THIRDAMENDMENT

Exhibit 10.5.2

THIRD AMENDMENT

THIRD AMENDMENT, dated as of December 16, 2005 (this “Amendment”), to the Amended and Restated Credit Agreement, dated as of May 12, 2004 (the “Credit Agreement”), among INFRASOURCE SERVICES, INC., a Delaware corporation (“Holdings”), INFRASOURCE INCORPORATED, a Delaware corporation (the “Borrower”), the several banks and other financial institutions or entities from time to time parties thereto (the “Lenders”), LASALLE BANK NATIONAL ASSOCIATION, as syndication agent, and BARCLAYS BANK PLC, as administrative agent (the “Administrative Agent”).

W I T N E S S E T H:

WHEREAS, the Borrower has requested that the Lenders agree to amend certain provisions in the Credit Agreement upon the terms and subject to the conditions set forth herein; and

WHEREAS, the Lenders have agreed to such amendments only upon the terms and subject to the conditions set forth herein;

NOW, THEREFORE, in consideration of the premises and the mutual covenants contained herein and in the Credit Agreement, the parties hereto hereby agree as follows:

1.             Defined Terms.  Unless otherwise defined herein, all capitalized terms used herein shall have the meanings given to them in the Credit Agreement.

2.             Amendment to Section 1.1 (Defined Terms).  Section 1.1 of the Credit Agreement is hereby amended by deleting clause (h) of the “Consolidated Adjusted EBITDA” definition in its entirety and substituting in lieu thereof the following:

“(h)  each of (x) non-cash expenses relating to stock-based compensation, including stock options, restricted stock grants and employee stock purchase plans and (y) cash payments or cash distributions in compliance with Section 7.6(b)”

3.             Amendment to Section 7.7 (Capital Expenditures).  Section 7.7 of the Credit Agreement is hereby amended by deleting the first sentence of such Section in its entirety and substituting in lieu thereof the following:

“Make or commit to make any Capital Expenditure, except Capital Expenditures of the Borrower and its Subsidiaries in the ordinary course of business not exceeding, for any fiscal year of the Borrower set forth in the table below, the amount set forth in such table for such fiscal year; provided, that (a) up to 50% of any such amount referred to above, if not so expended in the fiscal year for which it is permitted, may be carried over for expenditure in the next succeeding fiscal year and (b) Capital Expenditures made pursuant to this Section during any fiscal year shall be deemed made, first, in respect of amounts permitted for such fiscal year as provided above and, second, in respect of amounts carried over from the prior fiscal year pursuant to clause (a) above.”

4.             Representations and Warranties.  (a)  Credit Agreement Representations and Warranties.  On and as of the date hereof and after giving effect to this Amendment, Holdings and the

Borrower hereby confirm, reaffirm and restate the representations and warranties set forth in Sections 4 of the Credit Agreement mutatis mutandis, except to the extent that such representations and warranties expressly relate to a specific earlier date in which case Holdings and the Borrower hereby confirm, reaffirm and restate such representations and warranties as of such earlier date.

(b)           Power; Authorization; Enforceable Obligations.  Each Loan Party has the requisite corporate or other power and authority, and the legal right, to make, deliver and perform the Loan Documents to which it is a party, as amended, in the case of the Credit Agreement, by this Amendment.  Each Loan Party has taken all necessary steps to authorize the execution, delivery and performance of Loan Documents to which it is a party, as amended, in the case of the Credit Agreement, by this Amendment.  The Credit Agreement, as amended by this Amendment, continues to constitute a legal, valid and binding obligation of each Loan Party party thereto, enforceable against each such Loan Party in accordance with its terms, except as enforceability maybe limited by applicable bankruptcy, insolvency, reorganization, moratorium or similar laws affecting the enforcement of creditors’ rights generally and by general equitable principles (whether enforcement is sought by proceedings in equity or at law).

(c)           No Legal Bar.  The execution, delivery and performance of this Amendment and any other related documents will not violate any Requirement of Law or any material Contractual Obligation of any Group Member and will not result in, or require, the creation or imposition of any Lien on any of their respective properties or revenue pursuant to any Requirement of Law or any such material Contractual Obligation (other than the Liens created by the Security Documents).

5.             Conditions to Effectiveness.  This Amendment shall become effective on the date upon which the Administrative Agent shall have received this Amendment, executed by the Administrative Agent, the Borrower, Holdings, the Subsidiary Guarantors and the Required Lenders.

6.             Continuing Effect.  Except as expressly amended hereby, the Credit Agreement shall continue to be and shall remain in full force and effect in accordance with its terms.

7.             Expenses.  The Borrower agrees to pay and reimburse the Administrative Agent for all of its reasonable out-of-pocket costs and expenses incurred in connection with the negotiation, preparation, execution and delivery of this Amendment, including the reasonable fees and expenses of counsel.

8.             Counterparts.  This Amendment may be executed on any number of separate counterparts, and all of said counterparts taken together shall be deemed to constitute one and the same instrument. Delivery of an executed signature page of this Amendment by facsimile transmission shall be effective as delivery of a manually executed counterpart hereof.

9.             GOVERNING LAW.  THIS AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED AND INTERPRETED IN ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK.

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.

ACKNOWLEDGEMENT AND CONSENT

Each of the undersigned Subsidiary Guarantors hereby acknowledges and consents to the foregoing Third Amendment.