Document:

<PAGE>

                          SUPPLEMENTAL TRUST INDENTURE

                                      FROM

                          NORTHERN STATES POWER COMPANY
                            (A MINNESOTA CORPORATION)

                                       TO

                            BNY MIDWEST TRUST COMPANY

                            EFFECTIVE AUGUST 1, 2002

                         SUPPLEMENTAL TO TRUST INDENTURE
                             DATED FEBRUARY 1, 1937

                                       AND

                            SUPPLEMENTAL AND RESTATED
                                 TRUST INDENTURE
                                DATED MAY 1, 1988

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                                             PAGE

<S>                                                                                                         <C>
Parties..........................................................................................................1

Recitals.........................................................................................................1

Form of Bonds of Series due August 28, 2012......................................................................3

Form of Trustee's Certificate....................................................................................8

Further Recitals.................................................................................................8

ARTICLE I             SPECIFIC SUBJECTION OF ADDITIONAL PROPERTY TO THE LIEN OF THE ORIGINAL INDENTURE..........13
         Section 1.01.         .................................................................................13

ARTICLE II            DEFINITIONS...............................................................................15
         Section 2.01.         .................................................................................15

ARTICLE III           PROVISIONS OF 8.00% SERIES A AND SERIES B FIRST MORTGAGE BONDS DUE AUGUST 28, 2012........17
         Section 3.01.         .................................................................................17
         Section 3.02.         .................................................................................18
         Section 3.03.         .................................................................................20
         Section 3.04.         .................................................................................21
         Section 3.05.         .................................................................................21
         Section 3.06.         .................................................................................24
         Section 3.07.         .................................................................................24
         Section 3.08.         .................................................................................25
         Section 3.09.         .................................................................................28

ARTICLE IV            APPOINTMENT OF AUTHENTICATING AGENT.......................................................28
         Section 4.01.         .................................................................................28
         Section 4.02.         .................................................................................28
         Section 4.03.         .................................................................................29
         Section 4.04.         .................................................................................30

ARTICLE V             FINANCING STATEMENT TO COMPLY WITH THE UNIFORM COMMERCIAL CODE............................30
         Section 5.01.         .................................................................................30
         Section 5.02.         .................................................................................30
         Section 5.03.         .................................................................................30
         Section 5.04.         .................................................................................31
</TABLE>

                                      -i-

<PAGE>

                                TABLE OF CONTENTS
                                   (continued)

<TABLE>
<CAPTION>
                                                                                                             PAGE

<S>                                                                                                         <C>
         Section 5.05.         .................................................................................31
         Section 5.06.         .................................................................................34

ARTICLE VI            AMENDMENTS TO INDENTURE...................................................................35
         Section 6.01.         .................................................................................35

ARTICLE VII           MISCELLANEOUS.............................................................................35
         Section 7.01.         .................................................................................35
         Section 7.02.         .................................................................................35
         Section 7.03.         .................................................................................35
         Section 7.04.         .................................................................................36
         Section 7.05.         .................................................................................36
         Section 7.06.         .................................................................................36
</TABLE>

                                      -ii-

<PAGE>

         Supplemental Trust Indenture, made effective as of the 1st day of
August, 2002, by and between NORTHERN STATES POWER COMPANY (formerly Northern
Power Corporation), a corporation duly organized and existing under and by
virtue of the laws of the State of Minnesota, having its principal office in the
County of Minneapolis, Minnesota (the "Company"), party of the first part, and
BNY MIDWEST TRUST COMPANY, a corporation duly organized and existing under and
by virtue of the laws of the State of Illinois, having its principal office in
the City of Chicago, Illinois (as successor Trustee to Harris Trust and Savings
Bank) (the "Trustee"), party of the second part;

WITNESSETH:

         WHEREAS, a predecessor in interest to the Company, Xcel Energy Inc.
(formerly Northern States Power Company), a corporation duly organized and
existing under and by virtue of the laws of the State of Minnesota (the
"Predecessor Company") has heretofore executed and delivered to the Trustee its
Trust Indenture (the "1937 Indenture"), made as of February 1, 1937, whereby the
Predecessor Company granted, bargained, sold, warranted, released, conveyed,
assigned, transferred, mortgaged, pledged, set over and confirmed to the Trustee
and to its respective successors in trust, all property, real, personal and
mixed then owned or thereafter acquired or to be acquired by the Predecessor
Company (except as therein excepted from the lien thereof) and subject to the
rights reserved by the Predecessor Company in and by the provisions of the 1937
Indenture, to be held by said Trustee in trust in accordance with the provisions
of the 1937 Indenture for the equal pro rata benefit and security of all and
each of the bonds issued and to be issued thereunder in accordance with the
provisions thereof; and

         WHEREAS, the Predecessor Company heretofore has executed and delivered
to the Trustee a Supplemental Trust Indenture, made as of June 1, 1942, whereby
the Predecessor Company conveyed, assigned, transferred, mortgaged, pledged, set
over, and confirmed to the Trustee, and its respective successors in said trust,
additional property acquired by it subsequent to the date of the 1937 Indenture;
and

         WHEREAS, the Predecessor Company prior to August 1, 2000, and
thereafter, the Company, heretofore has executed and delivered to the Trustee
the following additional Supplemental Trust Indentures which, in addition to
conveying, assigning, transferring, mortgaging, pledging, setting over, and
confirming to the Trustee, and its respective successors in said trust,
additional property acquired by it subsequent to the preparation of the next
preceding Supplemental Trust Indenture and adding to the covenants, conditions,
and agreements of the 1937 Indenture certain additional covenants, conditions,
and agreements to be observed by the Company, created the following series of
First Mortgage Bonds:

<Table>
<Caption>
                   DATE OF SUPPLEMENTAL
                     TRUST INDENTURE                                 DESIGNATION OF SERIES
                  ----------------------                             ---------------------
<S>               <C>                                        <C>
                  February 1, 1944                           Series due February 1, 1974 (retired)
                  October 1, 1945                            Series due October 1, 1975 (retired)
                  July 1, 1948                               Series due July 1, 1978 (retired)
                  August 1, 1949                             Series due August 1, 1979 (retired)
                  June 1, 1952                               Series due June 1, 1982 (retired)
</TABLE>

                                       1

<PAGE>

<Table>
<Caption>
                   DATE OF SUPPLEMENTAL
                     TRUST INDENTURE                                 DESIGNATION OF SERIES
                  ----------------------                             ---------------------
<S>               <C>                                        <C>
                  October 1, 1954                            Series due October 1, 1984 (retired)
                  September 1, 1956                          Series due 1986 (retired)
                  August 1, 1957                             Series due August 1, 1987 (redeemed)
                  July 1, 1958                               Series due July 1, 1988 (retired)
                  December 1, 1960                           Series due December 1, 1990 (retired)
                  August 1, 1961                             Series due August 1, 1991 (retired)
                  June 1, 1962                               Series due June 1, 1992 (retired)
                  September 1, 1963                          Series due September 1, 1993 (retired)
                  August 1, 1966                             Series due August 1, 1996 (redeemed)
                  June 1, 1967                               Series due June 1, 1995 (redeemed)
                  October 1, 1967                            Series due October 1, 1997 (redeemed)
                  May 1, 1968                                Series due May 1, 1998 (redeemed)
                  October 1, 1969                            Series due October 1, 1999 (redeemed)
                  February 1, 1971                           Series due March 1, 2001 (redeemed)
                  May 1, 1971                                Series due June 1, 2001 (redeemed)
                  February 1, 1972                           Series due March 1, 2002 (redeemed)
                  January 1, 1973                            Series due February 1, 2003 (redeemed)
                  January 1, 1974                            Series due January 1, 2004 (redeemed)
                  September 1, 1974                          Pollution Control Series A (redeemed)
                  April 1, 1975                              Pollution Control Series B (redeemed)
                  May 1, 1975                                Series due May 1, 2005 (redeemed)
                  March 1, 1976                              Pollution Control Series C (retired)
                  June 1, 1981                               Pollution Control Series D, E and F (redeemed)
                  December 1, 1981                           Series due December 1, 2011 (redeemed)
                  May 1, 1983                                Series due May 1, 2013 (redeemed)
                  December 1, 1983                           Pollution Control Series G (redeemed)
                  September 1, 1984                          Pollution Control Series H (redeemed)
                  December 1, 1984                           Resource Recovery Series I (redeemed)
                  May 1, 1985                                Series due June 1, 2015 (redeemed)
                  September 1, 1985                          Pollution Control Series J, K and L
                  July 1, 1989                               Series due July 1, 2019 (redeemed)
                  June 1, 1990                               Series due June 1, 2020 (redeemed)
                  October 1, 1992                            Series due October 1, 1997 (retired)
                  April 1, 1993                              Series due April 1, 2003
                  December 1, 1993                           Series due December 1, 2000 (retired), and December 1,
                                                             2005
                  February 1, 1994                           Series due February 1, 1999 (retired)
                  October 1, 1994                            Series due October 1, 2001 (retired)
                  June 1, 1995                               Series due July 1, 2025
                  April 1, 1997                              Pollution Control Series M (redeemed), N, 0 and P
                  March 1, 1998                              Series due March 1, 2003, and March 1, 2028
                  May 1, 1999                                Resource Recovery Series Q
</TABLE>

                                       2
<PAGE>

<Table>
<Caption>
                   DATE OF SUPPLEMENTAL
                     TRUST INDENTURE                                 DESIGNATION OF SERIES
                  ----------------------                             ---------------------
<S>               <C>                                        <C>
                  June 1, 2000                               Resource Recovery Series R
                  June 1, 2002                               Series due August 15, 2003
                  July 1, 2002                               Pollution Control Series S; and
</Table>

         WHEREAS, on August 18, 2000 New Centuries Energies, Inc. was merged
with and into the Predecessor Company and the Predecessor Company changed its
corporate name from Northern States Power Company to Xcel Energy Inc.; and

         WHEREAS, pursuant to an Assignment and Assumption Agreement dated as of
August 18, 2000 between the Predecessor Company and the Company, substantially
all the assets of the Predecessor Company (other than the stock of the
Predecessor Company's subsidiaries) were conveyed to, and substantially all the
liabilities of the Predecessor Company, including liabilities created under the
Indenture, were assumed by, the Company (the "Assignment"); and

         WHEREAS, pursuant to the Supplemental Trust Indenture dated as of
August 1, 2000 among the Predecessor Company, the Company and Harris Trust and
Savings Bank, as Trustee, the requirements and conditions precedent set forth in
the Original Indenture and the Restated Indenture (each as hereinafter defined)
with respect to the Assignment were satisfied; and

         WHEREAS, the 1937 Indenture and all of the foregoing Supplemental Trust
Indentures are referred to herein collectively as the "Original Indenture"; and

         WHEREAS, the Predecessor Company heretofore has executed and delivered
to the Trustee a Supplemental and Restated Trust Indenture, dated May 1, 1988
(the "Restated Indenture"), which, in addition to conveying, assigning,
transferring, mortgaging, pledging, setting over, and confirming to the Trustee,
and its respective successors in said trust additional property acquired by it
subsequent to the preparation of the next preceding Supplemental Trust
Indenture, amended and restated the Original Indenture (except for those
Supplemental Trust Indentures executed after May 1, 1988); and

         WHEREAS, the Restated Indenture will not become effective and operative
until all bonds of each series issued under the Original Indenture prior to May
1, 1988, shall have been retired through payment or redemption (including those
bonds "deemed to be paid" within the meaning of that term as used in Article
XVIII of the 1937 Indenture) or until, subject to certain exceptions, the
holders of the requisite principal amount of such bonds shall have consented to
the amendments contained in the Restated Indenture (such date being herein
called the "Effective Date"); and

         WHEREAS, the Original Indenture and the Restated Indenture are referred
to herein collectively as the "Indenture"; and

                                       3

<PAGE>

         WHEREAS, pursuant to the Agreement of Resignation, Appointment and
Acceptance dated as of May 1, 2002 among the Company, BNY Midwest Trust Company,
as successor trustee, and Harris Trust and Savings Bank, the Trustee accepted
the rights, powers, duties and obligations of the trustee under the Indenture
effective as of May 9, 2002; and

         WHEREAS, the Indenture provides that bonds may be issued thereunder in
one or more series, each series to have such distinctive designation as the
Board of Directors of the Company may select for such series; and

         WHEREAS, the Company is desirous of providing for the creation of two
new series of First Mortgage Bonds, said new series of bonds to be designated
"First Mortgage Bonds, Series A due August 28, 2012" and "First Mortgage Bonds,
Series B due August 28, 2012," and the bonds of each such series to be issued as
registered bonds without coupons in denominations of a multiple of $1,000, and
the bonds of each such series to be substantially in the form and of the tenor
following with the redemption prices inserted therein in conformity with the
provisions of Section 3.03 hereof, to-wit:

           (Form of Bonds of Series [A](1) [B](2) due August 28, 2012)
                          NORTHERN STATES POWER COMPANY
             (Incorporated under the laws of the State of Minnesota)
                               First Mortgage Bond
                    Series [A](1) [B](2) Due August 28, 2012

No. _______________                                            $________________

[THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED (THE "SECURITIES ACT"). THE HOLDER HEREOF, BY PURCHASING THIS SECURITY,
AGREES FOR THE BENEFIT OF THE COMPANY THAT THIS SECURITY MAY NOT BE RESOLD,
PLEDGED OR OTHERWISE TRANSFERRED OTHER THAN (A)(1) TO THE COMPANY, (2) IN A
TRANSACTION ENTITLED TO AN EXEMPTION FROM REGISTRATION PROVIDED BY RULE 144
UNDER THE SECURITIES ACT, (3) SO LONG AS THIS SECURITY IS ELIGIBLE FOR RESALE
PURSUANT TO RULE 144A UNDER THE SECURITIES ACT ("RULE 144A"), TO A PERSON WHOM
THE SELLER REASONABLY BELIEVES IS A QUALIFIED INSTITUTIONAL BUYER WITHIN THE
MEANING OF RULE 144A PURCHASING FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A
QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS GIVEN THAT THE RESALE, PLEDGE OR
OTHER TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A, (4) OUTSIDE THE UNITED
STATES IN A TRANSACTION MEETING THE REQUIREMENTS OF REGULATION S UNDER THE
SECURITIES ACT, (5) IN ACCORDANCE WITH ANOTHER APPLICABLE EXEMPTION FROM THE
REGISTRATION REQUIREMENTS OF THE SECURITIES ACT (AND BASED UPON AN OPINION OF
COUNSEL ACCEPTABLE TO THE COMPANY) OR (6) PURSUANT TO A REGISTRATION STATEMENT
WHICH HAS BEEN DECLARED EFFECTIVE UNDER THE SECURITIES ACT AND (B) IN EACH CASE

                                       4

(1) To be inserted only in Series A Bonds due August 28, 2012.
(2) To be inserted only in Series B Bonds due August 28, 2012.
(3) To be inserted only in Series A Bonds due August 28, 2012 other than
    Regulation S Global Bonds.
(4) To be inserted only in Regulation S Global Bonds
(5) To be inserted only in Global Bonds.

<PAGE>

IN ACCORDANCE WITH ANY APPLICABLE SECURITIES LAWS OF EACH STATE OF THE UNITED
STATES. AN INSTITUTIONAL ACCREDITED INVESTOR HOLDING THIS SECURITY AGREES IT
WILL FURNISH TO THE COMPANY AND THE TRUSTEE SUCH CERTIFICATES AND OTHER
INFORMATION AS THEY MAY REASONABLY REQUIRE TO CONFIRM THAT ANY TRANSFER BY IT OF
THIS SECURITY COMPLIES WITH THE FOREGOING RESTRICTIONS. THE HOLDER HEREOF, BY
PURCHASING THIS SECURITY, REPRESENTS AND AGREES FOR THE BENEFIT OF THE COMPANY
THAT IT IS (1) A QUALIFIED INSTITUTIONAL BUYER WITHIN THE MEANING OF RULE 144A
OR (2) AN INSTITUTION THAT IS AN "ACCREDITED INVESTOR" AS DEFINED IN RULE
501(A)(1), (2),(3) OR (7) UNDER THE SECURITIES ACT AND THAT IT IS HOLDING THIS
SECURITY FOR INVESTMENT PURPOSES AND NOT FOR DISTRIBUTION OR (3) A NON-U.S.
PERSON OUTSIDE THE UNITED STATES WITHIN THE MEANING OF REGULATION S UNDER THE
SECURITIES ACT.;](3)

[THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED (THE "SECURITIES ACT"), AND ACCORDINGLY, MAY NOT BE OFFERED OR SOLD
WITHIN THE UNITED STATES OR TO OR FOR THE ACCOUNT OR BENEFIT OF, U.S. PERSONS
EXCEPT AS SET FORTH IN THE FOLLOWING SENTENCE. BY ITS ACQUISITION HEREOF, THE
HOLDER (1) REPRESENTS THAT IT IS NOT A U.S. PERSON AND IS ACQUIRING THIS
SECURITY IN AN OFFSHORE TRANSACTION, (2) BY ITS ACCEPTANCE HEREOF AGREES TO
OFFER, SELL OR OTHERWISE TRANSFER SUCH SECURITY, PRIOR TO THE DATE (THE "RESALE
RESTRICTION TERMINATION DATE") WHICH IS TWO YEARS AFTER THE LATER OF THE
ORIGINAL ISSUE DATE HEREOF AND THE LAST DATE ON WHICH THE ISSUER OR ANY
AFFILIATE OF THE ISSUER WAS THE OWNER OF THIS SECURITY (OR ANY PREDECESSOR OF
SUCH SECURITY), ONLY (A) TO THE ISSUER, (B) PURSUANT TO A REGISTRATION STATEMENT
THAT HAS BEEN DECLARED EFFECTIVE UNDER THE SECURITIES ACT, (C) FOR SO LONG AS
THE SECURITIES ARE ELIGIBLE FOR RESALE PURSUANT TO RULE 144A UNDER THE
SECURITIES ACT ("RULE 144A"), TO A PERSON IT REASONABLY BELIEVES IS A "QUALIFIED
INSTITUTIONAL BUYER" AS DEFINED IN RULE 144A THAT PURCHASES FOR ITS OWN ACCOUNT
OR FOR THE ACCOUNT OF A QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS GIVEN
THAT THE TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A, (D) PURSUANT TO OFFERS
AND SALES THAT OCCUR OUTSIDE THE UNITED STATES WITHIN THE MEANING OF REGULATION
S UNDER THE SECURITIES ACT, (E) TO AN INSTITUTIONAL "ACCREDITED INVESTOR" WITHIN
THE MEANING OF RULE 501(a)(1), (2), (3) OR (7) UNDER THE SECURITIES ACT THAT IS
AN INSTITUTIONAL INVESTOR ACQUIRING THE SECURITY FOR ITS OWN ACCOUNT OR FOR THE
ACCOUNT OF SUCH AN INSTITUTIONAL ACCREDITED INVESTOR, IN EACH CASE IN A MINIMUM
PRINCIPAL AMOUNT OF THE SECURITIES OF $250,000, FOR INVESTMENT PURPOSES AND NOT
WITH A VIEW TO OR FOR OFFER OR SALE IN CONNECTION WITH ANY DISTRIBUTION IN

                                       5

(1) To be inserted only in Series A Bonds due August 28, 2012.
(2) To be inserted only in Series B Bonds due August 28, 2012.
(3) To be inserted only in Series A Bonds due August 28, 2012 other than
    Regulation S Global Bonds.
(4) To be inserted only in Regulation S Global Bonds
(5) To be inserted only in Global Bonds.

<PAGE>

VIOLATION OF THE SECURITIES ACT OR (F) PURSUANT TO ANOTHER AVAILABLE EXEMPTION
FROM THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT, SUBJECT TO THE
ISSUER'S AND THE TRUSTEE'S RIGHTS PRIOR TO ANY SUCH OFFER, SALE OR TRANSFER
PURSUANT TO CLAUSES (D), (E) OR (F) TO REQUIRE THE DELIVERY OF AN OPINION OF
COUNSEL, CERTIFICATION AND/OR OTHER INFORMATION SATISFACTORY TO EACH OF THEM AND
IN THE CASE OF THE FOREGOING CLAUSE (E), A CERTIFICATE OF TRANSFER (A FORM OF
WHICH MAY BE OBTAINED FROM THE ISSUER OR THE TRUSTEE) COMPLETED AND DELIVERED BY
THE TRANSFEROR TO THE ISSUER AND THE TRUSTEE. THIS LEGEND WILL BE REMOVED AFTER
40 CONSECUTIVE DAYS BEGINNING ON AND INCLUDING THE LATER OF (A) THE DAY ON WHICH
THE SECURITIES ARE OFFERED TO PERSONS OTHER THAN DISTRIBUTORS (AS DEFINED IN
REGULATION S) AND (B) THE DATE OF THE CLOSING OF THE ORIGINAL OFFERING. AS USED
HEREIN, THE TERMS "OFFSHORE TRANSACTION", "UNITED STATES" AND "U.S. PERSON" HAVE
THE MEANINGS GIVEN TO THEM BY REGULATION S UNDER THE SECURITIES ACT.](4)

         [Unless this certificate is presented by an authorized representative
of The Depository Trust Company, a New York corporation, to the Company or its
agent for registration of transfer, exchange or payment, and any certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of The Depository Trust Company (and
any payment is made to Cede & Co. or to such other entity as is requested by an
authorized representative of The Depository Trust Company), 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.](5)

         NORTHERN STATES POWER COMPANY, a corporation organized and existing
under the laws of the State of Minnesota (the "Company"), for value received,
hereby promises to pay to [_____________] or its registered assigns, at the
office of the Trustee, in Chicago, Illinois, or, at the option of the registered
owner, at the agency of the Company in the Borough of Manhattan, City and State
of New York, an amount equal to [_________] Dollars [minus the aggregate
principal amount of any definitive bonds of this Series A due August 28, 2012
("Series A Bonds due August 28, 2012") issued in exchange for a portion or
portions hereof and minus the aggregate principal amount of any Series B Bonds
due August 28, 2012 (as such term is defined in the New Supplemental Indenture
(as hereinafter defined)) issued in exchange for a portion or portions of this
bond](1) (the difference thereof, the "Outstanding Principal"), in lawful money
of the United States of America, on the 28th day of August, 2012, and to pay
interest on the Outstanding Principal in like money at the rate of 8.00 percent
per annum [(subject to the paragraph of this bond which refers to a Special
Interest Premium)](1) from the last date to which interest has been paid or duly
provided for, or if no interest has been paid or duly provided for, from the
[date of this bond,](1) [last date to which interest was paid or duly provided
for on the Series A Bonds due August 28, 2012 (as such term is defined in the
New Supplemental Indenture) occurring prior to the date on which this bond was
issued, or if no interest has been paid or duly provided for on the Series A

                                       6

(1) To be inserted only in Series A Bonds due August 28, 2012.
(2) To be inserted only in Series B Bonds due August 28, 2012.
(3) To be inserted only in Series A Bonds due August 28, 2012 other than
    Regulation S Global Bonds.
(4) To be inserted only in Regulation S Global Bonds
(5) To be inserted only in Global Bonds.

<PAGE>

Bonds due August 28, 2012, from the date of the Series A Bonds due August 28,
2012,](2) until the Company's obligation with respect to the payment of such
Outstanding Principal shall be discharged; said interest being payable at the
option of the person entitled to such interest either at the office of the
Trustee, in Chicago, Illinois, or at the agency of the Company in the Borough of
Manhattan, City and State of New York, on the 28th day of February and on the
28th day of August in each year provided that as long as there is no existing
default in the payment of interest and except for the payment of defaulted
interest, the interest payable on any February 28 or August 28 will be paid to
the person in whose name this bond was registered at the close of business on
the record date (the February 13 prior to such February 28 or the August 13
prior to such August 28 (whether or not a business day)).

[EXCEPT UNDER THE LIMITED CIRCUMSTANCES DESCRIBED IN THE INDENTURE, THESE GLOBAL
BONDS MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE REGISTERED DEPOSITORY OR
BY A NOMINEE OF THE REGISTERED DEPOSITORY TO THE REGISTERED DEPOSITORY, ANOTHER
NOMINEE OF THE REGISTERED DEPOSITORY, A SUCCESSOR OF THE REGISTERED DEPOSITORY
OR A NOMINEE OF SUCH SUCCESSOR.](5)

         This bond is one of a duly authorized issue of bonds of the Company, of
the series and designation indicated on the face hereof, which issue of bonds
consists, or may consist, of several series of varying denominations, dates, and
tenor, all issued and to be issued under and equally secured (except insofar as
a sinking fund, or similar fund, established in accordance with the provisions
of the Indenture may afford additional security for the bonds of any specific
series) by a Trust Indenture dated February 1, 1937 (the "1937 Indenture"), as
supplemented by 51 supplemental trust indentures (collectively, the
"Supplemental Indentures"), a Supplemental and Restated Trust Indenture dated
May 1, 1988 (the "Restated Indenture") and a new supplemental trust indenture
effective as of August 1, 2002 for the bonds of this series (the "New
Supplemental Indenture"), executed by the Company to BNY MIDWEST TRUST COMPANY
(as successor trustee to Harris Trust and Savings Bank) (the "Trustee"). The
1937 Indenture, as supplemented by the Supplemental Indentures, the Restated
Indenture and the New Supplemental Indenture is referred to herein as the
"Indenture". Reference hereby is made to the Indenture for a description of the
property mortgaged and pledged, the nature and extent of the security, the
rights of the holders of the bonds as to such security, and the terms and
conditions upon which the bonds may be issued under the Indenture and are
secured. The principal hereof may be declared or may become due on the
conditions, in the manner and at the time set forth in the Indenture upon the
happening of a default as provided in the Indenture.

         With the consent of the Company and to the extent permitted by and as
provided in the Indenture, the rights and obligations of the Company and of the
holders of the bonds, and the terms and provisions of the Indenture and of any
instruments supplemental thereto may be modified or altered by affirmative vote
of the holders of at least 66 2/3% in principal amount of the bonds then
outstanding under the Indenture and any instruments supplemental thereto
(excluding bonds challenged and disqualified from voting by reason of the
Company's interest therein as provided in the Indenture); provided that without
the consent of all holders of all bonds affected no such modification or
alteration shall permit the extension of the maturity of the principal of any
bond or the reduction in the rate of interest thereon or any other modification
in the terms of payment of such principal or interest.

                                       7

(1) To be inserted only in Series A Bonds due August 28, 2012.
(2) To be inserted only in Series B Bonds due August 28, 2012.
(3) To be inserted only in Series A Bonds due August 28, 2012 other than
    Regulation S Global Bonds.
(4) To be inserted only in Regulation S Global Bonds
(5) To be inserted only in Global Bonds.

<PAGE>

         The Restated Indenture amends and restates the 1937 Indenture and the
Supplemental Indentures executed prior to May 1, 1988. The Restated Indenture
will become effective and operative (the "Effective Date") when all bonds of
each series issued under the Indenture prior to May 1, 1988 shall have been
retired through payment or redemption (including those bonds "deemed to be paid"
within the meaning of that term as used in Article XVII of the 1937 Indenture)
or until, subject to certain exceptions, the holders of the requisite principal
amount of such bonds shall have consented to the amendments contained in the
Restated Indenture. Holders of the bonds of this series and of each subsequent
series of bonds issued under the Indenture likewise will be bound by the
amendments contained in the Restated Indenture when they become effective and
operative. Reference is made to the Restated Indenture for a complete
description of the amendments contained therein to the 1937 Indenture and to the
Supplemental Indentures.

         The Company and the Trustee may deem and treat the person in whose name
this bond is registered as the absolute owner hereof for the purpose of
receiving payment and for all other purposes and shall not be affected by any
notice to the contrary.

         This bond is one of the series designated on the face hereof which
series is limited to [an amount equal to](2) $450,000,000 [minus the aggregate
principal amount of all outstanding Series A Bonds due August 28, 2012](2) in
aggregate principal amount as provided in the New Supplemental Indenture.

         The bonds of this Series [A](1) [B](2) due August 28, 2012, shall be
redeemable at the option of the Company as a whole or in part on any date upon
not less than 30 days' previous notice to be given in the manner and with the
effect provided in Section 2 of Article X of the 1937 Indenture (except that, on
and after the Effective Date, such notice shall be given in the manner and
effect provided in Section 10.02 of the Indenture) at a redemption price equal
to the greater of (a) the principal amount being redeemed or (b) the sum of the
present values of the remaining scheduled payments of principal and interest on
the bonds of this Series [A](1) [B](2) due August 28, 2012 that are being
redeemed, discounted to the redemption date on a semi-annual basis (assuming a
360-day year consisting of twelve 30-day months) at the Treasury Yield plus 50
basis points, plus in each case accrued and unpaid interest to the redemption
date.

         "Treasury Yield" means, with respect to any redemption date, 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 bonds of this series 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 the bonds of this series.

                                       8

(1) To be inserted only in Series A Bonds due August 28, 2012.
(2) To be inserted only in Series B Bonds due August 28, 2012.
(3) To be inserted only in Series A Bonds due August 28, 2012 other than
    Regulation S Global Bonds.
(4) To be inserted only in Regulation S Global Bonds
(5) To be inserted only in Global Bonds.

<PAGE>

         "Comparable Treasury Price" means, with respect to any redemption date,
(i) the average of the bid and asked prices for the Comparable Treasury Issue
(expressed in each case as a percentage of its principal amount) on the third
business day preceding such redemption date, as set forth in the daily
statistical release (or any successor release) published by the Federal Reserve
Bank of New York and designated "Composite 3:30 p.m. Quotations for U.S.
Government Securities" or (ii) if such release (or any successor release) is not
published or does not contain such prices on such business day, (A) the average
of the Reference Treasury Dealer Quotations for such redemption date, after
excluding the highest and lowest such Reference Treasury Dealer Quotations for
such redemption date, or (B) if the Trustee obtains fewer than four such
Reference Treasury Dealer Quotations, the average of all such Reference Treasury
Dealer Quotations.

         "Independent Investment Banker" means Lehman Brothers Inc. or its
successor or, if such firm is unwilling or unable to select the Comparable
Treasury Issue, one of the remaining Reference Treasury Dealers appointed by the
Trustee after consultation with the Company.

         "Reference Treasury Dealer" means (i) each of Lehman Brothers Inc. and
any other primary U.S. Government securities dealer in New York City (a "Primary
Treasury Dealer") designated by, and not affiliated with, Lehman Brothers Inc.
and their respective successors, provided, however, that if Lehman Brothers Inc.
or any of its designees shall cease to be a Primary Treasury Dealer, the Company
shall substitute therefor another Primary Treasury Dealer, and (ii) any other
Primary Treasury Dealer selected by the Company.

         "Reference Treasury Dealer Quotations" means, with respect to each
Reference Treasury Dealer and any redemption date, the average, as determined by
the Company, 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 Company by such Reference Treasury Dealer at 5:00 p.m. on the
third business day preceding such redemption date.

         Bonds of this series are not subject to a sinking fund.

         This bond is transferable as prescribed in the Indenture by the
registered owner hereof in person, or by his duly authorized attorney, at the
office of the Trustee in Chicago, Illinois, or at the option of the owner at the
agency of the Company in the Borough of Manhattan, City and State of New York,
or elsewhere if authorized by the Company, upon surrender and cancellation of
this bond, and thereupon a new bond or bonds of the same series and of a like
aggregate principal amount will be issued to the transferee in exchange therefor
as provided in the Indenture, upon payment of taxes or other governmental
charges, if any, that may be imposed in relation thereto.

                                       9

(1) To be inserted only in Series A Bonds due August 28, 2012.
(2) To be inserted only in Series B Bonds due August 28, 2012.
(3) To be inserted only in Series A Bonds due August 28, 2012 other than
    Regulation S Global Bonds.
(4) To be inserted only in Regulation S Global Bonds
(5) To be inserted only in Global Bonds.

<PAGE>

         Bonds of this series are interchangeable as to denominations in the
manner and upon the conditions prescribed in the Indenture.

         No charge shall be made by the Company for any exchange or transfer of
bonds of this Series [A](1) [B](2) due August 28, 2012, other than for taxes or
other governmental charges, if any, that may be imposed in relation thereto.

         The Company shall not be required to issue, transfer or exchange any
bond of this series during a period of ten (10) days immediately preceding any
selection of bonds of this series to be redeemed. The Company shall not be
required to transfer or exchange any bond of this series called or being called
for redemption in its entirety or to transfer or exchange the called portion of
a bond of this series which has been called for partial redemption.

         [The Company has entered into a Registration Rights Agreement dated as
of August 29, 2002 (the "Registration Rights Agreement") with the Initial
Purchasers (as defined therein). Pursuant to such Registration Rights Agreement,
the Company has agreed to file with the Securities and Exchange Commission (the
"SEC") a registration statement and/or a shelf registration statement under the
Securities Act of 1933 for an offer to exchange the bonds of this Series A due
August 28, 2012 for a like aggregate principal amount of Series B Bonds due
August 28, 2012 issued pursuant to the New Supplemental Indenture and subject to
the terms and conditions of the Registration Rights Agreement that are in all
material respects identical to the bonds of this Series A due August 28, 2012
except that such exchange Series B Bonds due August 28, 2012 shall be issued
pursuant to an effective registration statement, shall not be subject to the
paragraph of the bonds of this Series A due August 28, 2012 which refers to a
Special Interest Premium and shall not subject to certain restrictions on
transfer that are applicable to bonds of this Series A due August 28, 2012.](1)

         [Upon the occurrence of certain circumstances set forth in Section 2(e)
of the Registration Rights Agreement (including without limitation, the failure
of the Company to file a registration statement within the specified time
period, the failure of such registration statement and/or a shelf registration
statement (referred to therein) to become effective within the specified time
periods, the failure of a shelf registration statement to remain in effect or
the failure of the Company to exchange Series B Bonds due August 28, 2012 for
Series A Bonds due August 28, 2012 tendered for exchange pursuant to the terms
of the Registration Rights Agreement), the interest rate payable on this bond
shall increase (in addition to the interest rate set forth above) and additional
interest reflecting such increase shall accrue with respect to this bond, from
the date of such occurrence until but not including the date on which such
circumstances shall cease to exist as provided in Section 2(e) of the
Registration Rights Agreement, at the rate of one half of one percent (0.50%)
per annum (the "Special Interest Premium"), which additional interest shall be
payable hereon at the times, in the manner and subject to the same terms and
conditions set forth herein and in the New Supplemental Indenture, as though the
interest rate set forth above had been increased by one half of one percent
(0.50%) per annum; provided, however that the aggregate amount of any Special
Interest Premiums shall not exceed one half of one percent (0.50%) per annum
(regardless of whether multiple events triggering a Special Interest Premium
exist).](1)

                                       10

(1) To be inserted only in Series A Bonds due August 28, 2012.
(2) To be inserted only in Series B Bonds due August 28, 2012.
(3) To be inserted only in Series A Bonds due August 28, 2012 other than
    Regulation S Global Bonds.
(4) To be inserted only in Regulation S Global Bonds
(5) To be inserted only in Global Bonds.

<PAGE>

         No recourse shall be had for the payment of the principal of or the
interest on this bond, or any part thereof, or of any claim based hereon or in
respect hereof or of said Indenture, against any incorporator, or any past,
present, or future shareholder, officer or director of the Company or of any
predecessor or successor corporation, either directly or through the Company, or
through any such predecessor or successor corporation, or through any receiver
or a trustee in bankruptcy, whether by virtue of any constitution, statute, or
rule of law or by the enforcement of any assessment or penalty or otherwise, all
such liability being, by the acceptance hereof and as part of the consideration
for the issue hereof, expressly waived and released, as more fully provided in
the Indenture.

         This bond shall not be valid or become obligatory for any purpose
unless and until the certificate of authentication hereon shall have been signed
by or on behalf of BNY Midwest Trust Company (as successor trustee to Harris
Trust and Savings Bank), as Trustee under the Indenture, or its successor
thereunder.

         IN WITNESS WHEREOF, NORTHERN STATES POWER COMPANY has caused this bond
to be executed in its name by its President or a Vice President and its
corporate seal, or a facsimile thereof, to be hereto affixed and attested by its
Secretary or an Assistant Secretary.

Dated: [        ]                              NORTHERN STATES POWER
                                               COMPANY

       Attest:                                 By:
              ----------------------------        ------------------------------
              Secretary                           President

                                       11

(1) To be inserted only in Series A Bonds due August 28, 2012.
(2) To be inserted only in Series B Bonds due August 28, 2012.
(3) To be inserted only in Series A Bonds due August 28, 2012 other than
    Regulation S Global Bonds.
(4) To be inserted only in Regulation S Global Bonds
(5) To be inserted only in Global Bonds.

<PAGE>

                         (Form of Trustee's Certificate)
         This bond is one of the bonds of the Series designated thereon,
described in the within-mentioned Indenture.

                                       BNY MIDWEST TRUST COMPANY, as
                                       Trustee

                                       By:
                                           -------------------------------------
                                                  Authorized Officer

                                       12

(1) To be inserted only in Series A Bonds due August 28, 2012.
(2) To be inserted only in Series B Bonds due August 28, 2012.
(3) To be inserted only in Series A Bonds due August 28, 2012 other than
    Regulation S Global Bonds.
(4) To be inserted only in Regulation S Global Bonds
(5) To be inserted only in Global Bonds.

<PAGE>

and
         WHEREAS, the Company is desirous of conveying, assigning, transferring,
mortgaging, pledging, setting over, and confirming to the Trustee and to its
respective successors in trust, additional property acquired by it subsequent to
the date of the preparation of the Supplemental Trust Indenture dated as of
August 1, 2000; and

         WHEREAS, the Indenture provides in substance that the Company and the
Trustee may enter into indentures supplemental thereto for the purposes, among
others, of creating and setting forth the particulars of any new series of bonds
and of providing the terms and conditions of the issue of the bonds of any
series not expressly provided for in the Indenture and of conveying, assigning,
transferring, mortgaging, pledging, setting over and confirming to the Trustee
additional property of the Company, and for any other purpose not inconsistent
with the terms of the Indenture; and

         WHEREAS, the execution and delivery of this Supplemental Trust
Indenture have been duly authorized by a resolution adopted by the Board of
Directors of the Company;

         WHEREAS, the Trustee has duly determined to execute this Supplemental
Trust Indenture and to be bound, insofar as it may lawfully do so, by the
provisions hereof;

         NOW, THEREFORE, Northern States Power Company, in consideration of the
premises and of one dollar duly paid to it by the Trustee at or before the
ensealing and delivery of these presents, the receipt of which is hereby
acknowledged, and other good and valuable considerations, does hereby covenant
and agree to and with BNY Midwest Trust Company (as successor trustee to Harris
Trust and Savings Bank), as Trustee, and its successors in the trust under the
Indenture for the benefit of those who hold or shall hold the bonds, or any of
them, issued or to be issued thereunder, as follows:

                                   ARTICLE I

                  SPECIFIC SUBJECTION OF ADDITIONAL PROPERTY TO
                       THE LIEN OF THE ORIGINAL INDENTURE

         Section 1.01. The Company in order to better secure the payment, of
both the principal and interest of all bonds of the Company at any time
outstanding under the Indenture according to their tenor and effect and the
performance of and compliance with the covenants and conditions contained in the
Indenture, has granted, bargained, sold, warranted, released, conveyed,
assigned, transferred, mortgaged, pledged, set over, and confirmed and by these
presents does grant, bargain, sell, warrant, release, convey, assign, transfer,
mortgage, pledge, set over, and confirm to the Trustee and to its respective
successors in said trust forever, subject to the rights reserved by the Company
in and by the provisions of the Indenture, all of the property described and
mentioned or enumerated in a schedule annexed hereto and marked Schedule A,
reference to said schedule being made hereby with the same force and effect as
if the same were incorporated herein at length; together with all and singular
the tenements, hereditaments, and appurtenances belonging and in any way
appertaining to the aforesaid property or any part thereof with the reversion
and reversions, remainder and remainders, tolls, rents and revenues, issues,
income, products, and profits thereof;

                                       13

<PAGE>

         Also, in order to subject the personal property and chattels of the
Company to the lien of the Indenture and to conform with the provisions of the
Uniform Commercial Code, all fossil, nuclear, hydro, and other electric
generating plants, including buildings and other structures, turbines,
generators, exciters, boilers, reactors, nuclear fuel, other boiler plant
equipment, condensing equipment and all other generating equipment; substations;
electric transmission and distribution systems, including structures, poles,
towers, fixtures, conduits, insulators, wires, cables, transformers, services
and meters; steam heating mains and equipment; gas transmission and distribution
systems, including structures, storage facilities, mains, compressor stations,
purifier stations, pressure holders, governors, services, and meters; telephone
plant and related distribution systems; trucks and trailers; office, shop, and
other buildings and structures, furniture and equipment; apparatus and equipment
of all other kinds and descriptions; materials and supplies; all municipal and
other franchises, leaseholds, licenses, permits, privileges, patents and patent
rights; all shares of stock, bonds, evidences of indebtedness, contracts,
claims, accounts receivable, choses in action and other intangibles, all books
of account and other corporate records;

         Excluding, however, all merchandise and appliances heretofore or
hereafter acquired for the purpose of sale to customers and others;

         All the estate, right, title, interest, and claim, whatsoever, at law
as well as in equity which the Company now has or hereafter may acquire in and
to the aforesaid property and every part and parcel thereof subject, however, to
the right of the Company, until the happening of a completed default as defined
in Section 1 of Article XIII of the Original Indenture prior to the Effective
Date and upon the occurrence and continuation of a Completed Default as defined
in the Indenture on and after the Effective Date, to retain in its possession
all shares of stock, notes, evidences of indebtedness, other securities and cash
not expressly required by the provisions hereof to be deposited with the
Trustee, to retain in its possession all contracts, bills and accounts
receivable, motor cars, any stock of goods, wares and merchandise, equipment or
supplies acquired for the purpose of consumption in the operation, construction,
or repair of any of the properties of the Company, and to sell, exchange,
pledge, hypothecate, or otherwise dispose of any or all of such property so
retained in its possession free from the lien of the Indenture, without
permission or hindrance on the part of the Trustee, or any of the bondholders.
No person in any dealings with the Company in respect of any such property shall
be charged with any notice or knowledge of any such completed default (prior to
the Effective Date) or Completed Default (after the Effective Date) under the
Indenture while the Company is in possession of such property. Nothing contained
herein or in the Indenture shall be deemed or construed to require the deposit
with, or delivery to, the Trustee of any of such property, except such as is
specifically required to be deposited with the Trustee by some express provision
of the Indenture;

To have and to hold all said property, real, personal, and mixed, granted,
bargained, sold, warranted, released, conveyed, assigned, transferred,
mortgaged, pledged, set over, or confirmed by the Company as aforesaid, or
intended so to be, to the Trustee and its successors and assigns forever,
subject, however, to permitted liens as defined in Section 5 of Article I of the
1937 Indenture prior to the Effective Date and to Permitted Encumbrances on and
after the Effective Date and to the further reservations, covenants, conditions,
uses, and trusts set forth in the Indenture; in trust nevertheless for the same
purposes and upon the same conditions as are set forth in the Indenture.

                                       14

<PAGE>

                                   ARTICLE II

                                   DEFINITIONS

         SECTION 2.01.

         (a) Capitalized terms used herein and not otherwise defined herein
shall have the respective meanings ascribed thereto in the Indenture.

         (b) For all purposes of this Supplement Trust Indenture, except as
otherwise expressly provided or unless the context otherwise requires, the
following terms shall have the following respective meanings (such meanings
shall apply equally to both the singular and plural forms of the respective
terms):

         "Beneficial Owner" means any Participant or any person claiming a
beneficial ownership in any of the Series A or Series B Bonds due August 28,
2012 under or through the Registered Depository (or its nominee) or any
Participant.

         "Closing Date" means August 29, 2002, the date on which the Initial
Bonds are first issued and sold under the Indenture.

         "DTC" means The Depository Trust Company.

         "Exchange Act" means the Securities and Exchange Act of 1934, as
amended.

         "Exchange Bonds" means the Series B Bonds due August 28, 2012 to be
issued under the Indenture and this Supplemental Trust Indenture in exchange for
the Initial Bonds pursuant to the Exchange Offer.

         "Exchange Offer" means the offer by the Company, pursuant to an
effective registration statement filed with the Securities and Exchange
Commission (the "SEC"), to exchange all of the Series B Bonds due August 28,
2012 for all of the outstanding Series A Bonds due August 28, 2012 in accordance
with the terms and provisions of the Registration Rights Agreement.

         "Exchange Offer Consummation Date" means the date on which the Exchange
Offer is consummated in accordance with the terms and provisions of the
Registration Rights Agreement.

         "Global Bonds" means any Series A or Series B Bonds due August 28,
2012, the registered owner of which is the Registered Depository or its nominee.

         "Initial Bonds" means the Series A Bonds due August 28, 2012 being
issued by the Company under the Indenture and this Supplemental Trust Indenture
and sold to the Initial Purchasers pursuant to the Purchase Agreement.

         "Initial Purchasers" has the meaning set forth in the Purchase
Agreement.

                                       15

<PAGE>

         "Institutional Accredited Investor" shall have the meaning ascribed
thereto in Section 3.01(b) hereof.

         "Participant" means any participant of the Registered Depository.

         "Purchase Agreement" means the Purchase Agreement dated as of August
22, 2002 among the Company and the Initial Purchasers.

         "QIB" shall have the meaning given to such term in Section 3.01(b)
hereof.

         "Registered Depository" means any clearing agency registered with the
SEC pursuant to Section 17A of the Securities Exchange Act of 1934 (the
"Exchange Act") with whom the Company and the Trustee have entered into an
agreement providing that such clearing agency shall act as the depository and
clearing agency for the bonds of Series A and Series B due August 28, 2012. The
initial Registered Depository shall be DTC.

         "Registration Rights Agreement" means the Registration Rights Agreement
dated as of August 29, 2002 among the Company and the Initial Purchasers.

         "Regulation S" means Regulation S promoted under the Securities Act of
1933, as amended (the "Securities Act").

         "Regulation S Global Bond" means one or more Global Bonds deposited
with a custodian for, and registered in the name of a nominee of, the Registered
Depository, interest in which will be held for the benefit of purchasers of the
bonds in offshore transactions under Regulation S.

         "Resale Restriction Termination Date" means the period of two years
after the later of the original issue date of a Restricted Security and the last
date on which the Company or any affiliate of the Company was the owner of such
Restricted Security (or any predecessor of such Restricted Security).

         "Restricted Securities" shall have the meaning given to such term in
Section 3.08 hereof.

         "Rule 144A" means Rule 144A promulgated under the Securities Act.

         "Rule 144A Global Bond" means the one or more bonds deposited with a
custodian for, and registered in the name of a nominee of, the Registered
Depository, interests in which will be held for the benefit of U.S. purchasers
of bonds who are QIBs under Rule 144A.

         "Series A Bonds due August 28, 2012," "bonds of Series A due August 28,
2012" and words of like import shall have the meaning given to the term "Series
A Bonds due August 28, 2012" in Section 3.01(a) hereof.

         "Series B Bonds due August 28, 2012," "bonds of Series B due August 28,
2012" and words of like import shall have the meaning given to such term in
Section 3.01(a) hereof.

         "Series A and Series B Bonds due August 28, 2012" shall mean,
collectively, Series A Bonds due August 28, 2012 and Series B Bonds due August
28, 2012."

                                       16

<PAGE>

         "Series A or Series B Bonds due August 28, 2012" shall mean Series A
Bonds due August 28, 2012 or Series B Bonds due August 28, 2012, as the case may
be.

                                  ARTICLE III

                    PROVISIONS OF 8.00% SERIES A AND SERIES B
                    FIRST MORTGAGE BONDS DUE AUGUST 28, 2012

         SECTION 3.01. (a) There are hereby created two series of bonds
designated: (i) First Mortgage Bonds, Series A due August 28, 2012, in the
aggregate principal amount which at any time may not exceed $450,000,000 (the
"Series A Bonds due August 28, 2012"), and (ii) First Mortgage Bonds, Series B
due August 28, 2012, in an aggregate principal amount which at any time may not
exceed $450,000,000 less the aggregate principal amount of Series A Bonds due
August 28, 2012 then outstanding (the "Series B Bonds due August 28, 2012".

         The Series A Bonds due August 28, 2012 may forthwith be executed by the
Company substantially in the form set forth in the recitals, including the
relevant provisions as indicated therein and delivered to the Trustee for
authentication and delivery by the Trustee in accordance with the provisions of
the Indenture and this Supplemental Trust Indenture. On or prior to the Exchange
Offer Consummation Date, the Company may execute and deliver to the Trustee, and
upon delivery of a request from the Company to the Trustee in accordance with
the provisions of Article IV of the 1937 Indenture, the Trustee shall
authenticate and deliver, the Series B Bonds due August 28, 2012 substantially
in the form set forth in the recitals, including the relevant provisions as
indicated therein, in exchange for a like principal amount of Series A Bonds due
August 28, 2012 validly surrendered to the Company and/or the Trustee, as
applicable, pursuant to the Exchange Offer and in accordance with the
Registration Rights Agreement. Such request from the Company shall specify the
amount of the Series B Bonds due August 28, 2012 to be authenticated and
delivered and the date on which such Series B Bonds due August 28, 2012 are to
be authenticated and delivered. The aggregate principal amount of the Series A
Bonds due August 28, 2012 together with the Series B Bonds due August 28, 2012
outstanding at any time may not exceed $450,000,000.

         (b) (i) The Series A Bonds due August 28, 2012, if issued to persons
that are institutional "accredited investors" meeting the requirements of Rule
501(a)(1), (2), (3) or (7) under the Securities Act (each, an "Institutional
Accredited Investor") that are not QIBs (as defined below), shall, subject to
Sections 3.05(a) and 3.05(c), be issued in definitive form, registered in the
name of the purchaser thereof; and (ii) the Series A Bonds due August 28, 2012
(A) if issued to "qualified institutional buyers" (as defined in Rule 144A under
the Securities Act; each, a "QIB") in reliance on Rule 144A under the Securities
Act shall be issued in the form of one or more Global Bonds that are not
Regulation S Global Bonds, or (B) if issued in offshore transactions to non-U.S.
persons in reliance on Regulation S shall be issued in the form of one or more
Regulation S Global Bonds, shall be deposited on behalf of the purchasers of the
Initial Bonds represented thereby with the Trustee (at its respective address
for notices set forth in the Indenture), as custodian for the Registered
Depository, shall be registered in the name of the Registered Depository or its
nominee and the aggregate principal amount of Series A Bonds due August 28, 2012
so issued may from time to time be increased or decreased by adjustments made on
the records of the Trustee and the Registered Depository or its nominee.

                                       17

<PAGE>

         (c) Each of the Series A and Series B Bonds due August 28, 2012 shall
have and be subject to such other terms as are provided in the Indenture and
this Supplemental Trust Indenture.

         SECTION 3.02. The bonds of Series A and Series B due August 28, 2012
shall mature August 28, 2012, and shall be issued as registered bonds without
coupons in denominations of a multiple of $1,000. The bonds of said series shall
bear interest from their respective dates at the rate of 8.00% per annum payable
on the outstanding principal amount thereof (for purposes of determining the
outstanding principal amount of Series A Bonds due August 28, 2012, the
aggregate principal amount of all Series B Bonds due August 28, 2012 issued in
exchange for such Series A Bonds due August 28, 2012 in an Exchange Offer shall
be deducted from the principal amount of such Series A Bonds due August 28,
2012) and payable semi-annually on February 28and August 28th of each year;
provided, however, that interest payable on the Series A Bonds due August 28,
2012 shall be subject to increase by a maximum aggregate amount of one half of
one percent (0.50%) per annum (the "Special Interest Premium") upon the
occurrence of certain circumstances set forth in Section 2(e) of the
Registration Rights Agreement (including, without limitation, the failure of the
Company to file a registration statement within the specified time period, the
failure of such registration statement and/or a shelf registration statement to
become effective within the specified time periods, the failure of a shelf
registration statement to remain in effect or the failure of the Company to
exchange Series B Bonds due August 28, 2012 for Series A Bonds due August 28,
2012 tendered for exchange pursuant to the terms of the Registration Rights
Agreement), which Special Interest Premium shall accrue from the date of such
occurrence until but not including the date on which such circumstances shall
cease to exist, all as provided in Section 2(e) of the Registration Rights
Agreement. Subject to Section 3.05 hereof, the principal and interest shall be
payable at the office of the Trustee in Chicago, Illinois, or at the option of
the registered owner at the agency of the Company in the Borough of Manhattan,
City and State of New York, in lawful money of the United States of America.
Interest on the bonds of Series A and Series B due August 28, 2012 shall be
calculated on the basis of a 360-day year consisting of twelve 30-day months.

         Bonds of Series A due August 28, 2012 shall be dated as of the interest
payment date immediately preceding the authentication thereof by the Trustee
except that (i) if any bond shall be authenticated before February 28, 2003 it
shall be dated as of August 28, 2002 unless (iii) below is applicable, (ii) if
the Company shall at the time of the authentication of a bond of Series A due
August 28, 2012, be in default in the payment of interest upon the bonds of
Series A due August 28, 2012, such bond shall be dated as of the date of the
beginning of the earliest period for which such interest is so in default, and
(iii) as long as there is no existing default in the payment of interest on the
bonds of Series A due August 28, 2012, if any bond of Series A due August 28,
2012 shall be authenticated after the close of business on any Record Date but
on or prior to the interest payment date relating to such Record Date, it shall
be dated as of such interest payment date.

         Bonds of Series B due August 28, 2012 shall be dated as of the interest
payment date immediately preceding the authentication thereof by the Trustee
except that (i) if any bond of such series shall be authenticated before the
first interest payment date for said series, it shall be dated as of the last
interest payment date to which interest has been paid on the bonds of Series A
due August 28, 2012 that were exchanged for said bond of Series B due August 28,
2012, (ii) if the Company shall at the time of the authentication of a bond of

                                       18
<PAGE>

Series B due August 28, 2012, be in default in the payment of interest upon the
bonds of Series B due August 28, 2012 (or on any bonds of Series A due August
28, 2012 for which said bonds of Series B due August 28, 2012 were issued in
exchange), such bond shall be dated as of the date of the beginning of the
earliest period for which such interest is so in default, and (iii) as long as
there is no existing default in the payment of interest on the bonds of Series B
due August 28, 2012, if any bond of Series B due August 28, 2012 shall be
authenticated after the close of business on any Record Date but on or prior to
the interest payment date relating to such Record Date, it shall be dated as of
such interest payment date.

         As long as there is no existing default in the payment of interest on
the bonds of Series A or Series B due August 28, 2012, as the case may be, the
person in whose name any bond of such series 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 any transfer or exchange of any such bond of such series
subsequent to the Record Date and on or prior to such interest payment date,
except as and to the extent the Company shall default in the payment of the
interest due on such interest payment date, in which case such defaulted
interest shall be paid to the person in whose name such bond of such series is
registered on a Special Record Date for the payment of such defaulted interest
to be fixed by the Trustee, notice thereof shall be given to the registered
holder of any bond of such series not less than 10 days prior to such Special
Record Date, or may be paid at any time in any other lawful manner not
inconsistent with the requirements of any securities exchange on which the bonds
of such series may be listed, and upon such notice as may be required by such
exchange.

         The term "Record Date" as used herein with respect to any interest
payment date (February 28 or August 28) shall mean the February 13 prior to such
February 28 or August 13 prior to such August 28 (whether or not a business
day). The term "business day" as used in this Section 3.02 shall mean any day
other than a Saturday or Sunday or a day on which the offices of the Trustee in
the City of Chicago, Illinois, are closed pursuant to authorization of law.

         As used in this Section 3.02, the term "default in the payment of
interest" means failure to pay interest on the applicable interest payment date
disregarding any period of grace permitted by the Indenture.

         The "Special Record Date" as used herein shall be fixed in the
following manner. The Company shall notify the Trustee in writing of the amount
of defaulted interest proposed to be paid on each bond of Series A or Series B
due August 28, 2012, as the case may be, and the date of the proposed payment,
and at the same time the Company shall deposit with the Trustee an amount of
money equal to the aggregate amount proposed to be paid in respect of such
defaulted interest or shall make arrangements satisfactory to the Trustee for
such deposit prior to the date of the proposed payment, such money when
deposited to be held in trust for the benefit of the persons entitled to such
defaulted interest as provided in this Section 3.02. Thereupon the Trustee shall
fix a Special Record Date for the payment of such defaulted interest which shall
be not more than 15 nor less than 10 days prior to the date of the proposed
payment and not less than 10 days after the receipt by the Trustee of the notice
of the proposed payment. The Trustee shall promptly notify the Company of such
Special Record Date and, in the name and at the expense of the Company, shall
cause notice of the proposed payment of such defaulted interest and the Special

                                       19

<PAGE>

Record Date therefor to be mailed, first class postage prepaid, to each holder
of the bonds of the relevant series due August 28, 2012, at his, her or its
address as it appears in the bond register, not less than 10 days prior to such
Special Record Date. Notice of the proposed payment of such defaulted interest
and the Special Record Date therefor having been mailed as aforesaid, such
defaulted interest shall be paid to the persons in whose names the bonds of the
relevant series due August 28, 2012 are registered on such Special Record Date
and shall not be payable pursuant to the paragraph immediately following in this
Section 3.02.

         The Company may make payment of any defaulted interest in any other
lawful manner not inconsistent with the requirements of any securities exchange
on which the bonds of the relevant series due August 28, 2012, may be listed,
and upon such notice as may be required by such exchange, if, after notice is
given by the Company to the Trustee of the proposed payment pursuant to this
Section 3.02, such payment shall be deemed practicable by the Trustee.

         SECTION 3.03. The bonds of Series A and/or Series B due August 28,
2012, shall be redeemable at the option of the Company as a whole or in part on
any date upon not less than 30 days' previous notice to be given in the manner
and with the effect provided in Section 2 of Article X of the 1937 Indenture
(except that, on and after the Effective Date, such notice shall be given in the
manner and effect provided in Section 10.02 of the Indenture) at a redemption
price equal to the greater of (a) the principal amount being redeemed or (b) the
sum of the present values of the remaining scheduled payments of principal and
interest on the bonds of the relevant series due August 28, 2012 that are being
redeemed, discounted to the redemption date on a semi-annual basis (assuming a
360-day year consisting of twelve 30-day months) at the Treasury Yield plus 50
basis points, plus in each case accrued and unpaid interest to the redemption
date.

         "Treasury Yield" means, with respect to any redemption date, 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 bonds of this series 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 the bonds of this series.

         "Comparable Treasury Price" means, with respect to any redemption date,
(i) the average of the bid and asked prices for the Comparable Treasury Issue
(expressed in each case as a percentage of its principal amount) on the third
business day preceding such redemption date, as set forth in the daily
statistical release (or any successor release) published by the Federal Reserve
Bank of New York and designated "Composite 3:30 p.m. Quotations for U.S.
Government Securities" or (ii) if such release (or any successor release) is not
published or does not contain such prices on such business day, (A) the average
of the Reference Treasury Dealer Quotations for such redemption date, after
excluding the highest and lowest such Reference Treasury Dealer Quotations for
such redemption date, or (B) if the Trustee obtains fewer than four such
Reference Treasury Dealer Quotations, the average of all such Reference Treasury
Dealer Quotations.

                                       20

<PAGE>

         "Independent Investment Banker" means Lehman Brothers Inc. or, if such
firm is unwilling or unable to select the Comparable Treasury Issue, one of the
remaining Reference Treasury Dealers appointed by the Trustee after consultation
with the Company.

         "Reference Treasury Dealer" means (i) each of Lehman Brothers Inc. and
any other primary U.S. Government securities dealer in New York City (a "Primary
Treasury Dealer") designated by, and not affiliated with, Lehman Brothers Inc.
and their respective successors, provided, however, that if Lehman Brothers Inc.
or any of its designees shall cease to be a Primary Treasury Dealer, the Company
shall substitute therefor another Primary Treasury Dealer, and (ii) any other
Primary Treasury Dealer selected by the Company.

         "Reference Treasury Dealer Quotations" means, with respect to each
Reference Treasury Dealer and any redemption date, the average, as determined by
the Company, 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 Company by such Reference Treasury Dealer at 5:00 p.m. on the
third business day preceding such redemption date.

         The bonds of Series A and Series B due August 28, 2012 are not subject
to a sinking fund.

         SECTION 3.04. The bonds of Series A and Series B due August 28, 2012,
shall be executed on behalf of the Company by the manual signature of its
President or one of its Vice Presidents or with the facsimile signature of its
President or one of its Vice Presidents and its corporate seal shall be
thereunto affixed, or printed, lithographed, or engraved thereon, in facsimile,
and attested by the manual signature of its Secretary or one of its Assistant
Secretaries or with the facsimile signature of its Secretary or one of its
Assistant Secretaries. In case any of the officers who shall have signed any
bonds or attested the seal thereon or whose facsimile signature shall be borne
by the bonds shall cease to be such officers of the Company before the bonds so
signed and sealed actually shall have been authenticated by the Trustee or
delivered by the Company, such bonds nevertheless may be issued, authenticated,
and delivered with the same force and effect as though the person or persons who
signed such bonds and attested the seal thereon or whose facsimile signature is
borne by the bonds had not ceased to be such officer or officers of the Company.
Any bond issuable hereunder may be signed or attested by manual or facsimile
signature on behalf of the Company by such person as at the actual date of the
execution of such bond shall be the proper officer of the Company, although at
the date of issuance of such bond such person shall not have been an officer of
the Company.

         SECTION 3.05. (a) Except as provided in subsections (c), (f) and (g) of
this Section 3.05 and Sections 3.01(b), 3.06, 3.07 and 3.08 hereof, the
registered holder of all Series A and Series B Bonds due August 28, 2012 shall
be The Depository Trust Company ("DTC") or its nominee or a successor Registered
Depository or its nominee, and such bonds shall be registered in the name of
Cede & Co., as nominee for DTC, or a successor Registered Depository or its
nominee, if any. The Series A Bonds due August 28, 2012 shall initially be
issued in the form of one or more authenticated fully registered certificates in
the name of Cede & Co., as nominee for DTC, in the aggregate principal amount of
all Series A Bonds due August 28, 2012 authorized for issuance. Upon initial
issuance, the ownership of such bonds shall be registered in the bond register
kept by the Trustee in the name of Cede & Co., as nominee of DTC. Except as

                                       21

<PAGE>

otherwise provided in subsections (c), (f) and (g) of this Section 3.05 and
Sections 3.01(b), 3.06, 3.07 and 3.08 hereof, no person other than DTC shall
receive authenticated bond certificates evidencing the obligation of the Company
to make payments of principal of and interest on the Series A Bonds due August
28, 2012. Notwithstanding any other provision of this Supplemental Trust
Indenture to the contrary, so long as any Global Bonds are registered in the
name of Cede & Co., as nominee of DTC, all payments with respect to the
principal of, premium, if any, and interest on such Global Bonds and all notices
with respect to such Global Bonds shall be made and given, respectively, to DTC
as provided in the representation letter dated as of August 28, 2002 among DTC,
the Company and the Trustee and relating to such Global Bonds and in the rules
and regulations of DTC. The Trustee is hereby authorized and directed to comply
with all terms of such representation letter and of the rules and regulations of
DTC. Upon delivery by DTC to the Trustee of written notice to the effect that
DTC has determined to substitute a new nominee in place of Cede & Co., and
subject to the provisions of the Indenture and this Supplemental Trust Indenture
with respect to transfers of bonds, the word "Cede & Co." in this Supplemental
Trust Indenture shall refer to such new nominee of DTC.

         (b) The Trustee and the Company may treat the Registered Depository (or
its nominee) as the sole and exclusive registered holder of any and all Global
Bonds registered in its name for the purposes of payment of the principal of,
premium, if any, and interest on such Global Bonds and of giving any notice
permitted or required to be given to holders under the Indenture, except as
provided in Section 3.05(g) below; and neither the Trustee nor the Company shall
be affected by any notice to the contrary; and any provision of this
Supplemental Trust Indenture to the contrary notwithstanding, all such
principal, premium and interest shall be paid in accordance with the rules and
regulations of and agreements with the Registered Depository (or its nominee);
and the Trustee is hereby authorized and directed to comply with all such rules
and regulations and agreements. Neither the Trustee nor the Company shall have
any responsibility or obligation to any Participant, any Beneficial Owner or any
other person which is not shown on the bond register maintained by the Trustee
as being a registered holder, with respect to the accuracy of any records
maintained by the Registered Depository or any Participant; the payment to the
Registered Depository or any Participant of any amount in respect of the
principal of, premium, if any, or interest on Global Bonds held under or through
such Registered Agent or Participant; any notice which is permitted or required
to be given under the Indenture to registered holders of Global Bonds; or any
consent given or other action taken by the Registered Depository as bondholder.
The Trustee shall pay all principal of, premium, if any, and interest on the
Global Bonds registered in the name of the Registered Depository (or its
nominee) only to or "upon the order of" (as that term is used in the Uniform
Commercial Code as adopted in Minnesota and New York) the Registered Depository,
and all such payments shall be valid and effective to fully satisfy and
discharge the Company's obligations with respect to the principal of, premium,
if any, and interest on such Global Bonds to the extent of the sum or sums so
paid.

         (c) If the Company in its discretion determines that it is in the best
interests of the Beneficial Owners that they be able to obtain definitive bond
certificates, the Company may, or if the Beneficial Owner is an Institutional
Accredited Investor that is not a QIB, the Company shall, so notify the
Registered Depository and the Trustee, whereupon the Registered Depository will
notify such persons of the availability through the Registered Depository of
definitive bond certificates. In such event, subject to the provisions of
Section 3.08, the Trustee shall issue, transfer and exchange definitive bond
certificates for such Global Bonds as requested by the Registered Depository in
appropriate amounts pursuant to Article II of the 1937 Indenture prior to the
Effective Date, Article II of the Restated Indenture on and after the Effective
Date and Section 3.06 of this Supplemental Trust Indenture. The Company shall
pay all costs in connection with the production of bond certificates under this
Section 3.05(c).

                                       22

<PAGE>

         In connection with any notice or other communication to be provided
pursuant to the Indenture for the bonds of Series A or Series B due August 28,
2012 by the Company or the Trustee with respect to any consent or other action
to be taken by the registered holders of the bonds of such series, the Company
or the Trustee, as the case may be, shall seek to establish a record date to the
extent permitted by the Indenture for such consent or other action and give the
Registered Depository notice of such record date not less than fifteen (15)
calendar days in advance of such record date to the extent possible.

         (d) NEITHER THE COMPANY NOR THE TRUSTEE WILL HAVE ANY RESPONSIBILITY OR
OBLIGATIONS TO THE PARTICIPANTS OR THE BENEFICIAL OWNERS WITH RESPECT TO (1) THE
ACCURACY OF ANY RECORDS MAINTAINED BY THE REGISTERED DEPOSITORY OR ANY
PARTICIPANT; (2) THE PAYMENT BY THE REGISTERED DEPOSITORY OR ANY PARTICIPANT OF
ANY AMOUNT DUE TO ANY BENEFICIAL OWNER IN RESPECT OF THE PRINCIPAL OF, PREMIUM,
IF ANY, OR INTEREST ON ANY GLOBAL BONDS; (3) THE DELIVERY BY THE REGISTERED
DEPOSITORY OR ANY PARTICIPANT OF ANY NOTICE TO ANY BENEFICIAL OWNER WHICH IS
REQUIRED OR PERMITTED UNDER THE TERMS OF THE INDENTURE TO BE GIVEN TO REGISTERED
HOLDERS; (4) THE SELECTION OF THE BENEFICIAL OWNERS TO RECEIVE PAYMENT IN THE
EVENT OF ANY PARTIAL REDEMPTION OF ANY GLOBAL BONDS; OR (5) ANY CONSENT GIVEN OR
OTHER ACTION TAKEN BY THE REGISTERED DEPOSITORY AS A REGISTERED HOLDER.

         SO LONG AS THE NOMINEE OF THE REGISTERED DEPOSITORY IS THE REGISTERED
HOLDER OF ANY GLOBAL BONDS, REFERENCES HEREIN TO REGISTERED HOLDERS OF SUCH THE
BONDS SHALL MEAN SUCH NOMINEE AND SHALL NOT MEAN THE BENEFICIAL OWNERS OF THE
GLOBAL BONDS NOR THE PARTICIPANTS.

         (e) The Registered Depository may determine to discontinue providing
its services with respect to the bonds of Series A and Series B due August 28,
2012 at any time by giving written notice to the Company and the Trustee and
discharging its responsibilities with respect thereto under applicable law.
Under such circumstances (if there is no successor book-entry depository), the
Company and the Trustee shall be obligated (at the sole cost and expense of the
Company), subject to the provisions of Section 3.08 hereof, to deliver bond
certificates as described in this Supplemental Trust Indenture. If bond
certificates are issued, the provisions of the Indenture and this Supplemental
Trust Indenture shall apply to, among other things, the transfer and exchange of
such certificates and the method of payment of principal of, premium, if any,
and interest on such certificates. Whenever the Registered Depository requests
the Company and the Trustee to do so, the Company will direct the Trustee (at
the sole cost and expense of the Company) to cooperate with the Registered
Depository, subject to the provisions of Section 3.08, in taking appropriate
action after reasonable notice (1) to make available one or more separate

                                       23

<PAGE>

certificates evidencing the bonds of the relevant series held by any Participant
as Beneficial Owner to such Participant or (2) to arrange for another book-entry
depository to maintain custody of certificates evidencing the Series A and
Series B due August 28, 2012 registered in the name of the departing Registered
Depository or its nominee. Any successor book-entry depository must be a
clearing agency registered with the Securities and Exchange Commission pursuant
to Section 17A of the Securities Exchange Act of 1934 and must enter into an
agreement with the Company and the Trustee agreeing to act as the depository and
clearing agency for the bonds of Series A and Series B due August 28, 2012
(except as provided in Section 3.05(g) below). After such agreement has become
effective, the departing Registered Depository shall, subject to Section 3.08
hereof, present the Global Bonds for registration of transfer in accordance with
Section 12 of Article II of the 1937 Indenture prior to the Effective Date and
Section 2.12 of the Restated Indenture on and after the Effective Date, and the
Trustee shall register them in the name of the successor book-entry depository
or its nominee. If a successor book-entry depository has not accepted such
position before the effective date of the departing Registered Depository's
termination of its services, the book-entry system shall automatically terminate
and may not be reinstated without the consent of all registered holders of the
bonds of Series A and Series B due August 28, 2012.

         (f) The Company, in its sole discretion, may terminate the services of
the Registered Depository with respect to the Global Bonds of Series A and
Series B due August 28, 2012 if the Company determines that: (i) the Registered
Depository is unable to discharge its responsibilities with respect to such
Global Bonds; or (ii) it is not in the best interests of the Beneficial Owners
of the Series A and Series B Bonds due August 28, 2012 to remain registered in
the name of the Registered Depository or its nominee. After such event and if no
substitute book-entry depository is appointed by the Company, subject to Section
3.08 hereof, bond certificates will be delivered as described in the Indenture
and this Supplemental Trust Indenture.

         (g) Upon the termination of the services of the Registered Depository
with respect to the bonds of Series A and Series B due August 28, 2012 pursuant
to subsections (c), (f) or (g) of this Section 3.05 after which no substitute
book-entry depository is appointed, the bonds of Series A and Series B due
August 28, 2012 shall be registered in whatever name or names holders
transferring or exchanging such bonds shall, subject to the provisions of
Section 3.08, designate in accordance with the provisions of the Indenture and
this Supplemental Trust Indenture.

         SECTION 3.06. Subject to Section 3.08, the registered owner of any bond
or bonds of Series A due August 28, 2012 or of Series B due August 28, 2012, at
his, her, or its option may surrender the same with other bonds of the same
series at the office of the Trustee in Chicago, Illinois, or at the agency of
the Company in the Borough of Manhattan, City and State of New York, or
elsewhere if authorized by the Company, for cancellation, in exchange for other
bonds of the same series of higher or lower authorized denominations, but of the
same aggregate principal amount, bearing interest from its date, and upon
receipt of any payment required under the provisions of Section 3.09 hereof.
Thereupon the Company shall execute and deliver to the Trustee and the Trustee
shall authenticate and deliver such other registered bonds to such registered
owner at its office or at any other place specified as aforesaid.

                                       24

<PAGE>

         SECTION 3.07. Any Initial Bonds which are presented to the Company
and/or the Trustee for exchange pursuant to an Exchange Offer in accordance with
the terms thereof shall be exchanged for Exchange Bonds of equal principal
amount upon surrender to the Company and/or the Trustee of the Initial Bonds to
be exchanged; provided, however, that the Initial Bonds so surrendered for
exchange shall be duly endorsed and accompanied by a letter of transmittal or
written instrument of transfer in form satisfactory to the Company, duly
executed by the registered holder thereof or its attorney who shall be duly
authorized in writing to execute such document. Whenever any Initial Bonds are
so surrendered for exchange, the Company shall execute, and the Trustee shall
authenticate and deliver to and in the name of each registered holder that has
properly tendered its Initial Bonds for exchange, the same aggregate principal
amount of Exchange Bonds as the Initial Bonds that have been so surrendered.

         SECTION 3.08. (a) All Initial Bonds, whether definitive bonds or Global
Bonds, and all beneficial interests in one or more Initial Bonds, and all bonds
issued upon registration of, transfer of, or in exchange for, any such bonds
(other than Exchange Bonds or bonds sold pursuant to an effective registration
statement under the Securities Act or bonds issued, directly or indirectly, upon
registration of transfer of, or in exchange for, any such bonds), shall be
restricted securities (within the meaning of Rule 144 under the Securities Act;
hereinafter, collectively, "Restricted Securities") and shall be subject to the
restrictions on transfer provided in the legends set forth on the Restricted
Securities. The registered holder of each Restricted Security, by such
registered holder's acceptance thereof, agrees to be bound by such restrictions
on transfer. All Restricted Securities shall bear on their faces the applicable
legends limiting transferability set forth on the form of bond in the recitals
hereto.

         Institutional Accredited Investors that are not QIBs may hold interests
in the Initial Bonds only in definitive form. Any beneficial interest in a
Global Bond that is a Restricted Security and is transferred to an Institutional
Accredited Investor which is not a QIB will be delivered in the form of a
definitive bond and will cease to be an interest in such Global Bond.

         A holder of a beneficial interest in a Global Bond may, subject to the
limitations contained in this Section 3.08, exchange such beneficial interest
for one or more definitive bonds if (i) the Company notifies the Trustee in
writing that the Registered Depository is unwilling or unable to continue as
depository for such Global Bond, or the Registered Depository ceases to be a
"clearing agency" registered under the Exchange Act and a successor depository
is not appointed by the Company within 90 days of such notice or cessation or
(ii) the Company, at its option, notifies the Trustee in writing that it elects
to cause the issuance of definitive bonds. If an exchange of a Global Bond for a
definitive bond is made pursuant to clauses (i) or (ii) above, then, upon
surrender by the Registered Depository of any beneficial interest in the Global
Bonds, definitive bonds will be issued to each person that the Registered
Depository identifies as the beneficial owner of the bonds represented by the
Global Bonds. Upon any such issuance, the Trustee will be required to register
such definitive bonds in the name of such person or persons (or nominee of any
thereof) and cause the same to be delivered thereto. Unless determined otherwise
by the Company in accordance with applicable law, each such Global Bond and all
definitive bonds, upon transfer or exchange of beneficial interests in a Global
Bond (other than for an Exchange Bond) will bear the applicable legends limiting
transferability set forth on the form of bond in the recitals hereto.

                                       25

<PAGE>

         Each registered holder of a definitive bond or a beneficial interest in
a Global Bond that is a Restricted Security will be deemed to have represented
and agreed to offer, sell, pledge or otherwise transfer such Initial Bonds or
beneficial interest only in accordance with the legend set forth on the face of
the Restricted Securities.

         Upon the transfer, exchange or replacement of definitive bonds bearing
the legend, or upon request for removal of the legend on a definitive bond, the
Trustee will deliver bonds that do not bear such legend if the Trustee has been
provided evidence satisfactory to the Company and to the Trustee (which may
include an opinion of counsel) that neither the legend nor the restrictions on
transfer set forth therein are required to ensure compliance with the Securities
Act.

         Subject to the restrictions on transfer and exchange set forth herein
and in the Indenture, the holder of any bonds issued hereunder may transfer or
exchange such bonds in whole or in part (in a principal amount which is an
integral multiple of $1,000 or in an amount which is not an integral multiple of
$1,000 if the holder is transferring or exchanging all of the bonds of the
relevant series held by such holder) by surrendering them at the Corporate Trust
Office of the Trustee or at the office of the transfer agent, together with (a),
an executed instrument of assignment and transfer (in the case of a transfer) or
a written request for exchange (in the case of exchange), and, in the case of
Series A Bonds due August 28, 2012 that are Restricted Securities, a certificate
substantially in the form of Exhibit A hereto, and (b) additional certifications
and evidence that such transfer or exchange is in compliance with the Securities
Act and the restrictions on transfer set forth in such bonds as may be required
pursuant to the terms of this Supplemental Trust Indenture.

         Upon surrender of a definitive bond for transfer or exchange with the
appropriate documentation, or notification of a request for transfer or exchange
of a beneficial interest in a Global Bond for a definitive bond or bonds,
subject to the restrictions described herein and in the Indenture, the Trustee
will, within five business days of such request if made at the Corporate Trust
Office of the Trustee, or within 10 Business Days if made at the office of a
transfer agent (other than the Trustee), authenticate and deliver at the
Corporate Trust Office of the Trustee or the office of the transfer agent, as
the case may be, to the transferee (in the case of transfer) or registered
holder (in the case of exchange) or send by first class mail at the risk of the
transferee (in the case of transfer) or registered holder (in the case of
exchange) to such address as the transferee or Holder, as applicable, may
request, a definitive bond or bonds, as the case may require, for a like
aggregate principal amount and in such authorized denomination or denominations
as may be requested. The presentation for transfer or exchange of any definitive
bond will not be valid unless made at the Corporate Trust Office of the Trustee
or at the office of a transfer agent by the registered holder in person or by a
duly authorized attorney-in-fact.

         (b) The following provisions shall apply with respect to any proposed
transfer of a Rule 144A Global Bond or a beneficial interest therein or to a
definitive bond held of record by an Institutional Accredited Investor prior to
the expiration of the Resale Restriction Termination Date:

                  (i) a transfer of a Rule 144A Global Bond or a beneficial
         interest therein or a definitive bond held of record by an
         Institutional Accredited Investor to a QIB shall be made upon the

                                       26

<PAGE>

         representation of the transferee that it is purchasing the bond for its
         own account or an account with respect to which it exercises sole
         investment discretion and that it and any such account is a QIB and is
         aware that the sale to it is being made in reliance on Rule 144A and
         acknowledges that it has received such information regarding the
         Company as the undersigned has requested pursuant to Rule 144A or has
         determined not to request such information and that it is aware that
         the transferor is relying upon its foregoing representations in order
         to claim the exemption from registration provided by Rule 144A;

                  (ii) a transfer of a Rule 144A Global Bond or a beneficial
         interest therein or a definitive bond held of record by an
         Institutional Accredited Investor to an Institutional Accredited
         Investor shall be made upon receipt by the Trustee or its agent of a
         certificate substantially in the form set forth in Exhibit B annexed
         hereto from the proposed transferee and, if requested by the Company or
         the Trustee, the delivery of an opinion of counsel, certifications
         and/or other information satisfactory to each of them; and

                  (iii) a transfer of a Rule 144A Global Bond or a beneficial
         interest therein or a definitive bond held of record by an
         Institutional Accredited Investor to a non-U.S. person shall be made
         upon receipt by the Trustee or its agent of a certificate substantially
         in the form set forth in Exhibit C annexed hereto from the proposed
         transferee and, if requested by the Company or the Trustee, the
         delivery of an opinion of counsel, certifications and/or other
         information satisfactory to each of them.

         (c) The following provisions shall apply with respect to any proposed
transfer of a Regulation S Global Bond or a beneficial interest therein prior to
the expiration of the 40-day "distribution compliance period" within the meaning
of Rule 903 of Regulation S under the Securities Act (the "Distribution
Compliance Period"):

                  (i) a transfer of a Regulation S Global Bond or a beneficial
         interest therein to a QIB shall be made upon the representation of the
         transferee that it is purchasing the bond for its own account or an
         account with respect to which it exercises sole investment discretion
         and that it and any such account is a QIB and is aware that the sale to
         it is being made in reliance on Rule 144A and acknowledges that it has
         received such information regarding the Company as the undersigned has
         requested pursuant to Rule 144A or has determined not to request such
         information and that it is aware that the transferor is relying upon
         its foregoing representations in order to claim the exemption from
         registration provided by Rule 144A;

                  (ii) a transfer of a Regulation S Global Bond or a beneficial
         interest therein to an Institutional Accredited Investor shall be made
         upon receipt by the Trustee or its agent of a certificate substantially
         in the form set forth in Exhibit B annexed hereto from the proposed
         transferee and, if requested by the Company or the Trustee, the
         delivery of an opinion of counsel, certifications and/or other
         information satisfactory to each of them; and

                                       27

<PAGE>

                  (iii) a transfer of a Regulation S Global Bond or a beneficial
         interest therein to a non-U.S. person shall be made upon receipt by the
         Trustee or its agent of a certificate substantially in the form set
         forth in Exhibit C annexed hereto from the proposed transferee and, if
         requested by the Company or the Trustee, the delivery of an opinion of
         counsel, certifications and/or other information satisfactory to each
         of them.

         Prior to or on the expiration of the Distribution Compliance Period,
beneficial interests in a Regulation S Global Bond may only be held through the
operator of the Euroclear System ("Euroclear") or Clearstream Banking, a societe
anonyme ("Clearstream") (as indirect participants in DTC) or another agent
member of Euroclear and Clearstream acting for and on behalf of them, unless
exchanged for interests in the Rule 144A Global Bond in accordance with the
certification requirements hereof. During the Distribution Compliance Period,
interests in the Regulation S Global Bond, if any, may be exchanged for
interests in the Rule 144A Global Bond or for definitive bonds only in
accordance with the certification requirements described in this Section 3.08.

         After the expiration of the Distribution Compliance Period, interests
in the Regulation S Global Bond may be transferred without requiring the
certification set forth in Exhibit C annexed hereto or any additional
certification.

         As used in the preceding two paragraphs of this Section 3.08, the term
"transfer" encompasses any sale, transfer or other disposition of any bonds
referred to herein except for transfers from any registered holder to an
affiliate of such registered holder; provided, that such transferring registered
holder shall deliver a letter to the Trustee stating that the transferee is an
affiliate of such registered holder. The Trustee shall be entitled to rely on
and be fully protected in its reliance on such letter.

         SECTION 3.09. Notwithstanding the provisions of Section 11 of Article
II of the 1937 Indenture or of any provision of this Supplemental Trust
Indenture, the Company shall not be required to issue, transfer or exchange any
bond of Series A or Series B due August 28, 2012, as the case may be, during a
period of ten (10) days immediately preceding any selection of bonds of such
series to be redeemed. The Company shall not be required to transfer or exchange
any bond of Series A or Series B due August 28, 2012, as the case may be, called
or being called for redemption in its entirety or to transfer or exchange the
called portion of a bond of Series A or Series B due August 28, 2012, which has
been called for partial redemption. No charge shall be made by the Company for
any exchange or transfer pursuant to Sections 3.01(b), 3.05, 3.06, 3.07 or 3.08
hereof of bonds of Series A or Series B due August 28, 2012, as the case may be,
other than for taxes or other governmental charges, if any, that may be imposed
in relation thereto.

                                       28
<PAGE>

                                   ARTICLE IV

                       APPOINTMENT OF AUTHENTICATING AGENT

         SECTION 4.01. The Trustee shall, if requested in writing so to do by
the Company, promptly appoint an agent or agents of the Trustee who shall have
authority to authenticate registered bonds of Series A and Series B due August
28, 2012, in the name and on behalf of the Trustee. Such appointment by the
Trustee shall be evidenced by a certificate of a vice-president of the Trustee
delivered to the Company prior to the effectiveness of such appointment.

         SECTION 4.02. (a) Any such authenticating agent shall be acceptable to
the Company and at all times shall be a corporation which is organized and doing
business under the laws of the United States or of any State, is authorized
under such laws to act as authenticating agent, has a combined capital and
surplus of at least $10,000,000 and is subject to supervision or examination by
Federal or State authority. If such corporation publishes reports of condition
at least annually, pursuant to law or to the requirements of the aforesaid
supervising or examining authority, then for the purposes of this Section 4.02
the combined capital and surplus of such corporation shall be deemed to be its
combined capital and surplus as set forth in its most recent report of condition
so published.

         (b) Any corporation into which any authenticating agent may be merged
or converted or with which it may be consolidated, or any corporation resulting
from any merger, conversion, or consolidation to which any authenticating agent
shall be a party, or any corporation succeeding to the corporate agency business
of any authenticating agent, shall continue to be the authenticating agent
without the execution or filing of any paper or any further act on the part of
the Trustee or the authenticating agent.

         (c) Any authenticating agent at any time may resign by giving written
notice of resignation to the Trustee and to the Company. The Trustee may at any
time, and upon written request of the Company to the Trustee shall, terminate
the agency of any authenticating agent by giving written notice of termination
to such authenticating agent and to the Company. Upon receiving such a notice of
resignation or upon such a termination, or in case at any time any
authenticating agent shall cease to be eligible in accordance with the
provisions of this Section 4.02, the Trustee, unless otherwise requested in
writing by the Company, promptly shall appoint a successor authenticating agent,
which shall be acceptable to the Company. Any successor authenticating agent
upon acceptance of its appointment hereunder shall become vested with all the
rights, powers, duties, and responsibilities of its predecessor hereunder, with
like effect as if originally named. No successor authenticating agent shall be
appointed unless eligible under the provisions of this Section 4.02.

         (d) The Trustee agrees to pay to any authenticating agent, appointed in
accordance with the provisions of this Section 4.02, reasonable compensation for
its services, and the Trustee shall be entitled to be reimbursed for such
payments.

                                       29

<PAGE>

         SECTION 4.03. If an appointment is made pursuant to this Article IV,
the registered bonds of Series A and Series B due August 28, 2012 (issued after
such appointment), shall have endorsed thereon, in addition to the Trustee's
Certificate, an alternate Trustee's Certificate in the following form:

         This bond is one of the bonds of the Series designated thereon,
described in the within-mentioned Indenture.

                                       BNY MIDWEST TRUST COMPANY, as Trustee,

                                       -----------------------------------------
                                       By:

                                       AUTHENTICATING AGENT,

                                       -----------------------------------------
                                       By:
                                            AUTHORIZED OFFICER

         SECTION 4.04. No provision of this Article IV shall require the Trustee
to have at any time more than one such authenticating agent for any one State or
to appoint any such authenticating agent in the State in which the Trustee has
its principal place of business.

                                    ARTICLE V

                       FINANCING STATEMENT TO COMPLY WITH
                           THE UNIFORM COMMERCIAL CODE

         SECTION 5.01. The name and address of the debtor and secured party are
set forth below:

         Debtor:                    Northern States Power Company
                                    414 Nicollet Mall
                                    Minneapolis, Minnesota 55401

         Secured Party:             BNY Midwest Trust Company, Trustee
                                    2 North LaSalle Street
                                    Suite 1020
                                    Chicago, Illinois  60602

NOTE: Northern States Power Company, the debtor above named, is "a transmitting
utility" under the Uniform Commercial Code as adopted in Minnesota, North Dakota
and South Dakota.

                                       30

<PAGE>

         SECTION 5.02. Reference to Article I hereof is made for a description
of the property of the debtor covered by this Financing Statement with the same
force and effect as if incorporated in this Section at length.

         SECTION 5.03. The maturity dates and respective principal amounts of
obligations of the debtor secured and presently to be secured by the Indenture
and this Supplemental Trust Indenture, reference to all of which for the terms
and conditions thereof is hereby made with the same force and effect as if
incorporated herein at length, are as follows:

<Table>
<Caption>
   First Mortgage Bonds                                                     Principal Amount

<S>                                                                        <C>
Series due April 1, 2003.............................................          $ 80,000,000
Series due December 1, 2005..........................................          $ 70,000,000
Pollution Control Series J...........................................          $  5,450,000
Pollution Control Series K...........................................          $  3,400,000
Pollution Control Series L...........................................          $  4,850,000
Series due July 1, 2025..............................................          $250,000,000
Pollution Control Series N...........................................          $ 27,900,000
Pollution Control Series O...........................................          $ 50,000,000
Pollution Control Series P...........................................          $ 50,000,000
Series due March 1, 2003.............................................          $100,000,000
Series due March 1, 2028.............................................          $150,000,000
Resource Recovery Series Q...........................................          $ 15,170,000
Resource Recovery Series R...........................................          $ 19,615,000
Series due August 15, 2003...........................................          $308,000,000
Pollution Control Series S...........................................          $ 69,000,000
Series A and Series B due August 28, 2012............................          $450,000,000
</Table>

         SECTION 5.04. This Financing Statement is hereby adopted for all of the
First Mortgage Bonds of the Series mentioned above secured by said Indenture and
this Supplemental Trust Indenture.

         SECTION 5.05. The 1937 Indenture and the prior Supplemental Trust
Indentures, as set forth below, have been filed or recorded in each and every
office in the States of Minnesota, North Dakota, and South Dakota designated by
law for the filing or recording thereof in respect of all property of the
Company subject thereto:

Original Indenture
     Dated February 1, 1937

Supplemental Indenture
     Dated June 1, 1942

                                       31

<PAGE>

Supplemental Indenture
     Dated February 1, 1944

Supplemental Indenture
     Dated October 1, 1945

Supplemental Indenture
     Dated July 1, 1948

Supplemental Indenture
     Dated August 1, 1949

Supplemental Indenture
     Dated June 1, 1952

Supplemental Indenture
     Dated October 1, 1954

Supplemental Indenture
     Dated September 1, 1956

Supplemental Indenture
     Dated August 1, 1957

Supplemental Indenture
     Dated July 1, 1958

Supplemental Indenture
     Dated December 1, 1960

Supplemental Indenture
     Dated August 1, 1961

Supplemental Indenture
     Dated June 1, 1962

Supplemental Indenture
     Dated September 1, 1963

Supplemental Indenture
     Dated August 1, 1966

Supplemental Indenture
     Dated June 1, 1967

                                       32

<PAGE>

Supplemental Indenture
     Dated October  1, 1967

Supplemental Indenture
     Dated May 1, 1968

Supplemental Indenture
     Dated October 1, 1969

Supplemental Indenture
     Dated February 1, 1971

Supplemental Indenture
     Dated May 1, 1971

Supplemental Indenture
     Dated February 1, 1972

Supplemental Indenture
     Dated January 1, 1973

Supplemental Indenture
     Dated January 1, 1974

Supplemental Indenture
     Dated September 1, 1974

Supplemental Indenture
     Dated April 1, 1975

Supplemental Indenture
     Dated May 1, 1975

Supplemental Indenture
     Dated March 1, 1976

Supplemental Indenture
     Dated June 1, 1981

Supplemental Indenture
     Dated December 1, 1981

Supplemental Indenture
     Dated May 1, 1983

                                       33

<PAGE>

Supplemental Indenture
     Dated December 1, 1983

Supplemental Indenture
     Dated September 1, 1984

Supplemental Indenture
     Dated December 1, 1984

Supplemental Indenture
     Dated May 1, 1985

Supplemental Indenture
     Dated September 1, 1985

Supplemental Indenture
     Dated May 1, 1988

Supplemental Indenture
     Dated July 1, 1989

Supplemental Indenture
     Dated June 1, 1990

Supplemental Indenture
     Dated October 1, 1992

Supplemental Indenture
     Dated April 1, 1993

Supplemental Indenture
     Dated December 1, 1993

Supplemental Indenture
     Dated February 1, 1994

Supplemental Indenture
     Dated October 1, 1994

Supplemental Indenture
     Dated June 1, 1995

Supplemental Indenture
     Dated April 1, 1997

                                       34

<PAGE>

Supplemental Indenture
     Dated March 1, 1998

Supplemental Indenture
     Dated May 1, 1999

Supplemental Indenture
     Dated June 1, 2000

Supplemental Indenture
     Dated August 1, 2000

Supplemental Indenture
     Dated June 1, 2002

Supplemental Indenture
     Dated July 1, 2002

         SECTION 5.06. The property covered by this Financing Statement also
shall secure additional series of First Mortgage Bonds of the debtor which may
be issued from time to time in the future in accordance with the provisions of
the Indenture.

                                   ARTICLE VI

                             AMENDMENTS TO INDENTURE

         SECTION 6.01. Each holder or registered owner of a bond of any series
originally authenticated by the Trustee and originally issued by the Company
subsequent to May 1, 1985 and of any coupon pertaining to any such bond, by the
acquisition, holding or ownership of such bond and coupon, thereby consents and
agrees to, and shall be bound by, the provisions of Article VI of the
Supplemental Trust Indenture dated May 1, 1985. Each holder or registered owner
of a bond of any series (including bonds of Series A and Series B due August 28,
2012), originally authenticated by the Trustee and originally issued by the
Company subsequent to May 1, 1988 and of any coupon pertaining to such bond, by
the acquisition, holding or ownership of such bond and coupon, thereby consents
and agrees to, and shall be bound by, the provisions of the Supplemental and
Restated Trust Indenture dated May 1, 1988 upon the Effective Date.

                                   ARTICLE VII

                                  MISCELLANEOUS

         SECTION 7.01. The recitals of fact herein, except the recital that the
Trustee has duly determined to execute this Supplemental Trust Indenture and be
bound, insofar as it may lawfully so do, by the provisions hereof and in the
bonds shall be taken as statements of the Company and shall not be construed as
made by the Trustee. The Trustee makes no representations as to the value of any
of the property subject to the lien of the Indenture, or any part thereof, or as
to the title of the Company thereto, or as to the security afforded thereby and
hereby, or as to the validity of this Supplemental Trust Indenture or of the
bonds issued under the Indenture by virtue hereof (except the Trustee's
certificate) and the Trustee shall incur no responsibility in respect of such
matters.

                                       35

<PAGE>

         SECTION 7.02. This Supplemental Trust Indenture shall be construed in
connection with and as a part of the 1937 Indenture, as supplemented by the
Supplemental Trust Indentures dated June 1, 1942, February 1, 1944, October 1,
1945, July 1, 1948, August 1, 1949, June 1, 1952, October 1, 1954, September 1,
1956, August 1, 1957, July 1, 1958, December 1, 1960, August 1, 1961, June 1,
1962, September 1, 1963, August 1, 1966, June 1, 1967, October 1, 1967, May 1,
1968, October 1, 1969, February 1, 1971, May 1, 1971, February 1, 1972, January
1, 1973, January 1, 1974, September 1, 1974, April 1, 1975, May 1, 1975, March
1, 1976, June 1, 1981, December 1, 1981, May 1, 1983, December 1, 1983,
September 1, 1984, December 1, 1984, May 1, 1985, September 1, 1985, the
Supplemental and Restated Trust Indenture dated May 1, 1988 and the Supplemental
Trust Indentures dated July 1, 1989, June 1, 1990, October 1, 1992, April 1,
1993, December 1, 1993, February 1, 1994, October 1, 1994, June 1, 1995, April
1, 1997, March 1, 1998, May 1, 1999, June 1, 2000, August 1, 2000, June 1, 2002
and July 1, 2002.

         SECTION 7.03. (a) If any provision of this Supplemental Trust Indenture
limits, qualifies or conflicts with another provision of the Indenture required
to be included in indentures qualified under the Trust Indenture Act of 1939, as
amended (as enacted prior to the date of this Supplemental Trust Indenture) by
any of the provisions of Sections 310 to 317, inclusive, of the said Act, such
required provision shall control.

         (b) In case any one or more of the provisions contained in this
Supplemental Trust Indenture or in the bonds issued hereunder shall be invalid,
illegal, or unenforceable in any respect, the validity, legality and
enforceability of the remaining provisions contained herein and therein shall
not in any way be affected, impaired, prejudiced or disturbed thereby.

         SECTION 7.04. Wherever in this Supplemental Trust Indenture the word
"Indenture" is used without either prefix, "1937", "Original" or "Supplemental",
such word was used intentionally to include in its meaning both the 1937
Indenture and all indentures supplemental thereto.

         SECTION 7.05. Wherever in this Supplemental Trust Indenture either of
the parties hereto is named or referred to, this shall be deemed to include the
successors or assigns of such party, and all the covenants and agreements in
this Supplemental Trust Indenture contained by or on behalf of the Company or by
or on behalf of the Trustee shall bind and inure to the benefit of the
respective successors and assigns of such parties, whether so expressed or not.

         SECTION 7.06. (a) This Supplemental Trust Indenture may be
simultaneously executed in several counterparts, and all said counterparts
executed and delivered, each as an original, shall constitute but one and the
same instrument.

         (b) The Table of Contents and the descriptive headings of the several
Articles of this Supplemental Trust Indenture were formulated, used and inserted
in this Supplemental Trust Indenture for convenience only and shall not be
deemed to affect the meaning or construction of any of the provisions hereof.

                                       36

<PAGE>

         The total aggregate amount of obligations to be issued forthwith under
this Supplemental Trust Indenture is $450,000,000.

                                ----------------

                                       37

<PAGE>

         IN WITNESS WHEREOF, on this 21st day of August, A.D. 2002, NORTHERN
STATES POWER COMPANY, a Minnesota corporation, party of the first part, has
caused its corporate name and seal to be hereunto affixed and this Supplemental
Trust Indenture effective August 1, 2002 to be signed by its President or a Vice
President, and attested by its Secretary or an Assistant Secretary, for and in
its behalf, and BNY MIDWEST TRUST COMPANY (as successor trustee to Harris Trust
and Savings Bank), an Illinois corporation, as Trustee, party of the second
part, to evidence its acceptance of the trust hereby created, has caused its
corporate name and seal to be hereunto affixed, and this Supplemental Trust
Indenture effective August 1, 2002, to be signed by its President, a Vice
President, or an Assistant Vice President, and attested by its Secretary or an
Assistant Secretary, for and in its behalf.

                                       NORTHERN STATES POWER COMPANY

                                       /s/ Paul E. Pender
                                       -----------------------------------------
                                       By: Paul E. Pender
                                           Its: Vice President and Treasurer

Attest:

/s/ Nancy Haley
-------------------------------
Nancy Haley
Assistant Secretary

Executed by Northern States                                     (CORPORATE SEAL)
Power Company in the presence of:

/s/ Mary Schell
-----------------------------
Mary Schell, Witness

/s/ Elizabeth Blohm
-----------------------------
Elizabeth Blohm, Witness

<PAGE>

                                             BNY MIDWEST TRUST COMPANY,
                                             as Trustee

                                             /s/ J. Bartolini
                                             -----------------------------------
                                             By:  J. Bartolini
                                                  Its:  Vice President

Attest:

/s/ M. Callahan
----------------------------
M. Callahan
Assistant Vice President

Executed by BNY Midwest Trust Company in the presence of:

/s/ K. Gibson
----------------------------                                    (CORPORATE SEAL)
K. Gibson, Witness

/s/ A. Hernandez
----------------------------
A. Hernandez, Witness

<PAGE>

STATE OF MINNESOTA             )
                               )  ss.:
COUNTY OF HENNEPIN             )

         On this 21st day of August A.D. 2002, before me, Sharon Quellhorst, a
Notary Public in and for said County in the State aforesaid, personally appeared
Paul E. Pender and Nancy Haley, to me personally known, and to me known to be
the Vice President and Treasurer and Assistant Secretary, respectively, of
Northern States Power Company, one of the corporations described in and which
executed the within and foregoing instrument, and who, being by me severally
duly sworn, each for himself, did say that he, the said Paul E. Pender is a Vice
President and Treasurer, and she, the said Nancy Haley is the Assistant
Secretary, of said Northern States Power Company, a corporation; that the seal
affixed to the within and foregoing instrument is the corporate seal of said
corporation, and that said instrument was executed on behalf of said corporation
by authority of its stockholders and board of directors; and said Paul E. Pender
and Nancy Haley each acknowledged said instrument to be the free act and deed of
said corporation and that such corporation executed the same.

         WITNESS my hand and notarial seal, this 21st day of August, A.D. 2002.

/s/ Sharon Quellhorst
------------------------------------
Sharon Quellhorst
Notary Public
My commission expires January 31, 2005
                                                                   (NOTARY SEAL)

<PAGE>

STATE OF MINNESOTA             )
                               )  ss.:
COUNTY OF HENNEPIN             )

         Paul E. Pender and Nancy Haley, being severally duly sworn, each
deposes and says that he, the said Paul E. Pender is Vice President and
Treasurer, and she, the said Nancy Haley is Assistant Secretary, of Northern
States Power Company, the corporation described in and which executed the within
and foregoing Supplemental Trust Indenture, as mortgagor; and each for himself
further says that said Supplemental Trust Indenture was executed in good faith,
and not for the purpose of hindering, delaying, or defrauding any creditor of
the said mortgagor.

/s/ Paul E. Pender                                /s/ Nancy Haley
------------------------------                    ------------------------------
Paul E. Pender                                    Nancy Haley

       Subscribed and sworn to before me this 21st day of August, A.D. 2002.

/s/ Sharon Quellhorst
------------------------------
Sharon Quellhorst
Notary Public
My commission expires January 31, 2005
                                                           (NOTARY SEAL)

<PAGE>

STATE OF ILLINOIS              )
                               )  ss.:
COUNTY OF COOK                 )

         On this 13th  day of August A.D. 2002, before me, L. Garcia, a Notary
Public in and for said County in the State aforesaid, personally appeared J.
Bartolini and M. Callahan to me personally known, and to me known to be the Vice
President and Assistant Vice President, respectively, of BNY Midwest Trust
Company, one of the corporations described in and which executed the within and
foregoing instrument, and who, being by me severally duly sworn, each, did say
that she, the said J. Bartolini is a Vice President, and she, the said M.
Callahan, is the Assistant Vice President, of said BNY Midwest Trust Company, a
corporation; that the seal affixed to the within and foregoing instrument is the
corporate seal of said corporation, and that said instrument was executed on
behalf of said corporation by authority of its board of directors; and said J.
Bartolini and M. Callahan each acknowledged said instrument to be the free act
and deed of said corporation and that such corporation executed the same.

         WITNESS my hand and notarial seal, this 13th day of August A.D. 2002.

/s/ L. Garcia
--------------------------------
L. Garcia
Notary Public
My commission expires July 8, 2006
                                                                   (NOTARY SEAL)

<PAGE>

STATE OF ILLINOIS              )
                               )  ss.:
COUNTY OF COOK                 )

         J. Bartolini and M. Callahan, being severally duly sworn, each for
himself deposes and says that she, the said J. Bartolini, is Vice President, and
she, the said M. Callahan, is Assistant President, of BNY Midwest Trust Company,
the corporation described in and which executed the within and foregoing
Supplemental Trust Indenture, as mortgagee; and each for himself further says
that said Supplemental Trust Indenture was executed in good faith, and not for
the purpose of hindering, delaying, or defrauding any creditor of the mortgagor.

/s/ J. Bartolini                                  /s/ M. Callahan
------------------------------                    ------------------------------
J. Bartolini                                      M. Callahan

       Subscribed and sworn to before me this 13th day of August A.D. 2002.

/s/ L. Garcia
------------------------------
L. Garcia
Notary Public
My commission expires July 8, 2006
                                                                   (NOTARY SEAL)

<PAGE>

                                   SCHEDULE A

         The property referred to in Article II of the foregoing Supplemental
Trust Indenture from Northern States Power Company to BNY Midwest Trust Company,
Trustee, effective as of August 1, 2002, includes the following property
hereafter more specifically described. Such description, however, is not
intended to limit or impair the scope or intention of the general description
contained in the granting clauses or elsewhere in the Original Indenture.

                     I. PROPERTIES IN THE STATE OF MINNESOTA

         The following described real property, situate, lying and being in the
County of Stearns, to-wit:

         1.       That part of the West Half of the Northwest Quarter of Section
                  21, Township 123 North, Range 30 West, Stearns County,
                  Minnesota described as follows:

                  The south 325.00 feet of the east 750.00 feet, as measured at
                  right angles to the south and east lines of said West Half of
                  the Northwest Quarter, lying northerly of the northerly
                  right-of-way of County Road No. 158. Less and except the east
                  450.00 feet thereof.

                   II. GAS DISTRIBUTION SYSTEMS OF THE COMPANY
                            IN THE STATE OF MINNESOTA

         1.       A four-inch transmission main in Isanti and Sherburne Counties
                  extending approximately 23.01 miles (approximately 121,500
                  feet) known as the "Isanti Line".

         2.       A four-inch transmission main extending approximately 4.74
                  miles (approximately 25,000 feet) and a six-inch transmission
                  main extending approximately 3.79 miles (approximately 20,000
                  feet) in Wright County known as the "St. Michael Expansion".

<PAGE>

                                                                       EXHIBIT A

                        [Form of Transferor Certificate]

                  CERTIFICATE TO NORTHERN STATES POWER COMPANY
         AND TRUSTEE FIRST MORTGAGE BONDS, SERIES A DUE AUGUST 28, 2012

         This is to certify that as of the date hereof with respect to U.S.
$________ principal amount of the above-captioned securities presented or
surrendered on the date hereof (the "Surrendered Bonds") for registration of
transfer or for exchange where the securities issuable upon such exchange are to
be registered in a name other than that of the undersigned holder (each such
transaction being a "transfer"), the undersigned holder of the Surrendered Bonds
represents and certifies for the benefit of Northern States Power Company and
BNY Midwest Trust Company, as Trustee, that the transfer of Surrendered Bonds
associated with such transfer complies with the restrictive legend set forth on
the face of the Surrendered Bonds for the reason checked below:

[  ]     The Surrendered Bonds are being transferred to a person whom we
         reasonably believe is a "qualified institutional buyer" (as defined in
         Rule 144A under the Securities Act of 1933) (a "QIB") that purchases
         for its own account or for the account of a QIB to whom notice is given
         that the resale, pledge or transfer is being made in reliance on Rule
         144A under the Securities Act; or

[  ]     The Surrendered Bonds are being transferred to an institution that is
         an "accredited investor" meeting the requirements of Rule 501(a)(1),
         (2), (3) or (7) under the Securities Act that is acquiring the
         Surrendered Bonds for investment purposes and not for distribution;(1)
         or

[  ]     The transfer of the Surrendered Bonds complies with Rule 144 under the
         Securities Act;(2) or

[  ]     The transfer of the Surrendered Bonds complies with another applicable
         exemption from the registration requirements of the Securities Act.(2)

                                       [Name of holder]

Dated:                      ,
         ------------------  -------
[To be dated the date of presentation or surrender]

----------------
         1 These transfers require that the transferee deliver a letter
substantially in the form of Exhibit B to the Supplemental Trust Indenture dated
as of August 1, 2002 and may also require an opinion of counsel.

         2 These transfers may require an opinion of counsel.

<PAGE>

                                                                       EXHIBIT B

                        [Form of Institutional Accredited
                     Investor Transferee Compliance Letter]

Northern States Power Company
414 Nicollet Mall
Minneapolis, Minnesota 55401
Attention:  Investor Relations

BNY Midwest Trust Company, Trustee
2 North LaSalle Street
Suite 1020
Chicago, Illinois  60602
[Attention:                  ]
           ------------------

Dear Ladies and Gentlemen:

         In connection with our proposed purchase of $______ aggregate principal
amount of 8.00% First Mortgage Bonds, Series A due August 28, 2012 (the "Bonds")
of Northern States Power Company, a Minnesota corporation (the "Company"), we
confirm that:

                  1. We understand that the Bonds have not been registered under
         the Securities Act of 1933 (the "Securities Act") and may not be sold
         except as permitted in the following sentence. We agree, on our own
         behalf and on behalf of any accounts for which we are acting as
         hereinafter stated, to offer, sell, pledge or otherwise transfer such
         Bonds prior to the date which is two years after the later of the
         original issue date of the Bonds and the last date on which the Company
         or any affiliate of the Company was the owner of the Bond (or any
         predecessor of such Bond), only (i) to the Company, (ii) so long as
         such Bonds are eligible for resale pursuant to Rule 144A under the
         Securities Act ("Rule 144A"), to a person whom we reasonably believe is
         a "qualified institutional buyer" (as defined in Rule 144A) (a "QIB")
         that purchases for its own account or for the account of a QIB to whom
         notice is given that the resale, pledge or transfer is being made in
         reliance on Rule 144A (as indicated by the box checked by the
         transferor on the Transferor Certificate, a form of which is attached
         as Exhibit A to the Supplemental Trust Indenture relating to the Bonds,
         dated as of August 1, 2002), (iii) to an institution that is an
         "accredited investor" as defined in Rule 501(a)(1), (2), (3) or (7)
         under the Securities Act (as indicated by the box checked by the
         transferor on the Transferor Certificate, a form of which is attached
         as Exhibit A to the Supplemental Trust Indenture relating to the Bonds,
         dated as of August 1, 2002) that is acquiring the Bonds in a minimum
         amount of $250,000 for investment purposes and not for distribution and
         an Institutional Accredited Investor Transferee Compliance Letter in
         the form hereof is delivered to the Company and to the Trustee under
         the Indenture relating to the Bonds by such accredited investor, (iv)
         pursuant to any other available exemption from registration under the
         Securities Act, or (v) pursuant to an effective registration statement
         under the Securities Act, in each case in accordance with any
         applicable securities laws of any state of the United States, and we
         will notify any purchaser of the Bonds from us of the above resale
         restrictions, if then applicable. We further understand that in

<PAGE>

         connection with any transfer of the Bonds by us that the Company and
         the Trustee may request, and if so requested we will furnish, such
         opinions of counsel, certificates and/or other information as they may
         reasonably require to confirm that any such transfer complies with the
         foregoing restrictions.

                  2. We are an institutional investor and are an "accredited
         investor" (as defined in Rule 501(a)(1), (2), (3) or (7) under the
         Securities Act) and we have such knowledge and experience in financial
         and business matters as to be capable of evaluating the merits and
         risks of our investment in the Bonds, and we and any accounts for which
         we are acting are each able to bear the economic risk of our or its
         investment.

                  3. We understand that the Bonds will be issued solely in
         physical certificated form (and not in the form of interests in
         securities deposited with The Depository Trust Company) and the minimum
         principal amount of Bonds that may be purchased by an institutional
         accredited investor is $250,000.

                  4. We are acquiring the Bonds purchased by us for our own
         account or for one or more accounts as to each of which we exercise
         sole investment discretion.

                  5. You are entitled to rely upon this letter and you are
         irrevocably authorized to produce this letter or a copy hereof to any
         interested party in any administrative or legal proceeding or official
         inquiry with respect to the matters covered hereby.

                                        Very truly yours,

                                        ----------------------------------------
                                        (Name of Purchaser)

                                        By:
                                           -------------------------------------

Date:
      ---------------------------

<PAGE>

                                                                       EXHIBIT C

                   [Form of Regulation S Transfer Certificate]

                                                                          [date]
Northern States Power Company
414 Nicollet Mall
Minneapolis, Minnesota 55401
Attention:  Investor Relations

BNY Midwest Trust Company, Trustee
2 North LaSalle Street
Suite 1020
Chicago, Illinois  60602
[Attention:                 ]
           -----------------

Dear Ladies and Gentlemen:

         In connection with our proposed purchase of $______ aggregate principal
amount of 8.00% First Mortgage Bonds, Series A due August 28, 2012 (the "Bonds")
of Northern States Power Company, a Minnesota corporation (the "Company"), we
confirm that:

         (a)      the offer of the Bonds was not made to a person in the United
                  States;

         (b)      either (i) at the time the buy order was originated, the
                  transferee was outside the United States or we and any person
                  acting on our behalf reasonably believed that the transferee
                  was outside the United States or (ii) the transaction was
                  executed in, on or through the facilities of a designated
                  off-shore securities market and neither we nor any person
                  acting on our behalf knows that the transaction has been
                  pre-arranged with a buyer in the United States;

         (c)      no directed selling efforts have been made in the United
                  States in contravention of the requirements of Rule 903(b) or
                  Rule 904(b) of Regulation S, as applicable; and

         (d)      the transaction is not part of a plan or scheme to evade the
                  registration requirements of the Securities Act.

         In addition, if the sale is made during a Distribution Compliance
Period and the provisions of Rule 903(a)(3) or Rule 904(c)(1) of Regulation S
are applicable thereto, we confirm that such sale has been made in accordance
with the applicable provisions of Rule 903(c)(3) or Rule 904(c)(1), as the case
may be.

         The Company and the Trustee are entitled to rely upon this letter and
are irrevocably authorized to produce this letter or a copy hereof to any
interested party in any administrative or legal proceedings or official inquiry
with respect to the matters covered hereby. Terms used in this certificate have
the meanings set forth in Regulation S.

Very truly yours,

(Name of Transferor]

By:
    ---------------------------                     ---------------------------

<PAGE>

         This instrument was drafted by Northern States Power Company, 414
Nicollet Mall, Minneapolis, Minnesota 55401.

         Tax statements for the real property described in this instrument
should be sent to Northern States Power Company, 414 Nicollet Mall, Minneapolis,
Minnesota 55401.<PAGE>
                                                                 EXHIBIT 10.6.16

July 2, 2002

Mr. Mark Hood
67 Wellesley Drive
New Canaan, CT  06840

Dear Mark:

Based on your experience, background presented and the belief that we can
together help Panera grow into a significant national brand, Panera Bread is
pleased to offer you the position of Senior Vice-President of Finance and
Accounting, reporting to the Executive Vice President, Chief
Financial/Administrative Officer, Bill Moreton. We would like this position to
be effective on or before Monday, August 12, 2002.

Your salary for this position will be payable at the bi-weekly rate of $9,230.77
($240,000 annually). Your next scheduled review, based on your performance
and/or the profitability of the Company will be no later than April 1, 2003 and
any applicable pay adjustments will be prorated based on your date of hire. In
addition, it is our understanding that your compensation will include the
following:

     o    Consideration for 80,000 stock options, which vest to you over 5
          years, and is subject to approval of the Board of Directors. The price
          per share will be based on the closing share price on the date of the
          next Board of Director's meeting following your start date.

     o    You will be included in our 2002 Incentive Program. This program
          rewards you for the completion and quality of individually agreed upon
          objectives as well as the achievement of your business unit's
          financial goals and overall Company profitability. Your normal
          incentive target is 20% of your base rate (we refer to it as a
          "double" when you meet agreed upon expectations) with an upside
          potential of 40% ("homerun"-significantly exceeding expectations). For
          this plan year, you will be guaranteed a bonus of 20% of your base
          rate, prorated for your period of employment (August 12, 2002 -
          December 31, 2002). The payout will be approximately March 15, 2003.
          For the 2003 plan year, you will be guaranteed a 20% "double".

<PAGE>

          For all subsequent years, the incentive can be paid out in full or
          portion thereof, including 0% ("strike-out"), according to the
          company's financial performance and your individual performance. You
          must be employed with Panera on the date of payout in order to be
          eligible for the incentive payment. If the company strikes-out for the
          plan year, no incentive will be paid out. The plan design can be
          changed without notice.

     o    Car allowance of $5000 paid in bi-weekly increments of $192.31.

     o    Upon acceptance of this offer letter, we will provide you with
          house-hunting trips before your start date to find temporary housing.

     o    We will reimburse you up to $20,000 (therefore not taxable income to
          you) for all reasonable moving expenses associated with your
          relocation (moving expenses, temporary housing, mileage and associated
          meals). In order for reimbursement to be non-taxable for the move of
          your household goods, we will need to pay the mover directly. If you
          decide to use Panera's moving company, please advise us and they will
          be authorized to work with you on your move. Please keep any receipts
          for reasonable mileage and incidentals and we will reimburse you for
          those expenses, up to the total of $20,000 maximum. All receipts
          should be sent to the Support Center to the attention of Mark
          Shamalian, HR Generalist. In addition, you will receive a lump sum of
          $105,000 (taxable income to you), plus whatever you have not used of
          the $20,000 referenced above, which will be included on your W-2. By
          accepting this offer, you agree that you will reimburse Panera Bread a
          prorated portion of your relocation expenses if you voluntarily resign
          your employment with Panera Bread within two years of your start date.

     o    A severance agreement to cover the involuntary termination of your
          employment by Panera Bread other than "for cause" will provide one (1)
          year of salary continuance at the annual base compensation rate plus
          car allowance and medical and/or dental benefits in effect at the time
          of termination. Incentive plan payments are not included as part of
          your severance agreement; however, if you are severed during your
          guaranteed incentive period, the guaranteed incentive will be prorated
          for the number of months you were employed with us. Upon severance,
          new options cease to be awarded on your last day worked and existing
          options cease to vest. Further, severance is paid out bi-weekly,
          mitigated by future employment and provided after a signed release
          from you. A document for your signature will follow to confirm this
          portion of your offer, which will include a non-compete clause.

As a full-time Panera Bread employee, you will be eligible to participate in all
Panera Bread benefit plans. The waiting periods and premiums related to these
benefits and specific information about plan content will be explained during
the orientation process. Our benefit package is subject to ongoing review and
modifications from time to time. You will receive an Employee Handbook at your
benefits orientation, which will explain our vacation and holiday schedule.
Panera Bread is a non-smoking work facility. If you have specific questions
about our benefits, please contact Courtney Higgins at (314) 633-7318.

<PAGE>

Nothing in this letter is intended, or should be construed, to execute a
contract for a definite term. Either you or the Company is free to terminate the
employment relationship at any time.

This offer is also contingent on your ability to provide employment eligibility
documentation as required by law. Please indicate your acceptance of this offer
by signing and returning one original of this letter no later than Monday, July
22, 2002 after which time this offer will expire.

We believe that your background and experience will provide a solid foundation
for success with Panera Bread. We are extremely enthusiastic about working with
you. If you have any questions about the enclosed information, please let me
know. Once again, Mark, we welcome you to Panera Bread and we look forward to
your participation, energy, and contributions.

Sincerely,

/s/ Ron Shaich                         /s/ Bill Moreton
------------------------------         -------------------------------
Ron Shaich                             Bill Moreton
Chairman and CEO                       Executive Vice President, Chief
                                       Financial Officer

I have read and accepted the provisions as outlined above.

         7/22/02                               /s/ Mark Hood
------------------------------         -------------------------------
          Date                                   Mark Hood

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