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                      PUBLIC SERVICE COMPANY OF NEW MEXICO
                                       to
                              THE BANK OF NEW YORK
                        (formerly Irving Trust Company),
                                     Trustee




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


                       FIFTY-THIRD SUPPLEMENTAL INDENTURE

                           Dated as of March 11, 1998


            (Supplemental to Indenture of Mortgage and Deed of Trust
                            dated as of June 1, 1947)


        Making Provision for Certain Changes to the Indenture of Mortgage
             and Deed of Trust With the Consent of Holders of Bonds


               The Mortgage of which this instrument forms a part
                   covers real property, personal property and
                                    chattels.



           The above-described Indenture of Mortgage and Deed of Trust
                   contains after-acquired property provisions
              (subject to certain limitations on such provisions as
               therein expressed and subject to Article 6 of this
                      Fifty-third Supplemental Indenture).



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63028791.15                                                   Document No. 503




         FIFTY-THIRD  SUPPLEMENTAL  INDENTURE dated as of March 11, 1998 between
PUBLIC SERVICE COMPANY OF NEW MEXICO, a corporation organized and existing under
the laws of the State of New Mexico,  Alvarado Square,  Albuquerque,  New Mexico
87158 (hereinafter called the "Company"),  party of the first part, and THE BANK
OF NEW YORK  (formerly  Irving  Trust  Company),  a  corporation  organized  and
existing under the laws of the State of New York, One Wall Street, New York, New
York 10286 (hereinafter  sometimes called the "Trustee"),  as Trustee,  party of
the second part.

         WHEREAS, the Company did heretofore execute and deliver an Indenture of
Mortgage and Deed of Trust dated as of June 1, 1947 (hereinafter  referred to as
the "Original  Indenture"),  to the Trustee to secure an issue of First Mortgage
Bonds of the  Company,  issuable in series,  and created  thereunder  an initial
series of bonds,  designated as First  Mortgage  Bonds,  2-7/8% Series due 1977,
none of which bonds is presently outstanding; and

         WHEREAS, the Company did heretofore execute and deliver a certain First
Supplemental  Indenture  dated as of January 1, 1948, to the Trustee and created
thereunder a series of bonds  designated as First Mortgage Bonds,  3-3/8% Series
due 1978, none of which bonds is presently outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Second  Supplemental  Indenture dated as of December 1, 1948, to the Trustee and
created thereunder a series of bonds designated as First Mortgage Bonds,  3-3/8%
Series due 1977, none of which bonds is presently outstanding; and

         WHEREAS, the Company did heretofore execute and deliver a certain Third
Supplemental  Indenture dated as of December 1, 1950, to the Trustee and created
thereunder a series of bonds  designated as First Mortgage  Bonds, 3% Series due
1980, none of which bonds is presently outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Fourth  Supplemental  Indenture  dated as of March 1, 1952,  to the  Trustee and
created thereunder a series of bonds designated as First Mortgage Bonds,  3-3/4%
Series due 1982, none of which bonds is presently outstanding; and

         WHEREAS, the Company did heretofore execute and deliver a certain Fifth
Supplemental  Indenture  dated as of April 1, 1954,  to the  Trustee and created
thereunder a series of bonds  designated as First Mortgage Bonds,  3-5/8% Series
due 1984, none of which bonds is presently outstanding; and

         WHEREAS, the Company did heretofore execute and deliver a certain Sixth
Supplemental  Indenture dated as of July 1, 1955, to the Trustee for the purpose
of further  assuring,  conveying  and  confirming  unto the  Trustee  additional
property and also, by different description, certain property which is described
in the Granting Clauses of the Original Indenture,  no bonds having been created
or issued thereunder; and


63028791.15                                                   Document No. 503



         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Seventh  Supplemental  Indenture  dated as of June 1, 1958,  to the  Trustee and
created thereunder a series of bonds designated as First Mortgage Bonds,  4-3/8%
Series due 1988, none of which bonds is presently outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Eighth  Supplemental  Indenture dated as of February 1, 1961, to the Trustee and
created thereunder a series of bonds designated as First Mortgage Bonds,  4-7/8%
Series due 1991, none of which bonds is presently outstanding; and

         WHEREAS, the Company did heretofore execute and deliver a certain Ninth
Supplemental  Indenture  dated as of  January 1, 1967,  to the  Trustee  for the
purpose of modifying  certain  provisions  of the Original  Indenture,  no bonds
having been created or issued thereunder; and

         WHEREAS, the Company did heretofore execute and deliver a certain Tenth
Supplemental  Indenture  dated as of May 1, 1967,  to the  Trustee  and  created
thereunder a series of bonds  designated as First Mortgage Bonds,  5-7/8% Series
due 1997, none of which bonds is presently outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Eleventh  Supplemental  Indenture  dated as of April 1, 1969, to the Trustee and
created thereunder a series of bonds designated as First Mortgage Bonds,  7-1/4%
Series due 1999 (the "1969 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Twelfth  Supplemental  Indenture  dated as of September 15, 1971, to the Trustee
for the purpose of amending  the  Original  Indenture in one respect and for the
purpose of creating  thereunder a series of bonds  designated as First  Mortgage
Bonds, 8-1/8% Series due 2001 (the "1971 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Thirteenth  Supplemental Indenture dated as of June 15, 1972, to the Trustee and
created thereunder a series of bonds designated as First Mortgage Bonds,  7-1/2%
Series due 2002 (the "1972 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Fourteenth  Supplemental  Indenture  dated as of December  1, 1974  (hereinafter
referred to as the "Fourteenth Supplemental Indenture"),  to the Trustee for the
purpose of amending  the  Original  Indenture  in certain  respects  and for the
purpose  of  further  assuring,   conveying  and  confirming  unto  the  Trustee
additional property, no bonds having been created or issued thereunder; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Fifteenth  Supplemental Indenture dated as of March 15, 1975, to the Trustee and
created thereunder a series of bonds designated as First Mortgage Bonds,  9-1/8%
Series due 2005 (the "1975 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Sixteenth  Supplemental  Indenture dated as of April 1, 1976, to the Trustee and
created  thereunder a series of bonds  designated as First Mortgage Bonds,  1976
Pollution Control Series, none of which bonds is presently outstanding; and


63028791.15                                                   Document No. 503

                                       2



         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Seventeenth  Supplemental Indenture dated as of June 1, 1977, to the Trustee and
created thereunder a series of bonds designated as First Mortgage Bonds,  8-1/8%
Series due 2007 (the "1977 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Eighteenth  Supplemental Indenture dated as of March 1, 1978, to the Trustee and
created  thereunder a series of bonds  designated as First Mortgage Bonds,  1978
Pollution Control Series A, none of which bonds is presently outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Nineteenth Supplemental Indenture dated as of April 15, 1978, to the Trustee for
the  purpose of further  assuring,  conveying  and  confirming  unto the Trustee
additional property, no bonds having been created or issued thereunder; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Twentieth  Supplemental  Indenture  dated as of May 1, 1978,  to the Trustee and
created  thereunder a series of bonds  designated as First  Mortgage  Bonds,  9%
Series due 2008 (the "1978 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Twenty-first  Supplemental  Indenture  dated as of  September  1,  1979,  to the
Trustee and created  thereunder a series of bonds  designated as First  Mortgage
Bonds,  1979  Pollution  Control  Series  A,  none of which  bonds is  presently
outstanding hereunder; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Twenty-second Supplemental Indenture dated as of October 1, 1979, to the Trustee
for the purpose of amending  the  Original  Indenture in one respect and for the
purpose of creating  thereunder a series of bonds  designated as First  Mortgage
Bonds,  10-1/8% Series due 2004,  none of which bonds is presently  outstanding;
and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Twenty-third Supplemental Indenture dated as of May 15, 1980, to the Trustee and
created  thereunder a series of bonds  designated as First Mortgage Bonds,  1980
Pollution Control Series A, none of which bonds is presently outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Twenty-fourth  Supplemental  Indenture  dated as of September  15, 1980,  to the
Trustee and created  thereunder a series of bonds  designated as First  Mortgage
Bonds, 12.95% Series due 1985, none of which bonds is presently outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Twenty-fifth  Supplemental Indenture dated as of October 1, 1981, to the Trustee
and created  thereunder a series of bonds  designated as First  Mortgage  Bonds,
17-1/2% Series due 2011, none of which bonds is presently outstanding; and


63028791.15                                                   Document No. 503


                                       3


         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Twenty-sixth Supplemental Indenture dated as of November 1, 1982, to the Trustee
and created  thereunder a series of bonds  designated as First  Mortgage  Bonds,
13-1/8% Series due 2012, none of which bonds is presently outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Twenty-seventh  Supplemental  Indenture  dated as of September  1, 1983,  to the
Trustee and created  thereunder a series of bonds  designated as First  Mortgage
Bonds,  12-7/8% Series due 2013,  none of which bonds is presently  outstanding;
and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Twenty-eighth  Supplemental  Indenture  dated as of November  15,  1983,  to the
Trustee for the purpose of further  assuring,  conveying and confirming unto the
Trustee additional property,  no bonds having been created or issued thereunder;
and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Twenty-ninth Supplemental Indenture dated as of December 1, 1983, to the Trustee
and created  thereunder a series of bonds  designated as First  Mortgage  Bonds,
1983 Pollution  Control Series A, none of which bonds is presently  outstanding;
and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Thirtieth Supplemental Indenture dated as of August 15, 1984, to the Trustee and
created thereunder a series of bonds designated as First Mortgage Bonds, 13-1/8%
Series due 1994, none of which bonds is presently outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Thirty-first  Supplemental  Indenture  dated as of September  15,  1984,  to the
Trustee and created  thereunder a series of bonds  designated as First  Mortgage
Bonds,  1984  Pollution  Control  Series,  none  of  which  bonds  is  presently
outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Thirty-second  Supplemental  Indenture  dated as of  December  1,  1984,  to the
Trustee and created  thereunder a series of bonds  designated as First  Mortgage
Bonds,  1984  Pollution  Control  Series  A,  none of which  bonds is  presently
outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Thirty-third  Supplemental  Indenture  dated as of December  15, 1987 (the "33rd
Supplement"),  to the Trustee for the purpose of further assuring, conveying and
confirming unto the Trustee additional property, no bonds having been created or
issued thereunder; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Thirty-fourth  Supplemental  Indenture dated as of March 8, 1991, to the Trustee
and created  thereunder a series of bonds  designated as first  Mortgage  Bonds,
1991 Series A, none of which bonds is presently outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Thirty-fifth  Supplemental  Indenture  dated as of March 8, 1991, to the Trustee
and created  thereunder a series of bonds  designated as First  Mortgage  Bonds,
1991 Series B, none of which bonds is presently outstanding; and


63028791.15                                                   Document No. 503

                                       4


         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Thirty-sixth  Supplemental  Indenture  dated as of March 8, 1991, to the Trustee
and created  thereunder a series of bonds  designated as First  Mortgage  Bonds,
1991 Series C, none of which bonds is presently outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Thirty-seventh  Supplemental Indenture dated as of November 1, 1992 (hereinafter
referred to as the "Thirty-seventh  Supplemental Indenture"), to the Trustee and
created  thereunder a series of bonds  designated as First Mortgage Bonds,  1992
Pollution Control Series A (the "1992 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Thirty-eighth  Supplemental  Indenture dated as of January 1, 1993  (hereinafter
referred to as the "Thirty-eighth  Supplemental Indenture"),  to the Trustee and
created  thereunder two new series of bonds  designated as First Mortgage Bonds,
1993  Pollution  Control  Series A, and First  Mortgage  Bonds,  1993  Pollution
Control Series B (collectively, the "First 1993 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Thirty-ninth  Supplemental  Indenture  dated as of August 15, 1993  (hereinafter
referred to as the "Thirty-ninth  Supplemental  Indenture"),  to the Trustee and
created  thereunder a series of bonds  designated as First Mortgage Bonds,  1993
Pollution Control Series C (the "Second 1993 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Fortieth  Supplemental  Indenture  dated  as of  August  15,  1993  (hereinafter
referred  to as the  "Fortieth  Supplemental  Indenture"),  to the  Trustee  and
created  thereunder a series of bonds  designated as First Mortgage Bonds,  1993
Pollution  Control  Series D (the "Third 1993  Series";  together with the First
1993 Series and the Second 1993 Series, the "1993 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Forty-first Supplemental Indenture dated as of December 14, 1993, to the Trustee
and created  thereunder a series of bonds  designated as First  Mortgage  Bonds,
1993 Series A, none of which bonds is presently outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Forty-second  Supplemental  Indenture  dated as of  December  14,  1993,  to the
Trustee and created  thereunder a series of bonds  designated as First  Mortgage
Bonds, 1993 Series B, none of which bonds is presently outstanding; and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Forty-third  Supplemental Indenture dated as of June 7, 1995, to the Trustee and
created  thereunder a series of bonds  designated as First Mortgage Bonds,  1995
Series A (the "First 1995 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Forty-fourth Supplemental Indenture dated as of June 7, 1995, to the Trustee and
created  thereunder a series of bonds  designated as First Mortgage Bonds,  1995
Series B (together with the First 1995 Series, the "1995 Series"); and

63028791.15                                                   Document No. 503

                                       5



         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Forty-fifth  Supplemental  Indenture  dated as of December 1, 1996  (hereinafter
referred to as the  "Forty-fifth  Supplemental  Indenture"),  to the Trustee and
created  thereunder two series of bonds designated as First Mortgage Bonds, 1996
Pollution  Control Series A and First  Mortgage  Bonds,  1996 Pollution  Control
Series B (collectively, the "First 1996 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Forty-sixth  Supplemental  Indenture  dated as of December 1, 1996  (hereinafter
referred to as the  "Forty-sixth  Supplemental  Indenture"),  to the Trustee and
created  thereunder two series of bonds designated as First Mortgage Bonds, 1996
Pollution  Control Series C and First  Mortgage  Bonds,  1996 Pollution  Control
Series D (collectively, the "Second 1996 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Forty-seventh  Supplemental  Indenture dated as of December 1, 1996 (hereinafter
referred to as the "Forty-seventh  Supplemental Indenture"),  to the Trustee and
created  thereunder two series of bonds designated as First Mortgage Bonds, 1996
Pollution  Control Series E and First  Mortgage  Bonds,  1996 Pollution  Control
Series F (collectively, the "Third 1996 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Forty-eighth  Supplemental  Indenture dated as of December 1, 1996  (hereinafter
referred to as the "Forty-eighth  Supplemental  Indenture"),  to the Trustee and
created  thereunder a series of bonds  designated as First Mortgage Bonds,  1996
Pollution  Control  Series G (the "Fourth 1996 Series";  together with the First
1996  Series,  the  Second  1996  Series and the Third  1996  Series,  the "1996
Series");

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Forty-ninth  Supplemental  Indenture  dated as of February 1, 1997  (hereinafter
referred to as the  "Forty-ninth  Supplemental  Indenture"),  to the Trustee and
created  thereunder two series of bonds designated as First Mortgage Bonds, 1997
Pollution  Control Series A and First  Mortgage  Bonds,  1997 Pollution  Control
Series B (collectively, the "First 1997 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Fiftieth  Supplemental  Indenture  dated as of  February  1,  1997  (hereinafter
referred  to as the  "Fiftieth  Supplemental  Indenture"),  to the  Trustee  and
created  thereunder two series of bonds designated as First Mortgage Bonds, 1997
Pollution  Control Series C and First  Mortgage  Bonds,  1997 Pollution  Control
Series D (collectively, the "Second 1997 Series"); and

         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Fifty-first  Supplemental  Indenture  dated as of February 1, 1997  (hereinafter
referred to as the  "Fifty-first  Supplemental  Indenture"),  to the Trustee and
created  thereunder two series of bonds designated as First Mortgage Bonds, 1997
Pollution  Control Series E and First  Mortgage  Bonds,  1997 Pollution  Control
Series F (collectively, the "Third 1997 Series"); and

63028791.15                                                   Document No. 503

                                       6


         WHEREAS,  the  Company  did  heretofore  execute  and deliver a certain
Fifty-second  Supplemental  Indenture dated as of February 1, 1997  (hereinafter
referred to as the "Fifty-second  Supplemental  Indenture"),  to the Trustee and
created  thereunder a series of bonds  designated as First Mortgage Bonds,  1997
Pollution  Control  Series G (the "Fourth 1997 Series";  together with the First
1997  Series,  the  Second  1997  Series and the Third  1997  Series,  the "1997
Series"); and

         WHEREAS,  on  March  11,  1998,  all  bonds  of the  1995  Series  were
surrendered by the Company to the Trustee for cancellation; none of the bonds of
the 1995 Series is presently outstanding; and

         WHEREAS,  on March 11, 1998, (i) the Company deposited with the Trustee
in accordance  with the provisions of the Original  Indenture cash in the amount
necessary  for the  redemption of all bonds of the  following  series:  the 1969
Series,  the 1971 Series,  the 1972 Series, the 1975 Series, the 1977 Series and
the 1978  Series  (collectively,  the  "Defeased  Series"),  and (ii)  notice of
redemption  of the  Defeased  Series was given as in  Article 5 of the  Original
Indenture  provided;  none of the  bonds of the  Defeased  Series  is  presently
outstanding; and

         WHEREAS,  on March 11,  1998,  after giving  effect to such  surrender,
deposit and giving of notice,  the aggregate  principal  amount of bonds of each
series presently outstanding (the "Presently Outstanding Series") is as follows:

                                                  Principal Amount
                        Series                       Outstanding
                        ------                    ----------------
 
          1992 Series                               $ 37,300,000
          First 1993 Series (Series A)                26,000,000
          First 1993 Series (Series B)                20,000,000
          Second 1993 Series                         100,000,000
          Third 1993 Series                           36,000,000
          First 1996 Series (Series A)                17,712,379
          First 1996 Series (Series B)                 5,287,621
          Second 1996 Series (Series C)               30,838,793
          Second 1996 Series (Series D)                9,206,207
          Third 1996 Series (Series E)                28,493,828
          Third 1996 Series (Series F)                 8,506,172
          Fourth 1996 Series (Series G)               65,000,000
          First 1997 Series (Series A)                24,000,000
          First 1997 Series (Series B)                16,000,000
          Second 1997 Series (Series C)               22,200,000
          Second 1997 Series (Series D)               14,800,000
          Third 1997 Series (Series E)                13,800,000
          Third 1997 Series (Series F)                 9,200,000
          Fourth 1997 Series (Series G)               90,000,000
                                                    ------------
                                                    $574,345,000;  and
                                                    ============

63028791.15                                                   Document No. 503

                                       7


         WHEREAS,  all  bonds of the  Presently  Outstanding  Series  have  been
pledged in good faith by the Company as specified in the indentures supplemental
to the Original Indenture creating such series; and

         WHEREAS,  the pledgee of all of the bonds of the Presently  Outstanding
Series  (the  "Pledgee")  is not an  affiliate  of the  Company  or of any other
obligor on the bonds; and

         WHEREAS,  the Company  desires to change,  alter and amend the Original
Indenture (as heretofore  supplemented and amended) in certain respects;  and to
that end the  Company  desires to make,  execute  and  deliver to the  Trustee a
Supplemental Indenture in the form hereof for the purposes herein provided; and

         WHEREAS,  it is provided in Article 15 of the Original  Indenture  that
the Company and the Trustee,  with the consent of the holders of at least 75% in
aggregate principal amount of the bonds at any time outstanding,  may enter into
an indenture supplemental thereto for the purpose of changing or altering in any
manner  any of the  provisions  of the  Original  Indenture  subject  to certain
limitations specified in said Article 15; and

         WHEREAS,  the  Pledgee  has,  as to all  Presently  Outstanding  Series
(aggregating  $574,345,000 in principal amount) other than the First 1993 Series
($46,000,000  in principal  amount) and the Fourth 1996 Series  ($65,000,000  in
principal  amount)  (all bonds of the  Presently  Outstanding  Series other than
bonds  of the  First  1993  Series  and  bonds of the  Fourth  1996  Series  are
hereinafter  collectively  called the "Consenting  Bonds";  the Consenting Bonds
aggregating  $463,345,000  in  principal  amount),  consented  in  writing  (the
"Written  Consent"),  in the  manner  provided  in  Article  15 of the  Original
Indenture,  to the  execution  and  delivery  of this  Fifty-third  Supplemental
Indenture and the changes,  alterations and amendments to the Original Indenture
(as heretofore  supplemented and amended) made by this Fifty-third  Supplemental
Indenture,  and the Board of Directors has, by resolution,  duly  authorized and
directed the execution and delivery of this Fifty-third Supplemental Indenture;

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

         NOW, THEREFORE,  THIS FIFTY-THIRD  SUPPLEMENTAL  INDENTURE  WITNESSETH:
That Public Service Company of New Mexico,  in consideration of the premises and
of One Dollar  ($1.00) to it duly paid by the Trustee at or before the ensealing
and delivery of these presents, the receipt whereof is hereby acknowledged,  for
itself  and its  successors,  does  hereby  covenant  and  agree to and with the
Trustee and its  successors in the trust under the Original  Indenture,  for the
benefit  of those  who  shall  hold the  bonds,  or any of  them,  to be  issued
hereunder and thereunder, as hereinafter provided, as follows:

                                       8



                                   ARTICLE 1.

                          CHANGES TO ARTICLES 1 AND 3.

         SECTION 1.01.  Anything in Section 1.03(g) of the Original Indenture to
the  contrary  notwithstanding,  an  engineer  may also be a  limited  liability
company,  a limited liability  partnership,  a limited  partnership or any other
firm or person.

         SECTION 1.02.  Effective upon surrender for cancellation to the Trustee
of all Consenting Bonds, the Company shall no longer be entitled to apply to the
Trustee  for the  authentication  and  delivery  of bonds  under the  Indenture,
whether upon the basis of (i) property  additions  included in a computation  of
net property additions (Section 3.04), (ii) bonds theretofore  authenticated and
delivered  under the  Indenture  that shall have been paid,  retired,  redeemed,
cancelled or  surrendered to the Trustee for  cancellation,  or for the payment,
retirement or redemption of which moneys in the necessary amount shall have been
deposited with, or shall then be held, by the Trustee (Section 3.07), (iii) cash
(Section 3.08) or (iv) prior lien bonds (Section 3.11).


                                   ARTICLE 2.

                          CHANGES TO ARTICLES 4 AND 6.

         SECTION 2.01.  Effective upon surrender for cancellation to the Trustee
of all  Consenting  Bonds,  the following  Sections of Article 4 of the Original
Indenture (as heretofore  amended and  supplemented) are hereby deleted in their
entirety  and shall no longer  have any  force or  effect  as  covenants  of the
Company: Sections 4.07, 4.10, 4.11, 4.16, 4.17, 4.18, 4.19, 4.20, 4.21 and 4.22.

         SECTION 2.02.  Effective upon surrender for cancellation to the Trustee
of all Consenting  Bonds,  (i) the dollar amount in Section 4.06 of the Original
Indenture (as heretofore amended) is increased from $500,000 to $25,000,000, and
(ii) the  requirement  for an annual  certificate  described  in the  concluding
sentence of the first paragraph of such Section 4.06 is deleted.

         SECTION 2.03.  Effective upon surrender for cancellation to the Trustee
of all Consenting Bonds, the following new Section 4.25 is added to the Original
Indenture:

                  "Section  4.25.  The Company  covenants and agrees that (i) it
         will  request  releases  from the lien of this  Indenture  pursuant  to
         Section 8.14 only if it shall, not later than the effectiveness of such
         releases,  have  subjected to the operation and lien of this  Indenture
         property as would be included in the  definition of property  additions
         contained  in Section  1.05  which has a fair  value to the  Company at
         least equal to the fair value of the  property  the release of which is
         being  requested,  and  (ii) any  property  so to be  subjected  to the
         operation and lien of this Indenture shall not be subject to a mortgage
         or other lien (except permitted encumbrances) prior to the lien of this
         Indenture to secure bonds or other  evidences  of  indebtedness  of any
         person."

                                       9



         SECTION 2.04.  Effective upon surrender for cancellation to the Trustee
of all Consenting Bonds, Section 6.04(d) of the Original Indenture is amended to
eliminate therefrom any requirement that any report be filed by the Trustee with
the Securities and Exchange Commission.


                                   ARTICLE 3.

                              CHANGES TO ARTICLE 8.

         SECTION 3.01.  Effective upon surrender for cancellation to the Trustee
of all Consenting Bonds,  Section 8.03 is changed to (i) increase the percentage
in clause (ii)(a) of Section 8.03 from sixty per centum (60%) to one hundred per
centum (100%) and (ii) delete therefrom clause (ii) (b) in its entirety.

         SECTION 3.02.  Effective upon surrender for cancellation to the Trustee
of all Consenting  Bonds,  Section 8.04 is changed to increase the dollar amount
therein specified from $25,000 to $5,000,000.

         SECTION 3.03.  Effective upon surrender for cancellation to the Trustee
of all Consenting Bonds, Section 8.11 is changed as follows:

                  (A) subdivision (1) of Section 8.11 is changed to (i) decrease
         the percentage  amount in clause (a) of such  subdivision  from 166% to
         100%,  (ii) delete in their  entirety  clauses (b) and (c) of , and the
         proviso to, such  subdivision  and (iii) add a new clause (b):  "and/or
         (b) in an  amount  equal  to the  cost or  fair  value  to the  Company
         (whichever is less) of property  additions then being  subjected to the
         operation  and  lien of this  Indenture  by an  indenture  supplemental
         hereto";

                   (B) the third  paragraph  of  Section  8.11 is changed to (i)
         include a reference to subdivision  (1)(b) in addition to the reference
         to subdivision  (1)(a) and (ii) amend  sub-paragraph (a) thereof in its
         entirety to read as follows: "(a) an engineer's  certificate specifying
         the property  additions either (i) purchased,  constructed or otherwise
         acquired by the Company subsequent to the receipt by the Trustee of the
         trust  monies  being  withdrawn  or (ii) then  being  subjected  to the
         operation and lien of this  Indenture;  and  containing  the statements
         required by paragraphs (a) through (h) of subdivision (3)(B) of Section
         3.06 (with such  omissions  and  variations  as may be  appropriate  by
         reason of the fact  that the  withdrawal  of trust  moneys  under  this
         Section  8.11 rather than the  authentication  and delivery of bonds is
         being applied for;";

                   (C) the fourth  paragraph  of  Section  8.11  (pertaining  to
         former  subdivisions  (1)(b) and (c) of Section 8.11) is deleted in its
         entirety; and

                   (D) the sixth  paragraph of Section 8.11  (pertaining  to the
         purchase or redemption of bonds by the Trustee) is deleted therefrom.


                                       10


         SECTION 3.04.  Effective upon surrender for cancellation to the Trustee
of all Consenting Bonds, the following new Section 8.14 is added to the Original
Indenture:

                           "SECTION 8.14. The Trustee shall,  whenever from time
              to time requested by the Company, and without requiring compliance
              with any of the  provisions  of  Section  8.03 of this  Indenture,
              release  from  the  lien  of  this  Indenture  any  or  all of the
              mortgaged  property;  such  release to be made upon receipt by the
              Trustee of:

                       (A) A written  request of the  Company for the release of
                  any property, describing the same in reasonable detail.

                       (B) A certificate of the Company  stating that no default
                  as defined in Section 9.01 has happened and is continuing.

                       (C) An  engineer's  certificate,  made and dated not more
                  than sixty  (60) days  prior to the time of such  application,
                  setting forth in substance as follows:

                              (1) the then fair  value,  in the  opinion  of the
                             signer, of the property to be released;

                              (2) the then  fair  value to the  Company,  in the
                             opinion of the signer,  of any property as would be
                             included in the  definition  of property  additions
                             contained  in Section  1.05 which will be subjected
                             to the operation and lien of this Indenture in lieu
                             of the property  being  released,  which fair value
                             shall be at least  equal  to the  then  fair  value
                             specified  in  the  foregoing  clause  (1)  (if  an
                             independent  engineer's certificate as provided for
                             in the following sub-paragraph (D) is required, the
                             then  fair  value of the  property  to be  released
                             shall be deemed to be as stated in such  engineer's
                             certificate   or   such   independent    engineer's
                             certificate, whichever is the higher); and

                              (3) that such  release  is, in the  opinion of the
                             signer, desirable in the conduct of the business of
                             the Company and will not impair the security  under
                             this Indenture in  contravention  of the provisions
                             hereof.

                       (A) In case, as shown by said engineer's certificate, the
                  fair value of the  property  to be  released  and of all other
                  property or securities  released since the commencement of the
                  then current  calendar  year, as set forth in the  certificate
                  required  pursuant  to  sub-paragraph  (C),  and  any  similar
                  certificates  pursuant to any other sections of this Article 8
                  or any sections of any indenture  supplemental  hereto, is ten
                  per centum (10%) or more of the aggregate  principal amount of
                  bonds at the time  outstanding,  unless  the fair value of the
                  property to be released,  as set forth in the certificate,  is
                  less  than  $25,000  or less than one per  centum  (1%) of the
                  aggregate  principal amount of bonds at the time  outstanding,
                  an independent engineer's certificate, made and dated not more
                  than sixty  (60) days  prior to the date of such  application,
                  stating  that the  signer has  examined  the  written  request
                  furnished to the Trustee; stating as to such property the then


                                       11


                  fair value thereof in the opinion of the signer, together with
                  the  signer's  report  thereon  which  shall  contain  a brief
                  statement   of   the   conditions   governing   the   signer's
                  determination  of such  fair  value  and  stating  that in the
                  opinion  of the  signer  such  release  will  not  impair  the
                  security  under  this  Indenture  in   contravention   of  the
                  provisions  hereof;  and in case, as shown by said  engineer's
                  certificate, the consideration for the property to be released
                  includes additional property of a fair value to the Company of
                  not less than $25,000 and not less than one per centum (1%) of
                  the  aggregate  principal  amount  of the  bonds  at the  time
                  outstanding, and if such property has, within six months prior
                  to the date of acquisition  thereof by the Company,  been used
                  or operated by a person or persons other than the Company in a
                  business similar to that in which it has been or is to be used
                  or operated by the Company, a similar  independent  engineer's
                  certificate with respect to the then fair value to the Company
                  of such  additional  property  shall also be  furnished to the
                  Trustee.

                       (B) The indentures supplemental hereto, mortgages, deeds,
                  conveyances, assignments, transfers and instruments of further
                  assurance,  if any,  specified in clause (2) of the opinion of
                  counsel referred to in the following sub-paragraph (F).

                       (C) An opinion of counsel:

                              (1) stating that the  instruments  which have been
                             or are therewith  delivered to the Trustee  conform
                             to  the   requirements   of  this   Indenture   and
                             constitute    sufficient   authority   under   this
                             Indenture  for the  Trustee to execute  and deliver
                             the release requested, and that the property may be
                             released  from  the  operation  of the lien of this
                             Indenture   pursuant  to  the  provisions  of  this
                             Section 8.14; and

                              (2) specifying the indentures supplemental hereto,
                             mortgages,    deeds,   conveyances,    assignments,
                             transfers  and  instruments  of  further  assurance
                             which will be  sufficient  to subject to the direct
                             lien of this  Indenture  the property  described in
                             clause  (2)  of  the   above-mentioned   engineer's
                             certificate.

                       (A) A  certificate  of  the  Company  and an  opinion  of
                  counsel as to compliance with conditions precedent."

                                       12


         SECTION  3.05.  The following new Section 8.15 is added to the Original
Indenture:

                      "SECTION 8.15.  (a) The Trustee shall,  whenever from time
              to time requested by the Company, and without requiring compliance
              with any provisions of Section 8.03 of this Indenture or requiring
              the substitution of any property or securities  therefor,  release
              from  the  lien  of  this  Indenture  any or all of the  mortgaged
              property which,  on the date of such release:  (I) is (i) properly
              chargeable to any of the following accounts  established under the
              Uniform  System of Accounts  Prescribed  for Public  Utilities and
              Licensees  subject to the  provisions  of the Federal Power Act as
              promulgated by the Federal Energy Regulatory Commission (18 C.F.R.
              Part 101) (the "System of  Accounts"):  303,  370,  389, 390, 391,
              392, 394, 396, 397, 398 and 399, or (ii) property which is carried
              on the  Company's  books of account as  "nonutility  property"  or
              "plant held for future use",  in each case as more fully  detailed
              in Annex A to the Fifty-third  Supplemental  Indenture dated as of
              March 11,  1998,  which  supplemental  indenture  is an  indenture
              supplemental  hereto (the "Fifty-third  Supplemental  Indenture");
              and (II) is not  property  which is  included  or  intended  to be
              included under the lien of the Indenture  pursuant to Section 5.04
              of the Fifty-third Supplemental Indenture; such release to be made
              by the Trustee upon receipt of:

                           (A) A written  request of the Company for the release
                  of any property,  describing the same in reasonable detail and
                  stating,  as  applicable,  the  account  under  the  System of
                  Accounts to which the same is properly  chargeable or that the
                  property is  "nonutility  property"  or "plant held for future
                  use" as  detailed in Annex A to the  Fifty-third  Supplemental
                  Indenture.

                           (B) A  certificate  of the  Company  stating  that no
                  default  as  defined  in  Section  9.01  has  happened  and is
                  continuing.

                           (C) An  engineer's  certificate,  made and  dated not
                  more  than   sixty  (60)  days  prior  to  the  time  of  such
                  application, setting forth in substance as follows:

                                    (1) the then fair  value,  in the opinion of
                           the signer,  of the  property  to be released  (which
                           fair value,  when taken  together with the fair value
                           of any other property theretofore released under this
                           Section  8.15,   as  set  forth  in  the   applicable
                           certificate  required pursuant to this  sub-paragraph
                           (1), shall not exceed $56,000,000); and

                                    (2)  that  such  release  will  not,  in the
                           opinion of the signer, impair the security under this
                           Indenture in contravention of the provisions hereof.

                                       13


                           (D)  An   opinion  of   counsel   stating   that  the
                  instruments  that have been or are therewith  delivered to the
                  Trustee  conform to the  requirements  of this  Indenture  and
                  constitute  sufficient  authority under this Indenture for the
                  Trustee to execute and deliver the release requested, and that
                  the property may be released from the operation of the lien of
                  this  Indenture  pursuant to the  provisions  of this  Section
                  8.15.

                           (E) A  certificate  of the  Company and an opinion of
                  counsel as to compliance with conditions precedent.

                      (b) The  provisions of this Section 8.15 shall cease to be
              applicable  whenever the aggregate  principal amount of bonds then
              outstanding shall be less than $574,345,000."


                                   ARTICLE 4.

                             CHANGES TO ARTICLE 12.

         SECTION 4.01.  Effective upon surrender for cancellation to the Trustee
of all Consenting Bonds, anything in Article 12 of the Original Indenture to the
contrary notwithstanding,  consolidations,  mergers, conveyances,  transfers and
leases may  involve  any person  having  appropriate  authority  to carry on the
business or businesses in question and/or who is lawfully entitled to acquire or
lease and operate the mortgaged property.

         SECTION 4.02.  Effective upon surrender for cancellation to the Trustee
of all Consenting Bonds, Section 12.01 is changed by deleting therefrom in their
entirety the ultimate and the antepenultimate provisos thereto.


                                   ARTICLE 5.

                          RELEASE OF MORTGAGED PROPERTY
                    UPON CANCELLATION OF ALL CONSENTING BONDS

         SECTION 5.01.  Upon  surrender for  cancellation  to the Trustee of all
Consenting  Bonds,  unless a default as defined in Section  9.01 of the Original
Indenture  shall have occurred and be continuing,  the Trustee  shall,  whenever
from time to time  requested by the Company,  and without  requiring  compliance
with any of the  provisions of Section 8.03 of the Original  Indenture,  release
from the lien of the Indenture any or all of the mortgaged  property  other than
the  Palo  Verde  Property  (as  defined  in  Section  5.02 of this  Fifty-third
Supplemental Indenture); such release or releases to be made upon receipt by the
Trustee of:

                            (1) A written request of the Company for the release
                  of any  property,  either  describing  the same in  reasonable
                  detail or describing the same in sufficient  detail as may (in
                  the opinion of counsel) be  appropriate in order to effectuate
                  the release;

                            (2) A  certificate  of the Company  stating  that no
                  default as defined in Section 9.01 of the  Original  Indenture
                  has happened and is continuing;

                                       14


                            (3) An independent engineer's certificate,  made and
                  dated not more than  sixty (60) days prior to the date of such
                  application,  stating that the signer has examined the written
                  request furnished to the Trustee;  stating as to such property
                  the then fair  value  thereof in the  opinion  of the  signer,
                  together with the signer's  report thereon which shall contain
                  a brief  statement of the  conditions  governing  the signer's
                  determination  of such  fair  value  and  stating  that in the
                  opinion  of the  signer  such  release  will  not  impair  the
                  security  under  this  Indenture  in   contravention   of  the
                  provisions  hereof;  and in case, as shown by said  engineer's
                  certificate, the consideration for the property to be released
                  includes additional property of a fair value to the Company of
                  not less than $25,000 and not less than one per centum (1%) of
                  the  aggregate  principal  amount  of the  bonds  at the  time
                  outstanding, and if such property has, within six months prior
                  to the date of acquisition  thereof by the Company,  been used
                  or operated by a person or persons other than the Company in a
                  business similar to that in which it has been or is to be used
                  or operated by the Company, a similar  independent  engineer's
                  certificate with respect to the then fair value to the Company
                  of such  additional  property  shall also be  furnished to the
                  Trustee;  provided,  however, in the event that the Securities
                  and Exchange Commission shall have ordered that the Company be
                  relieved of its  obligation  under section 314(d) of the Trust
                  Indenture  Act of 1939 to  deliver an  independent  engineer's
                  certificate as  contemplated  by said Act in connection with a
                  release  pursuant to this Section  5.01,  the Company need not
                  deliver an independent engineer's certificate pursuant to this
                  sub-paragraph   (3)  but  shall   instead   only  deliver  the
                  independent engineer's certificate referenced in sub-paragraph
                  (4) of this Section 5.01;

                            (4) if, as contemplated by sub-paragraph (3) of this
                  Section 5.01, the independent  engineer's  certificate in such
                  sub-paragraph need not be delivered, an independent engineer's
                  certificate,  made and dated not more than (60) days  prior to
                  the date of such  application,  stating  that the  signer  has
                  examined the written request to the Trustee; stating as to the
                  property  remaining subject to the lien of the Indenture after
                  giving  effect to the  release  or  releases  for  which  such
                  application  is being made, the then fair value thereof in the
                  opinion  of the  signer,  together  with the  signer's  report
                  thereon  which  shall   contain  a  brief   statement  of  the
                  conditions  governing the signer's  determination of such fair
                  value; and

                            (5) A  certificate  of the Company and an opinion of
                  counsel as to compliance with conditions precedent.

         SECTION  5.02.  "Palo  Verde  Property"  shall  mean (i) the PVNGS Land
located in  Maricopa  County,  Arizona  (the PVNGS Plant  Site,  the  Hassayampa
Pumping Station and Effluent Pipeline and Miscellaneous Real Property Interests)
previously  described  in the 33rd  Supplement  (recorded  January  11,  1988 as
Instrument  No.  88-011327),  but only to the extent of the Company's  undivided
ownership  interest  therein  (and  not  of  its  undivided  leasehold  interest
therein),  including equitable  ownership  (including the Company's interests in
ATI Title Agency of Arizona Trust No. 530 as described in the Fifteenth  Amended


                                       15


Affidavit of Trustee Trust No. 530 described below),  and (ii) PVNGS and Related
Improvements previously described in the 33rd Supplement, but only to the extent
of the Company's  undivided  ownership  interest  therein (and not its undivided
leasehold interest  therein);  provided,  however,  that Palo Verde Property (1)
shall  not  include  the  transmission   facilities  and  oil  and  diesel  fuel
inventories  excluded from the 33rd  Supplement  pursuant to  exclusions  1.III,
1.IV,  2.III,  2.IV,  3.III and 3.IV under the  caption  "B.  PVNGS and  Related
Improvements" in the 33rd Supplement,  (2) shall include the Company's ownership
interests in Units 1 and 2 of PVNGS and common  facilities of PVNGS as described
in (i) Deed dated as of March 9, 1998 from State  Street Bank and Trust  Company
(successor to The First National Bank of Boston), a Massachusetts trust company,
in its capacity as Owner  Trustee (the "PV1  Trustee")  under that certain Trust
Agreement dated as of December 16, 1985 (as amended as of April 30 and September
2,  1992)  with the  Company  (assignee  of  Burnham  Leasing  Corporation,  the
beneficiary originally named in said Trust Agreement),  to the Company, recorded
on March 10, 1998 in the records of Maricopa  County,  Arizona as Instrument No.
98-0185678; (ii) Deed and Bill of Sale dated as of March 9, 1998 between the PV1
Trustee and the  Company,  recorded on March 10, 1998 in the Records of Maricopa
County,  Arizona as Instrument No.  98-0185679;  (iii) Deed dated as of March 9,
1998 from State Street Bank and Trust Company  (successor to The First  National
Bank of Boston), a Massachusetts trust company, in its capacity as Owner Trustee
(the "PV2 Trustee")  under that certain Trust  Agreement  dated as of August 12,
1986  (as  amended  as of April  30 and  September  2,  1992)  with the  Company
(assignee of Burnham Leasing  Corporation,  the beneficiary  originally named in
said Trust Agreement), to the Company, recorded on March 10, 1998 in the records
of Maricopa County, Arizona as Instrument No. 98-0185682;  (iv) Deed and Bill of
Sale dated as of March 9, 1998 between the PV2 Trustee and the Company, recorded
on March 10, 1998 in the Records of Maricopa  County,  Arizona as Instrument No.
98-0185683;  and (v) Fifteenth  Amended Affidavit of Trustee Trust No. 530 dated
March 10, 1998 of ATI Title Agency of Arizona, Inc., as Trustee of its Trust No.
530, as recorded on March 10, 1998 in the Records of Maricopa  County,  Arizona,
as Instrument No. 98-0185686 (the documents referenced in subclauses (i) through
(v)  of  this  clause  (2)  being  hereinafter  referred  to  as  the  "Transfer
Documents");  (3) shall not  include  the  Company's  9.6%  undivided  ownership
interest  in  the  ANPP  High  Voltage   Switchyard  (as  defined  in  the  33rd
Supplement),  and (4)  shall  not  include  the  Company's  undivided  ownership
interests in any other  transmission  facilities  located wholly or partially on
any of the real  property  constituting  the  PVNGS  Land  pursuant  to the 33rd
Supplement.

         SECTION 5.03. If any property  released from the Lien of this Indenture
as  provided  in Section  5.01 of this  Fifty-third  Supplemental  Indenture  or
otherwise in the Original Indenture (as changed by this Fifty-third Supplemental
Indenture)  shall  continue to be owned by the Company after such release,  this
Indenture  shall not become or be, or be  required  to become or be, a lien upon
such  property or any  improvement,  extension  or addition to such  property or
renewals,  replacements  or  substitutions  of or for any  part or parts of such
property  unless  the  Company  shall  execute  and  deliver  to the  Trustee an
indenture supplemental to the Indenture, in recordable form, containing a grant,
conveyance, transfer and mortgage thereof.

         SECTION 5.04.  Effective upon surrender for cancellation to the Trustee
of all Consenting  Bonds,  this Indenture shall not become or be, or be required
to become or be, a lien upon any  property  acquired  by the Company on or after
such  effectiveness  except that the lien of this  Indenture  shall  include any
improvement, extension or addition to any property not released from the lien of
this  Indenture  pursuant  to  Section  5.01  of this  Fifty-third  Supplemental
Indenture and any renewals,  replacements or substitutions of or for any part or
parts of such property.


                                       16


         SECTION 5.05.  Effective upon surrender for cancellation to the Trustee
of all  Consenting  Bonds,  anything in the Original  Indenture  (as  heretofore
amended) to the  contrary  notwithstanding,  the Trustee  shall  forthwith,  and
without necessity for an application,  request, officers' certificate or opinion
of counsel  (except as may  otherwise be required by the Trust  Indenture Act of
1939, as amended),  release any and all trust moneys (as defined in Section 8.11
of the Original Indenture) then held by the Mortgage Trustee.



                                   ARTICLE 6.

                           CHANGES TO GRANTING CLAUSES


         SECTION 6.01. The Company confirms,  acknowledges and agrees that, upon
execution,  delivery and  recordation of the Transfer  Documents,  the Company's
right, title and interest in and to the property transferred,  assigned, granted
and  conveyed  by the  Transfer  Documents  became  subject  to the  lien of the
Indenture by virtue of the after-acquired property clauses thereof.

         SECTION 6.02.  Effective  upon (i) surrender  for  cancellation  to the
Trustee  of  all  Consenting  Bonds,  and  (ii)  the  execution,   delivery  and
recordation of the Transfer Documents,  all provisions of the Original Indenture
as heretofore  supplemented and amended  subjecting to the lien of the Indenture
after-acquired property (including,  but without limitation,  the full paragraph
on page 69 of the Original  Indenture and the first two paragraphs on page 70 of
the Original Indenture,  immediately  preceding the caption "Excepted Property")
are hereby deleted in their entirety and shall cease to have any force or effect
whatsoever,  subject,  however,  to the  provisions  of  Section  5.04  of  this
Fifty-third Supplemental Indenture.

                                   ARTICLE 7.

                                  THE TRUSTEE.

         The Trustee accepts the trusts created by this Fifty-third Supplemental
Indenture  upon the terms and  conditions in the Original  Indenture and in this
Fifty-third  Supplemental Indenture set forth. Each and every term and condition
contained  in  Article  13  of  the  Original  Indenture  shall  apply  to  this
Fifty-third Supplemental Indenture with the same force and effect as if the same
were herein set forth in full, with such omissions, variations and modifications
thereof  as may be  appropriate  to make the same  conform  to this  Fifty-third
Supplemental Indenture.

         The recitals  contained  herein shall be taken as the statements of the
Company,  and the Trustee assumes no  responsibility  for the correctness of the
same.

         To the extent  permitted  by Sections  13.02 and 13.03 of the  Original
Indenture,  and without  limitation of Section 13.06 of the Original  Indenture,
the Trustee may rely and shall be fully protected in acting upon any resolution,
certificate,  opinion, notice, request, consent, order, appraisal, report, bond,
or other  paper or  document  believed  by the Trustee to be genuine and to have
been signed or presented by the proper party or parties.


                                       17



                                   ARTICLE 8.

                            MISCELLANEOUS PROVISIONS.

         SECTION 8.01. The Original  Indenture is in all respects,  ratified and
confirmed,  and the Original Indenture,  this Fifty-third Supplemental Indenture
and all other indentures  supplemental to the Original  Indenture shall be read,
taken and construed as one and the same  instrument.  Except as provided by this
Fifty-third  Supplemental  Indenture,  neither the execution of this Fifty-third
Supplemental  Indenture  nor  anything  herein  contained  shall be construed to
impair  the  lien of the  Original  Indenture,  as  supplemented,  on any of the
property subject thereto, and such lien shall remain in full force and effect as
security  for all  bonds  now  outstanding  under the  Original  Indenture,  the
Thirty-seventh Supplemental Indenture, the Thirty-eighth Supplemental Indenture,
the Thirty-ninth  Supplemental  Indenture,  the Fortieth Supplemental Indenture,
the Forty-fifth  Supplemental Indenture, the Forty-sixth Supplemental Indenture,
the  Forty-seventh   Supplemental  Indenture,   the  Forty-eighth   Supplemental
Indenture,  the Forty-ninth  Supplemental  Indenture,  the Fiftieth Supplemental
Indenture,   the  Fifty-first   Supplemental   Indenture  or  the   Fifty-second
Supplemental  Indenture.  Except as  provided by this  Fifty-third  Supplemental
Indenture, all covenants and provisions of the Original Indenture shall continue
in full force and effect, and this Fifty-third Supplemental Indenture shall form
part of the Original  Indenture.  All terms defined in Article 1 of the Original
Indenture, as amended, shall, for all purposes of this Fifty-third  Supplemental
Indenture,  have the meanings in said  Article 1  specified,  unless the context
otherwise requires.

         SECTION  8.02.   This   Fifty-third   Supplemental   Indenture  may  be
simultaneously executed in any number of counterparts, and all such counterparts
executed and delivered,  each as an original,  shall  constitute but one and the
same instrument.

         SECTION  8.03.  In  connection  with any release of mortgaged  property
effected under the provisions of the Original Indenture (as heretofore modified)
or the  Fifty-third  Supplemental  Indenture,  upon request of the Company,  the
Trustee  shall  execute  and  deliver  such  additional  releases,   termination
statements and other  instruments as shall be necessary or  appropriate,  in the
opinion of the Company,  to evidence the release of such mortgage  property from
the lien of the Indenture.



                                       18




         IN WITNESS WHEREOF,  Public Service Company of New Mexico, party of the
first  part,  has caused its  corporate  name to be  hereunto  affixed  and this
instrument to be signed by its President or a Vice President or its Treasurer or
an  Assistant  Treasurer,  and its  corporate  seal to be  hereunto  affixed and
attested by its Secretary or an Assistant  Secretary for and in its behalf;  and
The Bank of New York, party of the second part, in evidence of its acceptance of
the trust hereby created,  has caused its corporate name to be hereunto affixed,
and this  instrument  to be signed by its  President  or a Vice  President or an
Assistant  Vice  President  and its  corporate  seal to be hereunto  affixed and
attested by one of its Assistant  Secretaries or Assistant Treasurers for and in
its behalf, all as of the day and year first above written.

                                   PUBLIC SERVICE COMPANY OF
                                   NEW MEXICO


                                   By
                                      --------------------------------
                                      Name:
                                      Title:

Attest:


- -------------------------
Secretary

(Corporate Seal)
                                   THE BANK OF NEW YORK,
                                   as Trustee


                                   By
                                      --------------------------------
                                        Van K. Brown
                                        Assistant Vice President

Attest:


- -------------------------
Assistant Treasurer

(Corporate Seal)



                                       19


STATE OF NEW YORK  )
                   ) ss:
COUNTY OF NEW YORK )

         On this 11th day of March, 1998, before me appeared Van K. Brown, to me
personally  known, who, being by me duly sworn, did depose and say that he is an
Assistant  Vice  President of THE BANK OF NEW YORK, and that the seal affixed to
said  instrument  is the  corporate  seal of said  corporation,  and  that  said
instrument  was signed and sealed in behalf of said  corporation by authority of
its Board of Directors, and said Van K. Brown acknowledged said instrument to be
the free act and deed of said corporation.



                                             -------------------------------
                                                      Notary Public








(Notarial Seal)



STATE OF NEW YORK   )
                    ) ss:
COUNTY OF NEW YORK  )

         This instrument was acknowledged before me on March 11, 1998, by Van K.
Brown as an Assistant Vice President of THE BANK OF NEW YORK.




                                             -------------------------------
                                                      Notary Public




                                                                         ANNEX A
                                                                  to Fifty-third
                                                          Supplemental Indenture

  I.     NONUTILITY PROPERTY

         A.  E.W.B.U (ELECTRIC)

                LAND: JOHN STREET SUB SITE
                LAND: MONROE SUB SITE
                LAND: RIBBLE WATER RIGHTS
                LAND: PERSON STATION-SCHWARTZMAN

         B.  G.C.N.M (GAS)

                LAND IN BELEN (LOT)

         C.  ENERGY SERVICES:

                L.V. ASYLUM PROPERTY (LAND)
                HAGGERMAN LAND & FENCE
                SANTA FE PUMP STATION SITE: COLLEGE ST.
                SANTA FE PUMP STATION SITE: OLD DEMPSEY
                SANTA FE TWO MILE RESERVOIR SITE TRACTS
                SANTA FE FILTER PLANT SITE 72 ACRES
                CORPORATE-ALLOCATED UTILITY PLANT
                LAND: PINO LA CIENAGE-WATER RIGHTS
                LAND: HAGGERMAN-WATER RIGHTS
                ENERGY SERVICE-G/L ONLY
                WATER SERVICES PROPERTY-G/L ONLY

         D.  CORPORATE;

                LAND: HQ
                LAND:AS
                LEASED FLOOR: HQ
                LEASED FLOOR: AS(FBI)


  II. PLANT HELD FOR FUTURE USE

         F.  E.W.B.U (ELECTRIC):

                LAND: NORTH ALBUQUERQUE ACRES
                LAND: RIO RANCHO ENCHANTED HILLS SUB.
                LAND: SANTA FE OLD SERVICE CENTER
                LAND: PRAGER STATION
                LAND: PERSON STATION


63028791.15                                                   Document No. 503