**Exhibit 4(f)**

**SUPPLEMENTAL INDENTURE**

Supplemental Indenture (this“Supplemental Indenture”), dated as of July 8, 2008, between Energy Future Intermediate Holding Company LLC (formerly known as InfrastruX Energy Services BPL LLC), a Delaware limited liability company (the “NewGuaranteeing Subsidiary”), a subsidiary of Energy Future Holdings Corp. (the “Issuer”), and The Bank of New York Mellon (formerly known as The Bank of New York), as trustee (the “Trustee”). 

W I T N E S S E T H 

WHEREAS, each of the Issuer and the Guarantors (as defined in the Indenture referred to below) has heretofore executed and delivered to the Trustee an Indenture (the “Indenture”), dated as of October 31, 2007,providing for the issuance of an unlimited aggregate principal amount of 10.875% Senior Notes due 2017 and 11.250%/12.000% Senior Toggle Notes due 2017 (together, the “Senior Notes”); 

WHEREAS, Energy Future Intermediate Holding Company LLC, a Delaware limited liability company (the “Old Guarantor”), wasmerged with and into the New Guaranteeing Subsidiary, which successor entity, pursuant to Section 5.01(c)(1)(B) of the Indenture, has assumed all of the obligations of the Old Guarantor under the Indenture and the Old Guarantor’s relatedGuarantee; 

WHEREAS, the Indenture provides that under certain circumstances the New Guaranteeing Subsidiary shall execute anddeliver to the Trustee a supplemental indenture pursuant to which the New Guaranteeing Subsidiary shall unconditionally guarantee all of the Issuer’s Obligations under the Senior Notes and the Indenture on the terms and conditions set forthherein and under the Indenture (the “Guarantee”); and 

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

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

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

2. ASSUMPTIONOFTHEINDENTUREANDTHEGUARANTEE. The New Guaranteeing Subsidiary, as the successor entity in the above-referenced merger, hereby assumes the Old Guarantor’s obligations under the Indenture and the Guarantee.

3. AGREEMENTTO GUARANTEE. The New Guaranteeing Subsidiary hereby agrees asfollows: 

(a) Along with all Guarantors named in the Indenture, to jointly and severally unconditionallyguarantee to each Holder of a Senior Note authenticated and delivered by the Trustee and to the Trustee and its successors and assigns, irrespective of the validity and enforceability of the Indenture, the Senior Notes or the obligations of theIssuer hereunder or thereunder, that: 

(i) the principal of and interest, premium and Additional Interest, ifany, on the Senior Notes will be promptly paid in full when due, whether at maturity, by acceleration, redemption or otherwise, and interest on the overdue principal of and interest on the Senior Notes, if any, if lawful, and all other obligationsof the Issuer to the Holders or the Trustee hereunder or thereunder will be promptly paid in full or performed, all in accordance with the terms hereof and thereof; and 

 

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(ii) in case of any extension of time of payment or renewal of any SeniorNotes or any of such other obligations, that same will be promptly paid in full when due or performed in accordance with the terms of the extension or renewal, whether at stated maturity, by acceleration or otherwise. Failing payment when due of anyamount so guaranteed or any performance so guaranteed for whatever reason, the Guarantors and the New Guaranteeing Subsidiary shall be jointly and severally obligated to pay the same immediately. This is a guarantee of payment and not a guarantee ofcollection. 

(b) The obligations hereunder shall be unconditional, irrespective of the validity, regularity orenforceability of the Senior Notes or the Indenture, the absence of any action to enforce the same, any waiver or consent by any Holder of the Senior Notes with respect to any provisions hereof or thereof, the recovery of any judgment against theIssuer, any action to enforce the same or any other circumstance which might otherwise constitute a legal or equitable discharge or defense of a guarantor. 

(c) The following is hereby waived: diligence, presentment, demand of payment, filing of claims with a court in the event of insolvency or bankruptcy of the Issuer, any right to require a proceeding firstagainst the Issuer, protest, notice and all demands whatsoever. 

(d) Except as set forth in Section 6hereto, this Guarantee shall not be discharged except by complete performance of the obligations contained in the Senior Notes, the Indenture and this Supplemental Indenture, and the New Guaranteeing Subsidiary accepts all obligations of a Guarantorunder the Indenture. 

(e) If any Holder or the Trustee is required by any court or otherwise to return to theIssuer, the Guarantors (including the New Guaranteeing Subsidiary), or any custodian, trustee, liquidator or other similar official acting in relation to either the Issuer or the Guarantors, any amount paid either to the Trustee or such Holder, thisGuarantee, to the extent theretofore discharged, shall be reinstated in full force and effect. 

(f) The NewGuaranteeing Subsidiary shall not be entitled to any right of subrogation in relation to the Holders in respect of any obligations guaranteed hereby until payment in full of all obligations guaranteed hereby. 

(g) As between the New Guaranteeing Subsidiary, on the one hand, and the Holders and the Trustee, on the other hand,(x) the maturity of the obligations guaranteed hereby may be accelerated as provided in Article 6 of the Indenture for the purposes of this Guarantee, notwithstanding any stay, injunction or other prohibition preventing such acceleration inrespect of the obligations guaranteed hereby, and (y) in the event of any declaration of acceleration of such obligations as provided in Article 6 of the Indenture, such obligations (whether or not due and payable) shall forthwith become dueand payable by the New Guaranteeing Subsidiary for the purpose of this Guarantee. 

 

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(h) The New Guaranteeing Subsidiary shall have the right to seekcontribution from any non-paying Guarantor so long as the exercise of such right does not impair the rights of the Holders under this Guarantee. 

(i) Pursuant to Section 10.02 of the Indenture, after giving effect to all other contingent and fixed liabilities that are relevant under any applicable Bankruptcy or fraudulent conveyance laws, andafter giving effect to any collections from, rights to receive contribution from or payments made by or on behalf of any other Guarantor in respect of the obligations of such other Guarantor under Article 10 of the Indenture, this new Guaranteeshall be limited to the maximum amount permissible such that the obligations of such New Guaranteeing Subsidiary under this Guarantee will not constitute a fraudulent transfer or conveyance. 

(j) This Guarantee shall remain in full force and effect and continue to be effective should any petition be filed by oragainst the Issuer for liquidation, reorganization, should the Issuer become insolvent or make an assignment for the benefit of creditors or should a receiver or trustee be appointed for all or any significant part of the Issuer’s assets, andshall, to the fullest extent permitted by law, continue to be effective or be reinstated, as the case may be, if at any time payment and performance of the Senior Notes are, pursuant to applicable law, rescinded or reduced in amount, or mustotherwise be restored or returned by any obligee on the Senior Notes and Guarantee, whether as a “voidable preference”, “fraudulent transfer” or otherwise, all as though such payment or performance had not been made. In the eventthat any payment or any part thereof, is rescinded, reduced, restored or returned, the Senior Note shall, to the fullest extent permitted by law, be reinstated and deemed reduced only by such amount paid and not so rescinded, reduced, restored orreturned. 

(k) In case any provision of this Guarantee shall be invalid, illegal or unenforceable, thevalidity, legality, and enforceability of the remaining provisions shall not in any way be affected or impaired thereby. 

(l) This Guarantee shall be a general senior unsecured obligation of such New Guaranteeing Subsidiary, ranking equally in right of payment with all existing and future Senior Indebtedness of the NewGuaranteeing Subsidiary, will be effectively subordinated to all Secured Indebtedness of such New Guaranteeing Subsidiary to the extent of the value of the collateral securing such indebtedness. The Guarantees will be senior in right of payment toall existing and future Subordinated Indebtedness of each Guarantor. The Senior Notes will be structurally subordinated to Indebtedness and other liabilities of Subsidiaries of the Issuer that do not Guarantee the Senior Notes, if any. 

(m) Each payment to be made by the New Guaranteeing Subsidiary in respect of this Guarantee shall be made without set-off,counterclaim, reduction or diminution of any kind or nature. 

4. EXECUTION ANDDELIVERY. The New Guaranteeing Subsidiary agrees that the Guarantee shall remain in full force and effect notwithstanding the absence of the endorsement of any notation of such Guarantee on the Senior Notes. 

5. MERGER, CONSOLIDATIONOR SALEOF ALLOR SUBSTANTIALLY ALL ASSETS. 

(a) Except asotherwise provided in Section 5.01(c) of the Indenture, the New Guaranteeing Subsidiary may not consolidate or merge with or into or wind up into (whether or not the Issuer or New Guaranteeing Subsidiary is the surviving corporation), or sell,assign, transfer, lease, convey or otherwise dispose of all or substantially all of its properties or assets, in one or more related transactions, to any Person unless: 

(i) (A) the New Guaranteeing Subsidiary is the surviving corporation or the Person formed by or surviving any suchconsolidation or merger (if other than the New Guaranteeing Subsidiary) or to which such sale, assignment, transfer, lease, conveyance or other disposition will have been made is a corporation, partnership, limited partnership, limited liabilitypartnership, limited liability corporation or trust organized or existing under the laws of the jurisdiction of organization of the New Guaranteeing Subsidiary, as the case may be, or the laws of the United States, any state thereof, the District ofColumbia, or any territory thereof (the New Guaranteeing Subsidiary or such Person, as the case may be, being herein called the “Successor Person”); 

 

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(B) the Successor Person, if other than the New Guaranteeing Subsidiary,expressly assumes all the obligations of the New Guaranteeing Subsidiary under the Indenture and the Registration Rights Agreement and the New Guaranteeing Subsidiary’s related Guarantee pursuant to supplemental indentures or other documents orinstruments in form reasonably satisfactory to the Trustee; 

(C) immediately after such transaction, noDefault exists; and 

(D) the Issuer shall have delivered to the Trustee an Officer’s Certificate and anOpinion of Counsel, each stating that such consolidation, merger or transfer and such supplemental indentures, if any, comply with the Indenture; or 

(ii) the transaction is made in compliance with Section 4.10 of the Indenture; 

(b) Subject to certain limitations described in the Indenture, the Successor Person will succeed to, and be substituted for, the New Guaranteeing Subsidiary under the Indenture and the New GuaranteeingSubsidiary’s Guarantee. Notwithstanding the foregoing, the New Guaranteeing Subsidiary may (i) merge into or transfer all or part of its properties and assets to another Guarantor or the Issuer, (ii) merge with an Affiliate of theIssuer solely for the purpose of reincorporating the New Guaranteeing Subsidiary in the United States, any state thereof, the District of Columbia or any territory thereof or (iii) convert into a corporation, partnership, limited partnership,limited liability corporation or trust organized or existing under the laws of the jurisdiction of organization of such Guarantor. 

6. RELEASES. The Guarantee of the New Guaranteeing Subsidiary shall be automatically and unconditionally released and discharged, and no further action by the New Guaranteeing Subsidiary, the Issuer or the Trustee is requiredfor the release of the New Guaranteeing Subsidiary’s Guarantee, upon: 

(1) (A) any sale, exchange ortransfer (by merger or otherwise) of the Capital Stock of the New Guaranteeing Subsidiary (including any sale, exchange or transfer), after which the New Guaranteeing Subsidiary is no longer a Restricted Subsidiary or all or substantially all theassets of the New Guaranteeing Subsidiary which sale, exchange or transfer is made in compliance with the applicable provisions of the Indenture; 

 

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(B) the release or discharge of the guarantee by the New GuaranteeingSubsidiary of the guarantee which resulted in the creation of the Guarantee, except a discharge or release by or as a result of payment under such guarantee; 

(C) the proper designation of the New Guaranteeing Subsidiary as an Unrestricted Subsidiary in compliance withSection 4.08 of the Indenture; or 

(D) the Issuer exercising its Legal Defeasance option or CovenantDefeasance option in accordance with Article 8 of the Indenture or the Issuer’s obligations under the Indenture being discharged in accordance with the terms of the Indenture; and 

(2) the New Guaranteeing Subsidiary delivering to the Trustee an Officer’s Certificate and an Opinion of Counsel, eachstating that all conditions precedent provided for in the Indenture relating to such transaction have been complied with. 

7.NO RECOURSE AGAINST OTHERS. No director, officer, employee, incorporator or stockholder of the New Guaranteeing Subsidiary shall have any liability for any obligations of the Issuer or theGuarantors (including the New Guaranteeing Subsidiary) under the Senior Notes, any 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 byaccepting Senior Notes waives and releases all such liability. The waiver and release are part of the consideration for issuance of the Senior Notes. 

8. GOVERNING LAW. THIS SUPPLEMENTAL INDENTURE WILL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK. 

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

10. EFFECTOFHEADINGS. The Section headings herein are for convenience only and shall not affect the construction hereof. 

11. 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 containedherein, all of which recitals are made solely by the New Guaranteeing Subsidiary. 

12. SUBROGATION. The NewGuaranteeing Subsidiary shall be subrogated to all rights of Holders of Senior Notes against the Issuer in respect of any amounts paid by the New Guaranteeing Subsidiary pursuant to the provisions of Section 3 hereof and Section 10.01 ofthe Indenture; provided that if an Event of Default has occurred and is continuing, the New Guaranteeing Subsidiary shall not be entitled to enforce or receive any payments arising out of, or based upon, such right of subrogation until allamounts then due and payable by the Issuer under the Indenture or the Senior Notes shall have been paid in full. 

13.BENEFITS ACKNOWLEDGED. The New Guaranteeing Subsidiary’s Guarantee is subject to the terms and conditions set forth in the Indenture. The New Guaranteeing Subsidiary acknowledges that it will receive direct andindirect benefits from the financing arrangements contemplated by the Indenture and this Supplemental Indenture and that the guarantee and waivers made by it pursuant to this Guarantee are knowingly made in contemplation of such benefits.

 

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14. SUCCESSORS. All agreements of the New Guaranteeing Subsidiary in thisSupplemental Indenture shall bind its Successors, except as otherwise provided in Section 3(k) hereof or elsewhere in this Supplemental Indenture. All agreements of the Trustee in this Supplemental Indenture shall bind its successors.

 

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

 
THE BANK OF NEW YORK MELLON (FORMERLY KNOWN AS THE BANK OF NEW YORK), as TrusteeBy: 
/s/ Remo Reale
 Name: Remo J. Reale Title: Vice PresidentENERGY FUTURE INTERMEDIATE HOLDING COMPANY LLC (FORMERLY KNOWN AS INFRASTRUX ENERGY SERVICES BPL LLC)By: 
/s/ Anthony R. Horton
 Name: Anthony R. Horton Title: Senior Vice President and Treasurer
 

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