AMENDMENT NO. 1 TO THE QUANTA SERVICES, INC. NON-EMPLOYEE DIRECTOR DEFERRED COMPENSATION PLAN

Exhibit 10.4

AMENDMENT NO. 1

TO THE

QUANTA SERVICES, INC.

NON-EMPLOYEE DIRECTOR DEFERRED COMPENSATION PLAN

THIS AMENDMENT NO. 1 to the Quanta Services, Inc. Non-Employee Director Deferred Compensation Plan (effective as of April 30, 2013) is adopted by Quanta Services, Inc. (“Quanta”) as of the 20^th day of December 2013, effective as set forth herein.

RECITALS

WHEREAS, Quanta has adopted and maintains the Plan, which is a non-qualified deferred compensation plan intended to comply with applicable requirements of Section 409A of the Internal Revenue Code of 1986, as amended (the “Code”), pursuant to which non-employee directors are permitted to defer all or a portion of their eligible director fees under the Plan;

WHEREAS, Quanta desires to amend the Plan to eliminate the requirement that deferred amounts will be paid earlier than the scheduled payment date in the event of a separation from service prior to such scheduled payment date effective with respect to amounts deferred under the Plan by a Participant pursuant to a deferral agreement entered into on or after December 13, 2013; and

WHEREAS, Quanta has reserved the right to amend the Plan pursuant to Article 8 thereof.

NOW, THEREFORE, pursuant to Article 8 of the Plan, Quanta hereby amends the Plan, effective as of the date hereof, in the following respects:

1. Section 6.2(a) of the Plan is hereby amended in its entirety to read as follows:

Effective December 13, 2013, except as otherwise provided in Article 8 hereof, a Participant’s Account (other than the Pre-2014 Amount (as defined below)) shall be distributed to the Participant (or, in the case of a Participant’s death, his or her Beneficiary) in its entirety no later than sixty (60) days after the earlier to occur of the following: (i) a Change in Control, and (ii) the date designated in a Deferral Agreement, which date shall be 3, 5, 7 or 10 years from the Award Date or, if elected by the Participant in the Deferral Agreement, the earlier of such date and the Participant’s Separation from Service, unless a subsequent deferral election is made pursuant to Section 6.2(b). Solely with respect to the Pre-2014 Amount, except as otherwise provided in Article 8 hereof, a Participant’s Account shall be distributed to the Participant (or, in the case of a Participant’s death, his or her Beneficiary) in its entirety no later than sixty (60) days after the earliest to occur of the following: (i) a Participant’s Separation from Service; (ii) a Change in Control; and (iii) the date designated in a Deferral Agreement, which date shall be 3, 5, 7 or 10 years from the Award Date, unless a subsequent deferral election is made pursuant to Section 6.2(b). The “Pre-2014 Amount” means those amounts deferred under the Plan by a Participant pursuant to a Deferral Agreement entered into prior to December 13, 2013 and any earnings thereon.

IN WITNESS WHEREOF, Quanta has adopted this Amendment No. 1 to the Plan as of the day and year first written above.