Common use of ADDENDUM Clause in Contracts

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Vice President Dated as of April 19, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. CREDIT SUISSE FIRST BOSTON, ACTING THROUGH ITS CAYMAN ISLANDS BRANCH By: /s/ ▇▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President Director By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Vice President Associate Dated as of April 1920, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. HSBC Bank USA, National Association By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Aldeanueva Name: ▇▇▇▇ ▇▇▇▇▇▇ Aldeanueva Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Vice President Dated as of April 19, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company Northern States Power Company, a Minnesota corporation (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇ BANK USA By: /s/ ▇▇▇▇▇ ▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Vice President Director Dated as of April 1921, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President The Bank of Tokyo-Mitsubishi, Ltd By: /s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇ Title: First Vice President VP & Manager Dated as of April 1920, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President KEYBANK NATIONAL ASSOCIATION By: /s/ ▇▇▇▇▇▇ ▇▇▇. ▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇. ▇▇▇▇▇ Title: First Vice President Dated as of April 1921, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. ▇▇▇▇▇▇ BROTHERS BANK, FSB By: /s/ ▇▇▇▇ ▇. ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇. ▇▇▇▇▇▇ Title: First Senior Vice President Dated as of April 1921, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company of Colorado (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Vice President Dated as of April 19, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company of Colorado (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President The Bank of Tokyo-Mitsubishi, Ltd. By: /s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇ Title: First Vice President VP & Manager Dated as of April 1920, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company Northern States Power Company, a Minnesota corporation (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. ▇▇▇▇▇▇ BROTHERS BANK, FSB By: /s/ ▇▇▇▇ ▇. ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇. ▇▇▇▇▇▇ Title: First Senior Vice President Dated as of April 1921, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇STREET COMMITMENT CORPORATION (Recourse only to assets of ▇▇▇▇▇▇▇ Street Commitment Corporation) By: /s/ Manda D’Agata Name: Manda D’Agata Title: First Assistant Vice President Dated as of April 19, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President Citibank, N.A. By: /s/ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Vice President Dated as of April 19, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company Northern States Power Company, a Minnesota corporation (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Vice President Dated as of April 19, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President Bank By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Vice President Dated as of April 1920, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇ BANK USA By: /s/ ▇▇▇▇▇ ▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Vice President Director Dated as of April 1921, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President SUMITOMO MITSUI BANKING CORPORATION By: /s/ ▇▇▇▇▇▇ ▇▇▇▇. ▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇. ▇▇▇▇ Title: First Senior Vice President Dated as of April 19, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company Northern States Power Company, a Minnesota corporation (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President Commerzbank AG, New York and Grand Cayman Branches By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Senior Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ Title: Vice President Dated as of April 1920, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President Commerzbank AG, New York and Grand Cayman Branches By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Senior Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ Title: Vice President Dated as of April 1920, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. The Bank of Nova Scotia By: /s/ ▇▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Vice President Managing Director Dated as of April 19, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company Northern States Power Company, a Minnesota corporation (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇STREET COMMITMENT CORPORATION (Recourse only to assets of ▇▇▇▇▇▇▇ Street Commitment Corporation) By: /s/ Manda D’Agata Name: Manda D’Agata Title: First Assistant Vice President Dated as of April 19, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President OF AMERICA, N.A. By: /s/ ▇▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇▇▇ Title: First Senior Vice President Dated as of April 1921, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. Mizuho Corporate Bank Ltd. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Senior Vice President Dated as of April 1920, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President BNP Paribas By: /s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇ Title: First Vice President Managing Director By: /s/ ▇▇▇▇▇ ▇▇▇▇▇▇▇ Name: ▇▇▇▇▇ ▇▇▇▇▇▇▇ Title: Managing Director Dated as of April 1921, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company Northern States Power Company, a Minnesota corporation (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. Mizuho Corporate Bank Ltd. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Senior Vice President Dated as of April 1920, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company Northern States Power Company, a Minnesota corporation (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. CREDIT SUISSE FIRST BOSTON, ACTING THROUGH ITS CAYMAN ISLANDS BRANCH By: /s/ ▇▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President Director By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Vice President Associate Dated as of April 1920, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company Northern States Power Company, a Minnesota corporation (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President Amarillo National Bank. By: /s/ ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇ Title: First Executive Vice President Dated as of April 1921, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company Northern States Power Company, a Minnesota corporation (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ NameFinancing, Inc. By: ▇/s/ ▇▇▇▇▇ ▇▇▇▇▇▇▇ Name: Cahal ▇. ▇▇▇▇▇▇▇ Title: First Vice President Dated as of April 1921, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company Northern States Power Company, a Minnesota corporation (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President BNP Paribas By: /s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇ Title: First Vice President Managing Director By: /s/ ▇▇▇▇▇ ▇▇▇▇▇▇▇ Name: ▇▇▇▇▇ ▇▇▇▇▇▇▇ Title: Managing Director Dated as of April 1921, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company of Colorado (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇STREET COMMITMENT CORPORATION (Recourse only to assets of ▇▇▇▇▇▇▇ Street Commitment Corporation) By: /s/ Manda D’Agata Name: Manda D’Agata Title: First Assistant Vice President Dated as of April 19, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company of Colorado (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ Financing, Inc. By: /s/ Cahal ▇▇ Name: . ▇▇▇▇▇▇▇ Name: Cahal ▇. ▇▇▇▇▇▇▇ Title: First Vice President Dated as of April 1921, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President Amarillo National Bank By: /s/ ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇ Title: First Executive Vice President Dated as of April 1921, 2005

ADDENDUM. The undersigned Lender (i) agrees to all of the provisions of the Credit Agreement, dated as of April 21, 2005 (the “Credit Agreement”), among Southwestern Public Service Company (the “Borrower”), the Lenders party thereto, the Documentation Agents and Syndication Agents named therein and JPMorgan Chase Bank, N.A., as Administrative Agent, and (ii) becomes a party thereto, as a Lender, with obligations applicable to such Lender thereunder, including, without limitation, the obligation to make extensions of credit to the Borrower in an aggregate principal amount not to exceed the amount of its Revolving Commitment as set forth opposite the undersigned Lender’s name in Schedule 1.1A to the Credit Agreement, as such amount may be changed from time to time as provided in the Credit Agreement. Unless otherwise defined herein, terms defined in the Credit Agreement and used herein shall have the meanings given to them in the Credit Agreement. KBC BANK N.V. By: /s/ ▇▇▇▇ ▇▇▇▇▇▇ Name: ▇▇▇▇ ▇▇▇▇▇▇ Title: Vice President By: /s/ ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Name: ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇ Title: First Vice President Dated as of April 19, 2005.