<PAGE>

                       AMENDMENT TO EMPLOYMENT AGREEMENT
                                      and
                  TERMINATION OF CHANGE IN CONTROL AGREEMENT
                  ------------------------------------------

     This amendment to the employment agreement entered into on the 1st day of
August, 1997, by and between New Century Energies, Inc. (the "Company") and Bill
D. Helton (the "Executive") (the "Employment Agreement"), and to the change in
control agreement entered into on the 1st day of August, 1997, by and between
the Company and the Executive (the "Change in Control Agreement"), is made
effective this 4th day of January, 2000.

                                   RECITALS
                                   --------

     WHEREAS, the Company and the Executive are parties to the Employment
Agreement and the Change in Control Agreement; and

     WHEREAS, the Executive and the Company have mutually agreed that the
Executive will retire effective as of March 1, 2000, and will thus not serve as
Chairman of the Board of Directors of the Company (the "Board") through May 31,
2001, as was previously agreed to and memorialized in the Employment Agreement;
and

     WHEREAS, the Executive and the Company have mutually agreed that, in
consideration for the Executive's agreement to amend his Employment Agreement
and terminate his Change in Control Agreement, thereby forfeiting certain
payments and benefits he otherwise would have been entitled to under such
agreements had he served as Chairman of the Board through May 31, 2001, the
Company shall provide to the Executive a lump sum cash payment, which payment is
intended to pay to the Executive an amount equal to the payments and benefits
that otherwise would have been provided to the Executive pursuant to the
Employment Agreement; and

     WHEREAS, to effectuate such agreements between the Company and the
Executive, the Company and the Executive wish to amend certain provisions in the
Employment Agreement and to terminate the Change in Control Agreement.

     NOW, THEREFORE, for valuable consideration, the receipt and sufficiency of
which is acknowledged by the Company and the Executive, the Company and the
Executive hereby agree as follows:

1.   Section 1 of the Employment Agreement shall be amended to read as follows:

          "1.  EMPLOYMENT PERIOD.  The Company shall employ the Executive, and
          the Executive shall serve the Company, on the terms and conditions set
          forth in this Agreement, for a period beginning at the Effective Time
          (as defined in the Reorganization Agreement, the "Effective Time") and
          ending on February 29, 2000 (the "Employment Period")."


2.   Paragraph (a) of Section 2 of the Employment Agreement shall be amended to
     read as follows:
<PAGE>

          "(a) During the Employment Period, the Executive shall serve as Chief
               Executive Officer of the Company and Chairman of the Board of
               Directors of the Company (the "Board").  The Executive shall
               serve as an employee of the Company with such duties and
               responsibilities as are customarily assigned to such positions,
               and such other duties and responsibilities not inconsistent
               therewith as may from time to time be assigned to him by the
               Board."

3.   A new sentence shall be added to the end of Section 4(c)(i) of the
     Employment Agreement, which new sentence shall read as follows:

          "The amendment of this Agreement and termination of the Executive's
          change in control agreement and the changes to the Executive's duties
          and responsibilities to and employment relationship with the Company
          made and/or provided for by the amendment and termination agreement
          entered into by and between the Executive and the Company on January
          4, 2000, shall not constitute Good Reason for purposes of this
          Agreement."

4.   A new paragraph (f) shall be added following paragraph (e) of Section 4 of
     the Employment Agreement, which new paragraph (f) shall read as follows:

          "(f) Retirement.  If the Executive is an employee of the Company or a
          successor thereto on the last day of the Employment Period, the
          Executive shall be deemed to have retired effective as of the
          immediately succeeding day (such retirement to be referred to herein
          as "Retirement").  During the period beginning on the first day of
          Retirement and ending on the first to occur of (i) May 31, 2001, or
          (ii) the consummation of the merger by and between the Company and
          Northern States Power Company, the Executive shall serve as Chairman
          Emeritus of the Board."

5.   The first sentence of paragraph (a) of Section 5 of the Employment
     Agreement shall be amended to read as follows:

          "If, during the Employment Period, the Company terminates the
          Executive's employment other than for Cause or Disability, or the
          Executive terminates employment for Good Reason, the Company shall
          continue to provide the Executive with the compensation and benefits
          set forth in paragraphs (a), (b) and (c) of Section 3 as if he had
          remained employed by the Company pursuant to this Agreement through
          May 31, 2001, and then retired (at which time he will be treated as
          eligible for all retiree welfare benefits and other benefits provided
          to retired senior executives, as set forth in Section 3(c)(ii) and
          (iii)); PROVIDED, that the Incentive Compensation for such period
          shall be based upon the target

                                       2
<PAGE>

          Incentive Compensation for the year in which the Date of Termination
          occurs; PROVIDED, further, that in lieu of stock options, restricted
          stock and other stock-based awards, the Executive shall be paid cash
          equal to the fair market value as of the Date of Termination (without
          regard to any restrictions and based upon a valuation model generally
          utilized for purposes of valuing comparable stock based compensation
          awards) of the stock options, restricted stock and other stock-based
          awards that would otherwise have been granted with such cash being
          paid within 90 days after the Date of Termination; PROVIDED, further,
          that to the extent any benefits described in paragraph (c) of Section
          3 cannot be provided pursuant to the plan or program maintained by the
          Company for its executives, the Company shall provide such benefits
          outside such plan or program at no additional cost (including, without
          limitation, tax cost) to the Executive and his family, and PROVIDED,
          finally, that during any period when the Executive is eligible to
          receive benefits of the type described in clause (B) of paragraph
          (c)(iii) of Section 3 under another employer-provided plan, the
          benefits provided by the Company under paragraph (a) of Section 5 may
          be made secondary to those provided under another plan."

6.   A new paragraph (d) shall be added following paragraph (c) of Section 5 of
     the Employment Agreement, which new paragraph (d) shall read as follows:

          "(d) Retirement.  If the Executive's employment is terminated because
          of the Executive's Retirement (as that term is defined in paragraph
          (f) of Section 4), then, as consideration for the Executive's
          agreement not to compete with the Company for a period of 24 months
          following the termination of his employment (as provided in the
          restrictive covenant contained in Section 8 hereof), and as
          consideration for the amendment of this Agreement and the termination
          of the Executive's change in control agreement pursuant to the
          amendment and termination agreement entered into by and between the
          Company and the Executive on January 4, 2000, which amendment and
          termination agreement provides for, among other things, the forfeiture
          of the right to serve as Chairman of the Board through May 31, 2001,
          forfeiture of the right to receive certain minimum levels of
          compensation and benefits through May 31, 2001, forfeiture of the
          right to receive severance payments and benefits in the event of
          certain qualifying terminations of employment and the termination of
          the Executive's change in control agreement and all rights thereunder,
          the Company shall pay to the Executive within 5 days of such
          Retirement, a lump sum cash payment of $2,481,969.05 and, in addition,
          shall provide an office and secretarial support for the Executive at
          the Company's expense in either Denver, Colorado or Amarillo, Texas
          (as determined by the Executive), or, in lieu

                                       3
<PAGE>

          thereof, shall provide such other equivalent arrangements as are
          mutually agreed upon by the Company and the Executive."

7.   All provisions of the Employment Agreement not specifically mentioned in
     this Agreement shall be considered modified to the extent necessary to be
     consistent with the changes made in this Agreement.

8.   If the Executive's employment is terminated because of the Executive's
     Retirement (as that term is defined in paragraph (f) of Section 4), the
     Change in Control agreement shall be deemed null and void effective as of
     the date of the Executive's Retirement and the Executive shall have no
     right to any severance or other benefits provided for thereunder and the
     Company shall have no further obligations thereunder.



Date:       1/5/00                     New Century Energies, Inc.
      ________________________

                                       By  /s/ Wayne Brunetti
                                         ____________________________
                                         Its


Attested:                              The Executive

/s/ Cathy J. Hart                          /s/ Bill D. Helton
______________________________         ______________________________
______________________________         Bill D. Helton


                                       4
<PAGE>

                   SECOND AMENDMENT TO EMPLOYMENT AGREEMENT


This amendment to the Employment Agreement entered into on the 1st day of
August, 1997, by and between New Century Energies, Inc. (the"Company") and Bill
D. Helton (the "Executive"), as amended (the "Employment Agreement"), is made
effective this 21st day of February, 2000.


Whereas, the Company and the Executive wish to change the date by which payment
is to be made to the Executive under paragraph 5(d) of the Employment Agreement,

Now therefore, for valuable consideration, the receipt and sufficiency of which
are hereby acknowledged by the Company and the Executive, the Company and the
Executive agree as follows:


1.   Paragraph (d) of Section 5 of the Employment Agreement is amended to
     provide that the time period within which the lump sum cash payment of
     $2,481,969.05 referenced therein shall be paid will be "within 25 days of
     such Retirement".



Date:    2/21/00
      ________________        New Century Energies, Inc.

                              By: /s/ Richard C. Kelly
                                  _________________________

                              Its: Executive Vice President
                                   ________________________

Date:   2/18/00               Executive
      ________________
                              /s/ Bill D. Helton
                              _____________________________
                              Bill D. Helton