Document:

<PAGE>
                                                                    EXHIBIT 4.1

                   AMENDMENT NO. 4 TO NOTE PURCHASE AGREEMENT

         This AMENDMENT NO. 4 TO NOTE PURCHASE AGREEMENT (this "AMENDMENT"),
dated as of October 9, 2003, is made by and among each OF QUANTA SERVICES, INC.,
a Delaware corporation (the "COMPANY") and each of the institutions listed on
Annex 1 hereto (such institutions being collectively referred to as the
"NOTEHOLDERS").

                                   BACKGROUND

         1. The Company and certain of the Noteholders are parties to that
certain Note Purchase Agreement (the "ORIGINAL NOTE PURCHASE AGREEMENT"), dated
as of March 1, 2000, that provides, among other things, for the sale by the
Company and the purchase by certain of the Noteholders of up to (a)
Seventy-Three Million Dollars ($73,000,000) in aggregate principal amount of the
Company's 8.46% Series 2000-A Senior Secured Notes, Tranche 1, due March 1, 2005
(the "SERIES A-1 NOTES"), (b) Forty-One Million Five Hundred Thousand Dollars
($41,500,000) in aggregate principal amount of the Company's 8.55% Series 2000-A
Senior Secured Notes, Tranche 2, due March 1, 2007 (the "SERIES A-2 NOTES") and
(c) Thirty-Five Million Five Hundred Thousand Dollars ($35,500,000) in aggregate
principal amount of the Company's 8.61% Series 2000-A Senior Secured Notes,
Tranche 3, due March 1, 2010 (the "SERIES A-3 NOTES" and, collectively with the
Series A-1 Notes and the Series A-2 Notes, the "SERIES A NOTES"). All of the
Series A Notes are currently outstanding.

         2. The Original Note Purchase Agreement has been supplemented in
certain respects pursuant to a First Supplement to Note Purchase Agreement (the
"FIRST SUPPLEMENT" and, together with the Original Note Purchase Agreement, the
"SUPPLEMENTED NOTE PURCHASE AGREEMENT"), dated as of September 1, 2000, by and
among the Company and certain of the Noteholders, that provides, among other
things, for the sale by the Company and the purchase by certain of the
Noteholders of up to (a) Thirty Million Dollars ($30,000,000) in aggregate
principal amount of the Company's 8.01% Series 2000-B Senior Secured Notes,
Tranche 1, due September 1, 2005 (the "SERIES B-1 NOTES"), (b) Five Million
Dollars ($5,000,000) in aggregate principal amount of the Company's 8.06% Series
2000-B Senior Secured Notes, Tranche 2, due September 1, 2006 (the "SERIES B-2
NOTES") and (c) Twenty-Five Million Dollars ($25,000,000) in aggregate principal
amount of the Company's 8.29% Series 2000-B Senior Secured Notes, Tranche 3, due
September 1, 2010 (the "SERIES B-3 NOTES" and, collectively with the Series B-1
Notes and the Series B-2 Notes, the "SERIES B NOTES" and the Series B Notes,
together with the Series A Notes, the "NOTES"). All of the Series B Notes are
currently outstanding.

         3. The Supplemented Note Purchase Agreement and the Notes were amended
in certain respects pursuant to Amendment No. 1 to Note Purchase Agreement,
dated as of August 12, 2002 ("AMENDMENT NO. 1"), Amendment No. 2 to Note
Purchase Agreement, dated as of December 20, 2002 ("AMENDMENT NO. 2") and
Amendment No. 3 to Note Purchase Agreement, dated as of September 30, 2003
("AMENDMENT NO. 3" and the Supplemented Note Purchase Agreement as amended by
Amendment No. 1, Amendment No. 2 and Amendment No. 3, the "EXISTING NOTE
PURCHASE AGREEMENT").

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         4. The Company and the Noteholders wish to amend the Existing Note
Purchase Agreement.

         NOW, THEREFORE, in order to induce the Noteholders to amend the
Existing Note Purchase Agreement and for other good and valuable consideration
(the receipt and sufficiency of which are hereby acknowledged), the Company
agrees with the Noteholders as follows:

SECTION 1.   DEFINED TERMS.

         All capitalized terms used, but not specifically defined, in this
Amendment have the respective meanings ascribed to them in the Existing Note
Purchase Agreement.

SECTION 2.   WARRANTIES AND REPRESENTATIONS.

         The Company warrants and represents to each Noteholder that as of the
date of this Amendment and as of the Fourth Amendment Effective Date (as defined
in Section 3):

         2.1 CORPORATE ORGANIZATION AND AUTHORITY. The Company is a corporation
duly organized, validly existing and in good standing under the laws of its
jurisdiction of incorporation, and is duly qualified as a foreign corporation
and is in good standing in each jurisdiction in which such qualification is
required by law, other than those jurisdictions as to which the failure to be so
qualified or in good standing could not, individually or in the aggregate,
reasonably be expected to have a Material Adverse Effect. The Company has the
corporate power and authority to transact the business it transacts and proposes
to transact, to execute and deliver this Amendment and to perform the provisions
hereof.

         2.2 NO MATERIAL ADVERSE CHANGE. Since December 31, 2002, except as
disclosed herein, in the Eleventh Amendment to the Third Amended and Restated
Credit Agreement or in one or more reports filed with the Securities and
Exchange Commission, there has been no change in the business, operations,
affairs, financial condition, assets or properties of the Company except for

              (a) changes in general, economic, market and industry conditions
         that are generally applicable to the Company and all other Persons that
         are in the same or similar businesses as the Company and are similarly
         situated, and

              (b) changes in the ordinary course of business,

that in the aggregate for all such changes, could not reasonably be expected to
have a Material Adverse Effect.

         2.3 FULL DISCLOSURE. Each written statement and all written materials
furnished by, or on behalf of, the Company to the Noteholders pursuant to
Sections 7.1 and 7.2 of the Existing Note Purchase Agreement, taken as a whole,
and each written statement and all written materials furnished by, or on behalf
of, the Company to the Noteholders in connection with this Amendment, taken as a
whole, do not contain any untrue statement of a material fact or omit a material
fact

                                       2

<PAGE>

necessary to make the statements contained therein not misleading in light of
the circumstances under which they were made. There is no fact known to the
Company which the Company has not disclosed to the Noteholders in writing which
could reasonably be expected to have a Material Adverse Effect.

         2.4 TRANSACTION IS LEGAL AND AUTHORIZED. The execution and delivery of
this Amendment by the Company, the consummation of each of the transactions
contemplated by this Amendment and the compliance by the Company with all the
provisions of this Amendment:

              (a) are within the corporate powers of the Company;

              (b) are in compliance with applicable law;

              (c) do not conflict with, result in any breach in any of the
         provisions of, constitute a default under, or result in the creation of
         any Lien upon any property of the Company under the provisions of, any
         order, judgment, decree or ruling of any court, arbitrator or
         Governmental Authority applicable to the Company;

              (d) do not conflict with, result in any breach of any of the
         provisions of, constitute a default under, or result in the creation of
         any Lien not permitted by ss.10.5 of the Existing Note Purchase
         Agreement upon any property of the Company under the provisions of, any
         charter instrument, bylaw or other constitutive document or instrument
         to which it is a party or by which it or any of its property is bound;
         and

              (e) do not in any material respect conflict with, result in any
         breach of any of the provisions of, constitute a default under, or
         result in the creation of any Lien not permitted by ss.10.5 of the
         Existing Note Purchase Agreement upon any property of the Company under
         the provisions of, any contract, agreement or indenture binding upon
         the Company or its property.

         2.5 AMENDMENT IS ENFORCEABLE. This Amendment is a legal, valid and
binding and enforceable obligation of the Company, enforceable against the
Company in accordance with its terms, except as the enforceability hereof may be
limited by applicable bankruptcy, reorganization, arrangement, insolvency,
moratorium or other similar laws affecting the enforceability of creditors'
rights generally and the application of general equitable principles.

         2.6 NO DEFAULTS. The Company is not in violation in any respect of any
term in any agreement or other instrument to which it is a party or by which it
or any of its property may be bound, except for such violations that, in the
aggregate for all such violations, could not reasonably be expected to have a
Material Adverse Effect.

2.7   PENDING LITIGATION.

              (a) There are no proceedings, actions or investigations pending,
         or to the knowledge of the Company, threatened against or affecting the
         Company in any court or before any Governmental Authority or
         arbitration board or tribunal that, in the aggregate

                                       3

<PAGE>

         for all such proceedings, actions and investigations, could reasonably
         be expected to have a Material Adverse Effect.

              (b) The Company is not in default with respect to any judgment,
         order, writ, injunction or decree of any court, Governmental Authority,
         arbitration board or tribunal that, in the aggregate for all such
         defaults, could reasonably be expected to have a Material Adverse
         Effect.

2.8 COMPLIANCE WITH LAW. The Company is not in violation of any law, ordinance,
governmental rule or regulation to which it is subject, except for such
violations that, in the aggregate for all such violations, could not reasonably
be expected to have a Material Adverse Effect.

         2.9 NO DEFAULTS. After giving effect to this Amendment, no Default or
Event of Default will exist.

SECTION 3.   CONDITIONS PRECEDENT.

         This Amendment shall have no effect until all of the following
conditions precedent shall have been fulfilled (such time of effectiveness being
herein referred to as THE "FOURTH AMENDMENT EFFECTIVE DATE"):

              (a) WARRANTIES AND REPRESENTATIONS TRUE. After giving effect to
         this Amendment, the warranties and representations set forth in the
         Existing Note Purchase Agreement and in Section 2 to this Amendment
         shall be true in all material respects (unless specifically limited to
         an earlier date, in which case, such representations and warranties
         were true as of such date).

              (b) NO PROHIBITED ACTION. No Default or Event of Default shall
         exist after giving effect to the consummation of the transactions
         contemplated by this Amendment.

              (c) CONSENT OF NOTEHOLDERS. The Company and the Required Holders
         shall have executed this Amendment.

              (d) PAYMENT OF NOTEHOLDER FEES AND EXPENSES. The Company shall
         have paid all fees and expenses of the Noteholders incurred in
         connection with this Amendment for which invoices have been delivered,
         including the fees and expenses of Bingham McCutchen LLP.

              (e) OFFICERS' CERTIFICATE. Each Noteholder shall have received a
         written certificate signed by an officer of the Company acceptable to
         the Required Holders as to (i) the absence of any action, suit,
         investigation or proceeding pending or, to the knowledge of the
         Company, threatened in any court or before any arbitrator or
         governmental authority that could reasonably be expected to materially
         and adversely affect (A) the financial condition of the Company and its
         Subsidiaries, taken as a whole, or (B) the ability of the Company and
         its Subsidiaries to perform their respective obligations under the
         Existing Note Purchase Agreement, the Notes or the Security

                                       4

<PAGE>

         Documents, as amended by this Amendment, (ii) the absence of any breach
         of any representation or warranty of the Company set out in the
         Existing Note Purchase Agreement, the Notes or the Security Documents,
         and (iii) the absence of any Default or Event of Default, after giving
         effect to this Amendment.

              (f) AMENDMENT OF BANK CREDIT AGREEMENT. An Eleventh Amendment to
         the Third Amended and Restated Secured Credit Agreement among the
         Company, as Borrower, the Financial Institutions party thereto, as
         Lenders, Bank of America, N.A., as Administrative Agent, and the other
         agents named therein (as amended, the "BANK CREDIT AGREEMENT") shall
         have been entered into by the Company and the Majority Lenders (as such
         term is defined in the Bank Credit Agreement), shall contain terms
         reasonably satisfactory to the Noteholders, and shall be in full force
         and effect, subject only to the effectiveness of this Amendment.

              (g) GUARANTORS' CONSENT. The Guarantors shall have executed and
         delivered the Consent attached hereto as Attachment A.

              (h) PROCEEDINGS SATISFACTORY. All proceedings taken in connection
         with the execution and delivery of this Amendment and the transactions
         contemplated hereby shall be reasonably satisfactory to the Noteholders
         and their special counsel.

SECTION 4.   AMENDMENTS TO EXISTING NOTE PURCHASE AGREEMENT.

         4.1 Section 10.16(f) is hereby amended by deleting the phrase
"$250,000,000" appearing in the first line thereof and replacing it with
"$275,000,000."

         4.2 Schedule B of the Existing Note Purchase Agreement is hereby
amended by adding the following definitions to read in their entirety as
follows:

              "AMENDMENT NO. 4" means that certain Amendment No. 4 to this Note
         Purchase Agreement, dated as of October 9, 2003.

              "FOURTH AMENDMENT EFFECTIVE DATE" means October 9, 2003.

SECTION 5.   EFFECT OF AMENDMENT.

         Except as expressly provided in this Amendment, the Existing Note
Purchase Agreement shall remain in full force and effect, without modification
or amendment. This Amendment shall be binding upon, and shall inure to the
benefit of, the successors and assigns of the parties hereto and the holders
from time to time of the Notes.

SECTION 6.   DUPLICATE ORIGINALS; EXECUTION IN COUNTERPART.

         Two or more duplicate originals of this Amendment may be signed by the
parties, each of which shall be an original but all of which together shall
constitute one and the same instrument. This Amendment may be executed in one or
more counterparts and shall be effective when at least

                                       5

<PAGE>

one counterpart shall have been executed by the Company and each of the
Noteholders (subject to Section 3 hereof) each as a party to this Amendment, and
each set of counterparts which, collectively, show execution by each such party
to this Amendment shall constitute one duplicate original.

SECTION 7.   GOVERNING LAW.

         THIS AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED AND ENFORCED IN
ACCORDANCE WITH, NEW YORK LAW WITHOUT REGARD TO PRINCIPLES OF CONFLICTS OF LAWS.

SECTION 8.                 RELEASE.

              (a) The Company and each Guarantor hereby unconditionally and
         irrevocably remises, acquits, and fully and forever releases and
         discharges the Noteholders and all respective affiliates and
         subsidiaries of the Noteholders, their respective officers, servants,
         employees, agents, attorneys, financial advisors, principals, directors
         and shareholders, and their respective heirs, legal representatives,
         successors and assigns (collectively, the "RELEASED LENDER PARTIES")
         from any and all claims, demands, causes of action, obligations,
         remedies, suits, damages and liabilities (collectively, the "BORROWER
         CLAIMS") of any nature whatsoever, whether now known, suspected or
         claimed, whether arising under common law, in equity or under statute,
         which the Company or any Guarantor ever had or now has against the
         Released Lender Parties which may have arisen at any time on or prior
         to the date of this Amendment and which were in any manner related to
         any of the Existing Note Purchase Agreement, the Notes or the Security
         Documents or the enforcement or attempted enforcement by the
         Noteholders of rights, remedies or recourses related thereto.

              (b) The Company and each Guarantor covenants and agrees never to
         commence, voluntarily aid in any way, prosecute or cause to be
         commenced or prosecuted against any of the Released Lender Parties any
         action or other proceeding based upon any of the Borrower Claims which
         may have arisen at any time on or prior to the date of this Amendment
         and were in any manner related to any of the Existing Note Purchase
         Agreement, the Notes or the Security Documents.

              (c) The agreements of the Company and each Guarantor set forth in
         this Section 9 shall survive termination of this Amendment, the
         Existing Note Purchase Agreement, the Notes and the Security Documents.

   [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK. NEXT PAGE IS SIGNATURE PAGE.]

                                       6

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         IN WITNESS WHEREOF, the Company and the Noteholders have executed this
Amendment as of the date first above written.

                                           QUANTA SERVICES, INC.

                                           By: /s/ JAMES H. HADDOX
                                               --------------------------------
                                               Name: James H. Haddox
                                               Title: Chief Financial Officer

ACCEPTED AND AGREED TO:

MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY

By:  David L. Babson and Company
     Incorporated, as Investment Advisor

By:  /s/ RICHARD MCGAULEY
     --------------------------------------
     Name: Richard McGauley
     Title: Managing Director

          Signature Page to Amendment No. 4 to Note Purchase Agreement

<PAGE>

         IN WITNESS WHEREOF, the Company and the Noteholders have executed this
Amendment as of the date first above written.

                                           QUANTA SERVICES, INC.

                                           By: /s/ JAMES H. HADDOX
                                               --------------------------------
                                               Name: James H. Haddox
                                               Title: Chief Financial Officer

ACCEPTED AND AGREED TO:

C.M. LIFE INSURANCE COMPANY

By:  David L. Babson and Company
     Incorporated, as Investment Advisor

By:  /s/ RICHARD MCGAULEY
     -----------------------------------
     Name: Richard McGauley
     Title:  Managing Director

          Signature Page to Amendment No. 4 to Note Purchase Agreement

<PAGE>

         IN WITNESS WHEREOF, the Company and the Noteholders have executed this
Amendment as of the date first above written.

                                           QUANTA SERVICES, INC.

                                           By: /s/ JAMES H. HADDOX
                                               --------------------------------
                                               Name: James H. Haddox
                                               Title: Chief Financial Officer

ACCEPTED AND AGREED TO:

UNITED OF OMAHA LIFE INSURANCE COMPANY

By:  /s/ EDWIN H. GARRISON, JR.
     ----------------------------------
     Name: Edwin H. Garrison, Jr.
     Title: First Vice President

          Signature Page to Amendment No. 4 to Note Purchase Agreement

<PAGE>

         IN WITNESS WHEREOF, the Company and the Noteholders have executed this
Amendment as of the date first above written.

                                            QUANTA SERVICES, INC.

                                            By: /s/ JAMES H. HADDOX
                                                -------------------------------
                                                Name: James H. Haddox
                                                Title: Chief Financial Officer

ACCEPTED AND AGREED TO:

COMPANION LIFE INSURANCE COMPANY

By:  /s/ EDWIN H. GARRISON, JR.
     ---------------------------------
     Name: Edwin H. Garrison, Jr.
     Title: Authorized Representative

          Signature Page to Amendment No. 4 to Note Purchase Agreement

<PAGE>

         IN WITNESS WHEREOF, the Company and the Noteholders have executed this
Amendment as of the date first above written.

                                           QUANTA SERVICES, INC.

                                           By:  /s/ JAMES H. HADDOX
                                                -------------------------------
                                                Name: James H. Haddox
                                                Title: Chief Financial Officer

ACCEPTED AND AGREED TO:

MINNESOTA LIFE INSURANCE COMPANY

By:  Advantus Capital Management, Inc.

By:  /s/ KATHLEEN H. PARKER
     ---------------------------------
     Name: Kathleen H. Parker
     Title: Vice President

          Signature Page to Amendment No. 4 to Note Purchase Agreement

<PAGE>

         IN WITNESS WHEREOF, the Company and the Noteholders have executed this
Amendment as of the date first above written.

                                            QUANTA SERVICES, INC.

                                            By:  /s/ JAMES H. HADDOX
                                                 ------------------------------
                                                 Name: James H. Haddox
                                                 Title: Chief Financial Officer

ACCEPTED AND AGREED TO:

AMERICAN FIDELITY ASSURANCE COMPANY

By:  Advantus Capital Management, Inc.

By:  /s/ KATHLEEN H. PARKER
     ---------------------------------
     Name: Kathleen H. Parker
     Title: Vice President

          Signature Page to Amendment No. 4 to Note Purchase Agreement

<PAGE>

         IN WITNESS WHEREOF, the Company and the Noteholders have executed this
Amendment as of the date first above written.

                                           QUANTA SERVICES, INC.

                                           By:  /s/ JAMES H. HADDOX
                                                -------------------------------
                                                Name: James H. Haddox
                                                Title: Chief Financial Officer

ACCEPTED AND AGREED TO:

MTL INSURANCE COMPANY

By:  Advantus Capital Management, Inc.

By:  /s/ KATHLEEN H. PARKER
     ---------------------------------
     Name: Kathleen H. Parker
     Title: Vice President

          Signature Page to Amendment No. 4 to Note Purchase Agreement

<PAGE>

         IN WITNESS WHEREOF, the Company and the Noteholders have executed this
Amendment as of the date first above written.

                                            QUANTA SERVICES, INC.

                                            By:  /s/ JAMES H. HADDOX
                                                 ------------------------------
                                                 Name: James H. Haddox
                                                 Title: Chief Financial Officer

ACCEPTED AND AGREED TO:

UNITY MUTUAL LIFE INSURANCE COMPANY - ANNUITY PORTFOLIO

By:  Advantus Capital Management, Inc.

By:  /s/ KATHLEEN H. PARKER
     ---------------------------------
     Name: Kathleen H. Parker
     Title: Vice President

          Signature Page to Amendment No. 4 to Note Purchase Agreement

<PAGE>

         IN WITNESS WHEREOF, the Company and the Noteholders have executed this
Amendment as of the date first above written.

                                          QUANTA SERVICES, INC.

                                          By:  /s/ JAMES H. HADDOX
                                               --------------------------------
                                               Name: James H. Haddox
                                               Title: Chief Financial Officer

ACCEPTED AND AGREED TO:

THE TRAVELERS INSURANCE COMPANY, FOR ITSELF
AND TWO OF ITS SEPARATE ACCOUNTS

By:  /s/ ROBERT M. MILLS
     ------------------------------------
     Name: Robert M. Mills
     Title: Investment Officer

          Signature Page to Amendment No. 4 to Note Purchase Agreement

<PAGE>

         IN WITNESS WHEREOF, the Company and the Noteholders have executed this
Amendment as of the date first above written.

                                           QUANTA SERVICES, INC.

                                           By:  /s/ JAMES H. HADDOX
                                                -------------------------------
                                                Name: James H. Haddox
                                                Title: Chief Financial Officer

ACCEPTED AND AGREED TO:

COLONIAL LIFE & ACCIDENT INSURANCE COMPANY

By:  Provident Investment Management, LLC, its Agent

By:  /s/ BEN VANCE
     -----------------------------------
     Name: Ben Vance
     Title: Vice President

          Signature Page to Amendment No. 4 to Note Purchase Agreement

<PAGE>

         IN WITNESS WHEREOF, the Company and the Noteholders have executed this
Amendment as of the date first above written.

                                         QUANTA SERVICES, INC.

                                         By:  /s/ JAMES H. HADDOX
                                              ---------------------------------
                                              Name: James H. Haddox
                                              Title: Chief Financial Officer

ACCEPTED AND AGREED TO:

UNUM LIFE INSURANCE COMPANY OF AMERICA

By:  Provident Investment Management, LLC, its Agent

By:  /s/ BEN VANCE
     ------------------------------
     Name: Ben Vance
     Title: Vice President

          Signature Page to Amendment No. 4 to Note Purchase Agreement

<PAGE>

         IN WITNESS WHEREOF, the Company and the Noteholders have executed this
Amendment as of the date first above written.

                                         QUANTA SERVICES, INC.

                                         By:  /s/ JAMES H. HADDOX
                                              ---------------------------------
                                              Name: James H. Haddox
                                              Title: Chief Financial Officer

ACCEPTED AND AGREED TO:

THRIVENT FINANCIAL FOR LUTHERANS (FORMERLY AID ASSOCIATION FOR LUTHERANS AND
SUCCESSOR BY MERGER TO LUTHERAN BROTHERHOOD)

By:  /s/ MARK SWENSON
     ----------------------------------
     Name: Mark O. Swenson
     Title: Vice President

          Signature Page to Amendment No. 4 to Note Purchase Agreement

<PAGE>

         IN WITNESS WHEREOF, the Company and the Noteholders have executed this
Amendment as of the date first above written.

                                           QUANTA SERVICES, INC.

                                           By:  /s/ JAMES H. HADDOX
                                                -------------------------------
                                                Name: James H. Haddox
                                                Title: Chief Financial Officer

ACCEPTED AND AGREED TO:

MODERN WOODMEN OF AMERICA

By:  /s/ MICHAEL E. DAU
     --------------------------------------
     Name: Michael E. Dau
     Title:  Manager, Fixed Income Division

          Signature Page to Amendment No. 4 to Note Purchase Agreement

<PAGE>

                                     ANNEX 1

Massachusetts Mutual Life Insurance Company
c/o David L. Babson & Company Inc.
1500 Main Street, Suite 2800
Springfield, MA 01115

C.M. Life Insurance Company
c/o David L. Babson & Company Inc.
1500 Main Street, Suite 2800
Springfield, MA 01115

United of Omaha Life Insurance Company
Mutual of Omaha Plaza
Omaha, NE 68175

Companion Life Insurance Company
Mutual of Omaha Plaza
Omaha, NE 68175

New York Life Insurance and Annuity Corporation
51 Madison Avenue
New York, NY 10010-1603

Minnesota Life Insurance Company
400 Robert Street North
St. Paul, MN 55101

American Fidelity Assurance Company
400 Robert Street North
St. Paul, MN 55101

MTL Insurance Company
400 Robert Street North
St. Paul, MN 55101

Unity Mutual Life Insurance Company - Annuity Portfolio
400 Robert Street North
St. Paul, MN 55101

Protective Life Insurance Company
P.O. Box 2606
Birmingham, AL 35202

                                   Annex 1-1

<PAGE>

Allstate Life Insurance Company
3075 Sanders Road, Suite G3A
Northbrook, IL  60062-7127

American Heritage Life Insurance Company
3075 Sanders Road, Suite G3A
Northbrook, IL  60062-7127

The Travelers Insurance Company, for itself and two of its Separate Accounts
242 Trumbull Street
P.O. Box 150449
Hartford, CT 06115-0419

Southern Farm Bureau Life Insurance Company
1401 Livingston Lane
Jackson, MS 39213

Colonial Life & Accident Insurance Company
One Fountain Square
Chattanooga, TN 37402

Unum Life Insurance Company of America
One Fountain Square
Chattanooga, TN 37402

Thrivent Financial for Lutherans
625 Fourth Avenue South
Minneapolis, MN 55415-1624

Phoenix Life Insurance Company
56 Prospect Street
Hartford, CT 06115-0480

Great-West Life & Annuity Insurance Company
8515 East Orchard Road, 3rd Floor, Tower 2
Englewood, CO 80111

Modern Woodmen of America
1701 First Avenue
Rock Island, IL 61201

American United Life Insurance Company
One American Square
Indianapolis, IN 46206

                                   Annex 1-2

<PAGE>

Pioneer Mutual Life Insurance Company
One American Square
Indianapolis, IN 46206

The State Life Insurance Company
One American Square
Indianapolis, IN 46206

The Guardian Life Insurance Company of America
700 South Street
Pittsfield, MA 01201

Security Financial Life Insurance Co.
200 Centennial Mall North
Lincoln, NE 68508

                                   Annex 1-3

<PAGE>

                                  ATTACHMENT A

                              CONSENT OF GUARANTORS

         The undersigned Guarantors, as party to the Guaranty Agreement dated as
of March 1, 2000, hereby consent to the foregoing Amendment dated as of even
date herewith, to which this consent is attached, and confirm that the Guaranty
Agreement remains in full force and effect after giving effect thereto and
represent and warrant that there is no defense, counterclaim or offset of any
type or nature under the Guaranty Agreement.

Dated as of October 9, 2003

                             GUARANTORS:

                             ADVANCED TECHNOLOGIES AND INSTALLATION CORPORATION
                             ALLTECK LINE CONTRACTORS (USA), INC.
                             ARBY CONSTRUCTION, INC.
                             AUSTIN TRENCHER, INC.
                             BRADFORD BROTHERS, INC.
                             CCLC, INC.
                             COMMUNICATION MANPOWER, INC.
                             CONTI COMMUNICATIONS, INC.
                             CROCE ELECTRIC COMPANY, INC.
                             CROWN FIBER COMMUNICATIONS, INC.
                             DILLARD SMITH CONSTRUCTION COMPANY
                             DRIFTWOOD ELECTRICAL CONTRACTORS, INC.
                             ENVIRONMENTAL PROFESSIONAL ASSOCIATES, LIMITED
                             FIVE POINTS CONSTRUCTION CO.
                             GLOBAL ENERCOM MANAGEMENT, INC.
                             GOLDEN STATE UTILITY CO.
                             H.L. CHAPMAN PIPELINE CONSTRUCTION, INC.
                             HAINES CONSTRUCTION COMPANY
                             INTERMOUNTAIN ELECTRIC, INC.
                             IRBY CONSTRUCTION COMPANY
                             LINE EQUIPMENT SALES CO., INC.
                             MANUEL BROS., INC.
                             MEARS GROUP, INC.
                             MEJIA PERSONNEL SERVICES, INC.
                             METRO UNDERGROUND SERVICES, INC.
                             MUSTANG LINE CONTRACTORS, INC.
                             NETWORK ELECTRIC COMPANY
                             NORTH PACIFIC CONSTRUCTION CO., INC.
                             NORTH SKY COMMUNICATIONS, INC.
                             PAR ELECTRICAL CONTRACTORS, INC.
                             PARKSIDE SITE & UTILITY COMPANY CORPORATION
                             PARKSIDE UTILITY CONSTRUCTION CORP.
                             P.D.G. ELECTRIC COMPANY
                             POTELCO, INC.
                             PROFESSIONAL TELECONCEPTS, INC. (IL)
                             PROFESSIONAL TELECONCEPTS, INC. (NY)

                                 Attachment A-4

<PAGE>

                             PWR FINANCIAL COMPANY
                             QPC, INC.
                             QSI, INC.
                             QUANTA HOLDINGS, INC.
                             QUANTA XXXI ACQUISITION, INC.
                             QUANTA LI ACQUISITION, INC.
                             QUANTA LIV ACQUISITION, INC.
                             QUANTA LVII ACQUISITION, INC.
                             QUANTA LVIII ACQUISITION, INC.
                             QUANTA LIX ACQUISITION, INC.
                             QUANTA LX ACQUISITION, INC.
                             QUANTA LXI ACQUISITION, INC.
                             QUANTA LXII ACQUISITION, INC.
                             QUANTA LXIII ACQUISITION, INC.
                             QUANTA LXIV ACQUISITION, INC.
                             QUANTA LXV ACQUISITION, INC.
                             QUANTA LXVI ACQUISITION, INC.
                             QUANTA LXVII ACQUISITION, INC.
                             QUANTA LXVIII ACQUISITION, INC.
                             QUANTA LXIX ACQUISITION, INC.
                             QUANTA LXX ACQUISITION, INC.
                             QUANTA LXXI ACQUISITION, INC.
                             QUANTA LXXII ACQUISITION, INC.
                             QUANTA LXXIII ACQUISITION, INC.
                             QUANTA UTILITY INSTALLATION CO., INC.
                             R.A. WAFFENSMITH & CO., INC.
                             SOUTHEAST PIPELINE CONSTRUCTION, INC.
                             SOUTHWEST TRENCHING COMPANY, INC.
                             SOUTHWESTERN COMMUNICATIONS, INC.
                             SPALJ CONSTRUCTION COMPANY
                             SUMTER UTILITIES, INC.
                             THE RYAN COMPANY, INC.
                             TOM ALLEN CONSTRUCTION COMPANY
                             TRANS TECH ACQUISITION, INC.
                             TRAWICK CONSTRUCTION COMPANY, INC.
                             TTGP, INC.
                             TTLP. INC.
                             TTM, INC.
                             TXLP, INC.
                             UNDERGROUND CONSTRUCTION CO., INC.
                             UTILCO, INC.
                             VCI TELECOM, INC.
                             W.C. COMMUNICATIONS, INC.

                                 Attachment A-5

<PAGE>

                                 W.H.O.M. CORPORATION

                                 By:  /s/ DANA GORDON
                                      -----------------------------------------
                                 Name:   Dana Gordon
                                 Title:  President or Vice-President of
                                         each Guarantor

                                 QDE LLC
                                 QUANTA DELAWARE, INC.
                                 QUANTA ASSET MANAGEMENT LLC

                                 By:  /s/ LINDA BUBACZ
                                      -----------------------------------------
                                 Name:   Linda Bubacz
                                 Title:  President

                                 NORTHERN LINE LAYERS, LLC
                                 BY:      PAR ELECTRICAL CONTRACTORS, INC.,
                                          ITS SOLE MEMBER

                                 By:  /s/ DANA GORDON
                                      -----------------------------------------
                                 Name:   Dana Gordon
                                 Title:  Vice President

                                 COAST TO COAST, LLC
                                 BY:  ENVIRONMENTAL PROFESSIONAL ASSOCIATES,
                                      LIMITED, ITS MEMBER

                                 By:  /s/ DANA GORDON
                                      -----------------------------------------
                                 Name:   Dana Gordon
                                 Title:  Vice President

                                 DOT  05, LLC
                                 TJADER, L.L.C.
                                 OKAY CONSTRUCTION COMPANY, LLC
                                 BY: SPALJ CONSTRUCTION COMPANY, ITS MEMBER

                                 By:  /s/ DANA GORDON
                                      -----------------------------------------
                                 Name:   Dana Gordon
                                 Title:  Vice President

                                 LAKE NORMAN PIPELINE, LLC
                                 BY: BRADFORD BROTHERS, INC., ITS MEMBER

                                 By:  /s/ DANA GORDON
                                      -----------------------------------------
                                 Name:   Dana Gordon
                                 Title:  Vice President

                                 Attachment A-6

<PAGE>

                                 MEARS/CPG, LLC
                                 MEARS ENGINEERING, LLC
                                 MEARS/HDD, LLC
                                 MEARS SERVICES, LLC
                                 BY: MEARS GROUP, INC., THE SOLE MEMBER OF
                                     EACH OF THE FOREGOING LIMITED LIABILITY
                                     COMPANIES

                                 By:  /s/ DANA GORDON
                                      -----------------------------------------
                                 Name:   Dana Gordon
                                 Title:  Vice President

                                 S.K.S. PIPELINERS, LLC
                                 BY: ARBY CONSTRUCTION, INC., ITS MEMBER

                                 By:  /s/ DANA GORDON
                                      -----------------------------------------
                                 Name:    Dana Gordon
                                 Title:   Vice President

                                 TNS-VA, LLC
                                 BY: PROFESSIONAL TELECONCEPTS, INC. (NY),
                                     ITS MEMBER

                                 By:  /s/ DANA GORDON
                                      -----------------------------------------
                                 Name:   Dana Gordon
                                 Title:  Vice President

                                 LINECO LEASING, LLC
                                 BY: MUSTANG LINE CONTRACTORS, INC.,
                                     ITS SOLE MEMBER

                                 By:  /s/ DANA GORDON
                                      -----------------------------------------
                                 Name:   Dana Gordon
                                 Title:  Vice President

                                 AIRLAN TELECOM SERVICES, L.P.
                                 NORTH HOUSTON POLE LINE, L.P.
                                 LINDSEY ELECTRIC, L.P.
                                 DIGCO UTILITY CONSTRUCTION, L.P.
                                 BY: MEJIA PERSONNEL SERVICES, INC.,
                                     ITS GENERAL PARTNER

                                 By:  /s/ DANA GORDON
                                      -----------------------------------------
                                 Name:   Dana Gordon
                                 Title:  Vice President

                                Attachement A-7

<PAGE>

                                QUANTA SERVICES MANAGEMENT PARTNERSHIP, L.P.
                                QUANTA ASSOCIATES, L.P.
                                BY: QSI, INC., ITS GENERAL PARTNER

                                By:  /s/ DANA GORDON
                                      -----------------------------------------
                                Name:   Dana Gordon
                                Title:  Vice President

                                TRANS TECH ELECTRIC, L.P.
                                BY: TTGP, INC., ITS GENERAL PARTNER

                                By: /s/ DANA GORDON
                                      -----------------------------------------
                                Name:   Dana Gordon
                                Title:  Vice President

                                PWR NETWORK, LLC
                                BY: PWR FINANCIAL COMPANY, ITS SOLE MEMBER

                                By:  /s/ DANA GORDON
                                      -----------------------------------------
                                Name:   Dana Gordon
                                Title:  Vice President

                                Q RESOURCES, LLC
                                BY: QUANTA HOLDINGS, INC., ITS MEMBER

                                By:  /s/ DANA GORDON
                                      -----------------------------------------
                                Name:   Dana Gordon
                                Title:  Vice President

                                QUANTA RECEIVABLES, L.P.
                                BY: PWR NETWORK, LLC, ITS GENERAL PARTNER
                                BY: PWR FINANCIAL COMPANY, ITS SOLE MEMBER

                                By:  /s/ DANA GORDON
                                      -----------------------------------------
                                Name:   Dana Gordon
                                Title:  Vice President

                                TOTAL QUALITY MANAGEMENT SERVICES, LLC
                                BY: ENVIRONMENTAL PROFESSIONAL ASSOCIATES, LTD.

                                By:  /s/ DANA GORDON
                                      -----------------------------------------
                                Name:   Dana Gordon
                                Title:  Vice President

                                 Attachment A-8<PAGE>
                                                                   EXHIBIT 10.1

                               ELEVENTH AMENDMENT
             TO THIRD AMENDED AND RESTATED SECURED CREDIT AGREEMENT

         THIS ELEVENTH AMENDMENT TO THIRD AMENDED AND RESTATED SECURED CREDIT
AGREEMENT (this "Amendment"), dated as of October 9, 2003, is entered into among
QUANTA SERVICES, INC., a Delaware corporation (the "Borrower"), the Lenders
(defined below) who are signatories hereto, and BANK OF AMERICA, N.A., as
administrative agent for the Lenders (in such capacity, the "Agent").
Capitalized terms used but not defined in this Amendment have the meaning given
them in the Credit Agreement (defined below).

                                   BACKGROUND

         A. The Borrower is party to that certain Third Amended and Restated
Secured Credit Agreement dated as of June 14, 1999 (as amended through the date
hereof and as may be further amended, restated or supplemented from time to
time, the "Credit Agreement"), among the Borrower, the Agent, and the lenders
from time to time party to the Credit Agreement (each a "Lender" and
collectively, the "Lenders").

         B. The Borrower, Majority Lenders and the Agent desire to make certain
amendments to the Credit Agreement.

         NOW, THEREFORE, in consideration of the covenants, conditions and
agreements hereinafter set forth, and for other good and valuable consideration,
the receipt and adequacy of which are all hereby acknowledged, the Borrower,
Majority Lenders and the Agent covenant and agree as follows:

         1. AMENDMENTS TO CREDIT AGREEMENT. The Credit Agreement is hereby
amended as follows:

              (a) Amendment to Section 6.10(a). Clause (a) of Section 6.10 is
         amended by adding a new sentence at the end thereto to read as follows:

              The amount of payments permitted pursuant to the foregoing clauses
              (D) and (E) shall be deemed to include the $15,000,000 which the
              Borrower is permitted to retain from the net offering proceeds in
              accordance with Section 2.10(c).

              (b) Amendment to Section 6.14. Section 6.14(i) is amended and
         restated in its entirety, as follows:

                           (i) Indebtedness not to exceed $275,000,000 at any
                  time under the 2003 Note Purchase Agreement, including without
                  limitation, the Indebtedness under the 2003 Convertible
                  Subordinated Notes; provided that, such Indebtedness is
                  unsecured and upon terms not materially less favorable than
                  the terms of the Convertible Subordinated Notes and is
                  otherwise on terms reasonably satisfactory to the Agent,
                  including without limitation ranking subordination terms at
                  least as favorable to the Lenders as those contained in the
                  Convertible Subordinated

<PAGE>

                  Notes, and provided further that all net cash proceeds from
                  the issuance of such Indebtedness are applied in accordance
                  with SECTION 2.10(C) of this Agreement, which contemplates
                  that such net cash proceeds in excess of $15,000,000 (which
                  $15,000,000 the Borrower is permitted to retain consistent
                  with Section 2.10(c)) will be allocated to the Lenders and to
                  the holders of the Senior Notes (based on the proportion of
                  the Commitment Amount under this Agreement and the proportion
                  of the outstanding principal amount of the Senior Notes to
                  the sum of both) and applied as follows: (A) with respect to
                  the proceeds allocated to the Lenders, paid to the Agent as
                  a prepayment of the Loans, and if all Loans have been
                  satisfied, to the Agent as cash collateral for the
                  outstanding L/C Obligations (which security interest shall
                  be expressly senior to any security interest in
                  such cash collateral which secures the Senior Notes),
                  in each case together with a corresponding, automatic
                  and permanent reduction of the Commitment Amount by the amount
                  of net proceeds that would be allocated to the Lenders if the
                  Loans and L/C Obligations exceeded such amount of net proceeds
                  (and not any lesser amount which may ultimately be allocated
                  to the Lenders if the Loans and L/C Obligations are less than
                  such amount of net proceeds), and if all of the L/C
                  Obligations have been so cash collateralized, to the holders
                  of the Senior Notes to be applied in accordance with Section
                  8.8(e) of the Note Purchase Agreement, and (B) with respect to
                  the proceeds allocated to the holders of the Senior Notes,
                  paid to such holders to be applied in accordance with Section
                  8.8(e) of the Note Purchase Agreement; and

              (c) Notwithstanding anything in this Agreement to the contrary,
         the Borrower shall be permitted to disregard any Make-Whole Amount (as
         defined in the Note Purchase Agreement) paid or required to be paid as
         a result of or in connection with the 2003 Note Purchase Agreement or
         any offering or issuance of the 2003 Convertible Subordinated Notes for
         purposes of any determination of the Borrower's compliance with any
         covenant contained in Section 6.20, 6.21, 6.22, 6.23 or 6.24 of this
         Agreement.

         2. REPRESENTATIONS AND WARRANTIES. Each of the Borrower and the
Guarantors represents and warrants to the Lenders that (a) it possesses all
requisite power and authority to execute, deliver and comply with the terms of
this Amendment, (b) this Amendment has been duly authorized and approved by all
requisite corporate, partnership or limited liability company action, as
applicable, by it, (c) no consent of any Person that has not been obtained is
required for its execution and delivery of this Amendment, (d) its execution and
delivery of this Amendment will not violate its organizational documents, (e)
the representations and warranties in each Credit Document to which it is a
party are true and correct in all material respects on and as of the date of
this Amendment as though made on the date of this Amendment (except to the
extent that such representations and warranties speak to a specific date), (f)
it is in full compliance with all covenants and agreements contained in each
Credit Document to which it is a party, and (g) no Default or Event of Default
exists as of the date of this Amendment.

         3. RELEASE.

              (a) The Borrower and each Guarantor hereby unconditionally and
         irrevocably remises, acquits, and fully and forever releases and
         discharges the Agent and the Lenders

                                       2

<PAGE>

         and all respective affiliates and subsidiaries of the Agent and the
         Lenders, their respective officers, servants, employees, agents,
         attorneys, financial advisors, principals, directors and shareholders,
         and their respective heirs, legal representatives, successors and
         assigns (collectively, the "Released Lender Parties") from any and all
         claims, demands, causes of action, obligations, remedies, suits,
         damages and liabilities (collectively, the "Borrower Claims") of any
         nature whatsoever, whether now known, suspected or claimed, whether
         arising under common law, in equity or under statute, which the
         Borrower or any Guarantor ever had or now has against the Released
         Lender Parties which may have arisen at any time on or prior to the
         date of this Amendment and which were in any manner related to any of
         the Credit Documents or the enforcement or attempted enforcement by the
         Agent or the Lenders of rights, remedies or recourses related thereto.

              (b) The Borrower and each Guarantor covenants and agrees never to
         commence, voluntarily aid in any way, prosecute or cause to be
         commenced or prosecuted against any of the Released Lender Parties any
         action or other proceeding based upon any of the Borrower Claims which
         may have arisen at any time on or prior to the date of this Amendment
         and were in any manner related to any of the Credit Documents.

              (c) The agreements of the Borrower and each Guarantor set forth in
         this Section 3 shall survive termination of this Amendment and the
         other Credit Documents.

         4. CONDITIONS OF EFFECTIVENESS. This Amendment shall be effective,
without any other action by the parties hereto, immediately upon the
satisfaction or waiver of each of the following conditions precedent and only if
all such conditions precedent to effectiveness are satisfied or waived on or
prior to October 31, 2003:

              (a) the Agent shall receive counterparts of this Amendment
         executed by the Majority Lenders, the Borrower and the Guarantors;

              (b) the representations and warranties set forth in Section 2 of
         this Amendment shall be true and correct;

              (c) all reasonable out-of-pocket fees and expenses of the Agent in
         connection with the Credit Documents, including its reasonable
         out-of-pocket legal and other professional fees and expenses incurred
         by the Agent, including, without limitation, such fees and expenses of
         Winstead Sechrest & Minick P.C., shall have been paid;

              (d) the Agent shall receive evidence reasonably satisfactory to
         the Agent that the Borrower has entered into an amendment to the Note
         Purchase Agreement in form and substance reasonably satisfactory to the
         Agent;

              (e) the Agent shall receive a written certificate signed by an
         officer of the Borrower acceptable to the Agent as to (i) the absence
         of any action, suit, investigation or proceeding pending or, to the
         knowledge of the Borrower, threatened in any court or before any
         arbitrator or governmental authority that could reasonably be expected
         to materially and adversely affect (A) the financial condition of the
         Borrower and its Subsidiaries, taken as a whole, or (B) the ability of
         the Borrower and its Subsidiaries to

                                       3

<PAGE>

         perform their respective obligations under the Credit Documents, as
         amended by the Amendment, (ii) the absence of a material breach of any
         representation or warranty of the Borrower set out in the Credit
         Documents, and (iii) the absence of any Default or Event of Default,
         after giving effect to this Amendment; and

              (f) the Agent shall receive, in form and substance reasonably
         satisfactory to the Agent and its counsel, such other documents,
         certificates and instruments as the Agent shall reasonably require.

         5. CREDIT DOCUMENT: REFERENCE TO CREDIT AGREEMENT. This Amendment is a
Credit Document. Upon the effectiveness of this Amendment, 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
Amendment.

         6. COUNTERPARTS; EXECUTION VIA FACSIMILE. This Amendment may be
executed in one or more counterparts, each of which shall be deemed an original,
but all of which together shall constitute one and the same instrument. This
Amendment may be validly executed and delivered by facsimile or other electronic
transmission.

         7. GOVERNING LAW; BINDING EFFECT. This Amendment shall be governed by
and construed in accordance with the internal laws of the State of Texas and
shall be binding upon the Borrower, the Agent, each Lender and their respective
successors and assigns.

         8. HEADINGS. Section headings in this Amendment are included herein for
convenience of reference only and shall not constitute a part of this Amendment
for any other purpose.

         9. NO ORAL AGREEMENTS. THIS WRITTEN AGREEMENT AND THE OTHER CREDIT
DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL
AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE
PARTIES.

                     REMAINDER OF PAGE INTENTIONALLY BLANK.
                             SIGNATURE PAGES FOLLOW.

                                       4

<PAGE>

         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed and delivered by their proper and duly authorized officers as of
the day and year first above written.

BORROWER:

QUANTA SERVICES, INC.

By:  /s/ JAMES H. HADDOX
     -----------------------------------
     Name: James H. Haddox
     -----------------------------------
     Title: Chief Financial Officer
     -----------------------------------

AGENT:

BANK OF AMERICA, N.A., AS AGENT

By:  /s/ DAVID A. JOHANSON
     -----------------------------------
     Name: David A. Johanson
     -----------------------------------
     Title: Vice President
     -----------------------------------

                       ELEVENTH AMENDMENT TO THIRD AMENDED
                      AND RESTATED SECURED CREDIT AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

         Lender signature page to that certain Eleventh Amendment to Third
Amended and Restated Secured Credit Agreement dated to be effective as of
October 9, 2003, by and among Quanta Services, Inc., the Lenders party thereto,
and Bank of America, N.A., as Agent for the Lenders.

BANK OF AMERICA, N.A.

By: /s/ GARY L. MINGLE

Name: Gary L. Mingle

Title: Senior Vice President

<PAGE>

         Lender signature page to that certain Eleventh Amendment to Third
Amended and Restated Secured Credit Agreement dated to be effective as of
October 9, 2003, by and among Quanta Services, Inc., the Lenders party thereto,
and Bank of America, N.A., as Agent for the Lenders.

BANK OF NOVA SCOTIA

By: /s/ STEPHEN C. LEVI

Name: Stephen C. Levi

Title: Director

<PAGE>

         Lender signature page to that certain Eleventh Amendment to Third
Amended and Restated Secured Credit Agreement dated to be effective as of
October 9, 2003, by and among Quanta Services, Inc., the Lenders party thereto,
and Bank of America, N.A., as Agent for the Lenders.

CREDIT LYONNAIS NEW YORK BRANCH

By: /s/ ATTILA KOC

Name: Attila Koc

Title: Senior Vice President

<PAGE>

         Lender signature page to that certain Eleventh Amendment to Third
Amended and Restated Secured Credit Agreement dated to be effective as of
October 9, 2003, by and among Quanta Services, Inc., the Lenders party thereto,
and Bank of America, N.A., as Agent for the Lenders.

JP MORGAN CHASE

By: /s/ ROBERT MENDOZA

Name: Robert Mendoza

Title: Vice President

<PAGE>

         Lender signature page to that certain Eleventh Amendment to Third
Amended and Restated Secured Credit Agreement dated to be effective as of
October 9, 2003, by and among Quanta Services, Inc., the Lenders party thereto,
and Bank of America, N.A., as Agent for the Lenders.

GUARANTY BANK

By: /s/ SCOTT BREWER

Name: Scott Brewer

Title: VP

<PAGE>

         Lender signature page to that certain Eleventh Amendment to Third
Amended and Restated Secured Credit Agreement dated to be effective as of
October 9, 2003, by and among Quanta Services, Inc., the Lenders party thereto,
and Bank of America, N.A., as Agent for the Lenders.

WACHOVIA BANK, NATIONAL ASSOCIATION

By: /s/ STEVEN L. HIPSMAN

Name: Steven L. Hipsman

Title: Director

<PAGE>

         Lender signature page to that certain Eleventh Amendment to Third
Amended and Restated Secured Credit Agreement dated to be effective as of
October 9, 2003, by and among Quanta Services, Inc., the Lenders party thereto,
and Bank of America, N.A., as Agent for the Lenders.

COMERICA BANK

By: /s/ WILLIAM S. ROGERS

Name: William S. Rogers

Title: Vice President

<PAGE>

         Lender signature page to that certain Eleventh Amendment to Third
Amended and Restated Secured Credit Agreement dated to be effective as of
October 9, 2003, by and among Quanta Services, Inc., the Lenders party thereto,
and Bank of America, N.A., as Agent for the Lenders.

SUN TRUST BANK

By: /s/ J. SCOTT DEVINEY

Name: J. Scott Deviney

Title: Director

<PAGE>

         Lender signature page to that certain Eleventh Amendment to Third
Amended and Restated Secured Credit Agreement dated to be effective as of
October 9, 2003, by and among Quanta Services, Inc., the Lenders party thereto,
and Bank of America, N.A., as Agent for the Lenders.

LASALLE BANK NATIONAL ASSOCIATION

By: /s/ RICHARD J. KRESS

Name: Richard J. Kress

TITLE: FIRST VICE PRESIDENT

<PAGE>

                        GUARANTORS' CONSENT AND AGREEMENT

As an inducement to the Lenders to execute, and in consideration of the Lenders'
execution of this Amendment, each of the undersigned hereby consents to this
Amendment and agrees that the same shall in no way release, diminish, impair,
reduce or otherwise adversely affect the obligations and liabilities of the
undersigned under their respective Guaranties described in the Credit Agreement
executed by the undersigned, or any agreements, documents or instruments
executed by any of the undersigned, all of which obligations and liabilities
are, and shall continue to be, in full force and effect. This consent and
agreement shall be binding upon the undersigned, and their respective successors
and assigns, and shall inure to the benefit of the Lenders, and their respective
successors and assigns.

                             ADVANCED TECHNOLOGIES AND INSTALLATION CORPORATION
                             ALLTECK LINE CONTRACTORS (USA), INC.
                             ARBY CONSTRUCTION, INC.
                             AUSTIN TRENCHER, INC.
                             BRADFORD BROTHERS, INC.
                             CCLC, INC.
                             COMMUNICATION MANPOWER, INC.
                             CONTI COMMUNICATIONS, INC.
                             CROCE ELECTRIC COMPANY, INC.
                             CROWN FIBER COMMUNICATIONS, INC.
                             DILLARD SMITH CONSTRUCTION COMPANY
                             DRIFTWOOD ELECTRICAL CONTRACTORS, INC.
                             ENVIRONMENTAL PROFESSIONAL ASSOCIATES, LIMITED
                             FIVE POINTS CONSTRUCTION CO.
                             GLOBAL ENERCOM MANAGEMENT, INC.
                             GOLDEN STATE UTILITY CO.
                             H. L. CHAPMAN PIPELINE CONSTRUCTION, INC.
                             HAINES CONSTRUCTION COMPANY
                             INTERMOUNTAIN ELECTRIC, INC.
                             IRBY CONSTRUCTION COMPANY
                             LINE EQUIPMENT SALES CO., INC.
                             MANUEL BROS., INC.
                             MEARS GROUP, INC.
                             MEJIA PERSONNEL SERVICES, INC.
                             METRO UNDERGROUND SERVICES, INC.
                             MUSTANG LINE CONTRACTORS, INC.
                             NETWORK ELECTRIC COMPANY
                             NORTH PACIFIC CONSTRUCTION CO., INC.
                             NORTH SKY COMMUNICATIONS, INC.
                             PAR ELECTRICAL CONTRACTORS, INC.

                       ELEVENTH AMENDMENT TO THIRD AMENDED
                      AND RESTATED SECURED CREDIT AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                             PARKSIDE SITE & UTILITY COMPANY CORPORATION
                             PARKSIDE UTILITY CONSTRUCTION CORP.
                             P.D.G. ELECTRIC COMPANY
                             POTELCO, INC.
                             PROFESSIONAL TELECONCEPTS, INC. (IL)
                             PROFESSIONAL TELECONCEPTS, INC. (NY)
                             PWR FINANCIAL COMPANY
                             QPC, INC.
                             QSI, INC.
                             QUANTA HOLDINGS, INC.
                             QUANTA XXXI ACQUISITION, INC.
                             QUANTA LI ACQUISITION, INC.
                             QUANTA LIV ACQUISITION, INC.
                             QUANTA LVII ACQUISITION, INC.
                             QUANTA LVIII ACQUISITION, INC.
                             QUANTA LIX ACQUISITION, INC.
                             QUANTA LX ACQUISITION, INC.
                             QUANTA LXI ACQUISITION, INC.
                             QUANTA LXII ACQUISITION, INC.
                             QUANTA LXIII ACQUISITION, INC.
                             QUANTA LXIV ACQUISITION, INC.
                             QUANTA LXV ACQUISITION, INC.
                             QUANTA LXVI ACQUISITION, INC.
                             QUANTA LXVII ACQUISITION, INC.
                             QUANTA LXVIII ACQUISITION, INC.
                             QUANTA LXIX ACQUISITION, INC.
                             QUANTA LXX ACQUISITION, INC.
                             QUANTA LXXI ACQUISITION, INC.
                             QUANTA LXXII ACQUISITION, INC.
                             QUANTA LXXIII ACQUISITION, INC.
                             QUANTA UTILITY INSTALLATION CO., INC,
                             R. A. WAFFENSMITH & CO., INC.
                             SOUTHEAST PIPELINE CONSTRUCTION, INC.
                             SOUTHWESTERN COMMUNICATIONS, INC.
                             SOUTHWEST TRENCHING COMPANY, INC.
                             SPALJ CONSTRUCTION COMPANY
                             SUMTER UTILITIES, INC.
                             THE RYAN COMPANY, INC.
                             TOM ALLEN CONSTRUCTION COMPANY
                             TRANS TECH ACQUISITION, INC.
                             TRAWICK CONSTRUCTION COMPANY, INC.
                             TTGP, INC.
                             TTLP, INC.
                             TTM, INC.
                             TXLP, INC.
                             UNDERGROUND CONSTRUCTION CO., INC.

                       ELEVENTH AMENDMENT TO THIRD AMENDED
                      AND RESTATED SECURED CREDIT AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                UTILCO, INC.
                                VCI TELCOM, INC.
                                                 W.C. COMMUNICATIONS, INC.
                                W.H.O.M. CORPORATION

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, President or Vice President
                                     of each Guarantor

                                QDE LLC
                                QUANTA DELAWARE, INC.
                                QUANTA ASSET MANAGEMENT LLC

                                By:  /s/ LINDA BUBACZ
                                     ------------------------------------------
                                     Linda Bubacz, President

                                COAST TO COAST, LLC

                                By:  Environmental Professional Associates,
                                     Limited, Its Member

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, Vice President

                                NORTHERN LINE LAYERS, LLC

                                By: PAR Electrical Contractors, Inc., Its Member

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, Vice President

                       ELEVENTH AMENDMENT TO THIRD AMENDED
                      AND RESTATED SECURED CREDIT AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                DOT 05, LLC
                                TJADER, L.L.C.
                                OKAY CONSTRUCTION COMPANY, LLC

                                By:   Spalj Construction Company, Its Member

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, Vice President

                                LAKE NORMAN PIPELINE, LLC

                                By:   Bradford Brothers, Inc., Its Member

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, Vice President

                                MEARS/CPG, LLC
                                MEARS ENGINEERING, LLC
                                MEARS/HDD, LLC
                                MEARS SERVICES, LLC

                                By:  Mears Group, Inc., The Sole Member of each
                                     of the foregoing limited liability
                                     companies

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, Vice President

                                S.K.S. PIPELINERS, LLC

                                By:   Arby Construction, Inc., Its Member

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, Vice President

                       ELEVENTH AMENDMENT TO THIRD AMENDED
                      AND RESTATED SECURED CREDIT AGREEMENT
                                 SIGNATURE PAGE

<PAGE>
                                TNS-VA, LLC

                                By: Professional Teleconcepts, Inc. (NY),
                                    Its Member

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, Vice President

                                LINECO LEASING, LLC

                                By:  Mustang Line Contractors, Inc.,
                                     Its Sole Member

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, Vice President

                                AIRLAN TELECOM SERVICES, L.P.
                                NORTH HOUSTON POLE LINE, L.P.
                                LINDSEY ELECTRIC, L.P.
                                DIGCO UTILITY CONSTRUCTION, L.P.

                                By:  Mejia Personnel Services, Inc., Its
                                     General Partner

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, Vice President

                                QUANTA SERVICES MANAGEMENT PARTNERSHIP, L.P.
                                QUANTA ASSOCIATES, L.P.

                                By:   QSI, Inc., Its General Partner

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, Vice President

                       ELEVENTH AMENDMENT TO THIRD AMENDED
                      AND RESTATED SECURED CREDIT AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                TRANS TECH ELECTRIC, L.P.

                                By:  TTGP, Inc., Its General Partner

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, Vice President

                                PWR NETWORK, LLC

                                By:   PWR Financial Company, Its Sole Member

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, Vice President

                                Q RESOURCES, LLC

                                By:  Quanta Holdings, Inc.

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, Vice President

                                QUANTA RECEIVABLES, L.P.

                                By:  PWR Network, LLC, Its General Partner

                                By:  PWR Financial Company, Its Sole Member

                                By:  /s/ DANA GORDON
                                     ------------------------------------------
                                     Dana Gordon, Vice President

                       ELEVENTH AMENDMENT TO THIRD AMENDED
                      AND RESTATED SECURED CREDIT AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                              TOTAL QUALITY MANAGEMENT SERVICES, LLC

                              By:  Environmental Professional Associates, Ltd.,
                                   Its Sole Member

                              By:  /s/ DANA GORDON
                                   ------------------------------------------
                                   Dana Gordon, Vice President

                       ELEVENTH AMENDMENT TO THIRD AMENDED
                      AND RESTATED SECURED CREDIT AGREEMENT
                                 SIGNATURE PAGE

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