POWER OF ATTORNEY LETTER

POWER OF ATTORNEY

Know all by these present, that the undersigned hereby constitutes and appoints
Vincent A. Mercaldi, signing singly, the undersigned's true and lawful
attorney-in-fact to:

1 execute for and on behalf of the undersigned, in the undersigned's
capacity as a director and or officer of Quanta Services, Inc. the
"Company", Forms 3, 4, and 5 in accordance with Section 16a of the
Securities Exchange Act of 1934 and the rules thereunder

2 do and perform any and all acts for and on behalf of the undersigned
which may be necessary or desirable to complete and execute any such
Form 3, 4, or 5, complete and execute any amendment or amendments
thereto, and timely file such form with the United States Securities
and Exchange Commission and any stock exchange or similar authority
and

3 take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney in fact, may be of
benefit to, in the best interest of, or legally required by, the
undersigned, it being understood that the documents executed by such
attorney in fact on behalf of the undersigned pursuant to this Power\
of Attorney shall be in such form and shall contain such terms and
conditions as such attorney in fact may approve in such attorney
in facts discretion.

The undersigned hereby grants to such attorney in-fact full power and
authority to do and perform any and every act and thing whatsoever
requisite, necessary, or proper to be done in the exercise of any
of the rights and powers herein granted, as fully to all intents
and purposes as the undersigned might or could do if personally
present, with full power of substitution or revocation, hereby
ratifying and confirming all that such attorney in fact, or such
attorney in fact's substitute or substitutes, shall lawfully do
or cause to be done by virtue of this power of attorney and the
rights and powers herein granted. The undersigned acknowledges
that the foregoing attorney in-fact, in serving in such capacity
at the request of the undersigned, are not assuming, nor is the
Company assuming, any of the undersigned's responsibilities to
comply with Section 16 of the Securities Exchange Act of 1934.

This Power of Attorney shall remain in full force and effect
until the undersigned is no longer required to file Forms 3, 4, and 5
with respect to the undersigned's holdings of and transactions in securities
issued by the Company, unless earlier revoked by the undersigned
in a signed writing delivered to the foregoing attorney in fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney
to be executed as of this 22nd day of November, 2005.

s/ Derrick A. Jensen