FIRST AMENDMENT TO THIRD AMENDEDAND RESTATED CREDIT AGREEMENT

Exhibit 10.4

FIRST AMENDMENT TO

THIRD AMENDED AND RESTATED CREDIT AGREEMENT

THIS FIRST AMENDMENT TO THIRD AMENDED AND RESTATED CREDIT AGREEMENT dated as of April 22, 2015 (the “Agreement”) is entered into among Quanta Services, Inc., a Delaware corporation (the “Company”), the Australian Borrowers, the Canadian Borrowers, the Guarantors, the Lenders party hereto and Bank of America, N.A., as Administrative Agent, Domestic Swing Line Lender and an L/C Issuer. All capitalized terms used herein and not otherwise defined herein shall have the meanings given to such terms in the Credit Agreement (as defined below).

RECITALS

WHEREAS, the Borrowers, the Guarantors, the Lenders and the Administrative Agent entered into that certain Third Amended and Restated Credit Agreement dated as of October 30, 2013 (as amended and modified from time to time, the “Credit Agreement”);

WHEREAS, the Company has requested that the Lenders amend the Credit Agreement as set forth in Section 1 below; and

WHEREAS, the Lenders have agreed to provide the requested amendments, subject to the terms and conditions set forth herein;

NOW, THEREFORE, in consideration of the premises and the mutual covenants contained herein, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree as follows:

1. Amendments. The Credit Agreement is hereby amended as follows:

(a) The definition of “Alternative Currency Sublimit” in Section 1.01 of the Credit Agreement is hereby amended and restated in its entirety to read as follows:

“Alternative Currency Sublimit” means an amount equal to the Aggregate Revolving Commitments. The Alternative Currency Sublimit is part of, and not in addition to, the Aggregate Revolving Commitments.

(b) In the definition of “Consolidated EBIT” set forth in Section 1.01 of the Credit Agreement, the reference to “2.0 to 1.0” in the proviso thereto is hereby replaced with a reference to “1.25 to 1.0”.

(c) In the definition of “Consolidated EBITDA” set forth in Section 1.01 of the Credit Agreement, the reference to “2.0 to 1.0” in the proviso thereto is hereby replaced with a reference to “1.25 to 1.0”.

(d) In Section 1.01 of the Credit Agreement, the following proviso is hereby added at the end of the definition of “Eurocurrency Rate”:

“; provided, further, that, if the Eurocurrency Rate shall be less than zero, such rate shall be deemed to be zero for purposes of this Agreement”.

(e) The following definition of “First Amendment” is hereby added to Section 1.01 of the Credit Agreement in the appropriate alphabetical order:

“First Amendment” means that certain First Amendment to Third Amended and Restated Credit Agreement among the Borrowers, the Guarantors, the Lenders party thereto and Bank of America, N.A. as Administrative Agent, Domestic Swing Line Lender and an L/C Issuer, dated as of April 22, 2015.

(f) In Section 1.01 of the Credit Agreement, clause (b) of the definition of “Interest Period” is hereby amended and restated in its entirety to read as follows:

(b) any Interest Period (other than a one week Interest Period) that begins on the last Business Day of a calendar month (or on a day for which there is no numerically corresponding day in the calendar month at the end of such Interest Period) shall end on the last Business Day of the calendar month at the end of such Interest Period; and

(g) In Section 1.01 of the Credit Agreement, the definition of “Loan Notice” is hereby amended and restated in its entirety to read as follows:

“Loan Notice” means a notice of (a) a Borrowing of Revolving Loans, (b) a conversion of Loans from one Type to the other or (c) a continuation of Eurocurrency Rate Loans, pursuant to Section 2.02(a), which, if in writing, shall be substantially in the form of Exhibit A, or such other form as may be approved by the Administrative Agent (including any form on an electronic platform or electronic transmission system as shall be approved by the Administrative Agent) and reasonably acceptable to the Company, appropriately completed and signed by a Responsible Officer of the applicable Borrower.

(h) In Section 1.01 of the Credit Agreement, the definition of “Responsible Officer” is hereby amended and restated in its entirety to read as follows:

“Responsible Officer” means the chief executive officer, president, chief financial officer, chief accounting officer, treasurer, assistant treasurer, general counsel, secretary or assistant secretary or, with respect to any Australian Borrower or Canadian Borrower (other than the Canadian FinanceCo Borrower), a director, of a Loan Party, or any other officer or employee of the applicable Loan Party designated in or pursuant to an agreement between the applicable Loan Party and the Administrative Agent. Any document delivered hereunder that is signed by a Responsible Officer of a Loan Party shall be conclusively presumed to have been authorized by all necessary corporate, partnership and/or other action on the part of such Loan Party and such Responsible Officer shall be conclusively presumed to have acted on behalf of such Loan Party.

(i) The following subsection (h) is hereby added to Section 3.01, immediately following subsection (g):

(h) For purposes of determining withholding Taxes imposed under the Foreign Account Tax Compliance Act (FATCA), from and after the effective date of the First Amendment, the Borrowers and the Administrative Agent shall treat (and the Lenders hereby authorize the Administrative Agent to treat) this Agreement as not qualifying as a “grandfathered obligation” within the meaning of Treasury Regulation Section 1.1471-2(b)(2)(i).

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(j) Section 7.02(a) of the Credit Agreement is hereby amended and restated in its entirety to read as follows:

(a) concurrently with the delivery of the financial statements referred to in Sections 7.01(a) and (b) (or not later than the last day allowed for delivery of the applicable financial statements pursuant to Sections 7.01(a) and (b), respectively), a duly completed Compliance Certificate signed by a Responsible Officer of the Company;

(k) Section 7.02(b) of the Credit Agreement is hereby amended and restated in its entirety to read as follows:

(b) concurrently with the delivery of the financial statements referred to in Sections 7.01(a) and (b) (or not later than the last day allowed for delivery of the applicable financial statements pursuant to Sections 7.01(a) and (b), respectively), any budget of the Company and its Subsidiaries which has been approved by the board of directors of the Company;

(l) Section 7.02(c) of the Credit Agreement is hereby amended and restated in its entirety to read as follows:

(c) concurrently with the delivery of the financial statements referred to in Section 7.01(a) (or not later than the last day allowed for delivery of the applicable financial statements pursuant to Section 7.01(a)), a certificate of a Responsible Officer of the Company containing information regarding the amount of all Dispositions, Involuntary Dispositions, Debt Issuances, Equity Issuances and Acquisitions, in any one instance exceeding $15,000,000, that occurred during the period covered by such financial statements;

(m) Section 7.02(g) of the Credit Agreement is hereby amended and restated in its entirety to read as follows:

(g) concurrently with the delivery of the financial statements referred to in Section 7.01(a) (or not later than the last day allowed for delivery of the applicable financial statements pursuant to Section 7.01(a)), (i) a certificate of a Responsible Officer of the Company listing (A) all registration numbers for all patents, trademarks, service marks, trade names and copyrights awarded to any Loan Party by the United States Copyright Office or the United States Patent and Trademark Office since the last day of the immediately preceding fiscal period and (B) all patent applications, trademark applications, service mark applications, trade names and copyrights awarded to any Loan Party by the United States Copyright Office or the United States Patent and Trademark Office since the last day of the immediately preceding fiscal period and the status of such application, and (ii) attaching the insurance binder or other evidence of insurance for any insurance coverage of the Company or any Subsidiary that was renewed, replaced or modified during the period covered by such financial statements.

(n) In Section 8.02(k) of the Credit Agreement, the reference to “2.0 to 1.0” is hereby replaced with a reference to “1.25 to 1.0”.

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(o) Section 8.03(e)(i) of the Credit Agreement is hereby amended and restated in its entirety to read as follows:

“obligations of any Borrower or any Subsidiary under surety bonds provided in the ordinary course of business (and indemnity and reimbursement obligations related thereto),”.

(p) In Section 8.03(m) of the Credit Agreement, the reference to “2.0 to 1.0” is hereby replaced with a reference to “1.25 to 1.0”.

(q) Section 11.06(f) of the Credit Agreement is hereby deleted in its entirety and replaced with:

(f) [reserved];

(r) The following new Section 11.22 of the Credit Agreement is hereby added immediately following Section 11.21:

11.22 Electronic Execution of Assignments and Other Documents.

The words “delivery,” “execute,” “execution,” “signed,” “signature,” and words of like import in any Loan Document or any other document executed in connection herewith shall be deemed to include electronic signatures, the electronic matching of assignment terms and contract formations on electronic platforms approved by the Administrative Agent, or the keeping of records in electronic form, each of which shall be of the same legal effect, validity or enforceability as a manually executed signature, physical delivery thereof or the use of a paper-based recordkeeping system, as the case may be, to the extent and as provided for in any applicable Law, including the Federal Electronic Signatures in Global and National Commerce Act, the New York State Electronic Signatures and Records Act, or any other similar state laws based on the Uniform Electronic Transactions Act; provided that notwithstanding anything contained herein to the contrary neither the Administrative Agent, any L/C Issuer, any Loan Party nor any Lender is under any obligation to agree to accept electronic signatures in any form or in any format unless expressly agreed to by the Administrative Agent, such L/C Issuer, such Loan Party or such Lender pursuant to procedures approved by it and provided further without limiting the foregoing, upon the request of any party, any electronic signature shall be promptly followed by such manually executed counterpart.

2. Conditions Precedent. This Agreement shall be effective upon receipt by the Administrative Agent of counterparts of this Agreement duly executed by each of the Borrowers, the Guarantors, the Required Lenders and Bank of America, N.A., as Administrative Agent.

3. Miscellaneous.

(a) The Credit Agreement, and the obligations of the Loan Parties thereunder and under the other Loan Documents, are hereby ratified and confirmed and shall remain in full force and effect according to their terms, as affected and amended by this Agreement.

(b) Upon the effectiveness of this Agreement, each reference in the Credit Agreement to “this Agreement,” “hereunder” or words of like import shall mean and be a reference to the Credit Agreement, as affected and amended by this Agreement.

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(c) Each Guarantor (i) acknowledges and consents to all of the terms and conditions of this Agreement, (ii) affirms all of its obligations under the Loan Documents and (iii) agrees that this Agreement and all documents executed in connection herewith do not operate to reduce or discharge its obligations under the Credit Agreement or the other Loan Documents.

(d) The Borrowers and the Guarantors hereby represent and warrant as follows:

(i) Each Loan Party has taken all necessary action to authorize the execution, delivery and performance of this Agreement;

(ii) This Agreement has been duly executed and delivered by the Loan Parties and constitutes each of the Loan Parties’ legal, valid and binding obligations, enforceable in accordance with its terms, except as such enforceability may be subject to (A) bankruptcy, insolvency, reorganization, fraudulent conveyance or transfer, moratorium or similar laws affecting creditors’ rights generally and (B) general principles of equity (regardless of whether such enforceability is considered in a proceeding at law or in equity); and

(iii) No consent, approval, authorization or order of, or filing, registration or qualification with, any court or governmental authority or third party is required in connection with the execution, delivery or performance by any Loan Party of this Agreement.

(e) The Loan Parties represent and warrant to the Lenders that (i) the representations and warranties of the Loan Parties set forth in Article VI of the Credit Agreement and in each other Loan Document are true and correct in all material respects as of the date hereof with the same effect as if made on and as of the date hereof, except to the extent such representations and warranties expressly relate solely to an earlier date, in which case they shall be true and correct as of such earlier date, and (ii) no event has occurred and is continuing which constitutes a Default or an Event of Default.

(f) This Agreement may be executed in any number of counterparts, each of which when so executed and delivered shall be an original, but all of which shall constitute one and the same instrument. Delivery of an executed counterpart of this Agreement by telecopy or digital/electronic transmission (e.g., PDF format) shall be effective as an original and shall constitute a representation that an executed original shall be delivered.

(g) THIS AGREEMENT AND THE RIGHTS AND OBLIGATIONS OF THE PARTIES HEREUNDER SHALL BE GOVERNED BY AND CONSTRUED AND INTERPRETED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

[Signature pages follow]

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IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be duly executed as of the date first above written.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.

FIRST AMENDMENT TO THIRD AMENDED

AND RESTATED LOAN AGREEMENT

QUANTA SERVICES, INC.