SUPPLEMENTAL INDENTURE

SUPPLEMENTAL INDENTURE

Dated as of May 1, 2008

To

Indenture of Mortgage and Deed of Trust

Dated as of May 1, 1921

as Amended and Restated

as of April 7, 2005

THE CONNECTICUT LIGHT AND POWER COMPANY

TO

DEUTSCHE BANK TRUST COMPANY AMERICAS

(f/k/a BANKERS TRUST COMPANY),

Trustee

5.65% First and Refunding Mortgage Bonds, 2008 Series   A, due 2018

THE CONNECTICUT LIGHT AND POWER COMPANY

Supplemental Indenture, Dated as of May 1, 2008

Table of Contents

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SUPPLEMENTAL INDENTURE , dated as of the first day of May 2008 between THE CONNECTICUT LIGHT AND POWER COMPANY , a corporation organized and existing under the laws of the State of Connecticut (hereinafter called “Company”), and DEUTSCHE BANK TRUST COMPANY AMERICAS (f/k/a BANKERS TRUST COMPANY) , a corporation organized and existing under the laws of the State of New York (hereinafter called “Trustee”).

WHEREAS, the Company heretofore duly executed, acknowledged and delivered to the Trustee a certain Indenture of Mortgage and Deed of Trust dated as of May 1, 1921, and seventy-six Supplemental Indentures thereto dated respectively as of May 1, 1921, February 1, 1924, July 1, 1926, June 20, 1928, June 1, 1932, July 1, 1932, July 1, 1935, September 1, 1936, October 20, 1936, December 1, 1936, December 1, 1938, August 31, 1944, September 1, 1944, May 1, 1945, October 1, 1945, November 1, 1949, December 1, 1952, December 1, 1955, January 1, 1958, February 1, 1960, April 1, 1961, September 1, 1963, April 1, 1967, May 1, 1967, January 1, 1968, October 1, 1968, December 1, 1969, January 1, 1970, October 1, 1970, December 1, 1971, August 1, 1972, April 1, 1973, March 1, 1974, February 1, 1975, September 1, 1975, May 1, 1977, March 1, 1978, September 1, 1980, October 1, 1981, June 30, 1982, October 1, 1982, July 1, 1983, January 1, 1984, October 1, 1985, September 1, 1986, April 1, 1987, October 1, 1987, November 1, 1987, April 1, 1988, November 1, 1988, June 1, 1989, September 1, 1989, December 1, 1989, April 1, 1992, July 1, 1992, October 1, 1992, July 1, 1993, July 1, 1993, December 1, 1993, February 1, 1994, February 1, 1994, June 1, 1994, October 1, 1994, June 1, 1996, January 1, 1997, May 1, 1997, June 1, 1997, June 1, 1997, May 1, 1998, May 1, 1998, September 1, 2004, September 1, 2004, April 1, 2005, June 1, 2006, March 1, 2007 and September 1, 2007 (said Indenture of Mortgage and Deed of Trust (i) as heretofore amended, being hereinafter generally called the “Mortgage Indenture,” and (ii) together with said Supplemental Indentures thereto, being hereinafter generally called the “Mortgage”), all of which have been duly recorded as required by law, for the purpose of securing its First and Refunding Mortgage Bonds (of which $1,431,845,000 aggregate principal amount are outstanding at the date of this Supplemental Indenture) in an unlimited amount, issued and to be issued for the purposes and in the manner therein provided, of which Mortgage this Supplemental Indenture is intended to be made a part, as fully as if therein recited at length;

WHEREAS, the Company by appropriate and sufficient corporate action in conformity with the provisions of the Mortgage has duly determined to create a further series of bonds under the Mortgage to be designated “5.65% First and Refunding Mortgage Bonds, 2008 Series A, due 2018” (hereinafter generally referred to as the “bonds of 2008 Series A”), to consist of fully registered bonds containing terms and provisions duly fixed and determined by the Board of Directors of the Company and expressed in this Supplemental Indenture, such fully registered bonds and the Trustee’s certificate of its authentication thereof to be substantially in the forms thereof respectively set forth in Schedule A appended hereto and made a part hereof; and

WHEREAS, the execution and delivery of this Supplemental Indenture and the issue of not in excess initially of Three Hundred Million Dollars ($300,000,000) in aggregate principal amount of bonds of 2008 Series A and other necessary actions have been duly authorized by the Board of Directors of the Company; and

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WHEREAS, the Company has purchased, constructed or otherwise acquired certain additional property not specifically described in the Mortgage but which is and is intended to be subject to the lien thereof, and proposes specifically to subject such additional property to the lien of the Indenture at this time; and

WHEREAS, the Company proposes to execute and deliver this Supplemental Indenture to provide for the issue of the bonds of 2008 Series A, to subject such additional property to the lien of the Mortgage and to confirm the lien of the Mortgage on the Property referred to below, all as permitted by Sections 401 and 1301 of the Mortgage Indenture; and

WHEREAS, all acts and things necessary to constitute this Supplemental Indenture a valid, binding and legal instrument and to make the bonds of 2008 Series A, when executed by the Company and authenticated by the Trustee, the valid, binding and legal obligations of the Company have been authorized and performed;

NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE OF MORTGAGE AND DEED OF TRUST WITNESSETH:

That in order to secure the payment of the principal of and interest on all bonds issued and to be issued under the Mortgage, according to their tenor and effect, and according to the terms of the Mortgage and this Supplemental Indenture, and to secure the performance of the covenants and obligations in said bonds and in the Mortgage and this Supplemental Indenture respectively contained, and for the better assuring and confirming unto the Trustee, its successor or successors and its or their assigns, upon the trusts and for the purposes expressed in the Mortgage and this Supplemental Indenture, all and singular the hereditaments, premises, estates and property of the Company thereby conveyed or assigned or intended so to be, or which the Company may thereafter have become bound to convey or assign to the Trustee, as security for said bonds (except such hereditaments, premises, estates and property as shall have been disposed of or released or withdrawn from the lien of the Mortgage and this Supplemental Indenture, in accordance with the provisions thereof and subject to alterations, modifications and changes in said hereditaments, premises, estates and property as permitted under the provisions thereof), the Company, for and in consideration of the premises and the sum of One Dollar ($1.00) to it in hand paid by the Trustee, the receipt whereof is hereby acknowledged, and of other valuable considerations, has granted, bargained, sold, assigned, mortgaged, pledged, transferred, set over, aliened, enfeoffed, released, conveyed and confirmed, and by these presents does grant, bargain, sell, assign, mortgage, pledge, transfer, set over, alien, enfeoff, release, convey and confirm unto said Deutsche Bank Trust Company Americas (f/k/a Bankers Trust Company), as Trustee, and its successor or successors in the trusts created by the Mortgage and this Supplemental Indenture, and its and their assigns, all of said hereditaments, premises, estates and property (except and subject as aforesaid), as fully as though described at length herein, including, without limitation of the foregoing, the property, rights and privileges of the Company described or referred to in Schedule B hereto.

Together with all plants, buildings, structures, improvements and machinery located upon said real estate or any portion thereof, and all rights, privileges and easements of every kind and nature appurtenant thereto, and all and singular the tenements, hereditaments and appurtenances belonging to the real estate or any part thereof described or referred to in Schedule B or intended

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so to be, or in any wise appertaining thereto, and the reversions, remainders, rents, issues and profits thereof, and also all the estate, right, title, interest, property, possession, claim and demand whatsoever, as well in law as in equity, of the Company, of, in and to the same and any and every part thereof, with the appurtenances; except and subject as aforesaid.

TO HAVE AND TO HOLD all and singular the property, rights and privileges hereby granted or mentioned or intended so to be, together with all and singular the reversions, remainders, rents, revenues, income, issues and profits, privileges and appurtenances, now or hereafter belonging or in any way appertaining thereto, unto the Trustee and its successor or successors in the trust created by the Mortgage and this Supplemental Indenture, and its and their assigns, forever, and with like effect as if the above described property, rights and privileges had been specifically described at length in the Mortgage and this Supplemental Indenture.

Subject, however, to permitted liens, as defined in the Mortgage Indenture.

IN TRUST, NEVERTHELESS, upon the terms and trusts of the Mortgage and this Supplemental Indenture for those who shall hold the bonds and coupons issued and to be issued thereunder, or any of them, without preference, priority or distinction as to lien of any of said bonds and coupons over any others thereof by reason of priority in the time of the issue or negotiation thereof, or otherwise howsoever, subject, however, to the provisions in reference to extended, transferred or pledged coupons and claims for interest set forth in the Mortgage and this Supplemental Indenture (and subject to any sinking fund that may heretofore have been or hereafter be created for the benefit of any particular series).

And it is hereby covenanted that all such bonds of 2008 Series A are to be issued, authenticated and delivered, and that the mortgaged premises are to be held by the Trustee, upon and subject to the trusts, covenants, provisions and conditions and for the uses and purposes set forth in the Mortgage and this Supplemental Indenture and upon and subject to the further covenants, provisions and conditions and for the uses and purposes hereinafter set forth, as follows, to wit:

ARTICLE 1.

FORM AND PROVISIONS OF BONDS OF 2008 SERIES A

SECTION 1.01. Designation; Amount . The bonds of 2008 Series A shall be designated “5.65% First and Refunding Mortgage Bonds, 2008 Series A, due 2018” and shall initially be authenticated in the aggregate principal amount of Three Hundred Million Dollars ($300,000,000). The initial issue of the bonds of 2008 Series A may be effected upon compliance with the applicable provisions of the Mortgage Indenture. Additional bonds of 2008 Series A, without limitation as to amount, having the same terms and conditions as the bonds of 2008 Series A (except for the date of original issuance, the initial interest payment date and the offering price) may also be issued by the Company without the consent of the holders of the bonds of 2008 Series A, pursuant to a separate supplemental indenture related thereto. Such additional bonds of 2008 Series A shall be part of the same series as the bonds of 2008 Series A.

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SECTION 1.02. Form of Bonds of 2008 Series A . The bonds of 2008 Series A shall be issued only in fully registered form without coupons in denominations of One Thousand Dollars ($1,000) and multiples thereof.

The bonds of 2008 Series A and the certificate of the Trustee upon said bonds shall be substantially in the forms thereof respectively set forth in Schedule A appended hereto.

SECTION 1.03. Provisions of Bonds of 2008 Series A; Interest Accrual . The bonds of 2008 Series A shall mature on May 1, 2018 and shall bear interest, including on overdue interest, payable semiannually on the first day of November and May of each year, commencing November 1, 2008, at the rate specified in their title, until the Company’s obligation in respect of the principal thereof shall be discharged; and shall be payable both as to principal and interest at the office or agency of the Company in the Borough of Manhattan, New York, New York, in any coin or currency of the United States of America which at the time of payment is legal tender for the payment of public and private debts. The interest on the bonds of 2008 Series A, whether in temporary or definitive form, shall be payable without presentation of such bonds; and only to or upon the written order of the registered holders thereof of record at the applicable record date (as hereinafter defined). The bonds of 2008 Series A shall be callable for redemption in whole or in part according to the terms and provisions herein in Article 2.

Each bond of 2008 Series A authenticated in accordance with the terms of this Supplemental Indenture shall be dated as of May 27, 2008 and shall bear interest on the principal amount thereof from the interest payment date next preceding the date of authentication thereof by the Trustee to which interest has been paid on the bonds of 2008 Series A, or if the date of authentication thereof is prior to November 1, 2008, then from May 27, 2008, or if the date of authentication thereof be an interest payment date to which interest is being paid or a date between the record date for any such interest payment date and such interest payment date, then from such interest payment date. Interest on the bonds of 2008 Series A shall be computed on the basis of a 360-day year consisting of twelve 30-day months, and with respect to any period less than a full month, on the basis of the actual number of days elapsed in such period.

The person in whose name any bond of 2008 Series A is registered at the close of business on any record date with respect to any interest payment date shall be entitled to receive the interest payable on such interest payment date notwithstanding the cancellation of such bond upon any registration of transfer or exchange thereof subsequent to the record date and prior to such interest payment date, except that if and to the extent the Company shall default in the payment of the interest due on such interest payment date, then such defaulted interest shall be paid to the person in whose name such bond is registered on a subsequent record date for the payment of defaulted interest if one shall have been established as hereinafter provided and otherwise on the date of payment of such defaulted interest. A subsequent record date may be established by the Company by notice mailed to the owners of bonds of 2008 Series A not less than ten (10) days preceding such record date, which record date shall not be more than thirty (30) days prior to the subsequent interest payment date. The term “record date” as used in this Section with respect to any regular interest payment (i.e., November 1 or May 1) shall mean the October 15 or April 15, as the case may be, next preceding such interest payment date, or if such October 15 or April 15 shall be a legal holiday or a day on which banking institutions in the Borough of Manhattan, New York, New York are authorized by law to close, the next preceding day which shall not be a legal holiday or a day on which such institutions are so authorized to close.

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SECTION 1.04. Transfer and Exchange of Bonds of 2008 Series A . The bonds of 2008 Series A may be surrendered for registration of transfer as provided in Section 305 of the Mortgage Indenture at the office or agency of the Company in the Borough of Manhattan, New York, New York, and may be surrendered at said office for exchange for a like aggregate principal amount of bonds of 2008 Series A of other authorized denominations. Notwithstanding the provisions of Section 305 of the Mortgage Indenture, no charge, except for taxes or other governmental charges, shall be made by the Company for any registration of transfer of bonds of 2008 Series A or for the exchange of any bonds of 2008 Series A for bonds of other authorized denominations.

SECTION 1.05. Consent to Amendment and Restatement of Mortgage Indenture . Each holder of a bond of 2008 Series A, solely by virtue of its acquisition thereof, including as an owner of a book-entry interest therein, shall have and be deemed to have consented, without the need for any further action or consent by such holder, to the amendment and restatement of the Mortgage Indenture in the form set forth in Schedule C to the Supplemental Indenture dated as of April 1, 2005.

ARTICLE 2.

REDEMPTION OF BONDS OF 2008 Series A

SECTION 2.01. Redemption of Bonds of 2008 Series A . The bonds of 2008 Series A are subject to redemption prior to maturity, as a whole at any time or in part from time to time, in accordance with the provisions of the Mortgage, upon not less than thirty (30) days and not more than sixty (60) days prior notice (which notice may be made subject to the deposit of redemption moneys with the Trustee before the date fixed for redemption) given by mail as provided in the Mortgage, at the option of the Company, at a redemption price equal to the greater of (i) 100% of the principal amount of the bonds of 2008 Series A being redeemed or (ii) the sum of the present values of the remaining scheduled