExchangeForLeaseFinancingTransactionLiabilities" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transaction Assets Obtained In Exchange For Lease Financing Transaction Liabilities </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LeaseFinancingTransactionAssetsObtainedInExchangeForLeaseFinancingTransactionLiabilities" xlink:href="pwr-20231231.xsd#pwr_LeaseFinancingTransactionAssetsObtainedInExchangeForLeaseFinancingTransactionLiabilities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LeaseFinancingTransactionAssetsObtainedInExchangeForLeaseFinancingTransactionLiabilities" xlink:to="lab_pwr_LeaseFinancingTransactionAssetsObtainedInExchangeForLeaseFinancingTransactionLiabilities" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenue_7207f910-e99b-48f9-8be2-99027a7c8f04_terseLabel_en-US" xlink:label="lab_pwr_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of customers representing ten percent or more of revenues </link:label>

<link:label id="lab_pwr_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenue_label_en-US" xlink:label="lab_pwr_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number Of Customers Representing Ten Percent Or More Of Revenue </link:label>

<link:label id="lab_pwr_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenue_documentation_en-US" xlink:label="lab_pwr_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenue" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number Of Customers Representing Ten Percent Or More Of Revenue </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenue" xlink:href="pwr-20231231.xsd#pwr_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenue" xlink:to="lab_pwr_NumberOfCustomersRepresentingTenPercentOrMoreOfRevenue" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_100be2c3-60b1-483e-8185-aa999460a333_negatedLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unamortized discount and financing costs </link:label>

<link:label id="lab_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_8b102c02-173a-4b79-8920-76941af6f418_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unamortized discount and deferred financing costs related to senior notes </link:label>

<link:label id="lab_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:to="lab_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_IntegralAffiliatesMember_b4bc2115-0069-414f-94fa-355d927d6bb3_terseLabel_en-US" xlink:label="lab_pwr_IntegralAffiliatesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Integral Affiliates </link:label>

<link:label id="lab_pwr_IntegralAffiliatesMember_label_en-US" xlink:label="lab_pwr_IntegralAffiliatesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Integral Affiliates [Member] </link:label>

<link:label id="lab_pwr_IntegralAffiliatesMember_documentation_en-US" xlink:label="lab_pwr_IntegralAffiliatesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Integral Affiliates </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_IntegralAffiliatesMember" xlink:href="pwr-20231231.xsd#pwr_IntegralAffiliatesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_IntegralAffiliatesMember" xlink:to="lab_pwr_IntegralAffiliatesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_0755dc6c-2f60-4bdb-ba8a-c9dd0d779cd0_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Future Minimum Lease Payments - Operating Leases </link:label>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_PoleReplacementPeriodBeforeFire_09112f14-81eb-4121-83b8-1da51a5b2646_terseLabel_en-US" xlink:label="lab_pwr_PoleReplacementPeriodBeforeFire" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Time of pole replacement before fire </link:label>

<link:label id="lab_pwr_PoleReplacementPeriodBeforeFire_label_en-US" xlink:label="lab_pwr_PoleReplacementPeriodBeforeFire" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Pole Replacement, Period Before Fire </link:label>

<link:label id="lab_pwr_PoleReplacementPeriodBeforeFire_documentation_en-US" xlink:label="lab_pwr_PoleReplacementPeriodBeforeFire" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Pole Replacement, Period Before Fire </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_PoleReplacementPeriodBeforeFire" xlink:href="pwr-20231231.xsd#pwr_PoleReplacementPeriodBeforeFire"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_PoleReplacementPeriodBeforeFire" xlink:to="lab_pwr_PoleReplacementPeriodBeforeFire" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RetainedEarningsUndistributedEarningsFromEquityMethodInvestees_72220dbd-83da-4e22-a389-43200cb79fa7_terseLabel_en-US" xlink:label="lab_us-gaap_RetainedEarningsUndistributedEarningsFromEquityMethodInvestees" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Undistributed earnings of unconsolidated affiliates </link:label>

<link:label id="lab_us-gaap_RetainedEarningsUndistributedEarningsFromEquityMethodInvestees_label_en-US" xlink:label="lab_us-gaap_RetainedEarningsUndistributedEarningsFromEquityMethodInvestees" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Retained Earnings, Undistributed Earnings from Equity Method Investees </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsUndistributedEarningsFromEquityMethodInvestees" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsUndistributedEarningsFromEquityMethodInvestees"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RetainedEarningsUndistributedEarningsFromEquityMethodInvestees" xlink:to="lab_us-gaap_RetainedEarningsUndistributedEarningsFromEquityMethodInvestees" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_SeniorNotesDueJanuary2032Member_41ed54c0-ce60-4ccf-bcf3-3b965bf5d70b_terseLabel_en-US" xlink:label="lab_pwr_SeniorNotesDueJanuary2032Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2.350% Senior Notes due January 2032 </link:label>

<link:label id="lab_pwr_SeniorNotesDueJanuary2032Member_label_en-US" xlink:label="lab_pwr_SeniorNotesDueJanuary2032Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Notes Due January 2032 [Member] </link:label>

<link:label id="lab_pwr_SeniorNotesDueJanuary2032Member_documentation_en-US" xlink:label="lab_pwr_SeniorNotesDueJanuary2032Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Notes Due January 2032 </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_SeniorNotesDueJanuary2032Member" xlink:href="pwr-20231231.xsd#pwr_SeniorNotesDueJanuary2032Member"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_SeniorNotesDueJanuary2032Member" xlink:to="lab_pwr_SeniorNotesDueJanuary2032Member" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock_d537e7d4-9243-415d-9baf-8eed5ff9a54c_terseLabel_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and Cash Equivalents </link:label>

<link:label id="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and Cash Equivalents, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:to="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_srt_ProductsAndServicesDomain_d68ce58e-8add-4ec3-8c78-3695ac2926b9_terseLabel_en-US" xlink:label="lab_srt_ProductsAndServicesDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product and Service [Domain] </link:label>

<link:label id="lab_srt_ProductsAndServicesDomain_label_en-US" xlink:label="lab_srt_ProductsAndServicesDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product and Service [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ProductsAndServicesDomain" xlink:to="lab_srt_ProductsAndServicesDomain" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_OtherPerfMeasureAmt_terseLabel_en-US" xlink:label="lab_ecd_OtherPerfMeasureAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Performance Measure, Amount </link:label>

<link:label id="lab_ecd_OtherPerfMeasureAmt_label_en-US" xlink:label="lab_ecd_OtherPerfMeasureAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Performance Measure, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_OtherPerfMeasureAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_OtherPerfMeasureAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_OtherPerfMeasureAmt" xlink:to="lab_ecd_OtherPerfMeasureAmt" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals_37b221b6-8bfe-462e-9e33-11ec999ed28b_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accruals and reserves </link:label>

<link:label id="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals" xlink:to="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccruals" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LeaseCostTableTextBlock_03e94d87-e787-4312-96a5-da27138fc581_terseLabel_en-US" xlink:label="lab_us-gaap_LeaseCostTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Components of Lease Costs </link:label>

<link:label id="lab_us-gaap_LeaseCostTableTextBlock_label_en-US" xlink:label="lab_us-gaap_LeaseCostTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease, Cost [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseCostTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LeaseCostTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LeaseCostTableTextBlock" xlink:to="lab_us-gaap_LeaseCostTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ContractWithCustomerAssetNetCurrent_3ec87397-48fe-4045-876f-b4bdfc3cd7ac_terseLabel_en-US" xlink:label="lab_us-gaap_ContractWithCustomerAssetNetCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract assets </link:label>

<link:label id="lab_us-gaap_ContractWithCustomerAssetNetCurrent_cfefc5b9-4476-4f73-8226-adc6eac22518_verboseLabel_en-US" xlink:label="lab_us-gaap_ContractWithCustomerAssetNetCurrent" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract assets </link:label>

<link:label id="lab_us-gaap_ContractWithCustomerAssetNetCurrent_label_en-US" xlink:label="lab_us-gaap_ContractWithCustomerAssetNetCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract with Customer, Asset, after Allowance for Credit Loss, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNetCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerAssetNetCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ContractWithCustomerAssetNetCurrent" xlink:to="lab_us-gaap_ContractWithCustomerAssetNetCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StandbyLettersOfCreditMember_ba3f876b-0d2c-4160-b79e-3e4749b7cea3_terseLabel_en-US" xlink:label="lab_us-gaap_StandbyLettersOfCreditMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Standby Letters of Credit </link:label>

<link:label id="lab_us-gaap_StandbyLettersOfCreditMember_label_en-US" xlink:label="lab_us-gaap_StandbyLettersOfCreditMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Standby Letters of Credit [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandbyLettersOfCreditMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StandbyLettersOfCreditMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StandbyLettersOfCreditMember" xlink:to="lab_us-gaap_StandbyLettersOfCreditMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_93e900b2-e85c-41c0-a80c-22d04af9081a_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash Flows from Investing Activities: </link:label>

<link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Cash Provided by (Used in) Investing Activities [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:to="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxAssetsEquityMethodInvestments_51d19031-3b89-49fb-ab40-e7efba8653f0_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsEquityMethodInvestments" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity method investments and non-controlling interests </link:label>

<link:label id="lab_us-gaap_DeferredTaxAssetsEquityMethodInvestments_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsEquityMethodInvestments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Equity Method Investments </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsEquityMethodInvestments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsEquityMethodInvestments"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsEquityMethodInvestments" xlink:to="lab_us-gaap_DeferredTaxAssetsEquityMethodInvestments" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PlanNameDomain_c68e2a5a-c060-4b17-9251-56ceff4bfc20_terseLabel_en-US" xlink:label="lab_us-gaap_PlanNameDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Plan Name [Domain] </link:label>

<link:label id="lab_us-gaap_PlanNameDomain_label_en-US" xlink:label="lab_us-gaap_PlanNameDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Plan Name [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PlanNameDomain" xlink:to="lab_us-gaap_PlanNameDomain" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CommonStockWithheldForSettlementOfEmployeeTaxLiabilitiesMember_05b00f6c-2795-43e4-b684-bf0d53cf09c0_terseLabel_en-US" xlink:label="lab_pwr_CommonStockWithheldForSettlementOfEmployeeTaxLiabilitiesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock Withheld for Settlement of Employee Tax Liabilities </link:label>

<link:label id="lab_pwr_CommonStockWithheldForSettlementOfEmployeeTaxLiabilitiesMember_label_en-US" xlink:label="lab_pwr_CommonStockWithheldForSettlementOfEmployeeTaxLiabilitiesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock Withheld For Settlement Of Employee Tax Liabilities [Member] </link:label>

<link:label id="lab_pwr_CommonStockWithheldForSettlementOfEmployeeTaxLiabilitiesMember_documentation_en-US" xlink:label="lab_pwr_CommonStockWithheldForSettlementOfEmployeeTaxLiabilitiesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock withheld for settlement of employee tax liabilities. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CommonStockWithheldForSettlementOfEmployeeTaxLiabilitiesMember" xlink:href="pwr-20231231.xsd#pwr_CommonStockWithheldForSettlementOfEmployeeTaxLiabilitiesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CommonStockWithheldForSettlementOfEmployeeTaxLiabilitiesMember" xlink:to="lab_pwr_CommonStockWithheldForSettlementOfEmployeeTaxLiabilitiesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_InterestExpense_9f2227a0-f2ff-4298-9a96-e17dd80e8383_negatedLabel_en-US" xlink:label="lab_us-gaap_InterestExpense" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest and other financing expenses </link:label>

<link:label id="lab_us-gaap_InterestExpense_label_en-US" xlink:label="lab_us-gaap_InterestExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest Expense </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpense"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InterestExpense" xlink:to="lab_us-gaap_InterestExpense" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CapitalExpendituresIncurredButNotYetPaid_13014751-764a-4899-b770-ca3e9529fa07_terseLabel_en-US" xlink:label="lab_us-gaap_CapitalExpendituresIncurredButNotYetPaid" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued capital expenditures </link:label>

<link:label id="lab_us-gaap_CapitalExpendituresIncurredButNotYetPaid_label_en-US" xlink:label="lab_us-gaap_CapitalExpendituresIncurredButNotYetPaid" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Capital Expenditures Incurred but Not yet Paid </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CapitalExpendituresIncurredButNotYetPaid"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid" xlink:to="lab_us-gaap_CapitalExpendituresIncurredButNotYetPaid" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_44e5caae-8afd-4493-9f41-50e416fe20d7_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Aggregate number of shares of common stock that may be issued </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinitelivedIntangibleAssetsAcquired1_39b24d3e-94fe-4134-9c91-405881734a72_verboseLabel_en-US" xlink:label="lab_us-gaap_FinitelivedIntangibleAssetsAcquired1" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Estimated Fair Value </link:label>

<link:label id="lab_us-gaap_FinitelivedIntangibleAssetsAcquired1_label_en-US" xlink:label="lab_us-gaap_FinitelivedIntangibleAssetsAcquired1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Assets Acquired </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1" xlink:to="lab_us-gaap_FinitelivedIntangibleAssetsAcquired1" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_TradingArrAxis_terseLabel_en-US" xlink:label="lab_ecd_TradingArrAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trading Arrangement: </link:label>

<link:label id="lab_ecd_TradingArrAxis_label_en-US" xlink:label="lab_ecd_TradingArrAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trading Arrangement [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_TradingArrAxis" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_TradingArrAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_TradingArrAxis" xlink:to="lab_ecd_TradingArrAxis" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LineOfCreditFacilityCovenantMaximumLeverageRatio_526dbbea-a80d-4a17-b87f-1154f72c640c_terseLabel_en-US" xlink:label="lab_pwr_LineOfCreditFacilityCovenantMaximumLeverageRatio" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Maximum consolidated leverage ratio permissible under credit agreement </link:label>

<link:label id="lab_pwr_LineOfCreditFacilityCovenantMaximumLeverageRatio_label_en-US" xlink:label="lab_pwr_LineOfCreditFacilityCovenantMaximumLeverageRatio" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Covenant, Maximum Leverage Ratio </link:label>

<link:label id="lab_pwr_LineOfCreditFacilityCovenantMaximumLeverageRatio_documentation_en-US" xlink:label="lab_pwr_LineOfCreditFacilityCovenantMaximumLeverageRatio" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Covenant, Maximum Leverage Ratio </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LineOfCreditFacilityCovenantMaximumLeverageRatio" xlink:href="pwr-20231231.xsd#pwr_LineOfCreditFacilityCovenantMaximumLeverageRatio"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LineOfCreditFacilityCovenantMaximumLeverageRatio" xlink:to="lab_pwr_LineOfCreditFacilityCovenantMaximumLeverageRatio" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UseOfEstimates_98fef22d-2275-4816-bd13-f302e3be79ab_terseLabel_en-US" xlink:label="lab_us-gaap_UseOfEstimates" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Use of Estimates and Assumptions </link:label>

<link:label id="lab_us-gaap_UseOfEstimates_label_en-US" xlink:label="lab_us-gaap_UseOfEstimates" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Use of Estimates, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UseOfEstimates" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UseOfEstimates"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UseOfEstimates" xlink:to="lab_us-gaap_UseOfEstimates" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DamagedLandArea_494d6704-173f-48e7-80f4-b1788c7a8190_terseLabel_en-US" xlink:label="lab_pwr_DamagedLandArea" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Damaged land (in acres) </link:label>

<link:label id="lab_pwr_DamagedLandArea_label_en-US" xlink:label="lab_pwr_DamagedLandArea" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Damaged Land, Area </link:label>

<link:label id="lab_pwr_DamagedLandArea_documentation_en-US" xlink:label="lab_pwr_DamagedLandArea" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Damaged Land, Area </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DamagedLandArea" xlink:href="pwr-20231231.xsd#pwr_DamagedLandArea"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DamagedLandArea" xlink:to="lab_pwr_DamagedLandArea" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongtermDebtTypeDomain_b85913c0-10be-4a8b-8309-ff6b41f9f603_terseLabel_en-US" xlink:label="lab_us-gaap_LongtermDebtTypeDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-term Debt, Type [Domain] </link:label>

<link:label id="lab_us-gaap_LongtermDebtTypeDomain_label_en-US" xlink:label="lab_us-gaap_LongtermDebtTypeDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Debt, Type [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongtermDebtTypeDomain" xlink:to="lab_us-gaap_LongtermDebtTypeDomain" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityFileNumber_07018a47-10ad-4555-806a-23b43d400c8a_terseLabel_en-US" xlink:label="lab_dei_EntityFileNumber" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity File Number </link:label>

<link:label id="lab_dei_EntityFileNumber_label_en-US" xlink:label="lab_dei_EntityFileNumber" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity File Number </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityFileNumber"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityFileNumber" xlink:to="lab_dei_EntityFileNumber" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LossContingenciesTable_b4bb683e-89de-4765-b2fd-88b0db721c47_terseLabel_en-US" xlink:label="lab_us-gaap_LossContingenciesTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss Contingencies [Table] </link:label>

<link:label id="lab_us-gaap_LossContingenciesTable_label_en-US" xlink:label="lab_us-gaap_LossContingenciesTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss Contingencies [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LossContingenciesTable" xlink:to="lab_us-gaap_LossContingenciesTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_d1985f71-4598-47d9-834f-67da5cb08e3a_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Thereafter </link:label>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, to be Paid, after Year Five </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_55096047-3ac2-470d-bf4b-63b99c4af7db_terseLabel_en-US" xlink:label="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2026 </link:label>

<link:label id="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_label_en-US" xlink:label="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Debt, Maturity, Year Three </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree" xlink:to="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions_5a089f6c-9205-4494-9dbe-a073278a5a13_negatedLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Reductions for tax positions of prior years </link:label>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions_label_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xlink:to="lab_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromPriorPeriodTaxPositions" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CanadaTransmissionProjectMember_0e2a11fa-d69e-43f4-99ad-94e9599689ac_terseLabel_en-US" xlink:label="lab_pwr_CanadaTransmissionProjectMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Canada Transmission Project </link:label>

<link:label id="lab_pwr_CanadaTransmissionProjectMember_label_en-US" xlink:label="lab_pwr_CanadaTransmissionProjectMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Canada Transmission Project [Member] </link:label>

<link:label id="lab_pwr_CanadaTransmissionProjectMember_documentation_en-US" xlink:label="lab_pwr_CanadaTransmissionProjectMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Canada Transmission Project </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CanadaTransmissionProjectMember" xlink:href="pwr-20231231.xsd#pwr_CanadaTransmissionProjectMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CanadaTransmissionProjectMember" xlink:to="lab_pwr_CanadaTransmissionProjectMember" xlink:type="arc" order="1"/>

<link:label id="lab_dei_AuditorFirmId_bf86d9d0-33d0-439c-a829-5e19b8e2a3da_terseLabel_en-US" xlink:label="lab_dei_AuditorFirmId" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Auditor Firm ID </link:label>

<link:label id="lab_dei_AuditorFirmId_label_en-US" xlink:label="lab_dei_AuditorFirmId" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Auditor Firm ID </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_AuditorFirmId" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_AuditorFirmId"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_AuditorFirmId" xlink:to="lab_dei_AuditorFirmId" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AmortizationOfIntangibleAssets_c5193968-53e8-4f7a-b20d-e9434ae80fe8_negatedLabel_en-US" xlink:label="lab_us-gaap_AmortizationOfIntangibleAssets" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amortization of intangible assets </link:label>

<link:label id="lab_us-gaap_AmortizationOfIntangibleAssets_17682c9d-bd05-4a8e-a09e-e8ced634e9f0_terseLabel_en-US" xlink:label="lab_us-gaap_AmortizationOfIntangibleAssets" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amortization of intangible assets </link:label>

<link:label id="lab_us-gaap_AmortizationOfIntangibleAssets_label_en-US" xlink:label="lab_us-gaap_AmortizationOfIntangibleAssets" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amortization of Intangible Assets </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfIntangibleAssets"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AmortizationOfIntangibleAssets" xlink:to="lab_us-gaap_AmortizationOfIntangibleAssets" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityShellCompany_49b25c30-6f30-49ec-9c58-f6d92c802145_terseLabel_en-US" xlink:label="lab_dei_EntityShellCompany" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Shell Company </link:label>

<link:label id="lab_dei_EntityShellCompany_label_en-US" xlink:label="lab_dei_EntityShellCompany" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Shell Company </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityShellCompany"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityShellCompany" xlink:to="lab_dei_EntityShellCompany" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessAcquisitionAcquireeDomain_0499b131-aacb-442d-bbc7-d06636340471_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionAcquireeDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisition, Acquiree [Domain] </link:label>

<link:label id="lab_us-gaap_BusinessAcquisitionAcquireeDomain_label_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionAcquireeDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Acquisition, Acquiree [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="lab_us-gaap_BusinessAcquisitionAcquireeDomain" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ForeignNetOperatingLossesMember_26ca8821-2ec5-4c6f-8303-5e653961e127_terseLabel_en-US" xlink:label="lab_pwr_ForeignNetOperatingLossesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign Net Operating Losses </link:label>

<link:label id="lab_pwr_ForeignNetOperatingLossesMember_label_en-US" xlink:label="lab_pwr_ForeignNetOperatingLossesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign Net Operating Losses [Member] </link:label>

<link:label id="lab_pwr_ForeignNetOperatingLossesMember_documentation_en-US" xlink:label="lab_pwr_ForeignNetOperatingLossesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign Net Operating Losses </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ForeignNetOperatingLossesMember" xlink:href="pwr-20231231.xsd#pwr_ForeignNetOperatingLossesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ForeignNetOperatingLossesMember" xlink:to="lab_pwr_ForeignNetOperatingLossesMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_UndergroundAndInfrastructureMember_c213c854-24d2-4b69-9c9a-4c6e4c27cba0_terseLabel_en-US" xlink:label="lab_pwr_UndergroundAndInfrastructureMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Underground and Infrastructure </link:label>

<link:label id="lab_pwr_UndergroundAndInfrastructureMember_222ff0f4-c8e5-417b-8125-b4609cb620b8_verboseLabel_en-US" xlink:label="lab_pwr_UndergroundAndInfrastructureMember" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Underground and Infrastructure Segment </link:label>

<link:label id="lab_pwr_UndergroundAndInfrastructureMember_label_en-US" xlink:label="lab_pwr_UndergroundAndInfrastructureMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Underground and Infrastructure [Member] </link:label>

<link:label id="lab_pwr_UndergroundAndInfrastructureMember_documentation_en-US" xlink:label="lab_pwr_UndergroundAndInfrastructureMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Underground and Infrastructure </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_UndergroundAndInfrastructureMember" xlink:href="pwr-20231231.xsd#pwr_UndergroundAndInfrastructureMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_UndergroundAndInfrastructureMember" xlink:to="lab_pwr_UndergroundAndInfrastructureMember" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_RestatementDeterminationDate_terseLabel_en-US" xlink:label="lab_ecd_RestatementDeterminationDate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restatement Determination Date </link:label>

<link:label id="lab_ecd_RestatementDeterminationDate_label_en-US" xlink:label="lab_ecd_RestatementDeterminationDate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Restatement Determination Date </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_RestatementDeterminationDate" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_RestatementDeterminationDate"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_RestatementDeterminationDate" xlink:to="lab_ecd_RestatementDeterminationDate" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_4d176965-9aaa-4c65-80c7-1ce8c34a86ec_terseLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Additions based on tax positions related to the current year </link:label>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_label_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:to="lab_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_Rule10b51ArrAdoptedFlag_terseLabel_en-US" xlink:label="lab_ecd_Rule10b51ArrAdoptedFlag" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Rule 10b5-1 Arrangement Adopted </link:label>

<link:label id="lab_ecd_Rule10b51ArrAdoptedFlag_label_en-US" xlink:label="lab_ecd_Rule10b51ArrAdoptedFlag" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Rule 10b5-1 Arrangement Adopted [Flag] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_Rule10b51ArrAdoptedFlag" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_Rule10b51ArrAdoptedFlag"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_Rule10b51ArrAdoptedFlag" xlink:to="lab_ecd_Rule10b51ArrAdoptedFlag" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_5f942690-2a0e-4690-bb6d-0aec5dfac213_periodStartLabel_en-US" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash, cash equivalents and restricted cash, beginning of year </link:label>

<link:label id="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_6b043bc9-72ad-44e6-85f6-0587912f4d09_periodEndLabel_en-US" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash, cash equivalents and restricted cash, end of year </link:label>

<link:label id="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_e007c420-4bce-4de7-8b8b-ec32d4ba7a97_totalLabel_en-US" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total cash, cash equivalents, and restricted cash reported in the statements of cash flows </link:label>

<link:label id="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_label_en-US" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:to="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OperatingLeaseCost_ec481090-e664-4ac0-90d1-f4d4eb9d23a7_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseCost" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease cost </link:label>

<link:label id="lab_us-gaap_OperatingLeaseCost_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseCost" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Cost </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseCost" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseCost"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseCost" xlink:to="lab_us-gaap_OperatingLeaseCost" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ExcavatorsUnionLocal731PensionFundMember_5b14cb16-340f-47ad-84ca-bb1dbcf4611e_terseLabel_en-US" xlink:label="lab_pwr_ExcavatorsUnionLocal731PensionFundMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excavators Union Local 731 Pension Fund </link:label>

<link:label id="lab_pwr_ExcavatorsUnionLocal731PensionFundMember_label_en-US" xlink:label="lab_pwr_ExcavatorsUnionLocal731PensionFundMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excavators Union Local 731 Pension Fund [Member] </link:label>

<link:label id="lab_pwr_ExcavatorsUnionLocal731PensionFundMember_documentation_en-US" xlink:label="lab_pwr_ExcavatorsUnionLocal731PensionFundMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excavators Union Local 731 Pension Fund [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ExcavatorsUnionLocal731PensionFundMember" xlink:href="pwr-20231231.xsd#pwr_ExcavatorsUnionLocal731PensionFundMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ExcavatorsUnionLocal731PensionFundMember" xlink:to="lab_pwr_ExcavatorsUnionLocal731PensionFundMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CommonStockSharesIssued_e1879961-54b6-43ea-a580-3affb70a932e_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockSharesIssued" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock, shares issued (in shares) </link:label>

<link:label id="lab_us-gaap_CommonStockSharesIssued_label_en-US" xlink:label="lab_us-gaap_CommonStockSharesIssued" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock, Shares, Issued </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesIssued"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockSharesIssued" xlink:to="lab_us-gaap_CommonStockSharesIssued" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_60a0948c-2d4b-4fe4-839f-9340195711c4_negatedLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Vested, shares (in shares) </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments_1a7a1651-df4f-4144-a695-966363904d0d_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from the sale or settlement of certain investments </link:label>

<link:label id="lab_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments_label_en-US" xlink:label="lab_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Sale, Maturity and Collection of Investments </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments" xlink:to="lab_us-gaap_ProceedsFromSaleMaturityAndCollectionsOfInvestments" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_02897877-4f36-44fe-a1d9-7d77c02ea242_terseLabel_en-US" xlink:label="lab_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Less — Current maturities of long-term debt </link:label>

<link:label id="lab_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent_label_en-US" xlink:label="lab_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Debt and Lease Obligation, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent" xlink:to="lab_us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_TreasuryStockCommonValue_dda9aa9d-a82b-48cc-bb6f-44c7ad3fc11d_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_TreasuryStockCommonValue" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Treasury stock, 28,440,462 and 27,707,927 common shares </link:label>

<link:label id="lab_us-gaap_TreasuryStockCommonValue_label_en-US" xlink:label="lab_us-gaap_TreasuryStockCommonValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Treasury Stock, Common, Value </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockCommonValue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TreasuryStockCommonValue" xlink:to="lab_us-gaap_TreasuryStockCommonValue" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_SilveradoWildfireMember_e0eaece0-b0c4-42f8-b08a-68e9b59e9315_terseLabel_en-US" xlink:label="lab_pwr_SilveradoWildfireMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Silverado Wildfire </link:label>

<link:label id="lab_pwr_SilveradoWildfireMember_label_en-US" xlink:label="lab_pwr_SilveradoWildfireMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Silverado Wildfire [Member] </link:label>

<link:label id="lab_pwr_SilveradoWildfireMember_documentation_en-US" xlink:label="lab_pwr_SilveradoWildfireMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Silverado Wildfire </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_SilveradoWildfireMember" xlink:href="pwr-20231231.xsd#pwr_SilveradoWildfireMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_SilveradoWildfireMember" xlink:to="lab_pwr_SilveradoWildfireMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongTermDebt_9bf03acc-02a2-42dc-8eea-16278f3d7fd3_terseLabel_en-US" xlink:label="lab_us-gaap_LongTermDebt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-term debt </link:label>

<link:label id="lab_us-gaap_LongTermDebt_label_en-US" xlink:label="lab_us-gaap_LongTermDebt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Debt </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermDebt" xlink:to="lab_us-gaap_LongTermDebt" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_NonCurrentDeferredIncomeTaxesAbstract_e76e893e-b6db-4a5a-808c-90b701a422bd_terseLabel_en-US" xlink:label="lab_pwr_NonCurrentDeferredIncomeTaxesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred income taxes: </link:label>

<link:label id="lab_pwr_NonCurrentDeferredIncomeTaxesAbstract_label_en-US" xlink:label="lab_pwr_NonCurrentDeferredIncomeTaxesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non Current Deferred Income Taxes [Abstract] </link:label>

<link:label id="lab_pwr_NonCurrentDeferredIncomeTaxesAbstract_documentation_en-US" xlink:label="lab_pwr_NonCurrentDeferredIncomeTaxesAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-current deferred income taxes. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_NonCurrentDeferredIncomeTaxesAbstract" xlink:href="pwr-20231231.xsd#pwr_NonCurrentDeferredIncomeTaxesAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_NonCurrentDeferredIncomeTaxesAbstract" xlink:to="lab_pwr_NonCurrentDeferredIncomeTaxesAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DebtInstrumentCovenantLeverageRatioMaximum_80c5bae4-c6f2-433f-b068-0e47d8187c0f_terseLabel_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantLeverageRatioMaximum" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Maximum consolidated leverage ratio </link:label>

<link:label id="lab_pwr_DebtInstrumentCovenantLeverageRatioMaximum_label_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantLeverageRatioMaximum" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Covenant, Leverage Ratio, Maximum </link:label>

<link:label id="lab_pwr_DebtInstrumentCovenantLeverageRatioMaximum_documentation_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantLeverageRatioMaximum" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Covenant, Leverage Ratio, Maximum </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DebtInstrumentCovenantLeverageRatioMaximum" xlink:href="pwr-20231231.xsd#pwr_DebtInstrumentCovenantLeverageRatioMaximum"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DebtInstrumentCovenantLeverageRatioMaximum" xlink:to="lab_pwr_DebtInstrumentCovenantLeverageRatioMaximum" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_e33edf7a-6c1d-4ada-9a4f-98543dabd959_terseLabel_en-US" xlink:label="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2027 </link:label>

<link:label id="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_label_en-US" xlink:label="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Debt, Maturity, Year Four </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour" xlink:to="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DeferredTaxAssetsLeasingArrangements_0424030d-836b-4bbd-9a7e-cd5fa461587b_terseLabel_en-US" xlink:label="lab_pwr_DeferredTaxAssetsLeasingArrangements" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease liabilities </link:label>

<link:label id="lab_pwr_DeferredTaxAssetsLeasingArrangements_label_en-US" xlink:label="lab_pwr_DeferredTaxAssetsLeasingArrangements" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Leasing Arrangements </link:label>

<link:label id="lab_pwr_DeferredTaxAssetsLeasingArrangements_documentation_en-US" xlink:label="lab_pwr_DeferredTaxAssetsLeasingArrangements" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Leasing Arrangements </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DeferredTaxAssetsLeasingArrangements" xlink:href="pwr-20231231.xsd#pwr_DeferredTaxAssetsLeasingArrangements"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DeferredTaxAssetsLeasingArrangements" xlink:to="lab_pwr_DeferredTaxAssetsLeasingArrangements" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CentralLaborersPensionFundMember_54ae0759-3c58-487c-829a-f4de16eee510_terseLabel_en-US" xlink:label="lab_pwr_CentralLaborersPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Central Laborers Pension Fund </link:label>

<link:label id="lab_pwr_CentralLaborersPensionFundMember_label_en-US" xlink:label="lab_pwr_CentralLaborersPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Central Laborers Pension Fund [Member] </link:label>

<link:label id="lab_pwr_CentralLaborersPensionFundMember_documentation_en-US" xlink:label="lab_pwr_CentralLaborersPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Central Laborers Pension Fund </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CentralLaborersPensionFundMember" xlink:href="pwr-20231231.xsd#pwr_CentralLaborersPensionFundMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CentralLaborersPensionFundMember" xlink:to="lab_pwr_CentralLaborersPensionFundMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_424618ef-ba3c-471e-84fa-fea466edaa43_terseLabel_en-US" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expected weighted average period to recognize compensation cost on RSUs to be settled in common stock (in years) </link:label>

<link:label id="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_label_en-US" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:to="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_e85b4121-a5cd-4393-88d7-ff7412f6a086_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other, net </link:label>

<link:label id="lab_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_label_en-US" xlink:label="lab_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from (Payments for) Other Financing Activities </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities" xlink:to="lab_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ComprehensiveIncomeNetOfTax_7369594e-e228-4ae3-91f9-afbde577b3d3_totalLabel_en-US" xlink:label="lab_us-gaap_ComprehensiveIncomeNetOfTax" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Comprehensive income attributable to common stock </link:label>

<link:label id="lab_us-gaap_ComprehensiveIncomeNetOfTax_label_en-US" xlink:label="lab_us-gaap_ComprehensiveIncomeNetOfTax" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Comprehensive Income (Loss), Net of Tax, Attributable to Parent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax" xlink:to="lab_us-gaap_ComprehensiveIncomeNetOfTax" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxReconciliationTaxContingencies_9d42a72f-b1db-4aeb-88dd-adff7d5f1eba_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationTaxContingencies" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Tax contingency reserves, net </link:label>

<link:label id="lab_us-gaap_IncomeTaxReconciliationTaxContingencies_label_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationTaxContingencies" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Tax Contingency, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationTaxContingencies" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxReconciliationTaxContingencies"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxReconciliationTaxContingencies" xlink:to="lab_us-gaap_IncomeTaxReconciliationTaxContingencies" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LineOfCreditFacilityAverageOutstandingAmount_307e7fa7-c89f-4f8f-87a6-854eddf92373_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityAverageOutstandingAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Average daily amount outstanding </link:label>

<link:label id="lab_us-gaap_LineOfCreditFacilityAverageOutstandingAmount_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityAverageOutstandingAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Average Outstanding Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityAverageOutstandingAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityAverageOutstandingAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityAverageOutstandingAmount" xlink:to="lab_us-gaap_LineOfCreditFacilityAverageOutstandingAmount" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StockIssuedDuringPeriodValueAcquisitions_0cb21789-bb32-4390-8f06-60327f7c7112_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueAcquisitions" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions </link:label>

<link:label id="lab_us-gaap_StockIssuedDuringPeriodValueAcquisitions_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueAcquisitions" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Issued During Period, Value, Acquisitions </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions" xlink:to="lab_us-gaap_StockIssuedDuringPeriodValueAcquisitions" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_PensionTrustFundForOperatingEngineersMember_53d795f3-dead-46ee-a237-1a7fd5b94f7d_terseLabel_en-US" xlink:label="lab_pwr_PensionTrustFundForOperatingEngineersMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Pension Trust Fund for Operating Engineers </link:label>

<link:label id="lab_pwr_PensionTrustFundForOperatingEngineersMember_label_en-US" xlink:label="lab_pwr_PensionTrustFundForOperatingEngineersMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Pension Trust Fund for Operating Engineers [Member] </link:label>

<link:label id="lab_pwr_PensionTrustFundForOperatingEngineersMember_documentation_en-US" xlink:label="lab_pwr_PensionTrustFundForOperatingEngineersMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Pension Trust Fund for Operating Engineers </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_PensionTrustFundForOperatingEngineersMember" xlink:href="pwr-20231231.xsd#pwr_PensionTrustFundForOperatingEngineersMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_PensionTrustFundForOperatingEngineersMember" xlink:to="lab_pwr_PensionTrustFundForOperatingEngineersMember" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityAddressAddressLine1_cfc00d91-39a5-4fd6-af5e-0a713549b712_terseLabel_en-US" xlink:label="lab_dei_EntityAddressAddressLine1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, Address Line One </link:label>

<link:label id="lab_dei_EntityAddressAddressLine1_label_en-US" xlink:label="lab_dei_EntityAddressAddressLine1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, Address Line One </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityAddressAddressLine1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityAddressAddressLine1" xlink:to="lab_dei_EntityAddressAddressLine1" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityUndiscountedExcessAmount_1bb3ec2a-4d97-4b51-a83e-c0d4ffbd86b3_negatedTotalLabel_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Less imputed interest </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityUndiscountedExcessAmount_label_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, Undiscounted Excess Amount </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityUndiscountedExcessAmount_documentation_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityUndiscountedExcessAmount" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, Undiscounted Excess Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingAndFinanceLeaseLiabilityUndiscountedExcessAmount" xlink:href="pwr-20231231.xsd#pwr_OperatingAndFinanceLeaseLiabilityUndiscountedExcessAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingAndFinanceLeaseLiabilityUndiscountedExcessAmount" xlink:to="lab_pwr_OperatingAndFinanceLeaseLiabilityUndiscountedExcessAmount" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ProceedsFromAdvancesForConstruction_757b86aa-f725-4443-89cf-e67fcd8c1668_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromAdvancesForConstruction" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Advance payments received </link:label>

<link:label id="lab_us-gaap_ProceedsFromAdvancesForConstruction_label_en-US" xlink:label="lab_us-gaap_ProceedsFromAdvancesForConstruction" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Advances for Construction </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromAdvancesForConstruction" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromAdvancesForConstruction"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromAdvancesForConstruction" xlink:to="lab_us-gaap_ProceedsFromAdvancesForConstruction" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_7117b321-fe67-47d3-a7a7-326717d4cf53_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2024 </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, to be Paid, Year One </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_AuditInformationAbstract_label_en-US" xlink:label="lab_pwr_AuditInformationAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Audit Information [Abstract] </link:label>

<link:label id="lab_pwr_AuditInformationAbstract_documentation_en-US" xlink:label="lab_pwr_AuditInformationAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Audit Information </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_AuditInformationAbstract" xlink:href="pwr-20231231.xsd#pwr_AuditInformationAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_AuditInformationAbstract" xlink:to="lab_pwr_AuditInformationAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RevenueRemainingPerformanceObligationPercentage_e42c6ed9-17a0-4fb7-b000-dd15ffa0f23d_terseLabel_en-US" xlink:label="lab_us-gaap_RevenueRemainingPerformanceObligationPercentage" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Percent of remaining performance obligation expected to be recognized </link:label>

<link:label id="lab_us-gaap_RevenueRemainingPerformanceObligationPercentage_label_en-US" xlink:label="lab_us-gaap_RevenueRemainingPerformanceObligationPercentage" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue, Remaining Performance Obligation, Percentage </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationPercentage"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage" xlink:to="lab_us-gaap_RevenueRemainingPerformanceObligationPercentage" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SubsequentEventMember_80c91f01-1e31-460a-8b5f-c7d725b2416d_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event </link:label>

<link:label id="lab_us-gaap_SubsequentEventMember_label_en-US" xlink:label="lab_us-gaap_SubsequentEventMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Subsequent Event [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventMember" xlink:to="lab_us-gaap_SubsequentEventMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability_11365adf-c19b-4e04-b914-5580763190ca_verboseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (decrease) in tax expense </link:label>

<link:label id="lab_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability_label_en-US" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability" xlink:to="lab_us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_BusinessCombinationContingentConsiderationArrangementsFinancialPerformanceObjectivesPostAcquisitionPeriod_361e6e41-97bd-4493-aab9-048963bc165c_terseLabel_en-US" xlink:label="lab_pwr_BusinessCombinationContingentConsiderationArrangementsFinancialPerformanceObjectivesPostAcquisitionPeriod" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Post-acquisition period, financial performance objectives </link:label>

<link:label id="lab_pwr_BusinessCombinationContingentConsiderationArrangementsFinancialPerformanceObjectivesPostAcquisitionPeriod_label_en-US" xlink:label="lab_pwr_BusinessCombinationContingentConsiderationArrangementsFinancialPerformanceObjectivesPostAcquisitionPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Contingent Consideration Arrangements, Financial Performance Objectives, Post-Acquisition Period </link:label>

<link:label id="lab_pwr_BusinessCombinationContingentConsiderationArrangementsFinancialPerformanceObjectivesPostAcquisitionPeriod_documentation_en-US" xlink:label="lab_pwr_BusinessCombinationContingentConsiderationArrangementsFinancialPerformanceObjectivesPostAcquisitionPeriod" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Contingent Consideration Arrangements, Financial Performance Objectives, Post-Acquisition Period </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_BusinessCombinationContingentConsiderationArrangementsFinancialPerformanceObjectivesPostAcquisitionPeriod" xlink:href="pwr-20231231.xsd#pwr_BusinessCombinationContingentConsiderationArrangementsFinancialPerformanceObjectivesPostAcquisitionPeriod"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_BusinessCombinationContingentConsiderationArrangementsFinancialPerformanceObjectivesPostAcquisitionPeriod" xlink:to="lab_pwr_BusinessCombinationContingentConsiderationArrangementsFinancialPerformanceObjectivesPostAcquisitionPeriod" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_SeniorNotesDueOctober2030Member_70e299e1-003a-461e-afd8-7dfeb2606117_terseLabel_en-US" xlink:label="lab_pwr_SeniorNotesDueOctober2030Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2.900% Senior Notes due October 2030 </link:label>

<link:label id="lab_pwr_SeniorNotesDueOctober2030Member_label_en-US" xlink:label="lab_pwr_SeniorNotesDueOctober2030Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Notes Due October 2030 [Member] </link:label>

<link:label id="lab_pwr_SeniorNotesDueOctober2030Member_documentation_en-US" xlink:label="lab_pwr_SeniorNotesDueOctober2030Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Notes Due October 2030 </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_SeniorNotesDueOctober2030Member" xlink:href="pwr-20231231.xsd#pwr_SeniorNotesDueOctober2030Member"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_SeniorNotesDueOctober2030Member" xlink:to="lab_pwr_SeniorNotesDueOctober2030Member" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock_2d71062d-33dc-43fe-8db5-8e9b709d9b5d_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Intangible Assets </link:label>

<link:label id="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Finite-Lived Intangible Assets [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeStatementAbstract_9d43e9e8-396b-451f-8c05-234e6baa7833_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeStatementAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Statement [Abstract] </link:label>

<link:label id="lab_us-gaap_IncomeStatementAbstract_label_en-US" xlink:label="lab_us-gaap_IncomeStatementAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Statement [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeStatementAbstract" xlink:to="lab_us-gaap_IncomeStatementAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentPeriodicPayment_78474cd7-0ef3-4c34-aada-83dac942c41e_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentPeriodicPayment" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Quarterly principal payments </link:label>

<link:label id="lab_us-gaap_DebtInstrumentPeriodicPayment_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentPeriodicPayment" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Periodic Payment </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPayment" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentPeriodicPayment"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentPeriodicPayment" xlink:to="lab_us-gaap_DebtInstrumentPeriodicPayment" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ContractWithCustomerBasisOfPricingAxis_924533c8-6626-46d8-b6a3-292f520c0c44_terseLabel_en-US" xlink:label="lab_us-gaap_ContractWithCustomerBasisOfPricingAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract with Customer, Basis of Pricing [Axis] </link:label>

<link:label id="lab_us-gaap_ContractWithCustomerBasisOfPricingAxis_label_en-US" xlink:label="lab_us-gaap_ContractWithCustomerBasisOfPricingAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract with Customer, Basis of Pricing [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerBasisOfPricingAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis" xlink:to="lab_us-gaap_ContractWithCustomerBasisOfPricingAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncreaseDecreaseInContractWithCustomerAsset_f763743a-0b07-469c-9812-8488c355c8bb_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInContractWithCustomerAsset" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract assets </link:label>

<link:label id="lab_us-gaap_IncreaseDecreaseInContractWithCustomerAsset_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInContractWithCustomerAsset" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Contract with Customer, Asset </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInContractWithCustomerAsset" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInContractWithCustomerAsset"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInContractWithCustomerAsset" xlink:to="lab_us-gaap_IncreaseDecreaseInContractWithCustomerAsset" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_InsiderTrdPoliciesProcAdoptedFlag_terseLabel_en-US" xlink:label="lab_ecd_InsiderTrdPoliciesProcAdoptedFlag" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insider Trading Policies and Procedures Adopted </link:label>

<link:label id="lab_ecd_InsiderTrdPoliciesProcAdoptedFlag_label_en-US" xlink:label="lab_ecd_InsiderTrdPoliciesProcAdoptedFlag" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insider Trading Policies and Procedures Adopted [Flag] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_InsiderTrdPoliciesProcAdoptedFlag" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_InsiderTrdPoliciesProcAdoptedFlag"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_InsiderTrdPoliciesProcAdoptedFlag" xlink:to="lab_ecd_InsiderTrdPoliciesProcAdoptedFlag" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CommonStockClassUndefinedMember_2294b0fe-d068-4f07-9ead-66069cdac280_terseLabel_en-US" xlink:label="lab_pwr_CommonStockClassUndefinedMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock </link:label>

<link:label id="lab_pwr_CommonStockClassUndefinedMember_label_en-US" xlink:label="lab_pwr_CommonStockClassUndefinedMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock Class Undefined [Member] </link:label>

<link:label id="lab_pwr_CommonStockClassUndefinedMember_documentation_en-US" xlink:label="lab_pwr_CommonStockClassUndefinedMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock class undefined. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CommonStockClassUndefinedMember" xlink:href="pwr-20231231.xsd#pwr_CommonStockClassUndefinedMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CommonStockClassUndefinedMember" xlink:to="lab_pwr_CommonStockClassUndefinedMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_AmortizationOfEquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity_aade57ed-c160-47bf-8f2f-8acca69f08eb_terseLabel_en-US" xlink:label="lab_pwr_AmortizationOfEquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amortization of the basis difference </link:label>

<link:label id="lab_pwr_AmortizationOfEquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity_label_en-US" xlink:label="lab_pwr_AmortizationOfEquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amortization Of Equity Method Investment, Difference Between Carrying Amount and Underlying Equity </link:label>

<link:label id="lab_pwr_AmortizationOfEquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity_documentation_en-US" xlink:label="lab_pwr_AmortizationOfEquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amortization Of Equity Method Investment, Difference Between Carrying Amount and Underlying Equity </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_AmortizationOfEquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity" xlink:href="pwr-20231231.xsd#pwr_AmortizationOfEquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_AmortizationOfEquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity" xlink:to="lab_pwr_AmortizationOfEquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_7798f0a4-10df-4f4f-8dea-27498b9c2186_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock-based compensation activity </link:label>

<link:label id="lab_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:to="lab_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DebtInstrumentCovenantAcquisitionThresholdForLeverageRatio_b5a214e2-17ec-45a1-99e2-6ee95f9e40b9_terseLabel_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantAcquisitionThresholdForLeverageRatio" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisition threshold for leverage ratio </link:label>

<link:label id="lab_pwr_DebtInstrumentCovenantAcquisitionThresholdForLeverageRatio_label_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantAcquisitionThresholdForLeverageRatio" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Covenant, Acquisition Threshold For Leverage Ratio </link:label>

<link:label id="lab_pwr_DebtInstrumentCovenantAcquisitionThresholdForLeverageRatio_documentation_en-US" xlink:label="lab_pwr_DebtInstrumentCovenantAcquisitionThresholdForLeverageRatio" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Covenant, Acquisition Threshold For Leverage Ratio </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DebtInstrumentCovenantAcquisitionThresholdForLeverageRatio" xlink:href="pwr-20231231.xsd#pwr_DebtInstrumentCovenantAcquisitionThresholdForLeverageRatio"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DebtInstrumentCovenantAcquisitionThresholdForLeverageRatio" xlink:to="lab_pwr_DebtInstrumentCovenantAcquisitionThresholdForLeverageRatio" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_faecd876-cd6e-4dea-b34a-41facd9ed2a8_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Provision at the statutory rate </link:label>

<link:label id="lab_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate_label_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:to="lab_us-gaap_IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EquityMethodInvestments_410972a4-200a-4ae0-b23f-db346fb26cc9_verboseLabel_en-US" xlink:label="lab_us-gaap_EquityMethodInvestments" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity method investments </link:label>

<link:label id="lab_us-gaap_EquityMethodInvestments_label_en-US" xlink:label="lab_us-gaap_EquityMethodInvestments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Method Investments </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestments"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquityMethodInvestments" xlink:to="lab_us-gaap_EquityMethodInvestments" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_InventoryNet_a0c547ab-17a1-4ca8-bffc-64a75cc1e8da_terseLabel_en-US" xlink:label="lab_us-gaap_InventoryNet" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventories </link:label>

<link:label id="lab_us-gaap_InventoryNet_label_en-US" xlink:label="lab_us-gaap_InventoryNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventory, Net </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InventoryNet"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InventoryNet" xlink:to="lab_us-gaap_InventoryNet" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ConstructionInProcessCostsIncurred_88f5f5f0-ba42-4eee-97d4-8b687c58b859_terseLabel_en-US" xlink:label="lab_pwr_ConstructionInProcessCostsIncurred" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Construction costs incurred </link:label>

<link:label id="lab_pwr_ConstructionInProcessCostsIncurred_label_en-US" xlink:label="lab_pwr_ConstructionInProcessCostsIncurred" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Construction In Process, Costs Incurred </link:label>

<link:label id="lab_pwr_ConstructionInProcessCostsIncurred_documentation_en-US" xlink:label="lab_pwr_ConstructionInProcessCostsIncurred" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Construction In Process, Costs Incurred </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ConstructionInProcessCostsIncurred" xlink:href="pwr-20231231.xsd#pwr_ConstructionInProcessCostsIncurred"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ConstructionInProcessCostsIncurred" xlink:to="lab_pwr_ConstructionInProcessCostsIncurred" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LandMember_c1f3f1a2-99f3-44e2-8463-cdd6e687bd5f_terseLabel_en-US" xlink:label="lab_us-gaap_LandMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Land </link:label>

<link:label id="lab_us-gaap_LandMember_label_en-US" xlink:label="lab_us-gaap_LandMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Land [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LandMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LandMember" xlink:to="lab_us-gaap_LandMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_bf34b61b-ffbe-42b5-b6f2-31257eb5f589_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other assets </link:label>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_StateAndLocalOperatingCarryforwardsMember_de4cb577-4d09-401d-96cd-d5af5b2710ef_terseLabel_en-US" xlink:label="lab_pwr_StateAndLocalOperatingCarryforwardsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> State And Local Operating Carryforwards </link:label>

<link:label id="lab_pwr_StateAndLocalOperatingCarryforwardsMember_label_en-US" xlink:label="lab_pwr_StateAndLocalOperatingCarryforwardsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> State And Local Operating Carryforwards [Member] </link:label>

<link:label id="lab_pwr_StateAndLocalOperatingCarryforwardsMember_documentation_en-US" xlink:label="lab_pwr_StateAndLocalOperatingCarryforwardsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> State And Local Operating Carryforwards </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_StateAndLocalOperatingCarryforwardsMember" xlink:href="pwr-20231231.xsd#pwr_StateAndLocalOperatingCarryforwardsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_StateAndLocalOperatingCarryforwardsMember" xlink:to="lab_pwr_StateAndLocalOperatingCarryforwardsMember" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_TotalShareholderRtnAmt_terseLabel_en-US" xlink:label="lab_ecd_TotalShareholderRtnAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total Shareholder Return Amount </link:label>

<link:label id="lab_ecd_TotalShareholderRtnAmt_label_en-US" xlink:label="lab_ecd_TotalShareholderRtnAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total Shareholder Return Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_TotalShareholderRtnAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_TotalShareholderRtnAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_TotalShareholderRtnAmt" xlink:to="lab_ecd_TotalShareholderRtnAmt" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PaymentsForRepurchaseOfCommonStock_9d16a3b1-d199-4ff9-bb2b-8042a92c28e7_negatedLabel_en-US" xlink:label="lab_us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Repurchase of common stock </link:label>

<link:label id="lab_us-gaap_PaymentsForRepurchaseOfCommonStock_label_en-US" xlink:label="lab_us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments for Repurchase of Common Stock </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:to="lab_us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityCommonStockSharesOutstanding_c477f9fa-2db6-47ac-b908-e35fdf9607c6_terseLabel_en-US" xlink:label="lab_dei_EntityCommonStockSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Common Stock, Shares Outstanding </link:label>

<link:label id="lab_dei_EntityCommonStockSharesOutstanding_label_en-US" xlink:label="lab_dei_EntityCommonStockSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Common Stock, Shares Outstanding </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityCommonStockSharesOutstanding"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityCommonStockSharesOutstanding" xlink:to="lab_dei_EntityCommonStockSharesOutstanding" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AdjToPeoCompFnTextBlock_terseLabel_en-US" xlink:label="lab_ecd_AdjToPeoCompFnTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustment To PEO Compensation, Footnote </link:label>

<link:label id="lab_ecd_AdjToPeoCompFnTextBlock_label_en-US" xlink:label="lab_ecd_AdjToPeoCompFnTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustment To PEO Compensation, Footnote [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AdjToPeoCompFnTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AdjToPeoCompFnTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AdjToPeoCompFnTextBlock" xlink:to="lab_ecd_AdjToPeoCompFnTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_d4bd2e92-b33d-4770-bca6-4568149fa687_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredForeignIncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign </link:label>

<link:label id="lab_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_label_en-US" xlink:label="lab_us-gaap_DeferredForeignIncomeTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Foreign Income Tax Expense (Benefit) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredForeignIncomeTaxExpenseBenefit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredForeignIncomeTaxExpenseBenefit"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredForeignIncomeTaxExpenseBenefit" xlink:to="lab_us-gaap_DeferredForeignIncomeTaxExpenseBenefit" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ParentMember_c29d8862-35ed-4abd-a653-3dcd5af571f6_terseLabel_en-US" xlink:label="lab_us-gaap_ParentMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total Stockholders' Equity </link:label>

<link:label id="lab_us-gaap_ParentMember_label_en-US" xlink:label="lab_us-gaap_ParentMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Parent [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParentMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ParentMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ParentMember" xlink:to="lab_us-gaap_ParentMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SegmentDomain_4bb8135d-d415-4122-900a-c4630992d72d_terseLabel_en-US" xlink:label="lab_us-gaap_SegmentDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segments [Domain] </link:label>

<link:label id="lab_us-gaap_SegmentDomain_label_en-US" xlink:label="lab_us-gaap_SegmentDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Segments [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SegmentDomain" xlink:to="lab_us-gaap_SegmentDomain" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_AccountsReceivableAllowanceForCreditLossWriteoffRecovery_bbcc9849-7005-4cdc-bd81-fe641f59f2ff_negatedTerseLabel_en-US" xlink:label="lab_pwr_AccountsReceivableAllowanceForCreditLossWriteoffRecovery" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Write-offs charged against the allowance net of recoveries of amounts previously written off </link:label>

<link:label id="lab_pwr_AccountsReceivableAllowanceForCreditLossWriteoffRecovery_label_en-US" xlink:label="lab_pwr_AccountsReceivableAllowanceForCreditLossWriteoffRecovery" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable, Allowance for Credit Loss, (Writeoff) Recovery </link:label>

<link:label id="lab_pwr_AccountsReceivableAllowanceForCreditLossWriteoffRecovery_documentation_en-US" xlink:label="lab_pwr_AccountsReceivableAllowanceForCreditLossWriteoffRecovery" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Receivable, Allowance for Credit Loss, (Writeoff) Recovery </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_AccountsReceivableAllowanceForCreditLossWriteoffRecovery" xlink:href="pwr-20231231.xsd#pwr_AccountsReceivableAllowanceForCreditLossWriteoffRecovery"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_AccountsReceivableAllowanceForCreditLossWriteoffRecovery" xlink:to="lab_pwr_AccountsReceivableAllowanceForCreditLossWriteoffRecovery" xlink:type="arc" order="1"/>

<link:label id="lab_srt_ConsolidationItemsDomain_dfceac4e-3214-49d2-85ac-3f6a51bf25d8_terseLabel_en-US" xlink:label="lab_srt_ConsolidationItemsDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Consolidation Items [Domain] </link:label>

<link:label id="lab_srt_ConsolidationItemsDomain_label_en-US" xlink:label="lab_srt_ConsolidationItemsDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Consolidation Items [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ConsolidationItemsDomain" xlink:to="lab_srt_ConsolidationItemsDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RetainedEarningsAccumulatedDeficit_553c8af1-be35-47ca-a80b-3116e1faa196_terseLabel_en-US" xlink:label="lab_us-gaap_RetainedEarningsAccumulatedDeficit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Retained earnings </link:label>

<link:label id="lab_us-gaap_RetainedEarningsAccumulatedDeficit_label_en-US" xlink:label="lab_us-gaap_RetainedEarningsAccumulatedDeficit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Retained Earnings (Accumulated Deficit) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RetainedEarningsAccumulatedDeficit" xlink:to="lab_us-gaap_RetainedEarningsAccumulatedDeficit" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ForeignCurrencyTranslationAdjustmentsMember_cf05562b-1dd5-491f-8bb4-33cb9fd7c3fb_terseLabel_en-US" xlink:label="lab_pwr_ForeignCurrencyTranslationAdjustmentsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign Currency Translation Adjustments </link:label>

<link:label id="lab_pwr_ForeignCurrencyTranslationAdjustmentsMember_label_en-US" xlink:label="lab_pwr_ForeignCurrencyTranslationAdjustmentsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign Currency Translation Adjustments [Member] </link:label>

<link:label id="lab_pwr_ForeignCurrencyTranslationAdjustmentsMember_documentation_en-US" xlink:label="lab_pwr_ForeignCurrencyTranslationAdjustmentsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign Currency Translation Adjustments </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ForeignCurrencyTranslationAdjustmentsMember" xlink:href="pwr-20231231.xsd#pwr_ForeignCurrencyTranslationAdjustmentsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ForeignCurrencyTranslationAdjustmentsMember" xlink:to="lab_pwr_ForeignCurrencyTranslationAdjustmentsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentFaceAmount_fc73ca23-ad30-4486-b88d-2066c5243e93_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentFaceAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt instrument </link:label>

<link:label id="lab_us-gaap_DebtInstrumentFaceAmount_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentFaceAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Face Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentFaceAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentFaceAmount" xlink:to="lab_us-gaap_DebtInstrumentFaceAmount" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AssetsCurrentAbstract_bef3ae02-2db4-4083-ac32-daca037c1777_terseLabel_en-US" xlink:label="lab_us-gaap_AssetsCurrentAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current Assets: </link:label>

<link:label id="lab_us-gaap_AssetsCurrentAbstract_label_en-US" xlink:label="lab_us-gaap_AssetsCurrentAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Assets, Current [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsCurrentAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsCurrentAbstract" xlink:to="lab_us-gaap_AssetsCurrentAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LeasesAbstract_02645641-91d1-4187-9d81-8e737d95de6f_terseLabel_en-US" xlink:label="lab_us-gaap_LeasesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Leases [Abstract] </link:label>

<link:label id="lab_us-gaap_LeasesAbstract_label_en-US" xlink:label="lab_us-gaap_LeasesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Leases [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeasesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LeasesAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LeasesAbstract" xlink:to="lab_us-gaap_LeasesAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_5673d213-77a5-4ac0-b07f-3d7665f570f0_terseLabel_en-US" xlink:label="lab_us-gaap_ComponentsOfDeferredTaxAssetsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred income tax assets: </link:label>

<link:label id="lab_us-gaap_ComponentsOfDeferredTaxAssetsAbstract_label_en-US" xlink:label="lab_us-gaap_ComponentsOfDeferredTaxAssetsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Components of Deferred Tax Assets [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComponentsOfDeferredTaxAssetsAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxAssetsAbstract" xlink:to="lab_us-gaap_ComponentsOfDeferredTaxAssetsAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityAddressStateOrProvince_bb5daa4f-6f3b-40f5-88c3-b476855cd8c9_terseLabel_en-US" xlink:label="lab_dei_EntityAddressStateOrProvince" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, State or Province </link:label>

<link:label id="lab_dei_EntityAddressStateOrProvince_label_en-US" xlink:label="lab_dei_EntityAddressStateOrProvince" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, State or Province </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityAddressStateOrProvince"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityAddressStateOrProvince" xlink:to="lab_dei_EntityAddressStateOrProvince" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_CompActuallyPaidVsTotalShareholderRtnTextBlock_terseLabel_en-US" xlink:label="lab_ecd_CompActuallyPaidVsTotalShareholderRtnTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Compensation Actually Paid vs. Total Shareholder Return </link:label>

<link:label id="lab_ecd_CompActuallyPaidVsTotalShareholderRtnTextBlock_label_en-US" xlink:label="lab_ecd_CompActuallyPaidVsTotalShareholderRtnTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Compensation Actually Paid vs. Total Shareholder Return [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_CompActuallyPaidVsTotalShareholderRtnTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_CompActuallyPaidVsTotalShareholderRtnTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_CompActuallyPaidVsTotalShareholderRtnTextBlock" xlink:to="lab_ecd_CompActuallyPaidVsTotalShareholderRtnTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill_e99baf06-b85e-43c0-ac0b-8b515b8e9458_negatedLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill </link:label>

<link:label id="lab_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill_label_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Liabilities, Goodwill </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill" xlink:to="lab_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearOne_254f68e1-4876-4225-b3f3-b3c5a0437d3e_terseLabel_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearOne" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Tax carryforwards expiring in year one </link:label>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearOne_label_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearOne" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expiration Amount Of State And Foreign Net Operating Loss Carryforwards Year One </link:label>

<link:label id="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearOne_documentation_en-US" xlink:label="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearOne" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Expiration amount of state and foreign net operating loss carryforwards year one. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearOne" xlink:href="pwr-20231231.xsd#pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearOne"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearOne" xlink:to="lab_pwr_ExpirationAmountOfStateAndForeignNetOperatingLossCarryforwardsYearOne" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDue_6b6d0a30-5df4-4e7e-bd07-8226ca58c109_totalLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDue" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total future minimum lease payments </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDue_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, to be Paid </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDue" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_11217322-3f70-4a7f-9d52-7243766e95cc_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash Flows from Operating Activities: </link:label>

<link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Cash Provided by (Used in) Operating Activities [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredCompensationArrangementWithIndividualContributionsByEmployer_60f73cda-f89a-4647-acd6-69da7e081a9e_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredCompensationArrangementWithIndividualContributionsByEmployer" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contributions to the deferred compensation plans </link:label>

<link:label id="lab_us-gaap_DeferredCompensationArrangementWithIndividualContributionsByEmployer_label_en-US" xlink:label="lab_us-gaap_DeferredCompensationArrangementWithIndividualContributionsByEmployer" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Compensation Arrangement with Individual, Contributions by Employer </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualContributionsByEmployer" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredCompensationArrangementWithIndividualContributionsByEmployer"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualContributionsByEmployer" xlink:to="lab_us-gaap_DeferredCompensationArrangementWithIndividualContributionsByEmployer" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ClassOfStockDomain_09d045c5-cead-41b8-8f97-10d856b90411_terseLabel_en-US" xlink:label="lab_us-gaap_ClassOfStockDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class of Stock [Domain] </link:label>

<link:label id="lab_us-gaap_ClassOfStockDomain_label_en-US" xlink:label="lab_us-gaap_ClassOfStockDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class of Stock [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ClassOfStockDomain" xlink:to="lab_us-gaap_ClassOfStockDomain" xlink:type="arc" order="1"/>

<link:label id="lab_srt_NameOfMajorCustomerDomain_2cd40599-1617-4844-8b83-8f22aec9c523_terseLabel_en-US" xlink:label="lab_srt_NameOfMajorCustomerDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer [Domain] </link:label>

<link:label id="lab_srt_NameOfMajorCustomerDomain_label_en-US" xlink:label="lab_srt_NameOfMajorCustomerDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_NameOfMajorCustomerDomain" xlink:to="lab_srt_NameOfMajorCustomerDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_02df1b5e-81b1-4172-a59c-2d15747e8eb1_terseLabel_en-US" xlink:label="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net income attributable to common stock, Basic </link:label>

<link:label id="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_label_en-US" xlink:label="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Income (Loss) Available to Common Stockholders, Basic </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:to="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OperatingLeaseLiability_e6c68fb9-291c-48ea-a36c-e2e8210b771d_verboseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total </link:label>

<link:label id="lab_us-gaap_OperatingLeaseLiability_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiability" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Liability </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiability"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseLiability" xlink:to="lab_us-gaap_OperatingLeaseLiability" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityCurrent_f36a99b7-ab01-499e-843d-d03842b3f5f1_negatedTerseLabel_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease liabilities, current </link:label>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityCurrent_label_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Operating Lease, Liability, Current </link:label>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityCurrent_documentation_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityCurrent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Operating Lease, Liability, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityCurrent" xlink:href="pwr-20231231.xsd#pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityCurrent" xlink:to="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CentralPensionFundOfIuoeAndParticipatingEmployersMember_b7b92f98-20fd-4331-bd0b-b5537efc843f_terseLabel_en-US" xlink:label="lab_pwr_CentralPensionFundOfIuoeAndParticipatingEmployersMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Central Pension Fund of the IUOE & Participating Employers </link:label>

<link:label id="lab_pwr_CentralPensionFundOfIuoeAndParticipatingEmployersMember_label_en-US" xlink:label="lab_pwr_CentralPensionFundOfIuoeAndParticipatingEmployersMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Central Pension Fund Of IUOE And Participating Employers [Member] </link:label>

<link:label id="lab_pwr_CentralPensionFundOfIuoeAndParticipatingEmployersMember_documentation_en-US" xlink:label="lab_pwr_CentralPensionFundOfIuoeAndParticipatingEmployersMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Central pension fund of the IUOE and participating employers. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CentralPensionFundOfIuoeAndParticipatingEmployersMember" xlink:href="pwr-20231231.xsd#pwr_CentralPensionFundOfIuoeAndParticipatingEmployersMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CentralPensionFundOfIuoeAndParticipatingEmployersMember" xlink:to="lab_pwr_CentralPensionFundOfIuoeAndParticipatingEmployersMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock_e78126ea-130d-440b-9fb0-150e36867d4e_terseLabel_en-US" xlink:label="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Description of Business </link:label>

<link:label id="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock_label_en-US" xlink:label="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock" xlink:to="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_TotalShareholderRtnVsPeerGroupTextBlock_terseLabel_en-US" xlink:label="lab_ecd_TotalShareholderRtnVsPeerGroupTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total Shareholder Return Vs Peer Group </link:label>

<link:label id="lab_ecd_TotalShareholderRtnVsPeerGroupTextBlock_label_en-US" xlink:label="lab_ecd_TotalShareholderRtnVsPeerGroupTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total Shareholder Return Vs Peer Group [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_TotalShareholderRtnVsPeerGroupTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_TotalShareholderRtnVsPeerGroupTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_TotalShareholderRtnVsPeerGroupTextBlock" xlink:to="lab_ecd_TotalShareholderRtnVsPeerGroupTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_edb197a8-8acf-441c-aea5-5586526b0b10_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Inventories </link:label>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_VestingDomain_fc62cc0d-9f97-4e1b-9980-20612978173d_terseLabel_en-US" xlink:label="lab_us-gaap_VestingDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Vesting [Domain] </link:label>

<link:label id="lab_us-gaap_VestingDomain_label_en-US" xlink:label="lab_us-gaap_VestingDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Vesting [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VestingDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VestingDomain" xlink:to="lab_us-gaap_VestingDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AccumulatedOtherComprehensiveIncomeMember_1ec12ed2-66c3-4f02-b0f9-8955bb4aea54_terseLabel_en-US" xlink:label="lab_us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accumulated Other Comprehensive Loss </link:label>

<link:label id="lab_us-gaap_AccumulatedOtherComprehensiveIncomeMember_label_en-US" xlink:label="lab_us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> AOCI Attributable to Parent [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:to="lab_us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_a4244909-2456-4751-b861-e95ce738098c_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid expenses and other current assets </link:label>

<link:label id="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Prepaid Expense and Other Assets </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:to="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AggtErrCompAmt_terseLabel_en-US" xlink:label="lab_ecd_AggtErrCompAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Aggregate Erroneous Compensation Amount </link:label>

<link:label id="lab_ecd_AggtErrCompAmt_label_en-US" xlink:label="lab_ecd_AggtErrCompAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Aggregate Erroneous Compensation Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AggtErrCompAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AggtErrCompAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AggtErrCompAmt" xlink:to="lab_ecd_AggtErrCompAmt" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_cae864f1-248d-4411-82d0-2e3ba4489b25_terseLabel_en-US" xlink:label="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] </link:label>

<link:label id="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_label_en-US" xlink:label="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis" xlink:to="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DefinedContributionPlanCostRecognized_ea4a0e5c-88fc-4336-a3c3-179791929bec_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedContributionPlanCostRecognized" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contributions to Quanta 401(k) Plan </link:label>

<link:label id="lab_us-gaap_DefinedContributionPlanCostRecognized_label_en-US" xlink:label="lab_us-gaap_DefinedContributionPlanCostRecognized" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Defined Contribution Plan, Cost </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanCostRecognized" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DefinedContributionPlanCostRecognized"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedContributionPlanCostRecognized" xlink:to="lab_us-gaap_DefinedContributionPlanCostRecognized" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AllExecutiveCategoriesMember_terseLabel_en-US" xlink:label="lab_ecd_AllExecutiveCategoriesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Executive Categories </link:label>

<link:label id="lab_ecd_AllExecutiveCategoriesMember_label_en-US" xlink:label="lab_ecd_AllExecutiveCategoriesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Executive Categories [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AllExecutiveCategoriesMember" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AllExecutiveCategoriesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AllExecutiveCategoriesMember" xlink:to="lab_ecd_AllExecutiveCategoriesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxReconciliationOtherAdjustments_5542e427-8303-4c77-8d3b-f928041690e9_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationOtherAdjustments" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other </link:label>

<link:label id="lab_us-gaap_IncomeTaxReconciliationOtherAdjustments_label_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationOtherAdjustments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Other Adjustments, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxReconciliationOtherAdjustments"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxReconciliationOtherAdjustments" xlink:to="lab_us-gaap_IncomeTaxReconciliationOtherAdjustments" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ShortTermLeaseAndVariableLeaseCost_5dcf6ddf-3239-42bd-a967-7b2c06c16df5_terseLabel_en-US" xlink:label="lab_pwr_ShortTermLeaseAndVariableLeaseCost" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Short-term and variable lease cost </link:label>

<link:label id="lab_pwr_ShortTermLeaseAndVariableLeaseCost_label_en-US" xlink:label="lab_pwr_ShortTermLeaseAndVariableLeaseCost" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Short-Term Lease And Variable Lease, Cost </link:label>

<link:label id="lab_pwr_ShortTermLeaseAndVariableLeaseCost_documentation_en-US" xlink:label="lab_pwr_ShortTermLeaseAndVariableLeaseCost" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Short-Term Lease And Variable Lease, Cost </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ShortTermLeaseAndVariableLeaseCost" xlink:href="pwr-20231231.xsd#pwr_ShortTermLeaseAndVariableLeaseCost"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ShortTermLeaseAndVariableLeaseCost" xlink:to="lab_pwr_ShortTermLeaseAndVariableLeaseCost" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LettersOfCreditAndBankGuaranteesMember_a75ae065-6f88-4714-815b-b8cfa4b679ab_terseLabel_en-US" xlink:label="lab_pwr_LettersOfCreditAndBankGuaranteesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Letters of Credit and Bank Guarantees </link:label>

<link:label id="lab_pwr_LettersOfCreditAndBankGuaranteesMember_label_en-US" xlink:label="lab_pwr_LettersOfCreditAndBankGuaranteesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Letters Of Credit and Bank Guarantees [Member] </link:label>

<link:label id="lab_pwr_LettersOfCreditAndBankGuaranteesMember_documentation_en-US" xlink:label="lab_pwr_LettersOfCreditAndBankGuaranteesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> The Letters Of Credit and Bank Guarantees. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LettersOfCreditAndBankGuaranteesMember" xlink:href="pwr-20231231.xsd#pwr_LettersOfCreditAndBankGuaranteesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LettersOfCreditAndBankGuaranteesMember" xlink:to="lab_pwr_LettersOfCreditAndBankGuaranteesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PlanNameAxis_7da01427-9121-4450-93ff-84e9986f8f9c_terseLabel_en-US" xlink:label="lab_us-gaap_PlanNameAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Plan Name [Axis] </link:label>

<link:label id="lab_us-gaap_PlanNameAxis_label_en-US" xlink:label="lab_us-gaap_PlanNameAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Plan Name [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PlanNameAxis" xlink:to="lab_us-gaap_PlanNameAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtDisclosureAbstract_567b5c22-1d90-48ba-957f-92055debf911_terseLabel_en-US" xlink:label="lab_us-gaap_DebtDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Disclosure [Abstract] </link:label>

<link:label id="lab_us-gaap_DebtDisclosureAbstract_label_en-US" xlink:label="lab_us-gaap_DebtDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Disclosure [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtDisclosureAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtDisclosureAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtDisclosureAbstract" xlink:to="lab_us-gaap_DebtDisclosureAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AssetsAndLiabilitiesLesseeAbstract_6d84e24c-7279-46bb-8f41-222bb36a63b3_terseLabel_en-US" xlink:label="lab_us-gaap_AssetsAndLiabilitiesLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease type </link:label>

<link:label id="lab_us-gaap_AssetsAndLiabilitiesLesseeAbstract_label_en-US" xlink:label="lab_us-gaap_AssetsAndLiabilitiesLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Assets and Liabilities, Lessee [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAndLiabilitiesLesseeAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsAndLiabilitiesLesseeAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsAndLiabilitiesLesseeAbstract" xlink:to="lab_us-gaap_AssetsAndLiabilitiesLesseeAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NumberOfReportableSegments_4f784562-68de-4b18-af71-d5ca569b04a5_terseLabel_en-US" xlink:label="lab_us-gaap_NumberOfReportableSegments" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of reportable segments </link:label>

<link:label id="lab_us-gaap_NumberOfReportableSegments_label_en-US" xlink:label="lab_us-gaap_NumberOfReportableSegments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of Reportable Segments </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NumberOfReportableSegments"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NumberOfReportableSegments" xlink:to="lab_us-gaap_NumberOfReportableSegments" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EarningsPerShareAbstract_47d7bd6e-17e2-49ed-b060-af15e256ca0f_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Earnings per share attributable to common stock: </link:label>

<link:label id="lab_us-gaap_EarningsPerShareAbstract_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Earnings Per Share [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareAbstract" xlink:to="lab_us-gaap_EarningsPerShareAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CommonStockValue_70bfbc75-ec61-40db-a248-4048b1bd8667_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock </link:label>

<link:label id="lab_us-gaap_CommonStockValue_label_en-US" xlink:label="lab_us-gaap_CommonStockValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock, Value, Issued </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockValue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockValue" xlink:to="lab_us-gaap_CommonStockValue" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentRedemptionPricePercentage_cc082888-5ad9-433d-9105-56abd9f7607b_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPricePercentage" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Redemption price </link:label>

<link:label id="lab_us-gaap_DebtInstrumentRedemptionPricePercentage_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPricePercentage" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Redemption Price, Percentage </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPricePercentage" xlink:to="lab_us-gaap_DebtInstrumentRedemptionPricePercentage" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_2a874465-ebfb-4226-a202-df8cf26dea20_terseLabel_en-US" xlink:label="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Organization, Consolidation and Presentation of Financial Statements [Abstract] </link:label>

<link:label id="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_label_en-US" xlink:label="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Organization, Consolidation and Presentation of Financial Statements [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:to="lab_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_TradeNamesMember_bb7efaae-6a3a-4209-962c-4a3cbc72cb59_terseLabel_en-US" xlink:label="lab_us-gaap_TradeNamesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trade names </link:label>

<link:label id="lab_us-gaap_TradeNamesMember_label_en-US" xlink:label="lab_us-gaap_TradeNamesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trade Names [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TradeNamesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TradeNamesMember" xlink:to="lab_us-gaap_TradeNamesMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingEngineersPensionTrustMember_3503650c-444c-4b1d-8aa0-7dd47166b95a_terseLabel_en-US" xlink:label="lab_pwr_OperatingEngineersPensionTrustMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Engineers Pension Trust </link:label>

<link:label id="lab_pwr_OperatingEngineersPensionTrustMember_label_en-US" xlink:label="lab_pwr_OperatingEngineersPensionTrustMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Engineers Pension Trust [Member] </link:label>

<link:label id="lab_pwr_OperatingEngineersPensionTrustMember_documentation_en-US" xlink:label="lab_pwr_OperatingEngineersPensionTrustMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Engineers Pension Trust </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingEngineersPensionTrustMember" xlink:href="pwr-20231231.xsd#pwr_OperatingEngineersPensionTrustMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingEngineersPensionTrustMember" xlink:to="lab_pwr_OperatingEngineersPensionTrustMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SeniorNotesMember_7559d919-3e67-49a0-bcb9-66aedec47be7_terseLabel_en-US" xlink:label="lab_us-gaap_SeniorNotesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Notes </link:label>

<link:label id="lab_us-gaap_SeniorNotesMember_label_en-US" xlink:label="lab_us-gaap_SeniorNotesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Notes [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SeniorNotesMember" xlink:to="lab_us-gaap_SeniorNotesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeasePrincipalPayments_9c15b483-66c1-4595-b3a6-91c166eb9600_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeasePrincipalPayments" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Financing cash flows used by finance leases </link:label>

<link:label id="lab_us-gaap_FinanceLeasePrincipalPayments_label_en-US" xlink:label="lab_us-gaap_FinanceLeasePrincipalPayments" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Principal Payments </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeasePrincipalPayments" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeasePrincipalPayments"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeasePrincipalPayments" xlink:to="lab_us-gaap_FinanceLeasePrincipalPayments" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock_fe22f02d-a2fc-4eed-a60e-bacdf61f6618_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Future Minimum Lease Payments - Finance Leases and Equipment Lease Financing Transactions </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, to be Paid, Maturity [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock" xlink:to="lab_us-gaap_FinanceLeaseLiabilityMaturityTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RevenueFromContractWithCustomerAbstract_label_en-US" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue from Contract with Customer [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenueFromContractWithCustomerAbstract" xlink:to="lab_us-gaap_RevenueFromContractWithCustomerAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AllIndividualsMember_terseLabel_en-US" xlink:label="lab_ecd_AllIndividualsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Individuals </link:label>

<link:label id="lab_ecd_AllIndividualsMember_label_en-US" xlink:label="lab_ecd_AllIndividualsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Individuals [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AllIndividualsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="lab_ecd_AllIndividualsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued_d690ed93-b650-454b-b81e-4aabcd1cebd4_terseLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued penalties on unrecognized tax benefits </link:label>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued_label_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecognized Tax Benefits, Income Tax Penalties Accrued </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued" xlink:to="lab_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAccrued" xlink:type="arc" order="1"/>

<link:label id="lab_srt_LitigationCaseTypeDomain_299cb874-13ac-4e21-bd4f-abcd364b85b5_terseLabel_en-US" xlink:label="lab_srt_LitigationCaseTypeDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Litigation Case [Domain] </link:label>

<link:label id="lab_srt_LitigationCaseTypeDomain_label_en-US" xlink:label="lab_srt_LitigationCaseTypeDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Litigation Case [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_LitigationCaseTypeDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_LitigationCaseTypeDomain" xlink:to="lab_srt_LitigationCaseTypeDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList_c4484d14-3a4d-41cb-9b02-919b66711c55_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Leased Asset, Type [Extensible Enumeration] </link:label>

<link:label id="lab_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList" xlink:to="lab_us-gaap_FinanceLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OtherNonoperatingIncomeExpense_ed207e7d-1566-44cd-be5b-5a492e5473fb_terseLabel_en-US" xlink:label="lab_us-gaap_OtherNonoperatingIncomeExpense" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other income (expense), net </link:label>

<link:label id="lab_us-gaap_OtherNonoperatingIncomeExpense_label_en-US" xlink:label="lab_us-gaap_OtherNonoperatingIncomeExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Nonoperating Income (Expense) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpense" xlink:to="lab_us-gaap_OtherNonoperatingIncomeExpense" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityFilerCategory_e779e2d9-f37b-485d-be14-529c8953840f_terseLabel_en-US" xlink:label="lab_dei_EntityFilerCategory" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Filer Category </link:label>

<link:label id="lab_dei_EntityFilerCategory_label_en-US" xlink:label="lab_dei_EntityFilerCategory" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Filer Category </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityFilerCategory"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityFilerCategory" xlink:to="lab_dei_EntityFilerCategory" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_25ad4cfb-b65a-424b-898f-6b99d4c94440_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Equity Method Investments [Line Items] </link:label>

<link:label id="lab_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems_label_en-US" xlink:label="lab_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Equity Method Investments [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEquityMethodInvestmentsLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" xlink:to="lab_us-gaap_ScheduleOfEquityMethodInvestmentsLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfTreasuryStockByClassTextBlock_2d219617-1ddb-4bc2-8ce2-ea40d149e994_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfTreasuryStockByClassTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Treasury Stock </link:label>

<link:label id="lab_us-gaap_ScheduleOfTreasuryStockByClassTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfTreasuryStockByClassTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Class of Treasury Stock [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfTreasuryStockByClassTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfTreasuryStockByClassTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfTreasuryStockByClassTextBlock" xlink:to="lab_us-gaap_ScheduleOfTreasuryStockByClassTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_NonPeoNeoAvgTotalCompAmt_terseLabel_en-US" xlink:label="lab_ecd_NonPeoNeoAvgTotalCompAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-PEO NEO Average Total Compensation Amount </link:label>

<link:label id="lab_ecd_NonPeoNeoAvgTotalCompAmt_label_en-US" xlink:label="lab_ecd_NonPeoNeoAvgTotalCompAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-PEO NEO Average Total Compensation Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_NonPeoNeoAvgTotalCompAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_NonPeoNeoAvgTotalCompAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_NonPeoNeoAvgTotalCompAmt" xlink:to="lab_ecd_NonPeoNeoAvgTotalCompAmt" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StatementTable_5f8b2515-0d67-45ea-b0ce-7cda772410ac_terseLabel_en-US" xlink:label="lab_us-gaap_StatementTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement [Table] </link:label>

<link:label id="lab_us-gaap_StatementTable_label_en-US" xlink:label="lab_us-gaap_StatementTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementTable" xlink:to="lab_us-gaap_StatementTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_a5c1bd61-dc06-47dd-9344-514064e1f111_verboseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insurance and other non-current liabilities </link:label>

<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Contingent Consideration, Liability, Noncurrent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent" xlink:to="lab_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent" xlink:type="arc" order="1"/>

<link:label id="lab_dei_CurrentFiscalYearEndDate_ae177205-6c99-40fb-bcdc-f2e72b6d1111_terseLabel_en-US" xlink:label="lab_dei_CurrentFiscalYearEndDate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current Fiscal Year End Date </link:label>

<link:label id="lab_dei_CurrentFiscalYearEndDate_label_en-US" xlink:label="lab_dei_CurrentFiscalYearEndDate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current Fiscal Year End Date </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_CurrentFiscalYearEndDate"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_CurrentFiscalYearEndDate" xlink:to="lab_dei_CurrentFiscalYearEndDate" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_EstimateMember_0d53c6b0-09ef-4c90-87e0-e8bdd5e2340f_terseLabel_en-US" xlink:label="lab_pwr_EstimateMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Estimate </link:label>

<link:label id="lab_pwr_EstimateMember_label_en-US" xlink:label="lab_pwr_EstimateMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Estimate [Member] </link:label>

<link:label id="lab_pwr_EstimateMember_documentation_en-US" xlink:label="lab_pwr_EstimateMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Estimate. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_EstimateMember" xlink:href="pwr-20231231.xsd#pwr_EstimateMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_EstimateMember" xlink:to="lab_pwr_EstimateMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StockRepurchaseProgramAuthorizedAmount1_19e2ddc7-970a-4028-8f00-3dca71943a8e_terseLabel_en-US" xlink:label="lab_us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Aggregate authorized amount of common stock to be repurchased </link:label>

<link:label id="lab_us-gaap_StockRepurchaseProgramAuthorizedAmount1_label_en-US" xlink:label="lab_us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Repurchase Program, Authorized Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:to="lab_us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentRelatedToForeignNetOperatingLossCarryforwards_53caca5f-1f18-4bab-a082-a38e140a79c9_negatedTerseLabel_en-US" xlink:label="lab_pwr_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentRelatedToForeignNetOperatingLossCarryforwards" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Change in expense related to foreign NOLs </link:label>

<link:label id="lab_pwr_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentRelatedToForeignNetOperatingLossCarryforwards_label_en-US" xlink:label="lab_pwr_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentRelatedToForeignNetOperatingLossCarryforwards" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Expense (Benefit), Continuing Operations, Adjustment Related to Foreign Net Operating Loss Carryforwards </link:label>

<link:label id="lab_pwr_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentRelatedToForeignNetOperatingLossCarryforwards_documentation_en-US" xlink:label="lab_pwr_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentRelatedToForeignNetOperatingLossCarryforwards" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Expense (Benefit), Continuing Operations, Adjustment Related to Foreign Net Operating Loss Carryforwards </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentRelatedToForeignNetOperatingLossCarryforwards" xlink:href="pwr-20231231.xsd#pwr_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentRelatedToForeignNetOperatingLossCarryforwards"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentRelatedToForeignNetOperatingLossCarryforwards" xlink:to="lab_pwr_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentRelatedToForeignNetOperatingLossCarryforwards" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AccountsPayableTradeCurrent_534490ac-ae0c-4809-8694-f4ed46deb379_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsPayableTradeCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts payable, trade </link:label>

<link:label id="lab_us-gaap_AccountsPayableTradeCurrent_label_en-US" xlink:label="lab_us-gaap_AccountsPayableTradeCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Payable, Trade, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableTradeCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableTradeCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsPayableTradeCurrent" xlink:to="lab_us-gaap_AccountsPayableTradeCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_7567ef4c-4710-47eb-b589-c4fa88858a0b_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation </link:label>

<link:label id="lab_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfEffectiveIncomeTaxRateReconciliationTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefits_28d51dc4-531b-4398-ba48-27ac4dab3037_terseLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefits" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total amount of unrecognized tax benefits relating to uncertain tax positions </link:label>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefits_b48231d5-ac8a-422f-a13e-d47de9424bf1_periodStartLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefits" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Balance at beginning of year </link:label>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefits_1060de6f-95bb-4835-875f-843e7e856ca2_periodEndLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefits" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Balance at end of year </link:label>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefits_ae710759-68f4-41b6-a8e5-2805413daafd_verboseLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefits" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecognized tax benefits </link:label>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefits_label_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefits" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecognized Tax Benefits </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefits"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecognizedTaxBenefits" xlink:to="lab_us-gaap_UnrecognizedTaxBenefits" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxAuthorityAxis_e0494eb3-ae2e-4f68-8cc6-060506bfa06b_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxAuthorityAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Authority [Axis] </link:label>

<link:label id="lab_us-gaap_IncomeTaxAuthorityAxis_label_en-US" xlink:label="lab_us-gaap_IncomeTaxAuthorityAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Authority [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxAuthorityAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis" xlink:to="lab_us-gaap_IncomeTaxAuthorityAxis" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_PeoName_terseLabel_en-US" xlink:label="lab_ecd_PeoName" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> PEO Name </link:label>

<link:label id="lab_ecd_PeoName_label_en-US" xlink:label="lab_ecd_PeoName" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> PEO Name </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_PeoName" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_PeoName"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_PeoName" xlink:to="lab_ecd_PeoName" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_AlternativeCurrencyTermRateMember_052a2145-29a2-483d-877d-adbf70547e73_terseLabel_en-US" xlink:label="lab_pwr_AlternativeCurrencyTermRateMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Alternative Currency Term Rate </link:label>

<link:label id="lab_pwr_AlternativeCurrencyTermRateMember_label_en-US" xlink:label="lab_pwr_AlternativeCurrencyTermRateMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Alternative Currency Term Rate [Member] </link:label>

<link:label id="lab_pwr_AlternativeCurrencyTermRateMember_documentation_en-US" xlink:label="lab_pwr_AlternativeCurrencyTermRateMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Alternative Currency Term Rate </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_AlternativeCurrencyTermRateMember" xlink:href="pwr-20231231.xsd#pwr_AlternativeCurrencyTermRateMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_AlternativeCurrencyTermRateMember" xlink:to="lab_pwr_AlternativeCurrencyTermRateMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtPolicyTextBlock_33637530-ca9f-4c19-81d1-af24ad84541e_terseLabel_en-US" xlink:label="lab_us-gaap_DebtPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Financing Costs </link:label>

<link:label id="lab_us-gaap_DebtPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_DebtPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtPolicyTextBlock" xlink:to="lab_us-gaap_DebtPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CommitmentAndContingenciesTable_8c14cab2-e36c-4a03-9a05-892647f8df58_terseLabel_en-US" xlink:label="lab_pwr_CommitmentAndContingenciesTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitment And Contingencies [Table] </link:label>

<link:label id="lab_pwr_CommitmentAndContingenciesTable_label_en-US" xlink:label="lab_pwr_CommitmentAndContingenciesTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitment And Contingencies [Table] </link:label>

<link:label id="lab_pwr_CommitmentAndContingenciesTable_documentation_en-US" xlink:label="lab_pwr_CommitmentAndContingenciesTable" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitment And Contingencies [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CommitmentAndContingenciesTable" xlink:href="pwr-20231231.xsd#pwr_CommitmentAndContingenciesTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CommitmentAndContingenciesTable" xlink:to="lab_pwr_CommitmentAndContingenciesTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BaseRateMember_32ebb29c-370a-4940-85c1-9a3bf018fe2d_terseLabel_en-US" xlink:label="lab_us-gaap_BaseRateMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Base Rate </link:label>

<link:label id="lab_us-gaap_BaseRateMember_label_en-US" xlink:label="lab_us-gaap_BaseRateMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Base Rate [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BaseRateMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BaseRateMember" xlink:to="lab_us-gaap_BaseRateMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_AssetsLesseeAbstract_b5ae2c5c-da60-411e-b6ad-75a2c239767f_terseLabel_en-US" xlink:label="lab_pwr_AssetsLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Assets: </link:label>

<link:label id="lab_pwr_AssetsLesseeAbstract_label_en-US" xlink:label="lab_pwr_AssetsLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Assets, Lessee [Abstract] </link:label>

<link:label id="lab_pwr_AssetsLesseeAbstract_documentation_en-US" xlink:label="lab_pwr_AssetsLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Assets, Lessee [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_AssetsLesseeAbstract" xlink:href="pwr-20231231.xsd#pwr_AssetsLesseeAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_AssetsLesseeAbstract" xlink:to="lab_pwr_AssetsLesseeAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfGoodwillTextBlock_69feaf3c-3ab9-4566-b424-701cffd13f1a_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfGoodwillTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary of Changes in Quanta's Goodwill </link:label>

<link:label id="lab_us-gaap_ScheduleOfGoodwillTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfGoodwillTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Goodwill [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfGoodwillTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfGoodwillTextBlock" xlink:to="lab_us-gaap_ScheduleOfGoodwillTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxAssetsTaxCreditCarryforwards_f0b2a39a-783c-4455-b934-bd6ab4ec1068_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxCreditCarryforwards" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Tax credits </link:label>

<link:label id="lab_us-gaap_DeferredTaxAssetsTaxCreditCarryforwards_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxCreditCarryforwards" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Tax Credit Carryforwards </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwards" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsTaxCreditCarryforwards"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsTaxCreditCarryforwards" xlink:to="lab_us-gaap_DeferredTaxAssetsTaxCreditCarryforwards" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_SeniorNotesDueOctober2041Member_ac687de4-b0c0-4a90-903f-20ee1099dee7_terseLabel_en-US" xlink:label="lab_pwr_SeniorNotesDueOctober2041Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 3.050% Senior Notes due October 2041 </link:label>

<link:label id="lab_pwr_SeniorNotesDueOctober2041Member_label_en-US" xlink:label="lab_pwr_SeniorNotesDueOctober2041Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Notes Due October 2041 [Member] </link:label>

<link:label id="lab_pwr_SeniorNotesDueOctober2041Member_documentation_en-US" xlink:label="lab_pwr_SeniorNotesDueOctober2041Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Senior Notes Due October 2041 </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_SeniorNotesDueOctober2041Member" xlink:href="pwr-20231231.xsd#pwr_SeniorNotesDueOctober2041Member"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_SeniorNotesDueOctober2041Member" xlink:to="lab_pwr_SeniorNotesDueOctober2041Member" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_InvestmentTableTextBlock_c23ef651-c2de-4a0c-8ce8-8761566b798c_terseLabel_en-US" xlink:label="lab_us-gaap_InvestmentTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Equity Investments </link:label>

<link:label id="lab_us-gaap_InvestmentTableTextBlock_label_en-US" xlink:label="lab_us-gaap_InvestmentTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investment [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InvestmentTableTextBlock" xlink:to="lab_us-gaap_InvestmentTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LaborersDistrictCouncilOfWPAPensionFundMember_ccb24482-7577-4308-8ced-3d514bdf4147_terseLabel_en-US" xlink:label="lab_pwr_LaborersDistrictCouncilOfWPAPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Laborers District Council of W PA Pension Fund </link:label>

<link:label id="lab_pwr_LaborersDistrictCouncilOfWPAPensionFundMember_label_en-US" xlink:label="lab_pwr_LaborersDistrictCouncilOfWPAPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Laborers District Council Of WPA Pension Fund [Member] </link:label>

<link:label id="lab_pwr_LaborersDistrictCouncilOfWPAPensionFundMember_documentation_en-US" xlink:label="lab_pwr_LaborersDistrictCouncilOfWPAPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Laborers district council of WPA pension fund. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LaborersDistrictCouncilOfWPAPensionFundMember" xlink:href="pwr-20231231.xsd#pwr_LaborersDistrictCouncilOfWPAPensionFundMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LaborersDistrictCouncilOfWPAPensionFundMember" xlink:to="lab_pwr_LaborersDistrictCouncilOfWPAPensionFundMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_PerformanceLettersOfCreditMember_a80bd422-bc60-4753-8756-382754369a2f_terseLabel_en-US" xlink:label="lab_pwr_PerformanceLettersOfCreditMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Performance Letters of Credit </link:label>

<link:label id="lab_pwr_PerformanceLettersOfCreditMember_label_en-US" xlink:label="lab_pwr_PerformanceLettersOfCreditMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Performance Letters Of Credit [Member] </link:label>

<link:label id="lab_pwr_PerformanceLettersOfCreditMember_documentation_en-US" xlink:label="lab_pwr_PerformanceLettersOfCreditMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Performance Letters Of Credit [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_PerformanceLettersOfCreditMember" xlink:href="pwr-20231231.xsd#pwr_PerformanceLettersOfCreditMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_PerformanceLettersOfCreditMember" xlink:to="lab_pwr_PerformanceLettersOfCreditMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OtherAccruedLiabilitiesCurrent_60307d2d-9797-4d85-8022-05cf2b83a3a7_terseLabel_en-US" xlink:label="lab_us-gaap_OtherAccruedLiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other accrued expenses </link:label>

<link:label id="lab_us-gaap_OtherAccruedLiabilitiesCurrent_label_en-US" xlink:label="lab_us-gaap_OtherAccruedLiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Accrued Liabilities, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAccruedLiabilitiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAccruedLiabilitiesCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherAccruedLiabilitiesCurrent" xlink:to="lab_us-gaap_OtherAccruedLiabilitiesCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CorporateNonSegmentMember_46f474aa-b7bb-4dd7-a127-fef3df0ea986_terseLabel_en-US" xlink:label="lab_us-gaap_CorporateNonSegmentMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Corporate and Non-Allocated </link:label>

<link:label id="lab_us-gaap_CorporateNonSegmentMember_label_en-US" xlink:label="lab_us-gaap_CorporateNonSegmentMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Corporate, Non-Segment [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateNonSegmentMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CorporateNonSegmentMember" xlink:to="lab_us-gaap_CorporateNonSegmentMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet_2ea08ae4-056c-496d-9c6b-dca991280fa4_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other assets and liabilities, net </link:label>

<link:label id="lab_us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Other Operating Assets and Liabilities, Net </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet" xlink:to="lab_us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage_444bfc1c-b6aa-44ab-aab0-54fdebb85357_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Instrument rate </link:label>

<link:label id="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Interest Rate, Stated Percentage </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:to="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_86c94968-7bb6-4df6-be75-df6ff6e29137_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts payable and accrued expenses </link:label>

<link:label id="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_6dcdc8a6-5f28-4a7a-9db8-4243fda360b2_totalLabel_en-US" xlink:label="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts payable and accrued expenses </link:label>

<link:label id="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_label_en-US" xlink:label="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Payable and Accrued Liabilities, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:to="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StatementOfFinancialPositionAbstract_cfe0b14e-5996-4d0b-a597-7a28eaef9886_terseLabel_en-US" xlink:label="lab_us-gaap_StatementOfFinancialPositionAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement of Financial Position [Abstract] </link:label>

<link:label id="lab_us-gaap_StatementOfFinancialPositionAbstract_label_en-US" xlink:label="lab_us-gaap_StatementOfFinancialPositionAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement of Financial Position [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementOfFinancialPositionAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract" xlink:to="lab_us-gaap_StatementOfFinancialPositionAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_FinanceLeaseAssetsAndLeaseFinancingTransactionsMember_786fdccc-8bde-4cd7-a62c-c8621b217f61_terseLabel_en-US" xlink:label="lab_pwr_FinanceLeaseAssetsAndLeaseFinancingTransactionsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance lease assets and lease financing transactions </link:label>

<link:label id="lab_pwr_FinanceLeaseAssetsAndLeaseFinancingTransactionsMember_label_en-US" xlink:label="lab_pwr_FinanceLeaseAssetsAndLeaseFinancingTransactionsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease Assets And Lease Financing Transactions [Member] </link:label>

<link:label id="lab_pwr_FinanceLeaseAssetsAndLeaseFinancingTransactionsMember_documentation_en-US" xlink:label="lab_pwr_FinanceLeaseAssetsAndLeaseFinancingTransactionsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease Assets And Lease Financing Transactions </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_FinanceLeaseAssetsAndLeaseFinancingTransactionsMember" xlink:href="pwr-20231231.xsd#pwr_FinanceLeaseAssetsAndLeaseFinancingTransactionsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_FinanceLeaseAssetsAndLeaseFinancingTransactionsMember" xlink:to="lab_pwr_FinanceLeaseAssetsAndLeaseFinancingTransactionsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StockholdersEquity_e8a99b0e-ef94-4233-a720-2a870138f35a_totalLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquity" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total stockholders’ equity </link:label>

<link:label id="lab_us-gaap_StockholdersEquity_label_en-US" xlink:label="lab_us-gaap_StockholdersEquity" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity, Attributable to Parent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquity" xlink:to="lab_us-gaap_StockholdersEquity" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_8c32e58f-9a4f-4e40-895c-623250b04e05_terseLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Portion that, if recognized, would reduce tax expense and effective tax rate </link:label>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_label_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecognized Tax Benefits that Would Impact Effective Tax Rate </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate" xlink:to="lab_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_40b85560-a736-4cd0-a3c7-448e88ddcc6b_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Finite-Lived Intangible Assets [Table] </link:label>

<link:label id="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Finite-Lived Intangible Assets [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="lab_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock_62870c0b-4b6b-4661-a11f-73cc743f6118_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Significant Estimates Used by Management in Determining Fair Values of Intangible Assets </link:label>

<link:label id="lab_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock_label_en-US" xlink:label="lab_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock" xlink:to="lab_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ContractWithCustomerContractValueSubsequentPaymentPeriod_3990ef99-83eb-4776-9373-95f155ba7933_terseLabel_en-US" xlink:label="lab_pwr_ContractWithCustomerContractValueSubsequentPaymentPeriod" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Term of post-construction operation and maintenance period </link:label>

<link:label id="lab_pwr_ContractWithCustomerContractValueSubsequentPaymentPeriod_label_en-US" xlink:label="lab_pwr_ContractWithCustomerContractValueSubsequentPaymentPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Contract Value, Subsequent Payment Period </link:label>

<link:label id="lab_pwr_ContractWithCustomerContractValueSubsequentPaymentPeriod_documentation_en-US" xlink:label="lab_pwr_ContractWithCustomerContractValueSubsequentPaymentPeriod" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Contract Value, Subsequent Payment Period </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ContractWithCustomerContractValueSubsequentPaymentPeriod" xlink:href="pwr-20231231.xsd#pwr_ContractWithCustomerContractValueSubsequentPaymentPeriod"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ContractWithCustomerContractValueSubsequentPaymentPeriod" xlink:to="lab_pwr_ContractWithCustomerContractValueSubsequentPaymentPeriod" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_7f487acd-556b-4796-b664-6c444348291e_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Assets, Major Class Name [Domain] </link:label>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Assets, Major Class Name [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ConcentrationRiskByTypeAxis_8832aea4-8801-4d1e-8748-8342832dcf26_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskByTypeAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Type [Axis] </link:label>

<link:label id="lab_us-gaap_ConcentrationRiskByTypeAxis_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskByTypeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Type [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis" xlink:to="lab_us-gaap_ConcentrationRiskByTypeAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_9f18aa7e-3bf5-4540-96f8-9a1185397345_terseLabel_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Term in years </link:label>

<link:label id="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_label_en-US" xlink:label="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:to="lab_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_FairValueInputsCustomerAttritionRates_4de5f859-3eba-4358-978e-fc74f61b8fb2_terseLabel_en-US" xlink:label="lab_pwr_FairValueInputsCustomerAttritionRates" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Customer attrition rates </link:label>

<link:label id="lab_pwr_FairValueInputsCustomerAttritionRates_label_en-US" xlink:label="lab_pwr_FairValueInputsCustomerAttritionRates" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair Value Inputs, Customer Attrition Rates </link:label>

<link:label id="lab_pwr_FairValueInputsCustomerAttritionRates_documentation_en-US" xlink:label="lab_pwr_FairValueInputsCustomerAttritionRates" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair Value Inputs, Customer Attrition Rates </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_FairValueInputsCustomerAttritionRates" xlink:href="pwr-20231231.xsd#pwr_FairValueInputsCustomerAttritionRates"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_FairValueInputsCustomerAttritionRates" xlink:to="lab_pwr_FairValueInputsCustomerAttritionRates" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_e13af425-2c4a-48b4-be6e-c0f666551e63_totalLabel_en-US" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income before income taxes </link:label>

<link:label id="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_label_en-US" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ElectricPowerMember_36657e4f-03b5-4075-bc6d-b2f2c701338d_terseLabel_en-US" xlink:label="lab_pwr_ElectricPowerMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Electric Power </link:label>

<link:label id="lab_pwr_ElectricPowerMember_aaa3f882-56db-4464-9af9-ec6f7e5e6ada_verboseLabel_en-US" xlink:label="lab_pwr_ElectricPowerMember" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Electric Power Segment </link:label>

<link:label id="lab_pwr_ElectricPowerMember_label_en-US" xlink:label="lab_pwr_ElectricPowerMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Electric Power [Member] </link:label>

<link:label id="lab_pwr_ElectricPowerMember_documentation_en-US" xlink:label="lab_pwr_ElectricPowerMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Electric Power Infrastructure [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ElectricPowerMember" xlink:href="pwr-20231231.xsd#pwr_ElectricPowerMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ElectricPowerMember" xlink:to="lab_pwr_ElectricPowerMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UnbilledContractsReceivable_8b24586c-aa2b-42d8-80c3-fd950b883f84_terseLabel_en-US" xlink:label="lab_us-gaap_UnbilledContractsReceivable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unbilled receivables </link:label>

<link:label id="lab_us-gaap_UnbilledContractsReceivable_label_en-US" xlink:label="lab_us-gaap_UnbilledContractsReceivable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unbilled Contracts Receivable </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnbilledContractsReceivable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnbilledContractsReceivable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnbilledContractsReceivable" xlink:to="lab_us-gaap_UnbilledContractsReceivable" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LiabilitiesLesseeAbstract_72a0297b-3cbb-4fee-8976-8effe16e6b1f_terseLabel_en-US" xlink:label="lab_pwr_LiabilitiesLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities: </link:label>

<link:label id="lab_pwr_LiabilitiesLesseeAbstract_label_en-US" xlink:label="lab_pwr_LiabilitiesLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities, Lessee [Abstract] </link:label>

<link:label id="lab_pwr_LiabilitiesLesseeAbstract_documentation_en-US" xlink:label="lab_pwr_LiabilitiesLesseeAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities, Lessee [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LiabilitiesLesseeAbstract" xlink:href="pwr-20231231.xsd#pwr_LiabilitiesLesseeAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LiabilitiesLesseeAbstract" xlink:to="lab_pwr_LiabilitiesLesseeAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity_5304e9a0-3586-4c35-85c6-60f66ecf930c_terseLabel_en-US" xlink:label="lab_us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Carrying amount that exceed share of underlying net equity in net assets </link:label>

<link:label id="lab_us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity_label_en-US" xlink:label="lab_us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Method Investment, Difference Between Carrying Amount and Underlying Equity </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity" xlink:to="lab_us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_7709dc7a-f3f8-42e3-af67-5eae8a88e65d_terseLabel_en-US" xlink:label="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] </link:label>

<link:label id="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_label_en-US" xlink:label="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable" xlink:to="lab_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationTable_a5682e26-3722-4d02-8acf-379e6fa4492c_terseLabel_en-US" xlink:label="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecorded Unconditional Purchase Obligation [Table] </link:label>

<link:label id="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationTable_label_en-US" xlink:label="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecorded Unconditional Purchase Obligation [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationTable" xlink:to="lab_us-gaap_UnrecordedUnconditionalPurchaseObligationTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesMember_961b0fa2-4c96-4856-a256-bb74efd0bf27_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts payable and accrued expenses </link:label>

<link:label id="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesMember_label_en-US" xlink:label="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts Payable and Accrued Liabilities [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesMember" xlink:to="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ExcessOfBaseRateDomesticBorrowingsOnlyMember_9b5d5e51-29b5-4c67-aa98-2b576044e0b4_terseLabel_en-US" xlink:label="lab_pwr_ExcessOfBaseRateDomesticBorrowingsOnlyMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess of Base Rate Domestic Borrowings Only </link:label>

<link:label id="lab_pwr_ExcessOfBaseRateDomesticBorrowingsOnlyMember_label_en-US" xlink:label="lab_pwr_ExcessOfBaseRateDomesticBorrowingsOnlyMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess Of Base Rate Domestic Borrowings Only [Member] </link:label>

<link:label id="lab_pwr_ExcessOfBaseRateDomesticBorrowingsOnlyMember_documentation_en-US" xlink:label="lab_pwr_ExcessOfBaseRateDomesticBorrowingsOnlyMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess Of Base Rate Domestic Borrowings Only [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ExcessOfBaseRateDomesticBorrowingsOnlyMember" xlink:href="pwr-20231231.xsd#pwr_ExcessOfBaseRateDomesticBorrowingsOnlyMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ExcessOfBaseRateDomesticBorrowingsOnlyMember" xlink:to="lab_pwr_ExcessOfBaseRateDomesticBorrowingsOnlyMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_8a43adcf-2da9-41ce-b7b1-192bf5132825_totalLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total identifiable net assets </link:label>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_34d57f3e-6d0d-430e-a6a0-24a555e06b31_terseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Stockholders' Equity [Roll Forward] </link:label>

<link:label id="lab_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Stockholders' Equity [Roll Forward] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:to="lab_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_NamedExecutiveOfficersFnTextBlock_terseLabel_en-US" xlink:label="lab_ecd_NamedExecutiveOfficersFnTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Named Executive Officers, Footnote </link:label>

<link:label id="lab_ecd_NamedExecutiveOfficersFnTextBlock_label_en-US" xlink:label="lab_ecd_NamedExecutiveOfficersFnTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Named Executive Officers, Footnote [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_NamedExecutiveOfficersFnTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_NamedExecutiveOfficersFnTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_NamedExecutiveOfficersFnTextBlock" xlink:to="lab_ecd_NamedExecutiveOfficersFnTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CostPlusContractMemberMember_5ff5ecc8-e138-402a-a658-13525cb961c0_terseLabel_en-US" xlink:label="lab_pwr_CostPlusContractMemberMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cost-plus contracts </link:label>

<link:label id="lab_pwr_CostPlusContractMemberMember_label_en-US" xlink:label="lab_pwr_CostPlusContractMemberMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cost-Plus Contract Member [Member] </link:label>

<link:label id="lab_pwr_CostPlusContractMemberMember_documentation_en-US" xlink:label="lab_pwr_CostPlusContractMemberMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cost-Plus Contract Member </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CostPlusContractMemberMember" xlink:href="pwr-20231231.xsd#pwr_CostPlusContractMemberMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CostPlusContractMemberMember" xlink:to="lab_pwr_CostPlusContractMemberMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractAssetsCurrent_be870be3-ab2c-448f-8b46-84d9df237e1d_terseLabel_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractAssetsCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract assets </link:label>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractAssetsCurrent_label_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractAssetsCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Contract Assets, Current </link:label>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractAssetsCurrent_documentation_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractAssetsCurrent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Contract Assets, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractAssetsCurrent" xlink:href="pwr-20231231.xsd#pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractAssetsCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractAssetsCurrent" xlink:to="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractAssetsCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_dei_DocumentFiscalPeriodFocus_d6dd37e3-42bd-4d6c-a867-4908df896a39_terseLabel_en-US" xlink:label="lab_dei_DocumentFiscalPeriodFocus" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Fiscal Period Focus </link:label>

<link:label id="lab_dei_DocumentFiscalPeriodFocus_label_en-US" xlink:label="lab_dei_DocumentFiscalPeriodFocus" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Fiscal Period Focus </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentFiscalPeriodFocus"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_DocumentFiscalPeriodFocus" xlink:to="lab_dei_DocumentFiscalPeriodFocus" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetUsefulLife_56ee54bf-959a-419b-9f6e-1cf4d3067e47_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Remaining Weighted Average Amortization Period </link:label>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetUsefulLife_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Asset, Useful Life </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_aea84689-c510-440f-aabf-aa01a6dc409e_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit facility available for revolving loans or issuing new letters of credit </link:label>

<link:label id="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Remaining Borrowing Capacity </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:to="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_9bd4eeb9-a548-4657-bc28-a30607dce22c_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2027 </link:label>

<link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Liability, to be Paid, Year Four </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OperatingLeaseExpense_8d33828d-525b-4bba-aabc-a491f26fd9fe_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseExpense" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease expense </link:label>

<link:label id="lab_us-gaap_OperatingLeaseExpense_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Expense </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseExpense"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseExpense" xlink:to="lab_us-gaap_OperatingLeaseExpense" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensation_0cbd2305-e37a-41ab-9e92-91bf50a138ce_verboseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensation" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-cash stock-based compensation </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensation_80c490dd-cb72-470a-ba47-75ad16a048e9_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensation" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-cash stock compensation expense </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensation_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Payment Arrangement, Noncash Expense </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensation"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensation" xlink:to="lab_us-gaap_ShareBasedCompensation" xlink:type="arc" order="1"/>

<link:label id="lab_srt_WeightedAverageMember_63caf22b-502e-4a83-8f80-91f8bc8ad4d0_terseLabel_en-US" xlink:label="lab_srt_WeightedAverageMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average </link:label>

<link:label id="lab_srt_WeightedAverageMember_label_en-US" xlink:label="lab_srt_WeightedAverageMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_WeightedAverageMember" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_WeightedAverageMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_WeightedAverageMember" xlink:to="lab_srt_WeightedAverageMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization_fe7b9567-d2cd-4e6e-b1d1-2daf00b4e6ec_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance lease assets and lease financing transactions </link:label>

<link:label id="lab_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Right-of-Use Asset, before Accumulated Amortization </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization" xlink:to="lab_us-gaap_FinanceLeaseRightOfUseAssetBeforeAccumulatedAmortization" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFour_86cc866b-eac5-4111-984e-1acb679621e3_totalLabel_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFour" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2027 </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFour_label_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFour" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, To Be Paid, Year Four </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFour_documentation_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFour" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, To Be Paid, Year Four </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFour" xlink:href="pwr-20231231.xsd#pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFour"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFour" xlink:to="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearFour" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LondonInterbankOfferedRateLIBOR1Member_66c326f9-3258-4817-89a1-692f595cf709_terseLabel_en-US" xlink:label="lab_pwr_LondonInterbankOfferedRateLIBOR1Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> London Interbank Offered Rate (LIBOR) </link:label>

<link:label id="lab_pwr_LondonInterbankOfferedRateLIBOR1Member_label_en-US" xlink:label="lab_pwr_LondonInterbankOfferedRateLIBOR1Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> London Interbank Offered Rate (LIBOR) 1 [Member] </link:label>

<link:label id="lab_pwr_LondonInterbankOfferedRateLIBOR1Member_documentation_en-US" xlink:label="lab_pwr_LondonInterbankOfferedRateLIBOR1Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> London Interbank Offered Rate (LIBOR) 1 </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LondonInterbankOfferedRateLIBOR1Member" xlink:href="pwr-20231231.xsd#pwr_LondonInterbankOfferedRateLIBOR1Member"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LondonInterbankOfferedRateLIBOR1Member" xlink:to="lab_pwr_LondonInterbankOfferedRateLIBOR1Member" xlink:type="arc" order="1"/>

<link:label id="lab_dei_CityAreaCode_b0e4a9af-9fd2-49ac-b8a5-56380425a06c_terseLabel_en-US" xlink:label="lab_dei_CityAreaCode" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> City Area Code </link:label>

<link:label id="lab_dei_CityAreaCode_label_en-US" xlink:label="lab_dei_CityAreaCode" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> City Area Code </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_CityAreaCode"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_CityAreaCode" xlink:to="lab_dei_CityAreaCode" xlink:type="arc" order="1"/>

<link:label id="lab_srt_ProductOrServiceAxis_514d4de8-a910-4001-ae04-392028f307ed_terseLabel_en-US" xlink:label="lab_srt_ProductOrServiceAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product and Service [Axis] </link:label>

<link:label id="lab_srt_ProductOrServiceAxis_label_en-US" xlink:label="lab_srt_ProductOrServiceAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Product and Service [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_ProductOrServiceAxis" xlink:to="lab_srt_ProductOrServiceAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EarningsPerShareTextBlock_8d3fef81-8bbe-435e-8fef-42c291180261_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Per Share Information </link:label>

<link:label id="lab_us-gaap_EarningsPerShareTextBlock_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Earnings Per Share [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareTextBlock" xlink:to="lab_us-gaap_EarningsPerShareTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock_90279b7a-6459-4953-ae90-51fd1a02e474_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary of RSUs and PSUs to be Settled in Common Stock Activity </link:label>

<link:label id="lab_us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Nonvested Share Activity [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfNonvestedShareActivityTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_Acquisitions2022Member_9b98f702-f9da-4e68-8db5-4c31c4402a98_terseLabel_en-US" xlink:label="lab_pwr_Acquisitions2022Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions 2022 </link:label>

<link:label id="lab_pwr_Acquisitions2022Member_label_en-US" xlink:label="lab_pwr_Acquisitions2022Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions 2022 [Member] </link:label>

<link:label id="lab_pwr_Acquisitions2022Member_documentation_en-US" xlink:label="lab_pwr_Acquisitions2022Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions 2022 </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_Acquisitions2022Member" xlink:href="pwr-20231231.xsd#pwr_Acquisitions2022Member"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_Acquisitions2022Member" xlink:to="lab_pwr_Acquisitions2022Member" xlink:type="arc" order="1"/>

<link:label id="lab_dei_DocumentFiscalYearFocus_fac75215-98c8-41b0-8d31-dda171a90552_terseLabel_en-US" xlink:label="lab_dei_DocumentFiscalYearFocus" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Fiscal Year Focus </link:label>

<link:label id="lab_dei_DocumentFiscalYearFocus_label_en-US" xlink:label="lab_dei_DocumentFiscalYearFocus" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Document Fiscal Year Focus </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_DocumentFiscalYearFocus"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_DocumentFiscalYearFocus" xlink:to="lab_dei_DocumentFiscalYearFocus" xlink:type="arc" order="1"/>

<link:label id="lab_srt_SegmentGeographicalDomain_82aa64c0-171c-490b-b301-ec5442b68ce9_terseLabel_en-US" xlink:label="lab_srt_SegmentGeographicalDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Geographical [Domain] </link:label>

<link:label id="lab_srt_SegmentGeographicalDomain_label_en-US" xlink:label="lab_srt_SegmentGeographicalDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Geographical [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_SegmentGeographicalDomain" xlink:to="lab_srt_SegmentGeographicalDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LesseeOperatingLeaseTermOfContract_e74fa15f-df97-46e6-9fd0-b6ee7f1c82f3_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseTermOfContract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease term (up to) </link:label>

<link:label id="lab_us-gaap_LesseeOperatingLeaseTermOfContract_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseTermOfContract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lessee, Operating Lease, Term of Contract </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseTermOfContract" xlink:to="lab_us-gaap_LesseeOperatingLeaseTermOfContract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CompensationRelatedCostsPolicyTextBlock_289984e2-45d7-457d-a9ae-13eed7be1d90_terseLabel_en-US" xlink:label="lab_us-gaap_CompensationRelatedCostsPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock-Based Compensation </link:label>

<link:label id="lab_us-gaap_CompensationRelatedCostsPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_CompensationRelatedCostsPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Compensation Related Costs, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CompensationRelatedCostsPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CompensationRelatedCostsPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CompensationRelatedCostsPolicyTextBlock" xlink:to="lab_us-gaap_CompensationRelatedCostsPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance_bf6cb2f0-85c0-4edd-b7d6-b24c55d4223f_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred compensation arrangement with individual, common stock reserved for future issuance (in shares) </link:label>

<link:label id="lab_us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance_label_en-US" xlink:label="lab_us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Compensation Arrangement with Individual, Common Stock Reserved for Future Issuance </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance" xlink:to="lab_us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_3bf840dc-448a-4c7f-a621-0ec409c4681a_terseLabel_en-US" xlink:label="lab_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Software implementation project </link:label>

<link:label id="lab_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_label_en-US" xlink:label="lab_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Software and Software Development Costs [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:to="lab_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareRepurchaseProgramDomain_fc60d94e-83e2-4a3f-9d65-fbbb7c85379d_terseLabel_en-US" xlink:label="lab_us-gaap_ShareRepurchaseProgramDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share Repurchase Program [Domain] </link:label>

<link:label id="lab_us-gaap_ShareRepurchaseProgramDomain_label_en-US" xlink:label="lab_us-gaap_ShareRepurchaseProgramDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share Repurchase Program [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareRepurchaseProgramDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain" xlink:to="lab_us-gaap_ShareRepurchaseProgramDomain" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AwardExrcPrice_terseLabel_en-US" xlink:label="lab_ecd_AwardExrcPrice" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Exercise Price </link:label>

<link:label id="lab_ecd_AwardExrcPrice_label_en-US" xlink:label="lab_ecd_AwardExrcPrice" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Exercise Price </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AwardExrcPrice" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AwardExrcPrice"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AwardExrcPrice" xlink:to="lab_ecd_AwardExrcPrice" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_EquityMethodInvestmentsNumberOfInvestmentsSold_512c472d-b177-4667-9831-9f03f47c674a_terseLabel_en-US" xlink:label="lab_pwr_EquityMethodInvestmentsNumberOfInvestmentsSold" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of investments sold </link:label>

<link:label id="lab_pwr_EquityMethodInvestmentsNumberOfInvestmentsSold_label_en-US" xlink:label="lab_pwr_EquityMethodInvestmentsNumberOfInvestmentsSold" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Method Investments, Number Of Investments Sold </link:label>

<link:label id="lab_pwr_EquityMethodInvestmentsNumberOfInvestmentsSold_documentation_en-US" xlink:label="lab_pwr_EquityMethodInvestmentsNumberOfInvestmentsSold" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Method Investments, Number Of Investments Sold </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_EquityMethodInvestmentsNumberOfInvestmentsSold" xlink:href="pwr-20231231.xsd#pwr_EquityMethodInvestmentsNumberOfInvestmentsSold"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_EquityMethodInvestmentsNumberOfInvestmentsSold" xlink:to="lab_pwr_EquityMethodInvestmentsNumberOfInvestmentsSold" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_001b7ffe-2ccb-4706-a70d-d4c49ba9799c_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Assets by Major Class [Axis] </link:label>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Assets by Major Class [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_FinanceLeasesCostAbstract_0070e02a-a25e-43cf-90b4-372abcf22537_terseLabel_en-US" xlink:label="lab_pwr_FinanceLeasesCostAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance lease cost: </link:label>

<link:label id="lab_pwr_FinanceLeasesCostAbstract_label_en-US" xlink:label="lab_pwr_FinanceLeasesCostAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Leases, Cost [Abstract] </link:label>

<link:label id="lab_pwr_FinanceLeasesCostAbstract_documentation_en-US" xlink:label="lab_pwr_FinanceLeasesCostAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Leases, Cost [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_FinanceLeasesCostAbstract" xlink:href="pwr-20231231.xsd#pwr_FinanceLeasesCostAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_FinanceLeasesCostAbstract" xlink:to="lab_pwr_FinanceLeasesCostAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_MultiemployerDefinedContributionPlansAndOtherBenefitPlansMember_9c98a28d-eeff-4f33-ab68-6fb76061a441_terseLabel_en-US" xlink:label="lab_pwr_MultiemployerDefinedContributionPlansAndOtherBenefitPlansMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Multiemployer Defined Contribution and Other Benefit Plans </link:label>

<link:label id="lab_pwr_MultiemployerDefinedContributionPlansAndOtherBenefitPlansMember_label_en-US" xlink:label="lab_pwr_MultiemployerDefinedContributionPlansAndOtherBenefitPlansMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Multiemployer Defined Contribution Plans And Other Benefit Plans [Member] </link:label>

<link:label id="lab_pwr_MultiemployerDefinedContributionPlansAndOtherBenefitPlansMember_documentation_en-US" xlink:label="lab_pwr_MultiemployerDefinedContributionPlansAndOtherBenefitPlansMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Multiemployer Defined Contribution Plans And Other Benefit Plans [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_MultiemployerDefinedContributionPlansAndOtherBenefitPlansMember" xlink:href="pwr-20231231.xsd#pwr_MultiemployerDefinedContributionPlansAndOtherBenefitPlansMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_MultiemployerDefinedContributionPlansAndOtherBenefitPlansMember" xlink:to="lab_pwr_MultiemployerDefinedContributionPlansAndOtherBenefitPlansMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DividendsCommonStockCash_52288e68-a9eb-41e6-be95-e436419f2a70_terseLabel_en-US" xlink:label="lab_us-gaap_DividendsCommonStockCash" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Dividends declared </link:label>

<link:label id="lab_us-gaap_DividendsCommonStockCash_label_en-US" xlink:label="lab_us-gaap_DividendsCommonStockCash" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Dividends, Common Stock, Cash </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DividendsCommonStockCash"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DividendsCommonStockCash" xlink:to="lab_us-gaap_DividendsCommonStockCash" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EquityClassOfTreasuryStockLineItems_dcb7bb44-86a6-4fd7-b4c1-65fc4dccb193_terseLabel_en-US" xlink:label="lab_us-gaap_EquityClassOfTreasuryStockLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity, Class of Treasury Stock [Line Items] </link:label>

<link:label id="lab_us-gaap_EquityClassOfTreasuryStockLineItems_label_en-US" xlink:label="lab_us-gaap_EquityClassOfTreasuryStockLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity, Class of Treasury Stock [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityClassOfTreasuryStockLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityClassOfTreasuryStockLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems" xlink:to="lab_us-gaap_EquityClassOfTreasuryStockLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_ba2bd6c3-6176-46bd-a40e-df2553936417_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill and Intangible Assets Disclosure [Abstract] </link:label>

<link:label id="lab_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract_label_en-US" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Goodwill and Intangible Assets Disclosure [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:to="lab_us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_InsuranceSettlementsReceivableCurrent_69ef8325-afd6-4efe-9d80-b57db23b09c6_terseLabel_en-US" xlink:label="lab_us-gaap_InsuranceSettlementsReceivableCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related insurance recoveries/receivables included in prepaid expenses and other current assets </link:label>

<link:label id="lab_us-gaap_InsuranceSettlementsReceivableCurrent_label_en-US" xlink:label="lab_us-gaap_InsuranceSettlementsReceivableCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insurance Settlements Receivable, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InsuranceSettlementsReceivableCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InsuranceSettlementsReceivableCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InsuranceSettlementsReceivableCurrent" xlink:to="lab_us-gaap_InsuranceSettlementsReceivableCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ContractWithCustomerBasisOfPricingDomain_3d1fb411-639b-49ef-9c0b-6006f21fe698_terseLabel_en-US" xlink:label="lab_us-gaap_ContractWithCustomerBasisOfPricingDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract with Customer, Basis of Pricing [Domain] </link:label>

<link:label id="lab_us-gaap_ContractWithCustomerBasisOfPricingDomain_label_en-US" xlink:label="lab_us-gaap_ContractWithCustomerBasisOfPricingDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract with Customer, Basis of Pricing [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain" xlink:to="lab_us-gaap_ContractWithCustomerBasisOfPricingDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ProfitLoss_c52f9efd-e7db-4891-a0b1-53c7f45a07d6_totalLabel_en-US" xlink:label="lab_us-gaap_ProfitLoss" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net income </link:label>

<link:label id="lab_us-gaap_ProfitLoss_dbd2a074-a95b-42d1-8d3b-5dae4a868338_terseLabel_en-US" xlink:label="lab_us-gaap_ProfitLoss" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net income </link:label>

<link:label id="lab_us-gaap_ProfitLoss_label_en-US" xlink:label="lab_us-gaap_ProfitLoss" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Income (Loss), Including Portion Attributable to Noncontrolling Interest </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProfitLoss"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProfitLoss" xlink:to="lab_us-gaap_ProfitLoss" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_RevenueRecognitionLineItems_9ed06162-1fb0-4858-993c-00bfd8f43ee0_terseLabel_en-US" xlink:label="lab_pwr_RevenueRecognitionLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue Recognition [Line Items] </link:label>

<link:label id="lab_pwr_RevenueRecognitionLineItems_label_en-US" xlink:label="lab_pwr_RevenueRecognitionLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue Recognition [Line Items] </link:label>

<link:label id="lab_pwr_RevenueRecognitionLineItems_documentation_en-US" xlink:label="lab_pwr_RevenueRecognitionLineItems" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue recognition. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_RevenueRecognitionLineItems" xlink:href="pwr-20231231.xsd#pwr_RevenueRecognitionLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_RevenueRecognitionLineItems" xlink:to="lab_pwr_RevenueRecognitionLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_EmployerTeamstersLocalNos175505PensionTrustFundMember_b6dabffd-8cc1-4184-9a9f-1bdad7cb8676_terseLabel_en-US" xlink:label="lab_pwr_EmployerTeamstersLocalNos175505PensionTrustFundMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employer - Teamsters Local Nos 175 & 505 Pension Trust Fund </link:label>

<link:label id="lab_pwr_EmployerTeamstersLocalNos175505PensionTrustFundMember_label_en-US" xlink:label="lab_pwr_EmployerTeamstersLocalNos175505PensionTrustFundMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employer-Teamsters Local Nos 175 & 505 Pension Trust Fund [Member] </link:label>

<link:label id="lab_pwr_EmployerTeamstersLocalNos175505PensionTrustFundMember_documentation_en-US" xlink:label="lab_pwr_EmployerTeamstersLocalNos175505PensionTrustFundMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employer-Teamsters Local Nos 175 & 505 Pension Trust Fund [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_EmployerTeamstersLocalNos175505PensionTrustFundMember" xlink:href="pwr-20231231.xsd#pwr_EmployerTeamstersLocalNos175505PensionTrustFundMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_EmployerTeamstersLocalNos175505PensionTrustFundMember" xlink:to="lab_pwr_EmployerTeamstersLocalNos175505PensionTrustFundMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DevelopedTechnologyRightsMember_15c22c78-28d5-4021-8575-40a659ffadf7_terseLabel_en-US" xlink:label="lab_us-gaap_DevelopedTechnologyRightsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Patented rights, developed technology, process certifications and other </link:label>

<link:label id="lab_us-gaap_DevelopedTechnologyRightsMember_label_en-US" xlink:label="lab_us-gaap_DevelopedTechnologyRightsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Developed Technology Rights [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DevelopedTechnologyRightsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DevelopedTechnologyRightsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DevelopedTechnologyRightsMember" xlink:to="lab_us-gaap_DevelopedTechnologyRightsMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_IncreasesDecreasesResultingFromAbstract_764a95e5-dc94-4250-8bb5-404fabbae2fa_terseLabel_en-US" xlink:label="lab_pwr_IncreasesDecreasesResultingFromAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increases (decreases) resulting from: </link:label>

<link:label id="lab_pwr_IncreasesDecreasesResultingFromAbstract_label_en-US" xlink:label="lab_pwr_IncreasesDecreasesResultingFromAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increases Decreases Resulting From [Abstract] </link:label>

<link:label id="lab_pwr_IncreasesDecreasesResultingFromAbstract_documentation_en-US" xlink:label="lab_pwr_IncreasesDecreasesResultingFromAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increases (decreases) resulting from. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_IncreasesDecreasesResultingFromAbstract" xlink:href="pwr-20231231.xsd#pwr_IncreasesDecreasesResultingFromAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_IncreasesDecreasesResultingFromAbstract" xlink:to="lab_pwr_IncreasesDecreasesResultingFromAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LiabilitiesAndStockholdersEquity_c287d607-d04b-471c-a2d0-01f7e8097c12_totalLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquity" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total liabilities and equity </link:label>

<link:label id="lab_us-gaap_LiabilitiesAndStockholdersEquity_label_en-US" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquity" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Liabilities and Equity </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="lab_us-gaap_LiabilitiesAndStockholdersEquity" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OtherAssetsNoncurrent_568e884a-ded7-4eea-9304-30e6538a4273_terseLabel_en-US" xlink:label="lab_us-gaap_OtherAssetsNoncurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other assets, net </link:label>

<link:label id="lab_us-gaap_OtherAssetsNoncurrent_label_en-US" xlink:label="lab_us-gaap_OtherAssetsNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Assets, Noncurrent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsNoncurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherAssetsNoncurrent" xlink:to="lab_us-gaap_OtherAssetsNoncurrent" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_PeerGroupTotalShareholderRtnAmt_terseLabel_en-US" xlink:label="lab_ecd_PeerGroupTotalShareholderRtnAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Peer Group Total Shareholder Return Amount </link:label>

<link:label id="lab_ecd_PeerGroupTotalShareholderRtnAmt_label_en-US" xlink:label="lab_ecd_PeerGroupTotalShareholderRtnAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Peer Group Total Shareholder Return Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_PeerGroupTotalShareholderRtnAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_PeerGroupTotalShareholderRtnAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_PeerGroupTotalShareholderRtnAmt" xlink:to="lab_ecd_PeerGroupTotalShareholderRtnAmt" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_137f8d7f-ef2e-4889-8fcb-c997105194ac_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Risk-free interest rate </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OperatingLeaseRightOfUseAsset_63cf4162-d0f7-4c4a-b283-63972e441c62_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease right-of-use assets </link:label>

<link:label id="lab_us-gaap_OperatingLeaseRightOfUseAsset_78a7d1cc-101c-40c2-b692-f69038e77ce4_verboseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease right-of-use assets </link:label>

<link:label id="lab_us-gaap_OperatingLeaseRightOfUseAsset_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Right-of-Use Asset </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseRightOfUseAsset" xlink:to="lab_us-gaap_OperatingLeaseRightOfUseAsset" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue_02f420d3-0740-44b1-9f1d-23c82ee8475c_totalLabel_en-US" xlink:label="lab_us-gaap_EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total equity investments </link:label>

<link:label id="lab_us-gaap_EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue_label_en-US" xlink:label="lab_us-gaap_EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Securities, FV-NI and without Readily Determinable Fair Value </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue" xlink:to="lab_us-gaap_EquitySecuritiesFvNiAndWithoutReadilyDeterminableFairValue" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_SecuredOvernightFinancingRateSOFRMember_8bda41f8-2a4f-45a0-a41f-9ed80a0175ec_terseLabel_en-US" xlink:label="lab_pwr_SecuredOvernightFinancingRateSOFRMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Secured Overnight Financing Rate (SOFR) </link:label>

<link:label id="lab_pwr_SecuredOvernightFinancingRateSOFRMember_label_en-US" xlink:label="lab_pwr_SecuredOvernightFinancingRateSOFRMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Secured Overnight Financing Rate (SOFR) [Member] </link:label>

<link:label id="lab_pwr_SecuredOvernightFinancingRateSOFRMember_documentation_en-US" xlink:label="lab_pwr_SecuredOvernightFinancingRateSOFRMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Secured Overnight Financing Rate (SOFR) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_SecuredOvernightFinancingRateSOFRMember" xlink:href="pwr-20231231.xsd#pwr_SecuredOvernightFinancingRateSOFRMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_SecuredOvernightFinancingRateSOFRMember" xlink:to="lab_pwr_SecuredOvernightFinancingRateSOFRMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentTable_74d914e3-7c33-404c-ba04-1dc93bbd0abb_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Long-term Debt Instruments [Table] </link:label>

<link:label id="lab_us-gaap_DebtInstrumentTable_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Long-Term Debt Instruments [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentTable" xlink:to="lab_us-gaap_DebtInstrumentTable" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_EquityValuationAssumptionDifferenceFnTextBlock_terseLabel_en-US" xlink:label="lab_ecd_EquityValuationAssumptionDifferenceFnTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Valuation Assumption Difference, Footnote </link:label>

<link:label id="lab_ecd_EquityValuationAssumptionDifferenceFnTextBlock_label_en-US" xlink:label="lab_ecd_EquityValuationAssumptionDifferenceFnTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Valuation Assumption Difference, Footnote [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_EquityValuationAssumptionDifferenceFnTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_EquityValuationAssumptionDifferenceFnTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_EquityValuationAssumptionDifferenceFnTextBlock" xlink:to="lab_ecd_EquityValuationAssumptionDifferenceFnTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CurrentForeignTaxExpenseBenefit_3420a86a-27bf-4159-bbaf-945210c76d4b_terseLabel_en-US" xlink:label="lab_us-gaap_CurrentForeignTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign </link:label>

<link:label id="lab_us-gaap_CurrentForeignTaxExpenseBenefit_label_en-US" xlink:label="lab_us-gaap_CurrentForeignTaxExpenseBenefit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current Foreign Tax Expense (Benefit) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrentForeignTaxExpenseBenefit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CurrentForeignTaxExpenseBenefit"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CurrentForeignTaxExpenseBenefit" xlink:to="lab_us-gaap_CurrentForeignTaxExpenseBenefit" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems_bbf1e2a1-25c8-4e22-a093-fd9c3680d310_terseLabel_en-US" xlink:label="lab_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Indefinite-lived Intangible Assets [Line Items] </link:label>

<link:label id="lab_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems_label_en-US" xlink:label="lab_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Indefinite-Lived Intangible Assets [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems" xlink:to="lab_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_srt_CurrencyAxis_43a38607-a654-45d4-8660-f47156dd5447_terseLabel_en-US" xlink:label="lab_srt_CurrencyAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Currency [Axis] </link:label>

<link:label id="lab_srt_CurrencyAxis_label_en-US" xlink:label="lab_srt_CurrencyAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Currency [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_srt_CurrencyAxis" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_CurrencyAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_CurrencyAxis" xlink:to="lab_srt_CurrencyAxis" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DomesticJointVenturesMember_6175cdcf-1c5d-4772-9872-e94b79a25e99_terseLabel_en-US" xlink:label="lab_pwr_DomesticJointVenturesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Held by Domestic Joint Ventures </link:label>

<link:label id="lab_pwr_DomesticJointVenturesMember_label_en-US" xlink:label="lab_pwr_DomesticJointVenturesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Domestic Joint Ventures [Member] </link:label>

<link:label id="lab_pwr_DomesticJointVenturesMember_documentation_en-US" xlink:label="lab_pwr_DomesticJointVenturesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Domestic Joint Ventures [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DomesticJointVenturesMember" xlink:href="pwr-20231231.xsd#pwr_DomesticJointVenturesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DomesticJointVenturesMember" xlink:to="lab_pwr_DomesticJointVenturesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList_eeb7e4e1-e27b-4a49-a801-d73448b8d4c1_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList" xlink:to="lab_us-gaap_FinanceLeaseLiabilityCurrentStatementOfFinancialPositionExtensibleList" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_46e91212-7143-49cc-8e37-dab7eff4549b_terseLabel_en-US" xlink:label="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net income attributable to common stock, Diluted </link:label>

<link:label id="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_label_en-US" xlink:label="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Income (Loss) Available to Common Stockholders, Diluted </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:to="lab_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_TrdArrDuration_terseLabel_en-US" xlink:label="lab_ecd_TrdArrDuration" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Arrangement Duration </link:label>

<link:label id="lab_ecd_TrdArrDuration_label_en-US" xlink:label="lab_ecd_TrdArrDuration" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trading Arrangement Duration </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_TrdArrDuration" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_TrdArrDuration"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_TrdArrDuration" xlink:to="lab_ecd_TrdArrDuration" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityAddressCityOrTown_8bd4c5d8-4621-4225-bdd8-aeba26619b4f_terseLabel_en-US" xlink:label="lab_dei_EntityAddressCityOrTown" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, City or Town </link:label>

<link:label id="lab_dei_EntityAddressCityOrTown_label_en-US" xlink:label="lab_dei_EntityAddressCityOrTown" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Address, City or Town </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityAddressCityOrTown"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityAddressCityOrTown" xlink:to="lab_dei_EntityAddressCityOrTown" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AwardTmgMnpiCnsdrdFlag_terseLabel_en-US" xlink:label="lab_ecd_AwardTmgMnpiCnsdrdFlag" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Timing MNPI Considered </link:label>

<link:label id="lab_ecd_AwardTmgMnpiCnsdrdFlag_label_en-US" xlink:label="lab_ecd_AwardTmgMnpiCnsdrdFlag" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Timing MNPI Considered [Flag] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AwardTmgMnpiCnsdrdFlag" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AwardTmgMnpiCnsdrdFlag"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AwardTmgMnpiCnsdrdFlag" xlink:to="lab_ecd_AwardTmgMnpiCnsdrdFlag" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RelatedPartyMember_721ed3c4-34b1-4dd2-a67d-c2a58aef195b_terseLabel_en-US" xlink:label="lab_us-gaap_RelatedPartyMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party </link:label>

<link:label id="lab_us-gaap_RelatedPartyMember_label_en-US" xlink:label="lab_us-gaap_RelatedPartyMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RelatedPartyMember" xlink:to="lab_us-gaap_RelatedPartyMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock_7164ada5-4ca4-4071-a114-bbf8424dc49a_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summarized Financial Information </link:label>

<link:label id="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Segment Reporting Information, by Segment [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xlink:to="lab_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfCashAndCashEquivalentsTable_dac1be50-9ed2-4ba9-88a4-fa92d9f60287_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfCashAndCashEquivalentsTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Cash and Cash Equivalents [Table] </link:label>

<link:label id="lab_us-gaap_ScheduleOfCashAndCashEquivalentsTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfCashAndCashEquivalentsTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Cash and Cash Equivalents [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfCashAndCashEquivalentsTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable" xlink:to="lab_us-gaap_ScheduleOfCashAndCashEquivalentsTable" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_EffectiveIncomeTaxRateReconciliationCompanyOwnedLifeInsurance_0d5eb1f7-9a09-472f-9998-3f8591b7fa24_terseLabel_en-US" xlink:label="lab_pwr_EffectiveIncomeTaxRateReconciliationCompanyOwnedLifeInsurance" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Company-owned life insurance </link:label>

<link:label id="lab_pwr_EffectiveIncomeTaxRateReconciliationCompanyOwnedLifeInsurance_label_en-US" xlink:label="lab_pwr_EffectiveIncomeTaxRateReconciliationCompanyOwnedLifeInsurance" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Company Owned Life Insurance </link:label>

<link:label id="lab_pwr_EffectiveIncomeTaxRateReconciliationCompanyOwnedLifeInsurance_documentation_en-US" xlink:label="lab_pwr_EffectiveIncomeTaxRateReconciliationCompanyOwnedLifeInsurance" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Company Owned Life Insurance </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_EffectiveIncomeTaxRateReconciliationCompanyOwnedLifeInsurance" xlink:href="pwr-20231231.xsd#pwr_EffectiveIncomeTaxRateReconciliationCompanyOwnedLifeInsurance"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_EffectiveIncomeTaxRateReconciliationCompanyOwnedLifeInsurance" xlink:to="lab_pwr_EffectiveIncomeTaxRateReconciliationCompanyOwnedLifeInsurance" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTextBlock_68c282e5-685d-45d2-bc66-0f37926cd10f_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Aggregate Fair Values of Outstanding and Unearned Contingent Consideration Liabilities </link:label>

<link:label id="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Business Acquisitions by Acquisition, Contingent Consideration [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTextBlock" xlink:to="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionContingentConsiderationTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LeaseCostAndLeaseFinancingTransactionCost_a8222112-cd63-4ac4-9382-97a74876d460_totalLabel_en-US" xlink:label="lab_pwr_LeaseCostAndLeaseFinancingTransactionCost" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total lease and lease financing transactions cost </link:label>

<link:label id="lab_pwr_LeaseCostAndLeaseFinancingTransactionCost_label_en-US" xlink:label="lab_pwr_LeaseCostAndLeaseFinancingTransactionCost" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Cost And Lease Financing Transaction Cost </link:label>

<link:label id="lab_pwr_LeaseCostAndLeaseFinancingTransactionCost_documentation_en-US" xlink:label="lab_pwr_LeaseCostAndLeaseFinancingTransactionCost" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Cost And Lease Financing Transaction Cost </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LeaseCostAndLeaseFinancingTransactionCost" xlink:href="pwr-20231231.xsd#pwr_LeaseCostAndLeaseFinancingTransactionCost"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LeaseCostAndLeaseFinancingTransactionCost" xlink:to="lab_pwr_LeaseCostAndLeaseFinancingTransactionCost" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions_3fa496ef-f38b-4aaa-8129-a0ec85cbc28e_negatedLabel_en-US" xlink:label="lab_us-gaap_IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity in earnings of unconsolidated affiliates, net of distributions </link:label>

<link:label id="lab_us-gaap_IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions_label_en-US" xlink:label="lab_us-gaap_IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income (Loss) from Equity Method Investments, Net of Dividends or Distributions </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions" xlink:to="lab_us-gaap_IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FairValueOfFinancialInstrumentsPolicy_36453e50-d7e1-413a-a0fa-847d4af7299b_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair Value Measurements </link:label>

<link:label id="lab_us-gaap_FairValueOfFinancialInstrumentsPolicy_label_en-US" xlink:label="lab_us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair Value of Financial Instruments, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueOfFinancialInstrumentsPolicy"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:to="lab_us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_cc01e937-9ab7-4e05-a561-5097739fd6c9_terseLabel_en-US" xlink:label="lab_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Remaining authorized share repurchase amount under repurchase program </link:label>

<link:label id="lab_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_label_en-US" xlink:label="lab_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock Repurchase Program, Remaining Authorized Repurchase Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:to="lab_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_TrdArrTerminationDate_terseLabel_en-US" xlink:label="lab_ecd_TrdArrTerminationDate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Termination Date </link:label>

<link:label id="lab_ecd_TrdArrTerminationDate_label_en-US" xlink:label="lab_ecd_TrdArrTerminationDate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trading Arrangement Termination Date </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_TrdArrTerminationDate" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_TrdArrTerminationDate"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_TrdArrTerminationDate" xlink:to="lab_ecd_TrdArrTerminationDate" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CommonStockSharesAuthorized_5110e526-b4bf-4070-b8cd-bd78a351e957_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockSharesAuthorized" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common stock, shares authorized (in shares) </link:label>

<link:label id="lab_us-gaap_CommonStockSharesAuthorized_label_en-US" xlink:label="lab_us-gaap_CommonStockSharesAuthorized" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Common Stock, Shares Authorized </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesAuthorized"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockSharesAuthorized" xlink:to="lab_us-gaap_CommonStockSharesAuthorized" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EquitySecuritiesFvNiGainLoss_4b42edbe-7f44-4e6d-953f-c8cc41a430f8_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_EquitySecuritiesFvNiGainLoss" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Loss from mark-to-market adjustment on investment </link:label>

<link:label id="lab_us-gaap_EquitySecuritiesFvNiGainLoss_label_en-US" xlink:label="lab_us-gaap_EquitySecuritiesFvNiGainLoss" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity Securities, FV-NI, Gain (Loss) </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesFvNiGainLoss" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquitySecuritiesFvNiGainLoss"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquitySecuritiesFvNiGainLoss" xlink:to="lab_us-gaap_EquitySecuritiesFvNiGainLoss" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ProjectContractTerminationMember_6107fc9c-62fb-43f6-83bb-2e4b90d57a97_terseLabel_en-US" xlink:label="lab_pwr_ProjectContractTerminationMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Termination of the Peru Telecommunications Project </link:label>

<link:label id="lab_pwr_ProjectContractTerminationMember_label_en-US" xlink:label="lab_pwr_ProjectContractTerminationMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Project Contract Termination [Member] </link:label>

<link:label id="lab_pwr_ProjectContractTerminationMember_documentation_en-US" xlink:label="lab_pwr_ProjectContractTerminationMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Project Contract Termination [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ProjectContractTerminationMember" xlink:href="pwr-20231231.xsd#pwr_ProjectContractTerminationMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ProjectContractTerminationMember" xlink:to="lab_pwr_ProjectContractTerminationMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_87c985c7-02a1-4bf4-b547-f77bae4ad02a_terseLabel_en-US" xlink:label="lab_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Indefinite-lived Intangible Assets [Axis] </link:label>

<link:label id="lab_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_label_en-US" xlink:label="lab_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Indefinite-Lived Intangible Assets [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="lab_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock_8a02d689-cbac-4ae5-8b07-cb4d9f96de96_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Estimated Fair Values of Identifiable Intangible Assets and Related Weighted Average Amortization </link:label>

<link:label id="lab_us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock_label_en-US" xlink:label="lab_us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived and Indefinite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock" xlink:to="lab_us-gaap_FiniteLivedAndIndefiniteLivedIntangibleAssetsAcquiredAsPartOfBusinessCombinationTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AwardTmgDiscLineItems_label_en-US" xlink:label="lab_ecd_AwardTmgDiscLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Timing Disclosures [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AwardTmgDiscLineItems" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AwardTmgDiscLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AwardTmgDiscLineItems" xlink:to="lab_ecd_AwardTmgDiscLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LineOfCreditFacilityOptionToIncreaseAmount_cd42c37a-2ddf-48d9-b444-53946bfed5ed_terseLabel_en-US" xlink:label="lab_pwr_LineOfCreditFacilityOptionToIncreaseAmount" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Option to increase revolving commitments under the credit agreement </link:label>

<link:label id="lab_pwr_LineOfCreditFacilityOptionToIncreaseAmount_label_en-US" xlink:label="lab_pwr_LineOfCreditFacilityOptionToIncreaseAmount" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Option To Increase, Amount </link:label>

<link:label id="lab_pwr_LineOfCreditFacilityOptionToIncreaseAmount_documentation_en-US" xlink:label="lab_pwr_LineOfCreditFacilityOptionToIncreaseAmount" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line Of Credit Facility, Option To Increase, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LineOfCreditFacilityOptionToIncreaseAmount" xlink:href="pwr-20231231.xsd#pwr_LineOfCreditFacilityOptionToIncreaseAmount"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LineOfCreditFacilityOptionToIncreaseAmount" xlink:to="lab_pwr_LineOfCreditFacilityOptionToIncreaseAmount" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_InvestmentTextBlock_e508851e-12a4-4e85-a146-352e8b6d9770_terseLabel_en-US" xlink:label="lab_us-gaap_InvestmentTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investments in Affiliates and Other Entities </link:label>

<link:label id="lab_us-gaap_InvestmentTextBlock_label_en-US" xlink:label="lab_us-gaap_InvestmentTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Investment [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InvestmentTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InvestmentTextBlock" xlink:to="lab_us-gaap_InvestmentTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_AllOtherPlansCanadaMember_00fe20e2-18e1-47c5-b2fe-e2724acf506d_terseLabel_en-US" xlink:label="lab_pwr_AllOtherPlansCanadaMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All other plans - Canada </link:label>

<link:label id="lab_pwr_AllOtherPlansCanadaMember_label_en-US" xlink:label="lab_pwr_AllOtherPlansCanadaMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Other Plans, Canada [Member] </link:label>

<link:label id="lab_pwr_AllOtherPlansCanadaMember_documentation_en-US" xlink:label="lab_pwr_AllOtherPlansCanadaMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Other Plans, Canada [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_AllOtherPlansCanadaMember" xlink:href="pwr-20231231.xsd#pwr_AllOtherPlansCanadaMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_AllOtherPlansCanadaMember" xlink:to="lab_pwr_AllOtherPlansCanadaMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest_b58bcd3b-b42d-4768-9077-dcf5fda8cb03_terseLabel_en-US" xlink:label="lab_us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Less: Comprehensive income attributable to non-controlling interests </link:label>

<link:label id="lab_us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest_label_en-US" xlink:label="lab_us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest" xlink:to="lab_us-gaap_ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_d60793f1-2cec-403e-88c4-f3ba1dc21828_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Fair value of vested restricted stock </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearOne_72eaf0fa-d038-45ad-8ed0-6ddeddb7b20f_totalLabel_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearOne" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2024 </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearOne_label_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearOne" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, To Be Paid, Year One </link:label>

<link:label id="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearOne_documentation_en-US" xlink:label="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearOne" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Lease, Liability, To Be Paid, Year One </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearOne" xlink:href="pwr-20231231.xsd#pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearOne"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearOne" xlink:to="lab_pwr_OperatingAndFinanceLeaseLiabilityToBePaidYearOne" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_IBEWLocal1249PensionPlanMember_ff4d80ab-24b7-45a3-8c4c-75c16f172476_terseLabel_en-US" xlink:label="lab_pwr_IBEWLocal1249PensionPlanMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> IBEW Local 1249 Pension Plan </link:label>

<link:label id="lab_pwr_IBEWLocal1249PensionPlanMember_label_en-US" xlink:label="lab_pwr_IBEWLocal1249PensionPlanMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> IBEW Local 1249 Pension Plan [Member] </link:label>

<link:label id="lab_pwr_IBEWLocal1249PensionPlanMember_documentation_en-US" xlink:label="lab_pwr_IBEWLocal1249PensionPlanMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> IBEW Local 1249 Pension Plan </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_IBEWLocal1249PensionPlanMember" xlink:href="pwr-20231231.xsd#pwr_IBEWLocal1249PensionPlanMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_IBEWLocal1249PensionPlanMember" xlink:to="lab_pwr_IBEWLocal1249PensionPlanMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CashFlowSupplementalDisclosuresTextBlock_f9c816a3-d28e-467b-b3a6-bc2052a3677e_terseLabel_en-US" xlink:label="lab_us-gaap_CashFlowSupplementalDisclosuresTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Supplemental Cash Flow Information </link:label>

<link:label id="lab_us-gaap_CashFlowSupplementalDisclosuresTextBlock_label_en-US" xlink:label="lab_us-gaap_CashFlowSupplementalDisclosuresTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash Flow, Supplemental Disclosures [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowSupplementalDisclosuresTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashFlowSupplementalDisclosuresTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashFlowSupplementalDisclosuresTextBlock" xlink:to="lab_us-gaap_CashFlowSupplementalDisclosuresTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxPolicyTextBlock_0881fa8c-a295-496e-b404-705236610fbe_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Taxes </link:label>

<link:label id="lab_us-gaap_IncomeTaxPolicyTextBlock_label_en-US" xlink:label="lab_us-gaap_IncomeTaxPolicyTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax, Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPolicyTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxPolicyTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxPolicyTextBlock" xlink:to="lab_us-gaap_IncomeTaxPolicyTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtCurrent_6aa99483-c500-49a7-a30f-082cb76531d1_terseLabel_en-US" xlink:label="lab_us-gaap_DebtCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Current maturities of long-term debt </link:label>

<link:label id="lab_us-gaap_DebtCurrent_label_en-US" xlink:label="lab_us-gaap_DebtCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtCurrent" xlink:to="lab_us-gaap_DebtCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_f82dc8d7-79dc-453c-9e57-afecc2f8e4f1_terseLabel_en-US" xlink:label="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid expenses and other current assets </link:label>

<link:label id="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_label_en-US" xlink:label="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Prepaid Expense and Other Assets, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:to="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_9d41b48e-9a2c-4d0b-b178-f8326ae8ed14_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2026 </link:label>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Asset, Expected Amortization, Year Three </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentRedemptionPeriodDomain_b18967f5-5038-4825-92e1-d7ecb7ab83bb_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Redemption, Period [Domain] </link:label>

<link:label id="lab_us-gaap_DebtInstrumentRedemptionPeriodDomain_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Redemption, Period [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:to="lab_us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_InsiderTradingArrLineItems_label_en-US" xlink:label="lab_ecd_InsiderTradingArrLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Insider Trading Arrangements [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_InsiderTradingArrLineItems" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_InsiderTradingArrLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_InsiderTradingArrLineItems" xlink:to="lab_ecd_InsiderTradingArrLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_FinancialInstrumentsMember_440fc9b9-d624-40f6-9bea-72ce1f92fa72_verboseLabel_en-US" xlink:label="lab_pwr_FinancialInstrumentsMember" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Financial Instruments </link:label>

<link:label id="lab_pwr_FinancialInstrumentsMember_label_en-US" xlink:label="lab_pwr_FinancialInstrumentsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Financial Instruments [Member] </link:label>

<link:label id="lab_pwr_FinancialInstrumentsMember_documentation_en-US" xlink:label="lab_pwr_FinancialInstrumentsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Financial Instruments </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_FinancialInstrumentsMember" xlink:href="pwr-20231231.xsd#pwr_FinancialInstrumentsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_FinancialInstrumentsMember" xlink:to="lab_pwr_FinancialInstrumentsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_fbf92c2f-2fce-4a10-96b3-902a03598a1e_terseLabel_en-US" xlink:label="lab_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party [Axis] </link:label>

<link:label id="lab_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_label_en-US" xlink:label="lab_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Related Party, Type [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:to="lab_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_6f5f5443-3559-42a5-a118-c145d0f300d9_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Stock-based compensation activity (in shares) </link:label>

<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:to="lab_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_Acquisitions2021Member_95e84534-f9a6-494e-9536-f3c133e4e73b_terseLabel_en-US" xlink:label="lab_pwr_Acquisitions2021Member" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2021 Acquisitions </link:label>

<link:label id="lab_pwr_Acquisitions2021Member_label_en-US" xlink:label="lab_pwr_Acquisitions2021Member" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions 2021 [Member] </link:label>

<link:label id="lab_pwr_Acquisitions2021Member_documentation_en-US" xlink:label="lab_pwr_Acquisitions2021Member" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions 2021 [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_Acquisitions2021Member" xlink:href="pwr-20231231.xsd#pwr_Acquisitions2021Member"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_Acquisitions2021Member" xlink:to="lab_pwr_Acquisitions2021Member" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityRegistrantName_c9bf128f-150c-40c3-b0e5-3f9c1573fb03_terseLabel_en-US" xlink:label="lab_dei_EntityRegistrantName" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Registrant Name </link:label>

<link:label id="lab_dei_EntityRegistrantName_label_en-US" xlink:label="lab_dei_EntityRegistrantName" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Registrant Name </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityRegistrantName"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityRegistrantName" xlink:to="lab_dei_EntityRegistrantName" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_MtrlTermsOfTrdArrTextBlock_terseLabel_en-US" xlink:label="lab_ecd_MtrlTermsOfTrdArrTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Material Terms of Trading Arrangement </link:label>

<link:label id="lab_ecd_MtrlTermsOfTrdArrTextBlock_label_en-US" xlink:label="lab_ecd_MtrlTermsOfTrdArrTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Material Terms of Trading Arrangement [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_MtrlTermsOfTrdArrTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_MtrlTermsOfTrdArrTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_MtrlTermsOfTrdArrTextBlock" xlink:to="lab_ecd_MtrlTermsOfTrdArrTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AwardTmgMethodTextBlock_terseLabel_en-US" xlink:label="lab_ecd_AwardTmgMethodTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Timing Method </link:label>

<link:label id="lab_ecd_AwardTmgMethodTextBlock_label_en-US" xlink:label="lab_ecd_AwardTmgMethodTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Award Timing Method [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AwardTmgMethodTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AwardTmgMethodTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AwardTmgMethodTextBlock" xlink:to="lab_ecd_AwardTmgMethodTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_44be81a3-8a4f-4f4e-96be-52ccf3ea43e4_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2025 </link:label>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Asset, Expected Amortization, Year Two </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_Locals302612OfTheIUOEEmployersConstructionIndustryRetirementFundMember_a4a37097-d8b0-4038-a572-7c8abd685bf1_terseLabel_en-US" xlink:label="lab_pwr_Locals302612OfTheIUOEEmployersConstructionIndustryRetirementFundMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Locals 302 & 612 of the IUOE - Employers Construction Industry Retirement Fund </link:label>

<link:label id="lab_pwr_Locals302612OfTheIUOEEmployersConstructionIndustryRetirementFundMember_label_en-US" xlink:label="lab_pwr_Locals302612OfTheIUOEEmployersConstructionIndustryRetirementFundMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Locals 302 & 612 of the IUOE - Employers Construction Industry Retirement Fund [Member] </link:label>

<link:label id="lab_pwr_Locals302612OfTheIUOEEmployersConstructionIndustryRetirementFundMember_documentation_en-US" xlink:label="lab_pwr_Locals302612OfTheIUOEEmployersConstructionIndustryRetirementFundMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Locals 302 & 612 of the IUOE - Employers Construction Industry Retirement Fund </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_Locals302612OfTheIUOEEmployersConstructionIndustryRetirementFundMember" xlink:href="pwr-20231231.xsd#pwr_Locals302612OfTheIUOEEmployersConstructionIndustryRetirementFundMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_Locals302612OfTheIUOEEmployersConstructionIndustryRetirementFundMember" xlink:to="lab_pwr_Locals302612OfTheIUOEEmployersConstructionIndustryRetirementFundMember" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AdjToCompAmt_terseLabel_en-US" xlink:label="lab_ecd_AdjToCompAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustment to Compensation, Amount </link:label>

<link:label id="lab_ecd_AdjToCompAmt_label_en-US" xlink:label="lab_ecd_AdjToCompAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustment to Compensation Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AdjToCompAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AdjToCompAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AdjToCompAmt" xlink:to="lab_ecd_AdjToCompAmt" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_d4163b33-14a6-4bab-bfe1-303af29050cf_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationAwardTrancheTwoMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unequal Installments </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationAwardTrancheTwoMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Payment Arrangement, Tranche Two [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember" xlink:to="lab_us-gaap_ShareBasedCompensationAwardTrancheTwoMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_AssetsNet_010bea49-8cef-4824-837b-c54c9325daaa_terseLabel_en-US" xlink:label="lab_us-gaap_AssetsNet" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net assets </link:label>

<link:label id="lab_us-gaap_AssetsNet_label_en-US" xlink:label="lab_us-gaap_AssetsNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Assets </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsNet"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsNet" xlink:to="lab_us-gaap_AssetsNet" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityNoncurrent_67b8e02e-cde1-4d4b-9c66-2cc94dbf6c66_negatedTerseLabel_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating lease liabilities, non-current </link:label>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityNoncurrent_label_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Operating Lease, Liability, Noncurrent </link:label>

<link:label id="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityNoncurrent_documentation_en-US" xlink:label="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityNoncurrent" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Operating Lease, Liability, Noncurrent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityNoncurrent" xlink:href="pwr-20231231.xsd#pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityNoncurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityNoncurrent" xlink:to="lab_pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityNoncurrent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_76418310-0642-4303-8a0b-7ce11cdf89ea_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Change in fair value of contingent consideration liabilities </link:label>

<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:to="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_55ebf316-2791-4105-9682-4d3afec6a8be_terseLabel_en-US" xlink:label="lab_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred income tax liabilities: </link:label>

<link:label id="lab_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract_label_en-US" xlink:label="lab_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Components of Deferred Tax Liabilities [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:to="lab_us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_MinorityInterest_7eaf49c1-96f0-43b4-9c16-7da09db96600_terseLabel_en-US" xlink:label="lab_us-gaap_MinorityInterest" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-controlling interests </link:label>

<link:label id="lab_us-gaap_MinorityInterest_label_en-US" xlink:label="lab_us-gaap_MinorityInterest" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity, Attributable to Noncontrolling Interest </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterest" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MinorityInterest"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MinorityInterest" xlink:to="lab_us-gaap_MinorityInterest" xlink:type="arc" order="1"/>

<link:label id="lab_dei_AuditorName_27b12eec-0435-4ce5-930a-2cf61db02993_terseLabel_en-US" xlink:label="lab_dei_AuditorName" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Auditor Name </link:label>

<link:label id="lab_dei_AuditorName_label_en-US" xlink:label="lab_dei_AuditorName" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Auditor Name </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_AuditorName" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_AuditorName"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_AuditorName" xlink:to="lab_dei_AuditorName" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncreaseDecreaseInDeferredCompensation_f6081b31-7bca-4701-9c87-564503f0f174_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInDeferredCompensation" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> (Loss) gain included in Selling, general and administrative expenses </link:label>

<link:label id="lab_us-gaap_IncreaseDecreaseInDeferredCompensation_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInDeferredCompensation" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Increase (Decrease) in Deferred Compensation </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInDeferredCompensation" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInDeferredCompensation"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInDeferredCompensation" xlink:to="lab_us-gaap_IncreaseDecreaseInDeferredCompensation" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_AcquisitionsIn2021ExcludingBlattnerMember_e38fda01-e4f6-48d1-8a9c-9865b2ca50ea_terseLabel_en-US" xlink:label="lab_pwr_AcquisitionsIn2021ExcludingBlattnerMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions In 2021 Excluding Blattner </link:label>

<link:label id="lab_pwr_AcquisitionsIn2021ExcludingBlattnerMember_label_en-US" xlink:label="lab_pwr_AcquisitionsIn2021ExcludingBlattnerMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions In 2021 Excluding Blattner [Member] </link:label>

<link:label id="lab_pwr_AcquisitionsIn2021ExcludingBlattnerMember_documentation_en-US" xlink:label="lab_pwr_AcquisitionsIn2021ExcludingBlattnerMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions In 2021 Excluding Blattner </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_AcquisitionsIn2021ExcludingBlattnerMember" xlink:href="pwr-20231231.xsd#pwr_AcquisitionsIn2021ExcludingBlattnerMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_AcquisitionsIn2021ExcludingBlattnerMember" xlink:to="lab_pwr_AcquisitionsIn2021ExcludingBlattnerMember" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_CompActuallyPaidVsNetIncomeTextBlock_terseLabel_en-US" xlink:label="lab_ecd_CompActuallyPaidVsNetIncomeTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Compensation Actually Paid vs. Net Income </link:label>

<link:label id="lab_ecd_CompActuallyPaidVsNetIncomeTextBlock_label_en-US" xlink:label="lab_ecd_CompActuallyPaidVsNetIncomeTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Compensation Actually Paid vs. Net Income [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_CompActuallyPaidVsNetIncomeTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_CompActuallyPaidVsNetIncomeTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_CompActuallyPaidVsNetIncomeTextBlock" xlink:to="lab_ecd_CompActuallyPaidVsNetIncomeTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_PeerGroupIssuersFnTextBlock_terseLabel_en-US" xlink:label="lab_ecd_PeerGroupIssuersFnTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Peer Group Issuers, Footnote </link:label>

<link:label id="lab_ecd_PeerGroupIssuersFnTextBlock_label_en-US" xlink:label="lab_ecd_PeerGroupIssuersFnTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Peer Group Issuers, Footnote [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_PeerGroupIssuersFnTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_PeerGroupIssuersFnTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_PeerGroupIssuersFnTextBlock" xlink:to="lab_ecd_PeerGroupIssuersFnTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityCentralIndexKey_ca819b89-c084-4191-9300-c3ad97dfde11_terseLabel_en-US" xlink:label="lab_dei_EntityCentralIndexKey" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Central Index Key </link:label>

<link:label id="lab_dei_EntityCentralIndexKey_label_en-US" xlink:label="lab_dei_EntityCentralIndexKey" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity Central Index Key </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityCentralIndexKey"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityCentralIndexKey" xlink:to="lab_dei_EntityCentralIndexKey" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ExcessOfFederalFundsRateMember_062077cd-fa02-4ee1-9296-67a3f7339f1d_terseLabel_en-US" xlink:label="lab_pwr_ExcessOfFederalFundsRateMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess of Federal Funds Rate </link:label>

<link:label id="lab_pwr_ExcessOfFederalFundsRateMember_label_en-US" xlink:label="lab_pwr_ExcessOfFederalFundsRateMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess Of Federal Funds Rate [Member] </link:label>

<link:label id="lab_pwr_ExcessOfFederalFundsRateMember_documentation_en-US" xlink:label="lab_pwr_ExcessOfFederalFundsRateMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Excess Of Federal Funds Rate [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ExcessOfFederalFundsRateMember" xlink:href="pwr-20231231.xsd#pwr_ExcessOfFederalFundsRateMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ExcessOfFederalFundsRateMember" xlink:to="lab_pwr_ExcessOfFederalFundsRateMember" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_NonRule10b51ArrTrmntdFlag_terseLabel_en-US" xlink:label="lab_ecd_NonRule10b51ArrTrmntdFlag" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-Rule 10b5-1 Arrangement Terminated </link:label>

<link:label id="lab_ecd_NonRule10b51ArrTrmntdFlag_label_en-US" xlink:label="lab_ecd_NonRule10b51ArrTrmntdFlag" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-Rule 10b5-1 Arrangement Terminated [Flag] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_NonRule10b51ArrTrmntdFlag" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_NonRule10b51ArrTrmntdFlag"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_NonRule10b51ArrTrmntdFlag" xlink:to="lab_ecd_NonRule10b51ArrTrmntdFlag" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingAndFinanceObligationFiscalYearMaturityAbstract_22ea6078-46c4-42b1-a608-73d8d433f4d9_terseLabel_en-US" xlink:label="lab_pwr_OperatingAndFinanceObligationFiscalYearMaturityAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total </link:label>

<link:label id="lab_pwr_OperatingAndFinanceObligationFiscalYearMaturityAbstract_label_en-US" xlink:label="lab_pwr_OperatingAndFinanceObligationFiscalYearMaturityAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Obligation Fiscal Year Maturity [Abstract] </link:label>

<link:label id="lab_pwr_OperatingAndFinanceObligationFiscalYearMaturityAbstract_documentation_en-US" xlink:label="lab_pwr_OperatingAndFinanceObligationFiscalYearMaturityAbstract" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating And Finance Obligation Fiscal Year Maturity </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingAndFinanceObligationFiscalYearMaturityAbstract" xlink:href="pwr-20231231.xsd#pwr_OperatingAndFinanceObligationFiscalYearMaturityAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingAndFinanceObligationFiscalYearMaturityAbstract" xlink:to="lab_pwr_OperatingAndFinanceObligationFiscalYearMaturityAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsGross_8ef31fb5-3904-419f-b5f1-0f5cc49a8aaf_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsGross" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Intangible Assets </link:label>

<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsGross_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsGross" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finite-Lived Intangible Assets, Gross </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsGross" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsGross" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_e72468e7-a28a-4489-96eb-8eabfd520599_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accounts receivable </link:label>

<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables" xlink:to="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxAuthorityDomain_43e0bd9a-5b29-4d0a-bacc-9fbb952d341f_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxAuthorityDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Authority [Domain] </link:label>

<link:label id="lab_us-gaap_IncomeTaxAuthorityDomain_label_en-US" xlink:label="lab_us-gaap_IncomeTaxAuthorityDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income Tax Authority [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxAuthorityDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain" xlink:to="lab_us-gaap_IncomeTaxAuthorityDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_EmployeeRelatedLiabilitiesCurrent_f03f2082-d76d-4e42-808b-bbd1f21831a8_terseLabel_en-US" xlink:label="lab_us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued compensation and related expenses </link:label>

<link:label id="lab_us-gaap_EmployeeRelatedLiabilitiesCurrent_label_en-US" xlink:label="lab_us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Employee-related Liabilities, Current </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:to="lab_us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_TrdArrIndName_terseLabel_en-US" xlink:label="lab_ecd_TrdArrIndName" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Name </link:label>

<link:label id="lab_ecd_TrdArrIndName_label_en-US" xlink:label="lab_ecd_TrdArrIndName" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Trading Arrangement, Individual Name </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_TrdArrIndName" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_TrdArrIndName"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_TrdArrIndName" xlink:to="lab_ecd_TrdArrIndName" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_DeferredTaxLiabilitiesRetainage_27ec33b2-af8e-44d1-bf19-df5cb90f09db_negatedTerseLabel_en-US" xlink:label="lab_pwr_DeferredTaxLiabilitiesRetainage" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Retainage </link:label>

<link:label id="lab_pwr_DeferredTaxLiabilitiesRetainage_label_en-US" xlink:label="lab_pwr_DeferredTaxLiabilitiesRetainage" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Liabilities, Retainage </link:label>

<link:label id="lab_pwr_DeferredTaxLiabilitiesRetainage_documentation_en-US" xlink:label="lab_pwr_DeferredTaxLiabilitiesRetainage" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Liabilities, Retainage </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_DeferredTaxLiabilitiesRetainage" xlink:href="pwr-20231231.xsd#pwr_DeferredTaxLiabilitiesRetainage"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_DeferredTaxLiabilitiesRetainage" xlink:to="lab_pwr_DeferredTaxLiabilitiesRetainage" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DisaggregationOfRevenueTableTextBlock_aa9af99b-2781-458e-9a79-9a88ba66397d_terseLabel_en-US" xlink:label="lab_us-gaap_DisaggregationOfRevenueTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue Disaggregated by Geographic Location and Contract Type </link:label>

<link:label id="lab_us-gaap_DisaggregationOfRevenueTableTextBlock_label_en-US" xlink:label="lab_us-gaap_DisaggregationOfRevenueTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Disaggregation of Revenue [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisaggregationOfRevenueTableTextBlock" xlink:to="lab_us-gaap_DisaggregationOfRevenueTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CommercialPaperProgramMember_7f44ba5e-0520-46e8-b4b3-c50ba92bdfff_terseLabel_en-US" xlink:label="lab_pwr_CommercialPaperProgramMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commercial Paper Program </link:label>

<link:label id="lab_pwr_CommercialPaperProgramMember_label_en-US" xlink:label="lab_pwr_CommercialPaperProgramMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commercial Paper Program [Member] </link:label>

<link:label id="lab_pwr_CommercialPaperProgramMember_documentation_en-US" xlink:label="lab_pwr_CommercialPaperProgramMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commercial Paper Program </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CommercialPaperProgramMember" xlink:href="pwr-20231231.xsd#pwr_CommercialPaperProgramMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CommercialPaperProgramMember" xlink:to="lab_pwr_CommercialPaperProgramMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_19263e78-24da-4d09-8931-8cbffec8a4a4_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign taxes </link:label>

<link:label id="lab_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential_label_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" xlink:to="lab_us-gaap_IncomeTaxReconciliationForeignIncomeTaxRateDifferential" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_09e0efcb-9223-4e98-af4d-2397103bae8d_terseLabel_en-US" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenues </link:label>

<link:label id="lab_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_label_en-US" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Revenue from Contract with Customer, Excluding Assessed Tax </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:to="lab_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:type="arc" order="1"/>

<link:label id="lab_dei_EntityDomain_91faf4f5-d497-426b-b45a-5e45b5847a15_terseLabel_en-US" xlink:label="lab_dei_EntityDomain" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity [Domain] </link:label>

<link:label id="lab_dei_EntityDomain_label_en-US" xlink:label="lab_dei_EntityDomain" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Entity [Domain] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_EntityDomain" xlink:to="lab_dei_EntityDomain" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CashAndCashEquivalentsLineItems_40edb356-7406-49e0-98d7-9ca92fcdaff7_terseLabel_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and Cash Equivalents [Line Items] </link:label>

<link:label id="lab_us-gaap_CashAndCashEquivalentsLineItems_label_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and Cash Equivalents [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems" xlink:to="lab_us-gaap_CashAndCashEquivalentsLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongtermDebtTypeAxis_9b3c48c6-1c11-411e-b06e-1ecefc89307a_terseLabel_en-US" xlink:label="lab_us-gaap_LongtermDebtTypeAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-term Debt, Type [Axis] </link:label>

<link:label id="lab_us-gaap_LongtermDebtTypeAxis_label_en-US" xlink:label="lab_us-gaap_LongtermDebtTypeAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Debt, Type [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongtermDebtTypeAxis" xlink:to="lab_us-gaap_LongtermDebtTypeAxis" xlink:type="arc" order="1"/>

<link:label id="lab_dei_AmendmentFlag_11e064b8-cce2-4680-afd4-2a6743ce6b7b_terseLabel_en-US" xlink:label="lab_dei_AmendmentFlag" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amendment Flag </link:label>

<link:label id="lab_dei_AmendmentFlag_label_en-US" xlink:label="lab_dei_AmendmentFlag" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Amendment Flag </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_AmendmentFlag"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_AmendmentFlag" xlink:to="lab_dei_AmendmentFlag" xlink:type="arc" order="1"/>

<link:label id="lab_dei_LegalEntityAxis_f00fd6f1-a86e-4452-b695-130328f87f2a_terseLabel_en-US" xlink:label="lab_dei_LegalEntityAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Legal Entity [Axis] </link:label>

<link:label id="lab_dei_LegalEntityAxis_label_en-US" xlink:label="lab_dei_LegalEntityAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Legal Entity [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_dei_LegalEntityAxis" xlink:to="lab_dei_LegalEntityAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_CashAndCashEquivalentsAxis_9017c13d-8b15-4d7f-805b-4916c312b683_terseLabel_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and Cash Equivalents [Axis] </link:label>

<link:label id="lab_us-gaap_CashAndCashEquivalentsAxis_label_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash and Cash Equivalents [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis" xlink:to="lab_us-gaap_CashAndCashEquivalentsAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets_780f0306-4155-459d-8422-4cd8929dea63_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other intangible assets </link:label>

<link:label id="lab_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Goodwill and Intangible Assets </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets" xlink:to="lab_us-gaap_DeferredTaxAssetsGoodwillAndIntangibleAssets" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_IntegralUnconsolidatedAffiliatesMember_f02ac3f4-03a8-4c8d-b9fc-36968ce4b884_terseLabel_en-US" xlink:label="lab_pwr_IntegralUnconsolidatedAffiliatesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Integral Unconsolidated Affiliates </link:label>

<link:label id="lab_pwr_IntegralUnconsolidatedAffiliatesMember_label_en-US" xlink:label="lab_pwr_IntegralUnconsolidatedAffiliatesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Integral Unconsolidated Affiliates [Member] </link:label>

<link:label id="lab_pwr_IntegralUnconsolidatedAffiliatesMember_documentation_en-US" xlink:label="lab_pwr_IntegralUnconsolidatedAffiliatesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Integral Unconsolidated Affiliates </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_IntegralUnconsolidatedAffiliatesMember" xlink:href="pwr-20231231.xsd#pwr_IntegralUnconsolidatedAffiliatesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_IntegralUnconsolidatedAffiliatesMember" xlink:to="lab_pwr_IntegralUnconsolidatedAffiliatesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_1640d87d-3956-4b10-89ea-0a87812138ac_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating leases </link:label>

<link:label id="lab_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating Lease, Weighted Average Discount Rate, Percent </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:to="lab_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LicensingAgreementsMember_8c40fa2a-f571-4cac-bc0a-2405f3cf3642_terseLabel_en-US" xlink:label="lab_us-gaap_LicensingAgreementsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Engineering license </link:label>

<link:label id="lab_us-gaap_LicensingAgreementsMember_label_en-US" xlink:label="lab_us-gaap_LicensingAgreementsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Licensing Agreements [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicensingAgreementsMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LicensingAgreementsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LicensingAgreementsMember" xlink:to="lab_us-gaap_LicensingAgreementsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_InterestPaidNet_dfe33a74-fea1-4a88-af7b-8ffcb6c3b4ac_negatedLabel_en-US" xlink:label="lab_us-gaap_InterestPaidNet" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest paid </link:label>

<link:label id="lab_us-gaap_InterestPaidNet_label_en-US" xlink:label="lab_us-gaap_InterestPaidNet" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Interest Paid, Excluding Capitalized Interest, Operating Activities </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaidNet" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestPaidNet"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InterestPaidNet" xlink:to="lab_us-gaap_InterestPaidNet" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_47c04d17-8a36-4b7d-8f4c-097a3fe142b8_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Number of common shares issued in connection with performance units (in shares) </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Shares Issued in Period </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense_98e577bb-883c-46d5-bcf6-71f0f233c957_negatedLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Taxes on certain equity method investments and non-controlling interests </link:label>

<link:label id="lab_us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense_label_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Effective Income Tax Rate Reconciliation, Noncontrolling Interest Income (Loss), Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense" xlink:to="lab_us-gaap_IncomeTaxReconciliationMinorityInterestIncomeExpense" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ConstructionContractingServicesBusinessAcquisitionMember_d032d513-32a0-4315-a316-8f2808445cb1_terseLabel_en-US" xlink:label="lab_pwr_ConstructionContractingServicesBusinessAcquisitionMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Construction Contracting Services Business Acquisition </link:label>

<link:label id="lab_pwr_ConstructionContractingServicesBusinessAcquisitionMember_label_en-US" xlink:label="lab_pwr_ConstructionContractingServicesBusinessAcquisitionMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Construction Contracting Services Business Acquisition [Member] </link:label>

<link:label id="lab_pwr_ConstructionContractingServicesBusinessAcquisitionMember_documentation_en-US" xlink:label="lab_pwr_ConstructionContractingServicesBusinessAcquisitionMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Construction Contracting Services Business Acquisition </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ConstructionContractingServicesBusinessAcquisitionMember" xlink:href="pwr-20231231.xsd#pwr_ConstructionContractingServicesBusinessAcquisitionMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ConstructionContractingServicesBusinessAcquisitionMember" xlink:to="lab_pwr_ConstructionContractingServicesBusinessAcquisitionMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationsPolicy_31f75a5b-9af2-4446-bf52-9df14794a96e_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationsPolicy" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Acquisitions </link:label>

<link:label id="lab_us-gaap_BusinessCombinationsPolicy_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationsPolicy" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combinations Policy [Policy Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationsPolicy" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationsPolicy"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationsPolicy" xlink:to="lab_us-gaap_BusinessCombinationsPolicy" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1_dad5837b-40c1-431b-b300-e5cdeb719c5e_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance leases </link:label>

<link:label id="lab_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Weighted Average Remaining Lease Term </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" xlink:to="lab_us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList_dd4c8108-39d0-4b18-ba03-9b926ada7738_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList" xlink:to="lab_us-gaap_FinanceLeaseLiabilityNoncurrentStatementOfFinancialPositionExtensibleList" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxLiabilities_8f172ee4-2d8b-4769-a38b-c76a3c8d626e_negatedTotalLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilities" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total net deferred income tax liabilities </link:label>

<link:label id="lab_us-gaap_DeferredTaxLiabilities_label_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilities" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Liabilities, Net </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilities" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilities"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxLiabilities" xlink:to="lab_us-gaap_DeferredTaxLiabilities" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ForeignJointVenturesMember_90c269cf-13ed-434e-8d1b-cc24e7055cc4_terseLabel_en-US" xlink:label="lab_pwr_ForeignJointVenturesMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Held by Foreign Joint Ventures </link:label>

<link:label id="lab_pwr_ForeignJointVenturesMember_label_en-US" xlink:label="lab_pwr_ForeignJointVenturesMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign Joint Ventures [Member] </link:label>

<link:label id="lab_pwr_ForeignJointVenturesMember_documentation_en-US" xlink:label="lab_pwr_ForeignJointVenturesMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Foreign Joint Ventures [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ForeignJointVenturesMember" xlink:href="pwr-20231231.xsd#pwr_ForeignJointVenturesMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ForeignJointVenturesMember" xlink:to="lab_pwr_ForeignJointVenturesMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_16125576-6c7f-45fc-8467-4d8076cd5ee9_terseLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted average diluted shares outstanding (in shares) </link:label>

<link:label id="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_efb5c5db-d49a-4186-9634-36ce62c44d0f_totalLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted average shares outstanding for diluted earnings per share attributable to common stock (in shares) </link:label>

<link:label id="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_label_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average Number of Shares Outstanding, Diluted </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_ForgoneRecoveryExplanationOfImpracticabilityTextBlock_terseLabel_en-US" xlink:label="lab_ecd_ForgoneRecoveryExplanationOfImpracticabilityTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Forgone Recovery, Explanation of Impracticability </link:label>

<link:label id="lab_ecd_ForgoneRecoveryExplanationOfImpracticabilityTextBlock_label_en-US" xlink:label="lab_ecd_ForgoneRecoveryExplanationOfImpracticabilityTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Forgone Recovery, Explanation of Impracticability [Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_ForgoneRecoveryExplanationOfImpracticabilityTextBlock" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_ForgoneRecoveryExplanationOfImpracticabilityTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_ForgoneRecoveryExplanationOfImpracticabilityTextBlock" xlink:to="lab_ecd_ForgoneRecoveryExplanationOfImpracticabilityTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_GrossAmountBeforeBalanceSheetPresentationNettingMember_ec809412-2146-43a9-86be-0dd3c7488996_terseLabel_en-US" xlink:label="lab_pwr_GrossAmountBeforeBalanceSheetPresentationNettingMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Gross Amount Before Balance Sheet Presentation Netting </link:label>

<link:label id="lab_pwr_GrossAmountBeforeBalanceSheetPresentationNettingMember_label_en-US" xlink:label="lab_pwr_GrossAmountBeforeBalanceSheetPresentationNettingMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Gross Amount Before Balance Sheet Presentation Netting [Member] </link:label>

<link:label id="lab_pwr_GrossAmountBeforeBalanceSheetPresentationNettingMember_documentation_en-US" xlink:label="lab_pwr_GrossAmountBeforeBalanceSheetPresentationNettingMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Gross Amount Before Balance Sheet Presentation Netting [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_GrossAmountBeforeBalanceSheetPresentationNettingMember" xlink:href="pwr-20231231.xsd#pwr_GrossAmountBeforeBalanceSheetPresentationNettingMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_GrossAmountBeforeBalanceSheetPresentationNettingMember" xlink:to="lab_pwr_GrossAmountBeforeBalanceSheetPresentationNettingMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimate_604d6711-6df5-4dd0-b7e0-6b004c19fc37_terseLabel_en-US" xlink:label="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimate" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Change in contract estimates, (favorable) unfavorable impact on operating results, amount </link:label>

<link:label id="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimate_label_en-US" xlink:label="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimate" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Cumulative Catch-Up Adjustment To Gross Profit, Change In Estimate </link:label>

<link:label id="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimate_documentation_en-US" xlink:label="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimate" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Cumulative Catch-Up Adjustment To Gross Profit, Change In Estimate </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimate" xlink:href="pwr-20231231.xsd#pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimate"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimate" xlink:to="lab_pwr_ContractWithCustomerCumulativeCatchUpAdjustmentToGrossProfitChangeInEstimate" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_aba565de-5ee1-43ba-a9b1-117c9eed002a_negatedLabel_en-US" xlink:label="lab_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Capital expenditures </link:label>

<link:label id="lab_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_label_en-US" xlink:label="lab_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Payments to Acquire Property, Plant, and Equipment </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:to="lab_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_CoSelectedMeasureAmt_terseLabel_en-US" xlink:label="lab_ecd_CoSelectedMeasureAmt" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Company Selected Measure Amount </link:label>

<link:label id="lab_ecd_CoSelectedMeasureAmt_label_en-US" xlink:label="lab_ecd_CoSelectedMeasureAmt" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Company Selected Measure Amount </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_CoSelectedMeasureAmt" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_CoSelectedMeasureAmt"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_CoSelectedMeasureAmt" xlink:to="lab_ecd_CoSelectedMeasureAmt" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LeaseCostAbstract_95333e2e-5204-4a13-9810-d610223b8a6b_terseLabel_en-US" xlink:label="lab_us-gaap_LeaseCostAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease and lease financing cost </link:label>

<link:label id="lab_us-gaap_LeaseCostAbstract_label_en-US" xlink:label="lab_us-gaap_LeaseCostAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease, Cost [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseCostAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LeaseCostAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LeaseCostAbstract" xlink:to="lab_us-gaap_LeaseCostAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_AllAcquisitionsMember_98c8c5c2-844b-49fb-b260-03a9dd100fcd_terseLabel_en-US" xlink:label="lab_pwr_AllAcquisitionsMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Acquisitions </link:label>

<link:label id="lab_pwr_AllAcquisitionsMember_label_en-US" xlink:label="lab_pwr_AllAcquisitionsMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Acquisitions [Member] </link:label>

<link:label id="lab_pwr_AllAcquisitionsMember_documentation_en-US" xlink:label="lab_pwr_AllAcquisitionsMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> All Acquisitions </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_AllAcquisitionsMember" xlink:href="pwr-20231231.xsd#pwr_AllAcquisitionsMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_AllAcquisitionsMember" xlink:to="lab_pwr_AllAcquisitionsMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_Assets_9cdb94af-15fe-48ab-93aa-978e242b7e06_totalLabel_en-US" xlink:label="lab_us-gaap_Assets" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total assets </link:label>

<link:label id="lab_us-gaap_Assets_label_en-US" xlink:label="lab_us-gaap_Assets" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Assets </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Assets"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Assets" xlink:to="lab_us-gaap_Assets" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AwardsCloseToMnpiDiscIndName_terseLabel_en-US" xlink:label="lab_ecd_AwardsCloseToMnpiDiscIndName" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Name </link:label>

<link:label id="lab_ecd_AwardsCloseToMnpiDiscIndName_label_en-US" xlink:label="lab_ecd_AwardsCloseToMnpiDiscIndName" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Awards Close in Time to MNPI Disclosures, Individual Name </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AwardsCloseToMnpiDiscIndName" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AwardsCloseToMnpiDiscIndName"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AwardsCloseToMnpiDiscIndName" xlink:to="lab_ecd_AwardsCloseToMnpiDiscIndName" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareRepurchaseProgramAxis_8d3676cc-6628-4363-bdf6-2b4887928ac7_terseLabel_en-US" xlink:label="lab_us-gaap_ShareRepurchaseProgramAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share Repurchase Program [Axis] </link:label>

<link:label id="lab_us-gaap_ShareRepurchaseProgramAxis_label_en-US" xlink:label="lab_us-gaap_ShareRepurchaseProgramAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share Repurchase Program [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareRepurchaseProgramAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareRepurchaseProgramAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis" xlink:to="lab_us-gaap_ShareRepurchaseProgramAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_1f3d6eea-a717-46cb-95af-6466d82b6ca6_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Thereafter </link:label>

<link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Liability, to be Paid, after Year Five </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueAfterYearFive" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OtherComprehensiveIncomeLossOtherNetOfTax_967da21f-18d4-4acc-b39d-d14552254857_terseLabel_en-US" xlink:label="lab_pwr_OtherComprehensiveIncomeLossOtherNetOfTax" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other income (loss) </link:label>

<link:label id="lab_pwr_OtherComprehensiveIncomeLossOtherNetOfTax_label_en-US" xlink:label="lab_pwr_OtherComprehensiveIncomeLossOtherNetOfTax" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Comprehensive Income (Loss), Other, Net Of Tax </link:label>

<link:label id="lab_pwr_OtherComprehensiveIncomeLossOtherNetOfTax_documentation_en-US" xlink:label="lab_pwr_OtherComprehensiveIncomeLossOtherNetOfTax" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Other Comprehensive Income (Loss), Other, Net of Tax </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OtherComprehensiveIncomeLossOtherNetOfTax" xlink:href="pwr-20231231.xsd#pwr_OtherComprehensiveIncomeLossOtherNetOfTax"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OtherComprehensiveIncomeLossOtherNetOfTax" xlink:to="lab_pwr_OtherComprehensiveIncomeLossOtherNetOfTax" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_f889a60b-80f0-4d13-a1d3-e1594782f741_terseLabel_en-US" xlink:label="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> 2028 </link:label>

<link:label id="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_label_en-US" xlink:label="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-Term Debt, Maturity, Year Five </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive" xlink:to="lab_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_CreditRiskGroupAxis_dc8ffff0-62e5-4752-9792-c24f60757458_terseLabel_en-US" xlink:label="lab_pwr_CreditRiskGroupAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Risk Group [Axis] </link:label>

<link:label id="lab_pwr_CreditRiskGroupAxis_label_en-US" xlink:label="lab_pwr_CreditRiskGroupAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Risk Group [Axis] </link:label>

<link:label id="lab_pwr_CreditRiskGroupAxis_documentation_en-US" xlink:label="lab_pwr_CreditRiskGroupAxis" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Credit Risk Group </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_CreditRiskGroupAxis" xlink:href="pwr-20231231.xsd#pwr_CreditRiskGroupAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_CreditRiskGroupAxis" xlink:to="lab_pwr_CreditRiskGroupAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_FinanceLeaseInterestPaymentOnLiability_c668fa74-52da-49a5-92e5-21aa3d734eaa_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseInterestPaymentOnLiability" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating cash flows used by finance leases </link:label>

<link:label id="lab_us-gaap_FinanceLeaseInterestPaymentOnLiability_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseInterestPaymentOnLiability" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Finance Lease, Interest Payment on Liability </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseInterestPaymentOnLiability" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeaseInterestPaymentOnLiability"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseInterestPaymentOnLiability" xlink:to="lab_us-gaap_FinanceLeaseInterestPaymentOnLiability" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentInterestRateDuringPeriod_bbde19ad-9ce5-44f4-a7c8-3fd174881395_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted-average interest rate </link:label>

<link:label id="lab_us-gaap_DebtInstrumentInterestRateDuringPeriod_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Interest Rate During Period </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:to="lab_us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_45ec2ccb-87f7-46a3-bd70-d6fe9522c438_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Vested, weighted average grant date fair value (in usd per share) </link:label>

<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_NonNeosMember_terseLabel_en-US" xlink:label="lab_ecd_NonNeosMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-NEOs </link:label>

<link:label id="lab_ecd_NonNeosMember_label_en-US" xlink:label="lab_ecd_NonNeosMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-NEOs [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_NonNeosMember" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_NonNeosMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_NonNeosMember" xlink:to="lab_ecd_NonNeosMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_Local697IBEWAndElectricalIndustryPensionFundMember_639d0526-5163-47f1-a811-a73ed96ac3e5_terseLabel_en-US" xlink:label="lab_pwr_Local697IBEWAndElectricalIndustryPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Local 697 I.B.E.W. and Electrical Industry Pension Plan </link:label>

<link:label id="lab_pwr_Local697IBEWAndElectricalIndustryPensionFundMember_label_en-US" xlink:label="lab_pwr_Local697IBEWAndElectricalIndustryPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Local 697 IBEW And Electrical Industry Pension Fund [Member] </link:label>

<link:label id="lab_pwr_Local697IBEWAndElectricalIndustryPensionFundMember_documentation_en-US" xlink:label="lab_pwr_Local697IBEWAndElectricalIndustryPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Local 697 IBEW And Electrical Industry Pension Fund [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_Local697IBEWAndElectricalIndustryPensionFundMember" xlink:href="pwr-20231231.xsd#pwr_Local697IBEWAndElectricalIndustryPensionFundMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_Local697IBEWAndElectricalIndustryPensionFundMember" xlink:to="lab_pwr_Local697IBEWAndElectricalIndustryPensionFundMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ConstructionInProgressMember_0de10670-2124-4fd2-ab64-b1182d66acff_terseLabel_en-US" xlink:label="lab_us-gaap_ConstructionInProgressMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Construction work in progress </link:label>

<link:label id="lab_us-gaap_ConstructionInProgressMember_label_en-US" xlink:label="lab_us-gaap_ConstructionInProgressMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Construction in Progress [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConstructionInProgressMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConstructionInProgressMember" xlink:to="lab_us-gaap_ConstructionInProgressMember" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_LeaseFinancingTransactionToBePaid_1e60ad27-a8bf-4916-98a3-3b18aafdb135_terseLabel_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionToBePaid" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease financing transaction, to be paid </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionToBePaid_label_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionToBePaid" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transaction, To Be Paid </link:label>

<link:label id="lab_pwr_LeaseFinancingTransactionToBePaid_documentation_en-US" xlink:label="lab_pwr_LeaseFinancingTransactionToBePaid" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Lease Financing Transaction, To Be Paid </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_LeaseFinancingTransactionToBePaid" xlink:href="pwr-20231231.xsd#pwr_LeaseFinancingTransactionToBePaid"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_LeaseFinancingTransactionToBePaid" xlink:to="lab_pwr_LeaseFinancingTransactionToBePaid" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_PipelineIndustryPensionFundMember_45136304-6b3f-4208-a8e4-143509ffc447_terseLabel_en-US" xlink:label="lab_pwr_PipelineIndustryPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Pipeline Industry Pension Fund </link:label>

<link:label id="lab_pwr_PipelineIndustryPensionFundMember_label_en-US" xlink:label="lab_pwr_PipelineIndustryPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Pipeline Industry Pension Fund [Member] </link:label>

<link:label id="lab_pwr_PipelineIndustryPensionFundMember_documentation_en-US" xlink:label="lab_pwr_PipelineIndustryPensionFundMember" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Pipeline Industry Pension Fund [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_PipelineIndustryPensionFundMember" xlink:href="pwr-20231231.xsd#pwr_PipelineIndustryPensionFundMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_PipelineIndustryPensionFundMember" xlink:to="lab_pwr_PipelineIndustryPensionFundMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_SummaryOfPositionsForWhichSignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTextBlock_f84ad8c8-61ad-4446-b049-ecd480038f66_terseLabel_en-US" xlink:label="lab_us-gaap_SummaryOfPositionsForWhichSignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Balances of Unrecognized Tax Benefits </link:label>

<link:label id="lab_us-gaap_SummaryOfPositionsForWhichSignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTextBlock_label_en-US" xlink:label="lab_us-gaap_SummaryOfPositionsForWhichSignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_SummaryOfPositionsForWhichSignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SummaryOfPositionsForWhichSignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SummaryOfPositionsForWhichSignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTextBlock" xlink:to="lab_us-gaap_SummaryOfPositionsForWhichSignificantChangeInUnrecognizedTaxBenefitsIsReasonablyPossibleTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_f4ac88ad-11f8-487e-9b9b-9723e7b843ae_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Cash Flows from Financing Activities: </link:label>

<link:label id="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net Cash Provided by (Used in) Financing Activities [Abstract] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:to="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ProceedsFromSaleOfPropertyPlantAndEquipmentAndInsuranceSettlement_e608809a-8057-405c-aff3-f8d1e674185d_terseLabel_en-US" xlink:label="lab_pwr_ProceedsFromSaleOfPropertyPlantAndEquipmentAndInsuranceSettlement" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from sale of and insurance settlements related to property and equipment </link:label>

<link:label id="lab_pwr_ProceedsFromSaleOfPropertyPlantAndEquipmentAndInsuranceSettlement_label_en-US" xlink:label="lab_pwr_ProceedsFromSaleOfPropertyPlantAndEquipmentAndInsuranceSettlement" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds From Sale of Property, Plant And Equipment And Insurance Settlement </link:label>

<link:label id="lab_pwr_ProceedsFromSaleOfPropertyPlantAndEquipmentAndInsuranceSettlement_documentation_en-US" xlink:label="lab_pwr_ProceedsFromSaleOfPropertyPlantAndEquipmentAndInsuranceSettlement" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds From Sale of Property, Plant And Equipment And Insurance Settlement </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ProceedsFromSaleOfPropertyPlantAndEquipmentAndInsuranceSettlement" xlink:href="pwr-20231231.xsd#pwr_ProceedsFromSaleOfPropertyPlantAndEquipmentAndInsuranceSettlement"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ProceedsFromSaleOfPropertyPlantAndEquipmentAndInsuranceSettlement" xlink:to="lab_pwr_ProceedsFromSaleOfPropertyPlantAndEquipmentAndInsuranceSettlement" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_NonPeoNeoMember_terseLabel_en-US" xlink:label="lab_ecd_NonPeoNeoMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-PEO NEO </link:label>

<link:label id="lab_ecd_NonPeoNeoMember_label_en-US" xlink:label="lab_ecd_NonPeoNeoMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-PEO NEO [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_NonPeoNeoMember" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_NonPeoNeoMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_NonPeoNeoMember" xlink:to="lab_ecd_NonPeoNeoMember" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_AdjToCompAxis_terseLabel_en-US" xlink:label="lab_ecd_AdjToCompAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustment to Compensation: </link:label>

<link:label id="lab_ecd_AdjToCompAxis_label_en-US" xlink:label="lab_ecd_AdjToCompAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Adjustment to Compensation [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_AdjToCompAxis" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_AdjToCompAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_AdjToCompAxis" xlink:to="lab_ecd_AdjToCompAxis" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_OperatingFinanceLeaseAndLeaseFinancingTransactionRightOfUseAsset_d2ed71b3-4cea-4a5b-80b2-cfc7c4321455_totalLabel_en-US" xlink:label="lab_pwr_OperatingFinanceLeaseAndLeaseFinancingTransactionRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Total lease and lease financing assets </link:label>

<link:label id="lab_pwr_OperatingFinanceLeaseAndLeaseFinancingTransactionRightOfUseAsset_label_en-US" xlink:label="lab_pwr_OperatingFinanceLeaseAndLeaseFinancingTransactionRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating, Finance Lease And Lease Financing Transaction, Right-Of-Use Asset </link:label>

<link:label id="lab_pwr_OperatingFinanceLeaseAndLeaseFinancingTransactionRightOfUseAsset_documentation_en-US" xlink:label="lab_pwr_OperatingFinanceLeaseAndLeaseFinancingTransactionRightOfUseAsset" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Operating, Finance Lease And Lease Financing Transaction, Right-Of-Use Asset </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_OperatingFinanceLeaseAndLeaseFinancingTransactionRightOfUseAsset" xlink:href="pwr-20231231.xsd#pwr_OperatingFinanceLeaseAndLeaseFinancingTransactionRightOfUseAsset"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_OperatingFinanceLeaseAndLeaseFinancingTransactionRightOfUseAsset" xlink:to="lab_pwr_OperatingFinanceLeaseAndLeaseFinancingTransactionRightOfUseAsset" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_8c16041e-d864-414b-bd22-9f187314e9de_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Value of Quanta common stock issued </link:label>

<link:label id="lab_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Business Combination, Consideration Transferred, Equity Interests Issued and Issuable </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable" xlink:to="lab_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_8a499252-f0db-4589-8287-b59217fdbf0a_verboseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Tax effect of state and foreign net operating loss carryforwards </link:label>

<link:label id="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_50330dbb-77d6-4024-b6e5-d6056962e299_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Net operating loss carryforwards </link:label>

<link:label id="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Assets, Operating Loss Carryforwards </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:to="lab_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentLineItems_e50240a6-dea5-41ad-a570-7f1471dcb4c3_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument [Line Items] </link:label>

<link:label id="lab_us-gaap_DebtInstrumentLineItems_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentLineItems" xlink:to="lab_us-gaap_DebtInstrumentLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_5180d694-cd43-4fe9-b19a-6349321e2cbc_terseLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted average basic shares outstanding (in shares) </link:label>

<link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_7d876026-d79c-4759-b73f-86931aeb65c0_verboseLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted average shares outstanding for basic earnings per share attributable to common stock (in shares) </link:label>

<link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_label_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Weighted Average Number of Shares Outstanding, Basic </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:to="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_8e4795ba-0b75-434c-a270-31672b188aef_negatedLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Property and equipment </link:label>

<link:label id="lab_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment_label_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Deferred Tax Liabilities, Property, Plant and Equipment </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" xlink:to="lab_us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ConcentrationRiskByBenchmarkAxis_24fdfa90-b5c4-4a55-8385-449a349c43f2_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Benchmark [Axis] </link:label>

<link:label id="lab_us-gaap_ConcentrationRiskByBenchmarkAxis_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Concentration Risk Benchmark [Axis] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="lab_us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_697c7460-1fed-4228-bfd1-c784a09685c2_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodTwoMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Redemption, Period Two </link:label>

<link:label id="lab_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentRedemptionPeriodTwoMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Debt Instrument, Redemption, Period Two [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember" xlink:to="lab_us-gaap_DebtInstrumentRedemptionPeriodTwoMember" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable_c9eb7ce7-cf68-401a-a643-deb93db7caca_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Indefinite-Lived Intangible Assets [Table] </link:label>

<link:label id="lab_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable_label_en-US" xlink:label="lab_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Indefinite-Lived Intangible Assets [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable" xlink:to="lab_us-gaap_ScheduleOfIndefiniteLivedIntangibleAssetsTable" xlink:type="arc" order="1"/>

<link:label id="lab_ecd_PvpTable_terseLabel_en-US" xlink:label="lab_ecd_PvpTable" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Pay vs Performance Disclosure </link:label>

<link:label id="lab_ecd_PvpTable_label_en-US" xlink:label="lab_ecd_PvpTable" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Pay vs Performance Disclosure [Table] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_ecd_PvpTable" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#ecd_PvpTable"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_ecd_PvpTable" xlink:to="lab_ecd_PvpTable" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_23a37e1b-33fd-4ba7-ace1-7f6dbbf95132_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Commitment fee </link:label>

<link:label id="lab_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Line of Credit Facility, Unused Capacity, Commitment Fee Percentage </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" xlink:to="lab_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_StatementLineItems_e551b083-c06e-4fd5-97b8-860327d0caa5_terseLabel_en-US" xlink:label="lab_us-gaap_StatementLineItems" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement [Line Items] </link:label>

<link:label id="lab_us-gaap_StatementLineItems_label_en-US" xlink:label="lab_us-gaap_StatementLineItems" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Statement [Line Items] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementLineItems" xlink:to="lab_us-gaap_StatementLineItems" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_IncomeLossFromEquityMethodInvestmentsIntegralUnconsolidatedAffiliates_739f2d13-fd34-480d-80cc-571621f5954a_terseLabel_en-US" xlink:label="lab_pwr_IncomeLossFromEquityMethodInvestmentsIntegralUnconsolidatedAffiliates" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Equity in earnings of integral unconsolidated affiliates </link:label>

<link:label id="lab_pwr_IncomeLossFromEquityMethodInvestmentsIntegralUnconsolidatedAffiliates_label_en-US" xlink:label="lab_pwr_IncomeLossFromEquityMethodInvestmentsIntegralUnconsolidatedAffiliates" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income (Loss) From Equity Method Investments, Integral Unconsolidated Affiliates </link:label>

<link:label id="lab_pwr_IncomeLossFromEquityMethodInvestmentsIntegralUnconsolidatedAffiliates_documentation_en-US" xlink:label="lab_pwr_IncomeLossFromEquityMethodInvestmentsIntegralUnconsolidatedAffiliates" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Income (Loss) From Equity Method Investments, Integral Unconsolidated Affiliates </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_IncomeLossFromEquityMethodInvestmentsIntegralUnconsolidatedAffiliates" xlink:href="pwr-20231231.xsd#pwr_IncomeLossFromEquityMethodInvestmentsIntegralUnconsolidatedAffiliates"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_IncomeLossFromEquityMethodInvestmentsIntegralUnconsolidatedAffiliates" xlink:to="lab_pwr_IncomeLossFromEquityMethodInvestmentsIntegralUnconsolidatedAffiliates" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_UnrecognizedTaxBenefitPortionThatIfRecognizedWouldReduceTaxExpenseAndEffectiveTaxRateUpperBound_45c0c337-515e-43cc-8c4d-8d1ec3d7be76_terseLabel_en-US" xlink:label="lab_pwr_UnrecognizedTaxBenefitPortionThatIfRecognizedWouldReduceTaxExpenseAndEffectiveTaxRateUpperBound" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Portion that, if recognized, would reduce tax expense and effective tax rate </link:label>

<link:label id="lab_pwr_UnrecognizedTaxBenefitPortionThatIfRecognizedWouldReduceTaxExpenseAndEffectiveTaxRateUpperBound_label_en-US" xlink:label="lab_pwr_UnrecognizedTaxBenefitPortionThatIfRecognizedWouldReduceTaxExpenseAndEffectiveTaxRateUpperBound" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecognized Tax Benefit Portion That If Recognized Would Reduce Tax Expense And Effective Tax Rate Upper Bound </link:label>

<link:label id="lab_pwr_UnrecognizedTaxBenefitPortionThatIfRecognizedWouldReduceTaxExpenseAndEffectiveTaxRateUpperBound_documentation_en-US" xlink:label="lab_pwr_UnrecognizedTaxBenefitPortionThatIfRecognizedWouldReduceTaxExpenseAndEffectiveTaxRateUpperBound" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecognized tax benefit portion that if recognized would reduce tax expense and effective tax rate upper bound. </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_UnrecognizedTaxBenefitPortionThatIfRecognizedWouldReduceTaxExpenseAndEffectiveTaxRateUpperBound" xlink:href="pwr-20231231.xsd#pwr_UnrecognizedTaxBenefitPortionThatIfRecognizedWouldReduceTaxExpenseAndEffectiveTaxRateUpperBound"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_UnrecognizedTaxBenefitPortionThatIfRecognizedWouldReduceTaxExpenseAndEffectiveTaxRateUpperBound" xlink:to="lab_pwr_UnrecognizedTaxBenefitPortionThatIfRecognizedWouldReduceTaxExpenseAndEffectiveTaxRateUpperBound" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued_0033445f-bbda-418f-a1b3-373c307ce170_terseLabel_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Accrued interest on unrecognized tax benefits </link:label>

<link:label id="lab_us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued_label_en-US" xlink:label="lab_us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Unrecognized Tax Benefits, Interest on Income Taxes Accrued </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued" xlink:to="lab_us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued" xlink:type="arc" order="1"/>

<link:label id="lab_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringSubsequentPeriod_67d5b175-7b60-4eee-b131-daf090c4109a_terseLabel_en-US" xlink:label="lab_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringSubsequentPeriod" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Aggregate consideration to be paid during the post-construction operation and maintenance period </link:label>

<link:label id="lab_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringSubsequentPeriod_label_en-US" xlink:label="lab_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringSubsequentPeriod" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Contract Value, Consideration To Be Transferred During Subsequent Period </link:label>

<link:label id="lab_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringSubsequentPeriod_documentation_en-US" xlink:label="lab_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringSubsequentPeriod" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Contract With Customer, Contract Value, Consideration To Be Transferred During Subsequent Period </link:label>

<link:loc xlink:type="locator" xlink:label="loc_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringSubsequentPeriod" xlink:href="pwr-20231231.xsd#pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringSubsequentPeriod"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringSubsequentPeriod" xlink:to="lab_pwr_ContractWithCustomerContractValueConsiderationToBeTransferredDuringSubsequentPeriod" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ScheduleOfDebtTableTextBlock_b03d0d1f-8d4c-4f6e-adf6-baa099197230_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfDebtTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Long-term Debt Obligations </link:label>

<link:label id="lab_us-gaap_ScheduleOfDebtTableTextBlock_label_en-US" xlink:label="lab_us-gaap_ScheduleOfDebtTableTextBlock" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Schedule of Debt [Table Text Block] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDebtTableTextBlock" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfDebtTableTextBlock"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfDebtTableTextBlock" xlink:to="lab_us-gaap_ScheduleOfDebtTableTextBlock" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_ProceedsFromLongTermLinesOfCredit_3f1d49b4-b21d-4756-b4c6-7327e40e7dae_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromLongTermLinesOfCredit" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Borrowings under credit facility and commercial paper program </link:label>

<link:label id="lab_us-gaap_ProceedsFromLongTermLinesOfCredit_label_en-US" xlink:label="lab_us-gaap_ProceedsFromLongTermLinesOfCredit" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Proceeds from Long-Term Lines of Credit </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLongTermLinesOfCredit" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromLongTermLinesOfCredit"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromLongTermLinesOfCredit" xlink:to="lab_us-gaap_ProceedsFromLongTermLinesOfCredit" xlink:type="arc" order="1"/>

<link:label id="lab_us-gaap_NoncontrollingInterestMember_85dbd863-1a03-433b-9d5e-09cab2cf6ee0_terseLabel_en-US" xlink:label="lab_us-gaap_NoncontrollingInterestMember" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Non-controlling Interests </link:label>

<link:label id="lab_us-gaap_NoncontrollingInterestMember_label_en-US" xlink:label="lab_us-gaap_NoncontrollingInterestMember" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xmlns:xml="http://www.w3.org/XML/1998/namespace" xml:lang="en-US"> Noncontrolling Interest [Member] </link:label>

<link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncontrollingInterestMember"/>

<link:labelArc xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NoncontrollingInterestMember" xlink:to="lab_us-gaap_NoncontrollingInterestMember" xlink:type="arc" order="1"/>

</link:labelLink>

</link:linkbase>

34 Previous Filings that this Filing References

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

11/02/23  Quanta Services, Inc.             10-Q        9/30/23  105:10M
 8/03/23  Quanta Services, Inc.             8-K:2,5,7,9 8/01/23   15:1.3M                                   Donnelley … Solutions/FA
 5/04/23  Quanta Services, Inc.             10-Q        3/31/23  102:10M
 3/14/23  Quanta Services, Inc.             8-K:5,9     3/09/23   11:182K                                   Donnelley … Solutions/FA
 1/19/23  Quanta Services, Inc.             8-K:5,9     1/13/23   11:366K                                   Donnelley … Solutions/FA
 8/24/22  Quanta Services, Inc.             8-K:1,2,9   8/23/22   12:1.8M                                   Donnelley … Solutions/FA
 5/31/22  Quanta Services, Inc.             8-K:5,9     5/27/22   11:174K                                   Donnelley … Solutions/FA
 3/08/22  Quanta Services, Inc.             8-K:5,9     3/02/22   11:179K                                   Donnelley … Solutions/FA
 2/25/22  Quanta Services, Inc.             10-K       12/31/21  137:18M
10/15/21  Quanta Services, Inc.             8-K:1,2,3,710/08/21   15:3.2M                                   Donnelley … Solutions/FA
 9/23/21  Quanta Services, Inc.             8-K:1,2,9   9/23/21   14:667K                                   Donnelley … Solutions/FA
 8/06/21  Quanta Services, Inc.             10-Q        6/30/21   97:11M
 3/30/21  Quanta Services, Inc.             8-K:5,9     3/25/21   11:182K                                   Donnelley … Solutions/FA
 9/25/20  Quanta Services, Inc.             8-K:1,2,8,9 9/22/20   14:2.3M                                   Donnelley … Solutions/FA
11/01/19  Quanta Services, Inc.             10-Q        9/30/19  113:14M
 9/09/19  Quanta Services, Inc.             8-K:1,2,9   9/06/19   11:394K                                   Donnelley … Solutions/FA
 5/24/19  Quanta Services, Inc.             8-K:5,8,9   5/22/19    6:322K                                   Donnelley … Solutions/FA
 3/26/19  Quanta Services, Inc.             8-K:5,8,9   3/22/19    5:56K                                    Donnelley … Solutions/FA
12/11/18  Quanta Services, Inc.             8-K:1,5,8,912/06/18    4:266K                                   Donnelley … Solutions/FA
10/15/18  Quanta Services, Inc.             8-K:1,2,9  10/10/18    3:1.3M                                   Donnelley … Solutions/FA
 8/07/18  Quanta Services, Inc.             10-Q        6/30/18  103:9.6M
11/09/17  Quanta Services, Inc.             10-Q        9/30/17   96:9.7M
11/06/17  Quanta Services, Inc.             8-K:1,2,9  10/31/17    2:152K                                   Donnelley … Solutions/FA
 3/01/17  Quanta Services, Inc.             10-K       12/31/16  136:10M                                    Donnelley … Solutions/FA
 8/08/16  Quanta Services, Inc.             10-Q        6/30/16   96:6.1M                                   Donnelley … Solutions/FA
12/23/15  Quanta Services, Inc.             8-K:1,2,9  12/18/15    4:3.5M                                   Donnelley … Solutions/FA
 3/01/13  Quanta Services, Inc.             10-K       12/31/12  100:11M                                    Donnelley … Solutions/FA
 8/08/12  Quanta Services, Inc.             10-Q        6/30/12   60:5.7M                                   Donnelley … Solutions/FA
 2/29/12  Quanta Services, Inc.             10-K       12/31/11   97:11M                                    Donnelley … Solutions/FA
 4/01/09  Quanta Services, Inc.             8-K:1,9     3/31/09    2:50K                                    Bowne - Houston/FA
 2/29/08  Quanta Services, Inc.             10-K       12/31/07    7:1.5M                                   Bowne - Houston/FA
12/04/06  Quanta Services, Inc.             8-K:1,9    11/28/06    2:512K                                   Bowne - Houston/FA
 3/16/05  Quanta Services, Inc.             8-K:1,2,9   3/14/05    4:681K                                   Bowne - Houston/FA
 2/09/98  Quanta Services, Inc.             S-1/A                  7:482K                                   Donnelley RR & So… Co/FA

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