Exhibit 4.1

This instrument was prepared

under the supervision of:

Kristen B. Parker, Associate General Counsel

Florida Power Corporation

d/b/a Progress Energy Florida, Inc.

299 First Avenue North

St. Petersburg, Florida 33701

FLORIDA POWER CORPORATION

d/b/a PROGRESS ENERGY FLORIDA, INC.

TO

THE BANK OF NEW YORK MELLON, TRUSTEE

FIFTY-FIRST

SUPPLEMENTAL INDENTURE

Dated as of November 1, 2012

This is a security agreement covering personal property as

well as a mortgage upon real estate and other property.

SUPPLEMENT TO INDENTURE

DATED AS OF JANUARY 1, 1944, AS SUPPLEMENTED

TABLE OF CONTENTS*

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RECITALS

SUPPLEMENTAL INDENTURE , dated as of the 1st day of November 2012, made and entered into by and between FLORIDA POWER CORPORATION d/b/a PROGRESS ENERGY FLORIDA, INC. , a corporation of the State of Florida (hereinafter sometimes called the “Company”), party of the first part, and THE BANK OF NEW YORK MELLON (formerly known of record as The Bank of New York), a New York banking corporation, whose post office address is 101 Barclay Street, New York, New York 10286, as successor trustee (hereinafter sometimes called the “Trustee”), party of the second part.

WHEREAS , the Company has heretofore executed and delivered an indenture of mortgage and deed of trust, titled the Indenture, dated as of January 1, 1944, and the same has been recorded in the public records and on the dates listed on Exhibit A hereto, and for the purpose of preventing the extinguishment of said Indenture under Chapter 712, Florida Statutes, the above-referred-to Indenture applicable to each county in which this instrument is recorded is hereby incorporated herein and made a part hereof by this reference thereto (said Indenture is hereinafter referred to as the “Original Indenture” and with the below-mentioned fifty Supplemental Indentures and this Supplemental Indenture and all other indentures, if any, supplemental to the Original Indenture collectively referred to as the “Indenture”), in and by which the Company conveyed and mortgaged to the Trustee certain property therein described to secure the payment of all bonds of the Company to be issued thereunder in one or more series; and

WHEREAS , pursuant to and under the terms of the Original Indenture, the Company issued $16,500,000 First Mortgage Bonds, 3 3/8% Series due 1974; and

WHEREAS , subsequent to the date of the execution and delivery of the Original Indenture, the Company has from time to time executed and delivered fifty indentures supplemental to the Original Indenture (together with this Supplemental Indenture, collectively, the “Supplemental Indentures”), providing for the creation of additional series of bonds secured by the Original Indenture and/or for amendment of certain terms and provisions of the Original Indenture and of indentures supplemental thereto, such Supplemental Indentures, and the purposes thereof, being as follows:

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WHEREAS , such Supplemental Indentures have each been recorded in the public records of the counties listed on Exhibit A hereto, on the dates and in the official record books and at the page numbers listed thereon; and

WHEREAS , subsequent to the date of the execution and delivery of the Fiftieth Supplemental Indenture the Company has purchased, constructed or otherwise acquired certain property hereinafter referred to, and the Company desires by this Supplemental Indenture to confirm the lien of the Original Indenture on such property; and

WHEREAS , pursuant to the Forty-Seventh Supplemental Indenture, JPMorgan Chase Bank, N.A., resigned as Trustee and The Bank of New York Mellon was appointed as the successor Trustee, effective December 13, 2007; and

WHEREAS, The Bank of New York Mellon is eligible and qualified to serve as Trustee under the Indenture; and

WHEREAS , the Company desires by this Supplemental Indenture to create two new series of bonds to be designated as (i) First Mortgage Bonds, 0.65% Series due 2015 (the “2015 Bonds”) and (ii) First Mortgage Bonds, 3.85% Series due 2042 (the “2042 Bonds” and together with the 2015 Bonds, sometimes herein collectively called the “New Series Bonds”), to be issued under the Original Indenture pursuant to Section 2.01 of the Original

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Indenture, and also desires to deliver to the Trustee prior to or simultaneously with the authentication and delivery of the initial issue of Six Hundred Fifty Million Dollars ($650,000,000) principal amount of New Series Bonds pursuant to Section 4.05 of the Original Indenture the documents and instruments required by said section; and

WHEREAS , the Company in the exercise of the powers and authority conferred upon and reserved to it under and by virtue of the Indenture, and pursuant to the resolutions of its Board of Directors (as defined in the Indenture, which definition includes any duly authorized committee of the Board of Directors, including the First Mortgage Bond Indenture Committee of the Board of Directors) has duly resolved and determined to make, execute and deliver to the Trustee a Supplemental Indenture in the form hereof for the purposes herein provided; and

WHEREAS , all conditions and requirements necessary to make this Supplemental Indenture a valid, binding and legal instrument in accordance with its terms have been done, performed and fulfilled, and the execution and delivery hereof have been in all respects duly authorized;

NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE WITNESSETH : That Florida Power Corporation d/b/a Progress Energy Florida, Inc., in consideration of the premises and of One Dollar ($1.00) and other good and valuable consideration to it duly paid by the Trustee at or before the ensealing and delivery of these presents, the receipt whereof is hereby acknowledged, and in order to secure the payment of both the principal of and interest and premium, if any, on the bonds from time to time issued and to be issued under the Indenture, according to their tenor and effect, does hereby confirm the grant, sale, resale, conveyance, assignment, transfer, mortgage and pledge of the property described in the Original Indenture and the Supplemental Indentures (except such properties or interests therein as may have been released or sold or disposed of in whole or in part as permitted by the provisions of the Original Indenture), and hath granted, bargained, sold, released, conveyed, assigned, transferred, mortgaged, pledged, set over and confirmed, and by these presents doth grant, bargain, sell, release, convey, assign, transfer, mortgage, pledge, set over and confirm unto The Bank of New York Mellon, as Trustee, and to its successors in the trust and to its successors and assigns, forever, all property, real, personal and mixed, tangible and intangible, owned by the Company on the date of the execution of this Supplemental Indenture or which may be hereafter acquired by it, including (but not limited to) all property which it has acquired subsequent to the date of execution of the Fiftieth Supplemental Indenture and situated in the State of Florida, including without limitation the property described on Exhibit B hereto (in all cases, except such property as is expressly excepted by the Original Indenture from the lien and operation thereof); and without in any way limiting or impairing by the enumeration of the same the scope and intent of the foregoing, all lands, power sites, flowage rights, water rights, water locations, water appropriations, ditches, flumes, reservoirs, reservoir sites, canals, raceways, dams, dam sites, aqueducts and all other rights or means for appropriating, conveying, storing and supplying water; all rights of way and roads; all plants for the generation of electricity by steam, water and/or other power; all power houses, facilities for utilization of natural gas, street lighting systems, if any, standards and other equipment incidental thereto, telephone, radio and television systems, microwave systems, facilities for utilization of water, steam heat and hot water plants, if any, all substations, lines, service and supply systems, bridges, culverts, tracks, offices, buildings and other structures and equipment and fixtures thereof; all machinery, engines, boilers, dynamos, electric machines, regulators, meters, transformers, generators, motors, electrical and mechanical appliances, conduits, cables, pipes, fittings, valves and connections, poles (wood, metal and concrete), and transmission lines, wires, cables, conductors, insulators, tools, implements, apparatus, furniture, chattels, and choses in action; all municipal and other franchises, consents, licenses or permits; all lines for the distribution of electric current, gas, steam heat or water for any purpose including towers, poles (wood, metal and concrete), wires, cables, pipes, conduits, ducts and all apparatus for use in connection therewith; all real estate, lands, easements, servitudes, licenses, permits, franchises, privileges, rights-of-way and other rights in or relating to real estate or the use and occupancy of the same (except as herein or in the Original Indenture or any of the Supplemental Indentures expressly excepted); all the right, title and interest of the Company in and to all other property of any kind or nature appertaining to and/or used and/or occupied and/or enjoyed in connection with any property hereinbefore, or in the Original Indenture and said Supplemental Indentures, described.

IT IS HEREBY AGREED by the Company that all the property, rights and franchises acquired by the Company after the date hereof (except any property herein or in the Original Indenture or any of the Supplemental Indentures expressly excepted) shall, subject to the provisions of Section 9.01 of the Original Indenture and to the extent permitted by law, be as fully embraced within the lien hereof as if such property, rights and franchises were now owned by the Company and/or specifically described herein and conveyed hereby.

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TOGETHER WITH all and singular the tenements, hereditaments and appurtenances belonging or in any way appertaining to the aforesaid mortgaged property or any part thereof, with the reversion and reversions, remainder and remainders and (subject to the provisions of Section 9.01 of the Original Indenture) the tolls, rents, revenues, issues, earnings, income, product and profits thereof, and all the estate, right, title and interest and claim whatsoever, at law as well as in equity, which the Company now has or may hereafter acquire in and to the aforesaid mortgaged property and every part and parcel thereof.

TO HAVE AND TO HOLD THE SAME unto The Bank of New York Mellon, as Trustee, and its successors in the trust and its assigns forever, but IN TRUST NEVERTHELESS upon the terms and trusts set forth in the Indenture, for the benefit and security of those who shall hold the bonds and coupons issued and to be issued under the Indenture, without preference, priority or distinction as to lien of any of said bonds and coupons over any others thereof by reason or priority in the time of the issue or negotiation thereof, or otherwise howsoever, subject, however, to the provisions of Sections 10.03 and 10.12 of the Original Indenture.

SUBJECT, HOWEVER , to the reservations, exceptions, conditions, limitations and restrictions contained in the several deeds, servitudes and contracts or other instruments through which the Company acquired, and/or claims title to and/or enjoys the use of the aforesaid properties; and subject also to encumbrances of the character defined in the Original Indenture as “excepted encumbrances” in so far as the same may attach to any of the property embraced herein.

Without derogating from the security and priority presently afforded by the Indenture and by law for all of the bonds of the Company that have been, are being, and may in the future be, issued pursuant to the Indenture, for purposes of obtaining any additional benefits and security provided by Section 697.04 of the Florida Statutes, the following provisions of this paragraph shall be applicable. The Indenture also shall secure the payment of both principal and interest and premium, if any, on the bonds from time to time hereafter issued pursuant to the Indenture, according to their tenor and effect, and the performance and observance of all the provisions of the Indenture (including any indentures supplemental thereto and any modification or alteration thereof made as therein provided), whether the issuance of such bonds may be optional or mandatory, and for any purpose, within twenty (20) years from the date of this Supplemental Indenture. The total amount of indebtedness secured by the Indenture may decrease or increase from time to time, but the total unpaid balance so secured at any one time shall not exceed the maximum principal amount of $10,000,000,000, plus interest and premium, if any, as well as any disbursements made for the payment of taxes, levies or insurance on the property encumbered by the Indenture, with interest on those disbursements, plus any increase in the principal balance as the result of negative amortization or deferred interest. For purposes of Section 697.04 of the Florida Statutes, the Original Indenture, as well as all of the indentures supplemental thereto that have been executed prior to the date of this Supplemental Indenture, are incorporated herein by this reference with the same effect as if they had been set forth in full herein.

And, upon the consideration hereinbefore set forth, the Company does hereby covenant and agree to and with the Trustee and its successors in trust under the Indenture for the benefit of those who shall hold bonds and coupons issued and to be issued under the Indenture, as follows:

ARTICLE I

THE NEW SERIES BONDS

A. CREATION OF FIRST MORTGAGE BONDS, 0.65% SERIES DUE 2015

Section 1. The Company hereby creates a new series of bonds, not limited in principal amount except as provided in the Original Indenture, to be issued under and secured by the Original Indenture, to be designated by the title “First Mortgage Bonds, 0.65% Series due 2015.” The initial issue of the 2015 Bonds shall consist of Two Hundred Fifty Million Dollars ($250,000,000) principal amount thereof. Subject to the terms of the Indenture, the principal amount of the 2015 Bonds is unlimited. The Company may, at its option in the future, issue additional 2015 Bonds.

The 2015 Bonds shall be issued only as registered bonds without coupons in the denomination of Two Thousand Dollars ($2,000) and any integral multiple of One Thousand Dollars ($1,000) above that amount.

Section 2. (a) The 2015 Bonds shall be issued in registered form without coupons and shall be issued initially in the form of one or more Global Bonds (each such Global Bond, a “2015 Global Bond”) to or on behalf of The

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Depository Trust Company (“DTC”), as depositary therefor (in such capacity, the “Depositary”), and registered in the name of such Depositary or its nominee. Any 2015 Bonds to be issued or transferred to, or to be held by or on behalf of DTC as such Depositary or such nominee (or any successor of such nominee) for such purpose shall bear the depositary legends in substantially the form set forth at the top of the form of the 2015 Bonds in Section C of this Article I, unless otherwise agreed by the Company, and in the case of a successor Depositary, such legend or legends as such Depositary and/or the Company shall require and to which each shall agree, in each case such agreement to be confirmed in writing to the Trustee. Principal of, and interest on, the 2015 Bonds and the Redemption Price (as defined below), if applicable, will be payable, the transfer of the 2015 Bonds will be registrable and the 2015 Bonds will be exchangeable for the 2015 Bonds bearing identical terms and provisions, at the office or agency of the Company in the Borough of Manhattan, The City and State of New York; provided, however, that payment of interest may be made at the option of the Company by check mailed to the registered holders thereof at their registered address; and further provided, however, that with respect to a 2015 Global Bond, the Company may make payments of principal of, and interest on, the 2015 Global Bond and the Redemption Price, if applicable, and interest on such 2015 Global Bond pursuant to and in accordance with such arrangements as are agreed upon by the Company and the Depositary for such 2015 Global Bond. The 2015 Bonds shall have the terms set forth in the form of the New Series Bond set forth in Section C of this Article I.

(b) Notwithstanding any other provision of this Subsection A.2 of this Article I or of Section 2.03 of the Original Indenture, except as contemplated by the provisions of paragraph (c) below, a 2015 Global Bond may be transferred, in whole but not in part and in the manner provided in Section 2.03 of the Original Indenture, only to a nominee of the Depositary for such 2015 Global Bond, or to the Depositary, or to a successor Depositary for such 2015 Global Bond selected or approved by the Company, or to a nominee of such successor Depositary.

(c) (1) If at any time the Depositary for a 2015 Global Bond notifies the Company that it is unwilling or unable to continue as the Depositary for such 2015 Global Bond or if at any time the Depositary for a 2015 Global Bond ceases to be a clearing agency registered under the Securities Exchange Act of 1934, as amended, at a time when the Depositary is required to be so registered to act as such Depositary, the Company shall appoint a successor Depositary with respect to such 2015 Global Bond. If a successor Depositary for such 2015 Global Bond is not appointed by the Company within 90 days after the Company receives such notice or becomes aware of such cessation, the Company will execute, and the Trustee, upon receipt of a Company order for the authentication and delivery of 2015 Bonds in the form of definitive certificates in exchange for such 2015 Global Bond, will authenticate and deliver, without service charge, 2015 Bonds in the form of definitive certificates of like tenor and terms in an aggregate principal amount equal to the principal amount of the 2015 Global Bond in exchange for such 2015 Global Bond. Such 2015 Bonds will be issued to and registered in the name of such person or persons as are specified by the Depositary.

(2) The Company may at any time and in its sole discretion (subject to the procedures of the Depositary) determine that any 2015 Bonds issued or issuable in the form of one or more 2015 Global Bonds shall no longer be represented by such 2015 Global Bond or Bonds. In any such event the Company will execute, and the Trustee, upon receipt of a Company order for the authentication and delivery of 2015 Bonds in the form of definitive certificates in exchange in whole or in part for such 2015 Global Bond or Bonds, will authenticate and deliver, without service charge, to each person specified by the Depositary, 2015 Bonds in the form of definitive certificates of like tenor and terms in an aggregate principal amount equal to the principal amount of such 2015 Global Bond or the aggregate principal amount of such 2015 Global Bonds in exchange for such 2015 Global Bond or Bonds.

(3) If at any time a completed default has occurred and is continuing with respect to the 2015 Bonds and beneficial owners of a majority in aggregate principal amount of the 2015 Bonds represented by 2015 Global Bonds advise the Depositary to cease acting as the Depositary, the Company will execute, and the Trustee, upon receipt of a Company order for the authentication and delivery of 2015 Bonds in the form of definitive certificates in exchange for such 2015 Global Bond, will authenticate and deliver, without service charge, 2015 Bonds in the form of definitive certificates of like tenor and terms in an aggregate principal amount equal to the principal amount of the 2015 Global Bond in exchange for such 2015 Global Bond. Such 2015 Bonds will be issued to and registered in the name of such person or persons as are specified by the Depositary.

(4) In any exchange provided for in any of the preceding three subparagraphs, the Company shall execute and the Trustee shall authenticate and deliver 2015 Bonds in the form of definitive certificates in authorized denominations. Upon the exchange of the entire principal amount of a 2015 Global Bond for 2015 Bonds in the form of definitive

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certificates, such 2015 Global Bond shall be canceled by the Trustee. Except as provided in the immediately preceding subparagraph, 2015 Bonds issued in exchange for a 2015 Global Bond pursuant to Subsection A.2 of this Article I shall be registered in such names and in such authorized denominations as the Depositary for such 2015 Global Bond, acting pursuant to instructions from its direct or indirect participants or otherwise, shall instruct the Trustee. Provided that the Company and the Trustee have so agreed, the Trustee shall deliver such 2015 Bonds to the persons in whose names the 2015 Bonds are so to be registered.

(5) Any endorsement of a 2015 Global Bond to reflect the principal amount thereof, or any increase or decrease in such principal amount, shall be made in such manner and by such person or persons as shall be specified in or pursuant to any applicable letter of representations or other arrangement entered into with, or procedures of, the Depositary with respect to such 2015 Global Bond or in the Company order delivered or to be delivered pursuant to Section 4.07 of the Original Indenture with respect thereto. Subject to the provisions of Section 4.07 of the Original Indenture, the Trustee shall deliver and redeliver any such 2015 Global Bond in the manner and upon instructions given by the person or persons specified in or pursuant to any applicable letter of representations or other arrangement entered into with, or procedures of, the Depositary with respect to such 2015 Global Bond or in any applicable Company order. If a Company order pursuant to Section 4.07 of the Original Indenture is so delivered, any instructions by the Company with respect to such 2015 Global Bond contained therein shall be in writing but need not be accompanied by or contained in an officers’ certificate and need not be accompanied by an opinion of counsel.

(6) The Depositary or, if there be one, its nominee, shall be the holder of a 2015 Global Bond for all purposes under the Indenture and the 2015 Bonds and beneficial owners with respect to such 2015 Global Bond shall hold their interests pursuant to applicable procedures of such Depositary. The Company, the Trustee and any bond registrar shall be entitled to deal with such Depositary for all purposes of the Indenture relating to such 2015 Global Bond (including the payment of principal, the Redemption Price, if applicable, and interest and the giving of instructions or directions by or to the beneficial owners of such 2015 Global Bond as the sole holder of such 2015 Global Bond and shall have no obligations to the beneficial owners thereof (including any direct or indirect participants in such Depositary)). None of the Company, the Trustee, any paying agent or bond registrar shall have any responsibility or liability for any aspect of the records relating to or payments made on account of beneficial ownership interests of a beneficial owner in or pursuant to any applicable letter of representations or other arrangement entered into with, or procedures of, the Depositary with respect to such 2015 Global Bond or for maintaining, supervising or reviewing any records relating to such beneficial ownership interests.

Section 3. November 20, 2012, shall be the date of the beginning of the first interest period for the 2015 Bonds. The first Interest Payment Date (as defined below) shall be May 15, 2013. The 2015 Bonds shall be dated as provided in Section 2.01 of the Original Indenture. The 2015 Bonds shall be payable on November 15, 2015, in such coin or currency of the United States of America as at the time of payment is legal tender for the payment of public and private debts, and shall bear interest, payable in like coin or currency, at the rate of 0.65% per annum, payable semiannually on May 15 and November 15 of each year (each an “Interest Payment Date”) to the persons in whose names the 2015 Bonds are registered at the close of business on the tenth calendar day next preceding the Interest Payment Date (i.e., May 5 and November 5, respectively) (each a “Regular Record Date”), provided, however, that so long as the 2015 Bonds are registered in the name of DTC, its nominee or a successor depository, the Regular Record Date for interest payable on any Interest Payment Date shall be the close of business on the business day immediately preceding such Interest Payment Date (each subject to certain exceptions provided in this Supplemental Indenture and the Indenture), until maturity, according to the terms of the bonds or on prior redemption or by declaration or otherwise, and at the highest rate of interest borne by any of the bonds outstanding under the Indenture from such date of maturity until they shall be paid or payment thereof shall have been duly provided for. Principal of, and interest on, the 2015 Bonds and the Redemption Price, if applicable, shall be payable at the office or agency of the Company in the Borough of Manhattan, The City of New York; provided, however , that payment of interest may be made, at the option of the Company, by check mailed by the Company or its affiliate to the person entitled thereto at his registered address. If a due date for the payment of interest, principal or the Redemption Price, if applicable, falls on a day that is not a business day, then the payment will be made on the next succeeding business day, and no interest will accrue on the amounts payable for the period from and after the original due date and until the next business day. The term “business day” means any day other than a Saturday or Sunday or day on which banking institutions in the City of New York are required or authorized to close.

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The 2015 Bonds shall be redeemable, in whole or in part at any time and from time to time, at the option of the Company, on any date prior to maturity (with respect to the 2015 Bonds, a “Redemption Date”), at a redemption price (with respect to the 2015 Bonds, the “Redemption Price”) equal to the greater of (i) 100% of the principal amount of the 2015 Bonds being redeemed and (ii) the sum of the present values of the remaining scheduled payments of principal and interest thereon (exclusive of interest accrued to such Redemption Date) discounted to such Redemption Date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate plus 5 basis points, plus, in either case, accrued and unpaid interest on the principal amount being redeemed to such Redemption Date.

For purposes of this Section 3, the following terms have the following meanings:

“Treasury Rate” means, with respect to any Redemption Date for the 2015 Bonds, the rate per annum equal to the semi-annual equivalent yield to maturity or interpolated maturity (on a day count basis) 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. The Treasury Rate shall be calculated on the third business day preceding the Redemption Date.

“Comparable Treasury Issue” means the United States Treasury security selected by the Quotation Agent as having an actual or interpolated maturity comparable to the remaining term of the 2015 Bonds to be redeemed that would be utilized, 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 such 2015 Bonds.

“Quotation Agent” means a Reference Treasury Dealer appointed by the Company.

“Comparable Treasury Price” means, with respect to any Redemption Date for the 2015 Bonds, (1) the average of the Reference Treasury Dealer Quotations for such Redemption Date, after excluding the highest and lowest such Reference Treasury Dealer Quotations, or (2) if fewer than four such Reference Treasury Dealer Quotations are obtained, the average of all such Reference Treasury Dealer Quotations.

“Reference Treasury Dealer” means each of Goldman, Sachs & Co., J.P. Morgan Securities LLC, Morgan Stanley & Co. LLC and RBC Capital Markets, LLC, plus one other financial institution appointed by the Company at the time of any redemption of the 2015 Bonds or their respective affiliates which are primary U.S. Government securities dealers in the United States (a “Primary Treasury Dealer”), and their respective successors; provided, however , that if any of the foregoing or their affiliates or successors ceases to be a Primary Treasury Dealer, the Company will substitute therefor another Primary Treasury Dealer.

“Reference Treasury Dealer Quotations” means, with respect to each Reference Treasury Dealer and any Redemption Date for the 2015 Bonds, the average, as determined by the Quotation Agent, 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 Quotation Agent by such Reference Treasury Dealer at 5:00 p.m., New York City time, on the third business day preceding such Redemption Date.

So long as the 2015 Bonds are registered in the name of DTC, its nominee or a successor depositary, if the Company elects to redeem less than all of the 2015 Bonds, DTC’s practice is to determine by lot the amount of the interest of each Direct Participant in the 2015 Bonds to be redeemed. At all other times, the Trustee shall draw by lot, in such manner as it deems appropriate, the particular 2015 Bonds, or portions of them, to be redeemed.

The 2015 Bonds shall also be redeemable, as a whole but not in part, at the Redemption Price in the event that (i) all the outstanding common stock of the Company shall be acquired by some governmental body or instrumentality and the Company elects to redeem all of the bonds of all series, the Redemption Date in any such event to be not more than one hundred twenty (120) days after the date on which all said stock is so acquired, or (ii) all, or substantially all, the mortgaged and pledged property constituting bondable property which at the time shall be subject to the lien of the Indenture as a first lien shall be released from the lien of the Indenture pursuant to the provisions thereof, and available moneys in the hands of the Trustee, including any moneys deposited by the Company available for the purpose, are sufficient to redeem all the bonds of all series at the redemption prices (together with accrued interest to the date of redemption) specified therein applicable to the redemption thereof upon the happening of such event.

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Notice of redemption shall be given by mail not less than 30 nor more than 90 days prior to the date fixed for redemption to the holders of 2015 Bonds to be redeemed (which, as long as the 2015 Bonds are held in the book-entry only system, will be the Depositary, its nominee or a successor depositary). On and after the date fixed for redemption (unless the Company defaults in the payment of the Redemption Price and interest accrued thereon to such date), interest on the 2015 Bonds or the portions of them so called for redemption shall cease to accrue. If the Company elects to redeem any 2015 Bonds, the Company will notify the Trustee of its election at least 45 days prior to the Redemption Date (or a shorter period acceptable to the Trustee). The Company will provide the Trustee a reasonably detailed computation of the Redemption Price with such notice (or, if not then known, the manner of calculation, with the actual computation provided by the Company to the Trustee promptly following its computation).

The 2015 Bonds of the several denominations are exchangeable for a like aggregate principal amount of other 2015 Bonds of other authorized denominations. Notwithstanding the provisions of Section 2.03 of the Original Indenture, for any exchange of the 2015 Bonds for other 2015 Bonds of different authorized denominations, or for any transfer of 2015 Bonds, the Company may require the payment of a sum sufficient to reimburse it for any tax or other governmental charge incident thereto only. The 2015 Bonds may be presented for transfer or exchange at the corporate trust office of the Trustee in New York, New York.

B. CREATION OF FIRST MORTGAGE BONDS, 3.85% SERIES DUE 2042

Section 1. The Company hereby creates a new series of bonds, not limited in principal amount except as provided in the Original Indenture, to be issued under and secured by the Original Indenture, to be designated by the title “First Mortgage Bonds, 3.85% Series due 2042.” The initial issue of the 2042 Bonds shall consist of Four Hundred Million Dollars ($400,000,000) principal amount thereof. Subject to the terms of the Indenture, the principal amount of the 2042 Bonds is unlimited. The Company may, at its option in the future, issue additional 2042 Bonds.

The 2042 Bonds shall be issued only as registered bonds without coupons in the denomination of Two Thousand Dollars ($2,000) and any integral multiple of One Thousand Dollars ($1,000) above that amount.

Section 2. (a) The 2042 Bonds shall be issued in registered form without coupons and shall be issued initially in the form of one or more Global Bonds (each such Global Bond, a “2042 Global Bond”) to or on behalf of The Depository Trust Company (“DTC”), as depositary therefor (in such capacity, the “Depositary”), and registered in the name of such Depositary or its nominee. Any 2042 Bonds to be issued or transferred to, or to be held by or on behalf of DTC as such Depositary or such nominee (or any successor of such nominee) for such purpose shall bear the depositary legends in substantially the form set forth at the top of the form of the 2042 Bonds in Section C of this Article I, unless otherwise agreed by the Company, and in the case of a successor Depositary, such legend or legends as such Depositary and/or the Company shall require and to which each shall agree, in each case such agreement to be confirmed in writing to the Trustee. Principal of, and interest on, the 2042 Bonds and the Redemption Price (as defined below), if applicable, will be payable, the transfer of the 2042 Bonds will be registrable and the 2042 Bonds will be exchangeable for the 2042 Bonds bearing identical terms and provisions, at the office or agency of the Company in the Borough of Manhattan, The City and State of New York; provided, however, that payment of interest may be made at the option of the Company by check mailed to the registered holders thereof at their registered address; and further provided, however, that with respect to a 2042 Global Bond, the Company may make payments of principal of, and interest on, the 2042 Global Bond and the Redemption Price, if applicable, and interest on such 2042 Global Bond pursuant to and in accordance with such arrangements as are agreed upon by the Company and the Depositary for such 2042 Global Bond. The 2042 Bonds shall have the terms set forth in the form of the New Series Bond set forth in Section C of this Article I.

(b) Notwithstanding any other provision of this Subsection B.2 of this Article I or of Section 2.03 of the Original Indenture, except as contemplated by the provisions of paragraph (c) below, a 2042 Global Bond may be transferred, in whole but not in part and in the manner provided in Section 2.03 of the Original Indenture, only to a nominee of the Depositary for such 2042 Global Bond, or to the Depositary, or to a successor Depositary for such 2042 Global Bond selected or approved by the Company, or to a nominee of such successor Depositary.

(c) (1) If at any time the Depositary for a 2042 Global Bond notifies the Company that it is unwilling or unable to continue as the Depositary for such 2042 Global Bond or if at any time the Depositary for a 2042 Global Bond ceases to be a clearing agency registered under the Securities Exchange Act of 1934, as amended, at a time when the

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Depositary is required to be so registered to act as such Depositary, the Company shall appoint a successor Depositary with respect to such 2042 Global Bond. If a successor Depositary for such 2042 Global Bond is not appointed by the Company within 90 days after the Company receives such notice or becomes aware of such cessation, the Company will execute, and the Trustee, upon receipt of a Company order for the authentication and delivery of 2042 Bonds in the form of definitive certificates in exchange for such 2042 Global Bond, will authenticate and deliver, without service charge, 2042 Bonds in the form of definitive certificates of like tenor and terms in an aggregate principal amount equal to the principal amount of the 2042 Global Bond in exchange for such 2042 Global Bond. Such 2042 Bonds will be issued to and registered in the name of such person or persons as are specified by the Depositary.

(2) The Company may at any time and in its sole discretion (subject to the procedures of the Depositary) determine that any 2042 Bonds issued or issuable in the form of one or more 2042 Global Bonds shall no longer be represented by such 2042 Global Bond or Bonds. In any such event the Company will execute, and the Trustee, upon receipt of a Company order for the authentication and delivery of 2042 Bonds in the form of definitive certificates in exchange in whole or in part for such 2042 Global Bond or Bonds, will authenticate and deliver, without service charge, to each person specified by the Depositary, 2042 Bonds in the form of definitive certificates of like tenor and terms in an aggregate principal amount equal to the principal amount of such 2042 Global Bond or the aggregate principal amount of such 2042 Global Bonds in exchange for such 2042 Global Bond or Bonds.

(3) If at any time a completed default has occurred and is continuing with respect to the 2042 Bonds and beneficial owners of a majority in aggregate principal amount of the 2042 Bonds represented by 2042 Global Bonds advise the Depositary to cease acting as the Depositary, the Company will execute, and the Trustee, upon receipt of a Company order for the authentication and delivery of 2042 Bonds in the form of definitive certificates in exchange for such 2042 Global Bond, will authenticate and deliver, without service charge, 2042 Bonds in the form of definitive certificates of like tenor and terms in an aggregate principal amount equal to the principal amount of the 2042 Global Bond in exchange for such 2042 Global Bond. Such 2042 Bonds will be issued to and registered in the name of such person or persons as are specified by the Depositary.

(4) In any exchange provided for in any of the preceding three subparagraphs, the Company shall execute and the Trustee shall authenticate and deliver 2042 Bonds in the form of definitive certificates in authorized denominations. Upon the exchange of the entire principal amount of a 2042 Global Bond for 2042 Bonds in the form of definitive certificates, such 2042 Global Bond shall be canceled by the Trustee. Except as provided in the immediately preceding subparagraph, 2042 Bonds issued in exchange for a 2042 Global Bond pursuant to Subsection B.2 of this Article I shall be registered in such names and in such authorized denominations as the Depositary for such 2042 Global Bond, acting pursuant to instructions from its direct or indirect participants or otherwise, shall instruct the Trustee. Provided that the Company and the Trustee have so agreed, the Trustee shall deliver such 2042 Bonds to the persons in whose names the 2042 Bonds are so to be registered.

(5) Any endorsement of a 2042 Global Bond to reflect the principal amount thereof, or any increase or decrease in such principal amount, shall be made in such manner and by such person or persons as shall be specified in or pursuant to any applicable letter of representations or other arrangement entered into with, or procedures of, the Depositary with respect to such 2042 Global Bond or in the Company order delivered or to be delivered pursuant to Section 4.07 of the Original Indenture with respect thereto. Subject to the provisions of Section 4.07 of the Original Indenture, the Trustee shall deliver and redeliver any such 2042 Global Bond in the manner and upon instructions given by the person or persons specified in or pursuant to any applicable letter of representations or other arrangement entered into with, or procedures of, the Depositary with respect to such 2042 Global Bond or in any applicable Company order. If a Company order pursuant to Section 4.07 of the Original Indenture is so delivered, any instructions by the Company with respect to such 2042 Global Bond contained therein shall be in writing but need not be accompanied by or contained in an officers’ certificate and need not be accompanied by an opinion of counsel.

(6) The Depositary or, if there be one, its nominee, shall be the holder of a 2042 Global Bond for all purposes under the Indenture and the 2042 Bonds and beneficial owners with respect to such 2042 Global Bond shall hold their interests pursuant to applicable procedures of such Depositary. The Company, the Trustee and any bond registrar shall be entitled to deal with such Depositary for all purposes of the Indenture relating to such 2042 Global Bond (including the payment of principal, the Redemption Price, if applicable, and interest and the giving of instructions or directions by or to the beneficial owners of such 2042 Global Bond as the sole holder of such 2042

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Global Bond and shall have no obligations to the beneficial owners thereof (including any direct or indirect participants in such Depositary)). None of the Company, the Trustee, any paying agent or bond registrar shall have any responsibility or liability for any aspect of the records relating to or payments made on account of beneficial ownership interests of a beneficial owner in or pursuant to any applicable letter of representations or other arrangement entered into with, or procedures of, the Depositary with respect to such 2042 Global Bond or for maintaining, supervising or reviewing any records relating to such beneficial ownership interests.

Section 3. November 20, 2012, shall be the date of the beginning of the first interest period for the 2042 Bonds. The first Interest Payment Date (as defined below) shall be May 15, 2013. The 2042 Bonds shall be dated as provided in Section 2.01 of the Original Indenture. The 2042 Bonds shall be payable on November 15, 2042, in such coin or currency of the United States of America as at the time of payment is legal tender for the payment of public and private debts, and shall bear interest, payable in like coin or currency, at the rate of 3.85% per annum, payable semiannually on May 15 and November 15 of each year (each an “Interest Payment Date”) to the persons in whose names the 2042 Bonds are registered at the close of business on the tenth calendar day next preceding the Interest Payment Date (i.e., May 5 and November 5, respectively) (each a “Regular Record Date”), provided, however, that so long as the 2042 Bonds are registered in the name of DTC, its nominee or a successor depository, the Regular Record Date for interest payable on any Interest Payment Date shall be the close of business on the business day immediately preceding such Interest Payment Date (each subject to certain exceptions provided in this Supplemental Indenture and the Indenture), until maturity, according to the terms of the bonds or on prior redemption or by declaration or otherwise, and at the highest rate of interest borne by any of the bonds outstanding under the Indenture from such date of maturity until they shall be paid or payment thereof shall have been duly provided for. Principal of, and interest on, the 2042 Bonds and the Redemption Price, if applicable, shall be payable at the office or agency of the Company in the Borough of Manhattan, The City of New York; provided, however , that payment of interest may be made, at the option of the Company, by check mailed by the Company or its affiliate to the person entitled thereto at his registered address. If a due date for the payment of interest, principal or the Redemption Price, if applicable, falls on a day that is not a business day, then the payment will be made on the next succeeding business day, and no interest will accrue on the amounts payable for the period from and after the original due date and until the next business day. The term “business day” means any day other than a Saturday or Sunday or day on which banking institutions in the City of New York are required or authorized to close.

At any time before May 15, 2042, the 2042 Bonds shall be redeemable, in whole or in part and from time to time, at the option of the Company, on any date (with respect to the 2042 Bonds, a “Redemption Date”), at a redemption price (with respect to the 2042 Bonds, the “Make-Whole Redemption Price”) equal to the greater of (i) 100% of the principal amount of the 2042 Bonds being redeemed and (ii) the sum of the present values of the remaining scheduled payments of principal and interest thereon (exclusive of interest accrued to such Redemption Date) discounted to such Redemption Date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the Treasury Rate plus 20 basis points, plus, in either case, accrued and unpaid interest on the principal amount being redeemed to such Redemption Date.

At any time on or after May 15, 2042, the 2042 Bonds shall be redeemable, in whole or in part and from time to time, at the option of the Company, at a redemption price (together with any Make-Whole Redemption Price, with respect to the 2042 Bonds, each a “Redemption Price”) equal to 100% of the principal amount of the 2042 Bonds being redeemed plus accrued and unpaid interest on the principal amount being redeemed to such Redemption Date.

For purposes of the second preceding paragraph of this Section 3, the following terms have the following meanings:

“Treasury Rate” means, with respect to any Redemption Date for the 2042 Bonds, the rate per annum equal to the semi-annual equivalent yield to maturity or interpolated maturity (on a day count basis) 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. The Treasury Rate shall be calculated on the third business day preceding the Redemption Date.

“Comparable Treasury Issue” means the United States Treasury security selected by the Quotation Agent as having an actual or interpolated maturity comparable to the remaining term of the 2042 Bonds to be redeemed that would be utilized, 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 such 2042 Bonds.

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“Quotation Agent” means a Reference Treasury Dealer appointed by the Company.

“Comparable Treasury Price” means, with respect to any Redemption Date for the 2042 Bonds, (1) the average of the Reference Treasury Dealer Quotations for such Redemption Date, after excluding the highest and lowest such Reference Treasury Dealer Quotations, or (2) if fewer than four such Reference Treasury Dealer Quotations are obtained, the average of all such Reference Treasury Dealer Quotations.

“Reference Treasury Dealer” means each of Goldman, Sachs & Co., J.P. Morgan Securities LLC, Morgan Stanley & Co. LLC and RBC Capital Markets, LLC, plus one other financial institution appointed by the Company at the time of any redemption of the 2042 Bonds or their respective affiliates which are primary U.S. Government securities dealers in the United States (a “Primary Treasury Dealer”), and their respective successors; provided, however , that if any of the foregoing or their affiliates or successors ceases to be a Primary Treasury Dealer, the Company will substitute therefor another Primary Treasury Dealer.

“Reference Treasury Dealer Quotations” means, with respect to each Reference Treasury Dealer and any Redemption Date for the 2042 Bonds, the average, as determined by the Quotation Agent, 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 Quotation Agent by such Reference Treasury Dealer at 5:00 p.m., New York City time, on the third business day preceding such Redemption Date.

So long as the 2042 Bonds are registered in the name of DTC, its nominee or a successor depositary, if the Company elects to redeem less than all of the 2042 Bonds, DTC’s practice is to determine by lot the amount of the interest of each Direct Participant in the 2042 Bonds to be redeemed. At all other times, the Trustee shall draw by lot, in such manner as it deems appropriate, the particular 2042 Bonds, or portions of them, to be redeemed.

The 2042 Bonds shall also be redeemable, as a whole but not in part, at the Make-Whole Redemption Price in the event that (i) all the outstanding common stock of the Company shall be acquired by some governmental body or instrumentality and the Company elects to redeem all of the bonds of all series, the Redemption Date in any such event to be not more than one hundred twenty (120) days after the date on which all said stock is so acquired, or (ii) all, or substantially all, the mortgaged and pledged property constituting bondable property which at the time shall be subject to the lien of the Indenture as a first lien shall be released from the lien of the Indenture pursuant to the provisions thereof, and available moneys in the hands of the Trustee, including any moneys deposited by the Company available for the purpose, are sufficient to redeem all the bonds of all series at the redemption prices (together with accrued interest to the date of redemption) specified therein applicable to the redemption thereof upon the happening of such event.

Notice of redemption shall be given by mail not less than 30 nor more than 90 days prior to the date fixed for redemption to the holders of 2042 Bonds to be redeemed (which, as long as the 2042 Bonds are held in the book-entry only system, will be the Depositary, its nominee or a successor depositary). On and after the date fixed for redemption (unless the Company defaults in the payment of the Redemption Price and interest accrued thereon to such date), interest on the 2042 Bonds or the portions of them so called for redemption shall cease to accrue. If the Company elects to redeem any 2042 Bonds, the Company will notify the Trustee of its election at least 45 days prior to the Redemption Date (or a shorter period acceptable to the Trustee). The Company will provide the Trustee a reasonably detailed computation of the Redemption Price with such notice (or if the Redemption Price includes the Make Whole Redemption Price, the manner of calculation, with the actual computation provided by the Company to the Trustee promptly following its computation).

The 2042 Bonds of the several denominations are exchangeable for a like aggregate principal amount of other 2042 Bonds of other authorized denominations. Notwithstanding the provisions of Section 2.03 of the Original Indenture, for any exchange of the 2042 Bonds for other 2042 Bonds of different authorized denominations, or for any transfer of 2042 Bonds, the Company may require the payment of a sum sufficient to reimburse it for any tax or other governmental charge incident thereto only. The 2042 Bonds may be presented for transfer or exchange at the corporate trust office of the Trustee in New York, New York.

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C. FORM OF THE NEW SERIES BONDS

The New Series Bonds shall be substantially in the following form, with such inclusions, omissions, and variations as the Board of Directors of the Company may determine in accordance with the provisions of the Indenture and with such variations, as between the 2015 Bonds and the 2042 Bonds, as set forth therein:

[FORM OF THE NEW SERIES BONDS]

[Insert applicable depositary legend or legends, which initially shall be the following:

THIS SECURITY IS A GLOBAL NOTE WITHIN THE MEANING OF THE INDENTURE HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY OR A NOMINEE THEREOF. THIS SECURITY MAY NOT BE EXCHANGED IN WHOLE OR IN PART FOR A SECURITY REGISTERED, AND NO TRANSFER OF THIS SECURITY IN WHOLE OR IN PART MAY BE REGISTERED, IN THE NAME OF ANY PERSON OTHER THAN SUCH DEPOSITARY OR A NOMINEE THEREOF, EXCEPT IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE INDENTURE.

UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION (“DTC”), TO FLORIDA POWER CORPORATION d/b/a PROGRESS ENERGY FLORIDA, INC. OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE, OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS 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 INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

THIS FIRST MORTGAGE BOND,     % SERIES DUE 20     MAY, UNDER CONDITIONS PROVIDED IN THE INDENTURE, BE EXCHANGED FOR FIRST MORTGAGE BONDS,     % SERIES DUE 20     IN THE FORM OF DEFINITIVE CERTIFICATES OF LIKE TENOR AND OF AN EQUAL AGGREGATE PRINCIPAL AMOUNT, IN AUTHORIZED DENOMINATIONS, REGISTERED IN THE NAMES OF SUCH PERSONS AS THE DEPOSITARY SHALL INSTRUCT THE TRUSTEE. ANY SUCH EXCHANGE SHALL BE MADE UPON RECEIPT BY THE TRUSTEE OF AN OFFICERS’ CERTIFICATE THEREFOR AND A WRITTEN INSTRUCTION FROM THE DEPOSITARY SETTING FORTH THE NAME OR NAMES IN WHICH THE TRUSTEE IS TO REGISTER SUCH FIRST MORTGAGE BONDS,     % SERIES DUE 20     IN THE FORM OF DEFINITIVE CERTIFICATES.]

FLORIDA POWER CORPORATION

d/b/a PROGRESS ENERGY FLORIDA, INC.

(Incorporated under the laws of the State of Florida)

FIRST MORTGAGE BOND,

% SERIES DUE 20

DUE                     , 20    

FLORIDA POWER CORPORATION d/b/a PROGRESS ENERGY FLORIDA, INC. , a corporation of the State of Florida (hereinafter called the Company), for value received, hereby promises to pay to                                          or registered assigns, on                      at the office or agency of the Company in the Borough of Manhattan, The City of New York,                      Dollars ($        ) in such coin or currency of the United States of America as at the time of payment is legal tender for the payment of public and private debts, and to pay interest thereon, semiannually on May 15 and November 15 of each year, commencing May 15, 2013, to the person in whose name this bond is registered at the close of business on the tenth calendar day

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next preceding the interest payment date (i.e., May 5 and November 5, respectively), provided, however , that so long as this bond is registered in the name of The Depository Trust Company, its nominee or a successor depository, the record date for interest payable on any interest payment date shall be the close of business on the business day immediately preceding such interest payment date (each subject to certain exceptions provided in the Mortgage hereinafter mentioned), at the rate of              per annum, at said office or agency in like coin or currency, from the date hereof until this bond shall mature, according to its terms or on prior redemption or by declaration or otherwise, and at the highest rate of interest borne by any of the bonds outstanding under the Mortgage hereinafter mentioned from such date of maturity until this bond shall be paid or the payment hereof shall have been duly provided for; provided, however , that payment of interest may be made at the option of the Company by check mailed by the Company or its affiliate to the person entitled thereto at his registered address. If a due date for the payment of interest, principal, or the Redemption Price, if applicable, falls on a day that is not a business day, then the payment will be made on the next succeeding business day, and no interest will accrue on the amounts payable for the period from and after the original due date and until the next business day. The term “business day” means any day other than a Saturday or Sunday or day on which banking institutions in the City of New York are required or authorized to close.

Additional provisions of this bond are set forth on the reverse hereof and such provisions shall for all purposes have the same effect as though fully set forth at this place.

This bond shall not become valid or obligatory for any purpose until The Bank of New York Mellon, or its successor as Trustee under the Mortgage, shall have signed the certificate of authentication endorsed hereon.

IN WITNESS WHEREOF, FLORIDA POWER CORPORATION d/b/a PROGRESS ENERGY FLORIDA, INC. has caused this bond to be signed in its name by its President or one of its Vice Presidents by his signature or a facsimile thereof, and its corporate seal, or a facsimile thereof, to be affixed hereto and attested by its Secretary or one of its Assistant Secretaries by his signature or a facsimile thereof.