
<PAGE>

                                March 31, 1998




Board of Directors
Northern States Power Company
414 Nicollet Mall
Minneapolis, Minnesota 55401

Ladies and Gentlemen:

     Included as Annex C to the Proxy Statement/Prospectus (the "Proxy 
Statement/Prospectus") of Northern States Power Company ("NSP") and Black 
Mountain Gas Company ("BMG") is our opinion letter to the Board of Directors 
of BMG dated December 29, 1997 (the "Opinion Letter"), with respect to the 
proposed merger of BMG with and into NSP.

     We hereby consent to the references to our firm and to the inclusion of 
the Opinion Letter in the Registration Statement of NSP (of which the Proxy 
Statement/Prospectus forms a part) filed with the Securities and Exchange 
Commission on or about April 1, 1998. In giving the foregoing consent, we do 
not admit that we come within the category of persons whose consent is 
required under Section 7 of the Securities Act of 1933, as amended, or the 
rules or regulations of the Securities and Exchange Commission thereunder, 
nor do we thereby admit that we are experts with respect to any part of the 
Proxy Statement/Prospectus (or the Registration Statement of which it forms a 
part) within the meaning of the term "experts" as used in the Securities Act 
of 1933, as amended, or the rules and regulations of the Securities and 
Exchange Commission thereunder.

                                       Very truly yours,

                                       PRINCIPAL FINANCIAL SECURITIES, INC.




                                       By: /s/ John W. Bishop
                                          ------------------------------------
                                          Managing Director
                                          Everen Securities, Inc.
                                          (Successor to PFS)



