Exhibit 4.1

SECOND SUPPLEMENTAL INDENTURE (this “Supplemental Indenture”), dated as of December 12, 2012, among Blair Park Services, LLC, a Delaware limited liability company, CCLC, Inc., a Delaware corporation, CMI Services, Inc., a Florida corporation, E A Technical Services, Inc., a Georgia corporation, Engineering Associates, Inc., a Georgia corporation, Global Enercom Management, Inc., a Delaware corporation, Golden State Utility Co., a Delaware corporation, InfraSource Telecommunication Services, LLC, a Delaware limited liability company, North Sky Communications, Inc., a Delaware corporation, Parkside Site & Utility Company Corporation, a Delaware corporation, Parkside Utility Construction Corp., a Delaware corporation, Pauley Construction Inc., an Arizona corporation, Professional Teleconcepts, Inc., an Illinois corporation, Professional Teleconcepts, Inc., a New York corporation, Quanta Wireless Solutions, Inc., a Delaware corporation, Spalj Construction Company, a Delaware corporation, Tjader, L.L.C., a Delaware corporation, Trawick Construction Company, Inc., a Florida corporation, VCI Construction, Inc., a Delaware corporation, VCI Utility Services, Inc., a Delaware corporation, Kanaan Communications, LLC, a Delaware limited liability company, and PBG Acquisition III, LLC, a Delaware limited liability company (each, a “Guaranteeing Subsidiary”), each, a subsidiary of Dycom Investments, Inc., a Delaware corporation (the “Company”), the Company, the other Guarantors (as defined in the Indenture referred to herein) and U.S. Bank National Association, as trustee under the Indenture referred to below (the “Trustee”).

W I T N E S S E T H

WHEREAS, the Company and the other Guarantors have heretofore executed and delivered to the Trustee an indenture, dated as of January 21, 2011 (the “Indenture”), providing for the issuance of 7.125% Senior Subordinated Notes due 2021 (the “Notes”);

WHEREAS, the Indenture provides that under certain circumstances a Guaranteeing Subsidiary shall execute and deliver to the Trustee a supplemental indenture pursuant to which such Guaranteeing Subsidiary shall unconditionally guarantee all of the Company’s Obligations under the Notes and the Indenture on the terms and conditions set forth herein (the “Note Guarantee”);

WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee is authorized to execute and deliver this Supplemental Indenture;

WHEREAS, this Supplemental Indenture has been duly authorized by all necessary corporate action on the part of the Company; and

WHEREAS, the Company has directed the Trustee to execute and deliver this Supplemental Indenture in accordance with Section 9.01 of the Indenture.

NOW, THEREFORE, in consideration of the foregoing and for other good and valuable consideration, the receipt of which is hereby acknowledged, each Guaranteeing Subsidiary and the Trustee mutually covenant and agree for the equal and ratable benefit of the Holders of the Notes as follows:

1. CAPITALIZED TERMS. Capitalized terms used herein without definition shall have the meanings assigned to them in the Indenture.

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2. AGREEMENT TO GUARANTEE. Each Guaranteeing Subsidiary hereby, jointly and severally, agrees to unconditionally guarantee on the terms and subject to the conditions set forth in the Note Guarantee and in the Indenture including but not limited to Article 11 thereof.

3. NO RECOURSE AGAINST OTHERS. No past, present or future director, officer, employee, incorporator, stockholder or agent of any Guaranteeing Subsidiary, as such, shall have any liability for any obligations of the Company or such Guaranteeing Subsidiary under the Notes, any Note Guarantees, the Indenture or this Supplemental Indenture or for any claim based on, in respect of, or by reason of, such obligations or their creation. Each Holder of the Notes by accepting a Note waives and releases all such liability. The waiver and release are part of the consideration for issuance of the Notes. Such waiver may not be effective to waive liabilities under the federal securities laws and it is the view of the SEC that such a waiver is against public policy.

4. NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW YORK SHALL GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL INDENTURE.

5. COUNTERPARTS. The parties may sign any number of copies of this Supplemental Indenture. Each signed copy shall be an original, but all of them together represent the same agreement.

6. EFFECT OF HEADINGS. The Section headings herein are for convenience only and shall not affect the construction hereof.

7. THE TRUSTEE. The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture or for or in respect of the recitals contained herein, all of which recitals are made solely by the applicable Guaranteeing Subsidiary and the Company.

[SIGNATURE PAGES FOLLOW]

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IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture to be duly executed and attested, all as of the date first above written.

Signature Page to Second Supplemental Indenture

Signature Page to Second Supplemental Indenture

Signature Page to Second Supplemental Indenture

Signature Page to Second Supplemental Indenture

Signature Page to Second Supplemental Indenture

Signature Page to Second Supplemental Indenture