VUHI FOURTH SUPPLEMENTAL INDENTURE

WHEREAS, the Company and the Initial Guarantors executed and delivered the Indenture dated as of October 19, 2001 (the “Base Indenture”) to the Trustee to provide for the Company’s unsecured notes, debentures or other evidence of indebtedness of the Company (collectively, the “Securities”), and the Guarantees (as hereinafter defined), to be issued from time to time in one or more series, as might be determined by the Company under the Base Indenture;

WHEREAS, pursuant to the terms of the Base Indenture, the Company desires to provide for the establishment of two new series of Securities to be known as its 5.45% Senior Notes due December 1, 2015 (the “2015 Notes”) and its 6.10% Senior Notes due December 1, 2035 (the “2035 Notes”, and together, the “Notes”) and the unconditional guarantees by the Guarantors (as defined herein) of the payment of the amounts owed with respect to the Notes (the “Guarantees”), the form and terms of such Notes and the terms, provisions and conditions of the Notes and the Guarantees to be set forth as provided in the Base Indenture and this Fourth Supplemental Indenture (together, the “Indenture”);

WHEREAS, the Company and the Initial Guarantors requested that the Trustee execute and deliver this Fourth Supplemental Indenture and all requirements necessary to make this Fourth Supplemental Indenture a valid, binding and enforceable instrument in accordance with its terms, and to make the Notes, when executed, authenticated and delivered by the Company and with the Guarantees endorsed thereon and executed by the Guarantors, the valid, binding and enforceable obligations of the Company and the Guarantors, as applicable, have been made:

NOW, THEREFORE, in consideration of the purchase and acceptance of the Notes by the Holders thereof, and for the purpose of setting forth, as provided in the Base Indenture, the form and terms of the Notes, each of the Company and the Initial Guarantors, as applicable, covenants and agrees with the Trustee as follows:

SECTION 1.1. Definition of Terms .

Unless the context otherwise requires:

(a)   a term defined in the Base Indenture has the same meaning when used in this Fourth Supplemental Indenture;

(b)   a term defined anywhere in this Fourth Supplemental Indenture has the same meaning throughout;

(c)   the singular includes the plural and vice versa;

(d)   headings are for convenience of reference only and do not affect interpretation;

(e)   the following terms have the meanings given to them in this Section 1.1(e):

“Notes” shall have the meaning specified in Section 2.1.

“Global Note” shall have the meaning set forth in Section 2.4.

“Guarantors” shall have the meaning specified in Section 2.1.

“Interest Payment Date” means June 1 and December 1 of each year, beginning June 1, 2006.

“Maturity Date” shall have the meaning specified in Section 2.2.

“Original Issue Date” means November 21, 2005.

“Redemption Price” shall have the meaning specified in Section 3.1.

“Regular Record Date” means, with respect to any Interest Payment Date for the Notes, the close of business on the fifteenth day of the month immediately preceding the month in which such Interest Payment Date falls.

The following terms shall have the respective meanings set forth in the recitals to this Fourth Supplemental Indenture:

“Base Indenture”

“Company”

“Guarantees”

“Indenture”

“Indiana Gas”

“Initial Guarantors”

“Fourth Supplemental Indenture”

“Securities”

“SIGECO”

“Trustee”

“VEDO”

SECTION 2.1. Designation and Principal Amount; Guarantees .

There is hereby authorized two series of Securities designated the 5.45% Senior Notes due December 1, 2015 limited (except as otherwise provided in Article 2 of the Base Indenture) in aggregate principal amount to $75,000,000, and the 6.10% Senior Notes due December 1, 2035 limited (except as otherwise provided in Article 2 of the Base Indenture) in aggregate principal amount to $75,000,000. The Notes may be issued from time to time upon written order of the Company for the authentication and delivery of Notes pursuant to Section 2.03 of the Base Indenture. Each of the Initial Guarantors (together with each other subsidiary of the Company that pursuant to the terms of the Indenture guarantees the Company’s obligations under the Notes and the Indenture, the “Guarantors”) unconditionally and jointly and severally guarantees to the Holders of the Notes upon which the Guarantees are endorsed, upon authentication and delivery by the Trustee, the due and punctual payment of the principal of, and interest on, and any Redemption Price with respect to, the Notes, when and as the same shall become due and payable, whether at Stated Maturity, upon acceleration or redemption or otherwise, in accordance with the terms of the Notes and of the Indenture.

SECTION 2.2. Maturity .

The date upon which the principal on the 2015 Notes shall become due and payable at final maturity is December 1, 2015 (the “2015 Maturity Date”) if not redeemed in full previously in accordance with Article III of this Fourth Supplemental Indenture. The date upon which the principal on the 2035 Notes shall become due and payable at final maturity is December 1, 2035 (the “2035 Maturity Date”, and the 2015 Maturity Date and the 2035 Maturity Date may sometimes hereinafter be referred to in the alternative as the “Maturity Date”) if not redeemed in full previously in accordance with Article III of this Fourth Supplemental Indenture.

SECTION 2.3. Form and Payment.

The Notes shall be issued in fully registered certificated form without interest coupons, bearing identical terms (except as otherwise provided in Article 2 of the Base Indenture). Principal of, and interest on, and any Redemption Price with respect to, the Notes will be payable, the transfer of such Notes will be registrable and such Notes will be exchangeable for Notes bearing identical terms at the office or agency of the Company maintained for such purpose as described below.

The Company hereby designates the Borough of Manhattan, The City of New York as a place of payment (“Place of Payment”) for the Notes, and the office or agency maintained by the Company in such Place of Payment for the purposes contemplated by this Section 2.3 shall initially be the Corporate Trust Office of the Trustee at 100 Wall Street, Suite 2000, New York, New York 10005, Attention: Richard Prokosch.

The Notes shall be issuable in denominations of $1,000 and integral multiples of $1,000 in excess thereof.

The Notes may be issued, in whole or in part, in permanent global form and, if issued in permanent global form, the Depository shall be The Depository Trust Company or such other depositary as any officer of the Company may from time to time designate.

The Registrar, the Paying Agent and the transfer agent for the Notes shall initially be the Trustee.

The Notes shall be in substantially the form set forth in Exhibits A-1 and A-2 hereto.

SECTION 2.4. Global Note .

(a)   Unless and until it is exchanged for Notes of the same series in registered certificated form, a global Note in principal amount equal to the aggregate principal amount of the 2015 Notes and a global Note in principal amount equal to the aggregate principal amount of the 2035 Notes (each a “Global Note”) may be transferred, in whole but not in part, only to the Depository or a nominee of the Depository, or to a successor Depository or to a nominee of such successor Depository.

(b)   If at any time (i) the Depository notifies the Company that it is unwilling or unable to continue as a Depository for the Global Notes and no successor Depository shall have been appointed within 90 days after such notification, (ii) the Depository ceases to be a clearing agency registered under the Securities Exchange Act of 1934 or any other applicable rule or regulation and no successor Depository shall have been appointed within 90 days after the Company becoming aware of the Depository’s ceasing to be so registered, (iii) the Company, in its sole discretion, determines that the Global Notes shall be so exchangeable or (iv) there shall have occurred and be continuing an Event of Default, the Company will execute, and, subject to Article 2 of the Base Indenture, the Trustee, upon written notice from the Company, will authenticate and deliver Notes of the same series, with the Guarantees endorsed thereon and executed by the Guarantors, in registered certificated form without coupons, in authorized denominations, and in an aggregate principal amount equal to the principal amount of the Global Note in exchange for such Global Note. Upon the exchange of the Global Note for such Notes in registered certificated form without coupons, in authorized denominations, the Global Note shall be cancelled by the Trustee. Such Notes in registered certificated form issued in exchange for the Global Note shall be registered in such names and in such authorized denominations as the Depository, pursuant to instructions from its direct or indirect participants or otherwise, shall instruct the Trustee. The Trustee shall deliver such Notes to the Depository for delivery to the Persons in whose names such Notes are so registered.

SECTION 2.5. Payment of Principal and Interest.

The 2015 Notes shall bear interest at the per annum rate of 5.45%. The 2035 Notes shall bear interest at the per annum rate of 6.10%. The following terms apply to the Notes:

Interest shall be paid semi-annually in arrears on each Interest Payment Date commencing on June 1, 2006. Payments of interest on the Notes will include interest accrued from, and including, the immediately preceding Interest Payment Date to which interest has been paid or duly provided for (or from, and including, the Original Issue Date if no interest has been paid or duly provided for) to, but excluding, the applicable Interest Payment Date or date of earlier redemption, as the case may be. Interest payments for the Notes shall be computed and paid on the basis of a 360-day year consisting of twelve 30-day months.

The interest so payable and punctually paid or duly provided for on any Interest Payment Date will be paid to the Holder(s) of the particular series of Notes as of the Regular Record Date for such Interest Payment Date. Any such interest that is not so punctually paid or duly provided for on any Interest Payment Date will forthwith cease to be payable to the Holders of the particular series of Notes as of the close of business on such Regular Record Date and may either be paid to the Person or Persons in whose name such Notes are registered at the close of business on a Special Record Date for the payment of such defaulted interest to be fixed by the Trustee, notice whereof shall be given to Holders of the particular series of Notes by the Trustee not less than fifteen (15) days prior to such Special Record Date, or be paid at any time in any other lawful manner, all as more fully provided in the Base Indenture.

Payment of the principal of, and any premium or interest on, the Notes due on the applicable Maturity Date or date of earlier redemption, as the case may be, shall be made in immediately available funds, upon presentation and surrender of the applicable Notes at the office or agency maintained by the Company for that purpose in the Borough of Manhattan, The City of New York, currently the office of the Trustee located at 100 Wall Street, Suite 2000, New York, New York 10005, or at such other paying agency in the Borough of Manhattan, The City of New York, as the Company may determine. Notwithstanding the foregoing, payment of interest due on any Interest Payment Date will be made by wire transfer of immediately available funds at such place and to such account at a banking institution in the United States as may be designated in wire transfer instructions received in writing by the Trustee at least sixteen (16) days prior to such Interest Payment Date. Any such wire transfer instructions received by the Trustee shall remain in effect until revoked by such Holder.

Any payments on the Notes will be made in such coin or currency of the United States of America as at the time of payment is legal tender for payment of public and private debts.

In the event that any Interest Payment Date or the applicable Maturity Date or date of earlier redemption falls on a day that is not a Business Day, the required payment of principal, premium and/or interest payable on such date shall be made on the next succeeding Business Day with the

same force and effect as if made on the date such payment was due, and no interest shall accrue with respect to such payment for the period from and after such Interest Payment Date or the applicable Maturity Date or date of earlier redemption, as the case may be, to the date of such payment on the next succeeding Business Day.

SECTION 3.1. Redemption at the Company’s Option.

Each series of Notes shall be subject to redemption at the option of the Company, in whole or in part, without premium or penalty, at any time, at a redemption price (the “Redemption Price”) equal to the greater of (1) 100% of the principal amount of the Notes to be redeemed and (2) the sum of the present values of the remaining scheduled payments of principal and interest (excluding interest accrued to the date of redemption) on the Notes to be redeemed discounted to the redemption date semi-annually (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate (as defined below) plus 20 basis points for the 2015 Notes and 25 basis points for the 2035 Notes, plus, in either case, any unpaid interest accrued on such Notes to the date of redemption.

In the event of redemption of a series of Notes in part only, a new Note or Notes of such series for the unredeemed portion will be issued in the name or names of the Holders thereof upon the presentation and surrender thereof, as set forth in Section 3A.08 of the Base Indenture.

Notice of redemption shall be given as provided in Section 3A.05 of the Base Indenture.

Any redemption of less than all of a series of Notes shall, with respect to the principal thereof, be divisible by $1,000.

For purposes of this Section:

“Treasury Rate” means, with respect to any redemption date applicable to a Note, the rate per annum equal to the semi-annual equivalent yield to maturity of the Comparable Treasury Issue, assuming a price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for such redemption date.

“Comparable Treasury Issue” means the United States Treasury security selected by an Independent Investment Banker as having a maturity comparable to the remaining term of the Notes to be redeemed that would be used, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the remaining term of the Notes to be redeemed.

“Independent Investment Banker” means one of the Reference Treasury Dealers appointed by the Trustee after consultation with the Company and the Guarantors.

“Comparable Treasury Price” means, with respect to any redemption date applicable to a Note, (1) if the Trustee obtains at least five Reference Treasury Dealer Quotations, the average of the three remaining Reference Treasury Dealer Quotations after excluding the highest and lowest Reference Treasury Dealer Quotations obtained, or (2) if the Trustee obtains fewer than five such Reference Treasury Dealer Quotations, the average of all Reference Treasury Dealer Quotations obtained.

“Reference Treasury Dealer Quotations” means, with respect to each Reference Treasury Dealer and any redemption date applicable to a Note, the average, as determined by the Trustee, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Trustee by such Reference Treasury Dealer at 5:00 p.m., New York City time, on the third Business Day preceding such redemption date.

“Reference Treasury Dealer” means each of LaSalle Financial Services, Inc., Wachovia Capital Markets, LLC, Fifth Third Securities, Inc. Wedbush Morgan Securities Inc., Banc of America Securities LLC, BNY Capital Markets, Inc., Morgan Keegan & Company, Inc., NatCity Investments, Inc., Piper Jaffray & Co., and their respective successors; provided, however, that if any of the foregoing shall cease to be a primary U.S. Government securities dealer in New York City (a “Primary Treasury Dealer”), such former dealer shall be replaced with another Primary Treasury Dealer.

SECTION 3.2. No Sinking Fund .

The Notes are not subject to, or entitled to the benefit of, any sinking fund.

SECTION 3.3. Defeasance .

Article 8 of the Base Indenture describing Defeasance and Covenant Defeasance shall apply to the Notes.

SECTION 4.1. Ratification of Indenture.

The Base Indenture, as supplemented by this Fourth Supplemental Indenture, is in all respects ratified and confirmed, and this Fourth Supplemental Indenture shall be deemed part of the Indenture in the manner and to the extent herein and therein provided.

SECTION 4.2. Trustee Not Responsible for Recitals.

The recitals herein contained are made by the Company and not by the Trustee, and the Trustee assumes no responsibility for the correctness thereof. The Trustee makes no representation as to the validity or sufficiency of this Fourth Supplemental Indenture.

SECTION 4.3. Governing Law .

This Fourth Supplemental Indenture and each Note issued hereunder shall be deemed to be contracts made under the internal laws of the State of Indiana and for all purposes shall be governed by and construed in accordance with the laws of said State without regard to principles of conflicts of law.

SECTION 4.4. Separability .

In case any one or more of the provisions contained in this Fourth Supplemental Indenture or in the Notes shall for any reason be held to be invalid, illegal or unenforceable in any respect, then, to the extent permitted by law, such invalidity, illegality or unenforceability shall not affect any other provisions of this Fourth Supplemental Indenture or of the Notes, but this Fourth Supplemental Indenture and the Notes shall be construed as if such invalid or illegal or unenforceable provision had never been contained herein or therein.

SECTION 4.5. Counterparts .

This Fourth Supplemental Indenture may be simultaneously executed in any number of counterparts, each of which when so executed shall be an original, and all such counterparts shall together constitute but one and the same instrument.

SECTION 4.6. Amendments .

Notwithstanding any other provision hereof, all amendments to the Base Indenture made hereby shall have effect only with respect to the Notes, and not with respect to the Securities of any other series created prior to or subsequent to the date hereof.

IN WITNESS WHEREOF, the parties hereto have caused this Fourth Supplemental Indenture to be duly executed by their respective officers thereunto duly authorized, on the date or dates indicated in the acknowledgments and as of the day and year first above written.

UNLESS THIS SECURITY IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (“DTC”), 55 WATER STREET, NEW YORK, NEW YORK TO THE ISSUER OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND SUCH SECURITY ISSUED IS REGISTERED IN THE NAME OF CEDE & CO., OR SUCH OTHER NAME AS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC, ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL, SINCE THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

UNLESS IT IS EXCHANGED IN WHOLE OR IN PART FOR SECURITIES IN DEFINITIVE REGISTERED FORM, THIS SECURITY MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY DTC TO A NOMINEE OF DTC OR BY A NOMINEE OF DTC TO DTC OR ANOTHER NOMINEE OF DTC OR BY DTC OR ANY SUCH NOMINEE TO A SUCCESSOR OF DTC OR A NOMINEE OF SUCH SUCCESSOR.

Vectren Utility Holdings, Inc., a corporation duly organized and existing under the laws of the State of Indiana (herein called the “Company”), for value received, hereby promises to pay, without relief from valuation or appraisement laws, to Cede & Co. or registered assigns, the principal sum of $75,000,000 on the Stated Maturity Date shown above or any earlier date of redemption in accordance with the provisions on the reverse hereof (each such date shall be referred to herein as the “Maturity Date” with respect to the principal payable on such date), and to pay interest on the outstanding principal of this Note, at the annual Rate of Interest shown above, from the Original Issue Date shown above or from the most recent Interest Payment Date (as hereinafter defined) to which interest has been paid or duly provided for, payable semi-annually in arrears on June 1 and December 1 of each year, commencing on June 1, 2006 (an “Interest Payment Date”), and on any earlier date of redemption, as the case may be.

The interest so payable and punctually paid or duly provided for on any Interest Payment Date will be paid to the Holder of this Note as of the Regular Record Date for such Interest Payment Date. Any such interest that is not so punctually paid or duly provided for on any Interest Payment Date will forthwith cease to be payable to the Holders of this Note as of the close of business on such

Regular Record Date and may either be paid to the Person or Persons in whose name this Note is registered at the close of business on a Special Record Date for the payment of such defaulted interest to be fixed by the Trustee referred to on the reverse hereof, notice whereof shall be given to Holders of the Notes by the Trustee not less than fifteen (15) calendar days prior to such Special Record Date, or be paid at any time in any other lawful manner, all as more fully provided in the Indenture referred to on the reverse hereof.

Interest payable on this Note on any Interest Payment Date and on any earlier date of redemption, as the case may be, will be the amount of interest accrued during the applicable Interest Period (as defined below) computed on the basis of a 360-day year of twelve 30-day months.

An “Interest Period” is each period from and including the immediately preceding Interest Payment Date to which interest has been paid or duly provided for (or from and including the Original Issue Date in the case of the initial Interest Period) to but excluding the applicable Interest Payment Date or the Maturity Date, as the case may be. If any Interest Payment Date or Maturity Date falls on a day that is not a Business Day, principal, premium and/or interest payable on such date will be paid on the succeeding Business Day with the same force and effect as if it were paid on the date such payment was due, and no interest will accrue on the amount so payable for the period from and after such date to such succeeding Business Day. “Business Day” means any day other than a Saturday, a Sunday, or other day on which commercial banks are authorized or required by law, regulation or executive order to close in The City of New York.

Payment of the principal of, and any premium or interest on, this Note due on the Maturity Date shall be made in immediately available funds, upon presentation and surrender of this Note at the office or agency maintained by the Company for that purpose in the Borough of Manhattan, The City of New York, currently the office of the Trustee located at 100 Wall Street, Suite 2000, New York, New York 10005, or at such other paying agency in the Borough of Manhattan, The City of New York, as the Company may determine. Notwithstanding the foregoing, payment of interest due on this Note on any Interest Payment Date will be made by wire transfer of immediately available funds at such place and to such account at a banking institution in the United States as may be designated in wire transfer instructions received in writing by the Trustee at least sixteen (16) days prior to such Interest Payment Date. Any such wire transfer instructions received by the Trustee shall remain in effect until revoked by such Holder.

Any payments on this Note will be made in such coin or currency of the United States of America as at the time of payment is legal tender for payment of public and private debts.

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