POWER OF ATTORNEY LETTER

POWER OF ATTORNEY

Know all by these present, that the undersigned hereby constitutes and appoints
each of Dana A. Gordon and 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 undersigneds 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 uch 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 each 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 facts 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 attorneys in fact in serving in such capacity
at the request of the undersigned are not assuming nor is the
Company assuming any of the undersigneds 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 undersigneds holdings of and transactions in securities
issued by the Company unless earlier revoked by the undersigned
in a signed writing delivered to the foregoing attorneys in fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of
Attorney to be executed as of this 26th day of May 2005.
/s/ Worthing F Jackman