Exhibit 31.1

I, James F. O’Neil III, certify that:

1. I have reviewed this amendment on Form 10-K/A to the annual report on Form 10-K of Quanta Services, Inc.;

2. Based on my knowledge, this report, as amended, does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report, as amended; and

3. Based on my knowledge, the financial statements, and other financial information included in this report, as amended, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report, as amended.

Date: May 31, 2013	By:	/s/ JAMES F. O’NEIL III
		James F. O’Neil III,
		President and Chief Executive Officer