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                         ARIZONA PUBLIC SERVICE COMPANY

                                       TO

                            THE CHASE MANHATTAN BANK

                                     TRUSTEE

                          Third Supplemental Indenture

                          Dated as of November 1, 1999

                                       To

                                    Indenture

                          Dated as of January 15, 1998

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


                          Floating Rate Notes Due 2001

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

     THIRD SUPPLEMENTAL INDENTURE, dated as of November 1, 1999, between Arizona
Public Service Company, a corporation duly organized and existing under the laws
of the State of Arizona  (herein  called the  "Company"),  having its  principal
office  at 400  North  Fifth  Street,  Phoenix,  Arizona  85004,  and The  Chase
Manhattan  Bank, a New York banking  corporation,  as Trustee (herein called the
"Trustee")  under the Indenture dated as of January 15, 1998 between the Company
and the Trustee (the "Indenture").

                             RECITALS OF THE COMPANY

     The Company has  executed  and  delivered  the  Indenture to the Trustee to
provide for the issuance from time to time of its unsecured debentures, notes or
other evidences of indebtedness (the "Securities"), said Securities to be issued
in one or more series as in the Indenture provided.

     Pursuant to the terms of the Indenture,  the Company desires to provide for
the  establishment of a new series of its Securities to be known as its Floating
Rate Notes Due 2001 (herein called the "Notes Due 2001"), the form and substance
of such Notes Due 2001 and the terms,  provisions,  and conditions thereof to be
set forth as provided in the Indenture and this Third Supplemental Indenture.

     All things  necessary  to make this Third  Supplemental  Indenture  a valid
agreement of the Company,  and to make the Notes Due 2001,  when executed by the
Company and authenticated and delivered by the Trustee, the valid obligations of
the Company, have been done.

          NOW, THEREFORE, THIS THIRD SUPPLEMENTAL INDENTURE WITNESSETH:

     For and in  consideration of the premises and the purchase of the Notes Due
2001 by the Holders  thereof,  and for the purpose of setting forth, as provided
in the  Indenture,  the form and  substance of the Notes Due 2001 and the terms,
provisions,  and conditions  thereof,  it is mutually agreed,  for the equal and
proportionate benefit of all Holders of the Notes Due 2001, as follows:

                                   ARTICLE ONE

                         GENERAL TERMS AND CONDITIONS OF
                               THE NOTES DUE 2001

     SECTION 101. There shall be and is hereby authorized a series of Securities
designated  the "Floating  Rate Notes Due 2001"  limited in aggregate  principal
amount to $250,000,000,  which amount shall be as set forth in any Company Order
for the  authentication and delivery of Notes Due 2001. The Notes Due 2001 shall
mature and the principal shall be due and payable  together with all accrued and
unpaid interest thereon on November 15, 2001, and shall be issued in the form of
registered Notes Due 2001 without coupons.

     SECTION  102.  The Notes Due 2001  shall be  issued in  certificated  form,
except that the Notes Due 2001 shall be issued initially as a Global Security to
and  registered  in the name of Cede & Co., as nominee of The  Depository  Trust
Company, as Depositary therefor. Any Notes Due 2001

                                        2

to be issued or  transferred  to, or to be held by, Cede & Co. (or any successor
thereof) for such purpose shall bear the depositary  legend in substantially the
form set forth at the top of the form of Note Due 2001 in Article Two hereof (in
lieu of that set forth in Section 204 of the Indenture), unless otherwise agreed
by the Company,  such agreement to be confirmed in writing to the Trustee.  Such
Global  Security  may be  exchanged  in  whole  or in part  for  Notes  Due 2001
registered,  and any transfer of such Global Security in whole or in part may be
registered,  in the name or names of  Persons  other than such  Depositary  or a
nominee thereof only under the circumstances set forth in Clause (2) of the last
paragraph  of  Section  305 of the  Indenture,  or such other  circumstances  in
addition to or in lieu of those set forth in Clause (2) of the last paragraph of
Section 305 of the Indenture as to which the Company shall agree, such agreement
to be confirmed in writing to the Trustee.  Principal  of, and premium,  if any,
and  interest on the Notes Due 2001 will be payable,  the  transfer of Notes Due
2001 will be registrable and Notes Due 2001 will be  exchangeable  for Notes Due
2001  bearing  identical  terms and  provisions,  at the office or agency of the
Company in the Borough of Manhattan,  The City and State of New York;  PROVIDED,
HOWEVER,  that  payment of interest  may be made at the option of the Company by
check  mailed to the  registered  holder at such  address as shall appear in the
Security Register.

     SECTION  103.  Each Note Due 2001 will bear  interest  at the rate of LIBOR
plus 0.72% from November 8, 1999 or from the most recent  Interest  Payment Date
(as  hereinafter  defined) to which  interest has been paid or duly provided for
until the principal  thereof is paid or made  available for payment,  payable on
February 15, May 15, August 15 and November 15 of each year (each,  an "Interest
Payment  Date"),  commencing  on February 15, 2000,  to the person in whose name
such Note Due 2001 or any  Predecessor  Security is registered,  at the close of
business  on  the  fifteenth  calendar  day,  whether  or  not a  Business  Day,
immediately  preceding the Interest Payment Date. Any such interest  installment
not punctually  paid or duly provided for shall forthwith cease to be payable to
the  registered  holders on such  regular  record  date,  and may be paid to the
person in whose name the Note Due 2001 (or one or more  Predecessor  Securities)
is registered  at the close of business on a special  record date to be fixed by
the Trustee for the payment of such defaulted interest,  notice whereof shall be
given to the  registered  holders  of the  Notes  Due 2001 not less than 10 days
prior to such  special  record  date,  or may be paid at any  time in any  other
lawful manner not inconsistent with the requirements of any securities  exchange
on which  the  Notes  Due 2001 may be  listed,  and upon  such  notice as may be
required by such exchange, all as more fully provided in the Indenture.

     The amount of interest payable for any period will be computed on the basis
of a 360-day year for the actual number of days elapsed.  The calculation agent,
initially  The Chase  Manhattan  Bank,  will  calculate the interest rate on the
Notes  Due  2001.  The  interest  rate will be equal to LIBOR  plus  0.72%.  The
interest  rate in effect for the period from  November  8, 1999 to February  15,
2000, the initial  Interest Reset Date, will be LIBOR, as determined on November
4, 1999, plus 0.72% (the "Initial  Interest Rate").  The calculation  agent will
reset the  interest  rate on each  Interest  Payment  Date  (each  such day,  an
"Interest  Reset Date").  The second  London  Business Day preceding an Interest
Reset Date will be the "Interest  Determination  Date" for that  Interest  Reset
Date. The interest rate in effect on each day that is not an Interest Reset Date
will be the interest

                                        3

rate  determined  as of  the  Interest  Determination  Date  pertaining  to  the
immediately  preceding  Interest  Reset Date. The interest rate in effect on any
day that is an Interest  Reset Date will be the interest  rate  determined as of
the Interest  Determination  Date pertaining to that Interest Reset Date, except
that the interest rate in effect for the period from and  including  November 8,
1999 to the first Interest Reset Date will be the Initial  Interest Rate. If any
Interest Payment Date (other than the Stated Maturity of the Notes Due 2001 or a
Redemption  Date therefor)  would otherwise be a day that is not a Business Day,
the Interest Payment Date will be postponed to the next succeeding Business Day,
except that if such Business Day falls in the next  succeeding  calendar  month,
such Interest Payment Date shall be the immediately  preceding  Business Day. If
the Stated Maturity of the Notes Due 2001 or any Redemption Date therefor is not
a Business Day, then payment of principal and interest payable on such date will
be made on the next  succeeding  day which is a Business  Day (and  without  any
interest or other  payment in respect of any such delay),  in each case with the
same force and effect as if made on such date.  A "Business  Day" shall mean any
day,  except a Saturday,  a Sunday or a legal holiday in The City of New York on
which banking  institutions  are  authorized  or required by law,  regulation or
executive  order to close;  provided that the day is also a London Business Day.
"London  Business Day" means any day on which  dealings in United States dollars
are transacted in the London interbank market.

     The  calculation  agent  will  determine  "LIBOR"  in  accordance  with the
following provisions:

     (i) With respect to any Interest Determination Date, LIBOR will be the rate
     for  deposits in United  States  dollars  having a maturity of three months
     commencing on the first day of the applicable  Interest Period that appears
     on  Telerate  Page 3750 as of 11:00 A.M.,  London  time,  on that  Interest
     Determination Date. If no rate appears,  LIBOR, in respect to that Interest
     Determination  Date,  will be determined in accordance  with the provisions
     described in (ii) below.

     (ii)  With  respect  to an  Interest  Determination  Date on  which no rate
     appears on Telerate Page 3750, as specified in (i) above,  the  calculation
     agent  will  request  the  principal  London  offices of each of four major
     reference  banks  in  the  London  interbank  market,  as  selected  by the
     calculation  agent,  to provide  the  calculation  agent  with its  offered
     quotation  for  deposits in United  States  dollars for the period of three
     months,  commencing on the first day of the applicable  Interest Period, to
     prime banks in the London  interbank  market at  approximately  11:00 A.M.,
     London time, on that Interest  Determination Date and in a principal amount
     that is representative for a single transaction in United States dollars in
     that market at that time. If at least two  quotations  are  provided,  then
     LIBOR on that Interest  Determination  Date will be the arithmetic  mean of
     those quotations.  If fewer than two quotations are provided, then LIBOR on
     the Interest  Determination  Date will be the arithmetic  mean of the rates
     quoted  at  approximately  11:00  A.M.,  in The  City of New  York,  on the
     Interest  Determination  Date by three  major banks in The City of New York
     selected by the  calculation  agent for loans in United  States  dollars to
     leading  European banks,  having a three-month  maturity and in a principal
     amount that is  representative  for a single  transaction  in United States
     dollars in that market at that time; provided,  however,  that if the banks
     selected  by the  calculation  agent are not  providing  quotations  in the
     manner  described by this  sentence,  LIBOR  determined as of that Interest
     Determination  Date will be LIBOR in effect on that Interest  Determination
     Date.

                                        4

     "Telerate Page 3750" means the display  designated as "Page 3750" on Bridge
Telerate,  Inc., or any  successor  service,  for the purpose of displaying  the
London interbank rates of major banks for United States dollars.

     "Interest Period" means the period from and including November 8, 1999, to,
and  excluding,  the first Interest  Payment Date  thereafter and then from, and
including, the immediately preceding Interest Payment Date to which interest has
been paid or duly provided for to, but excluding, the next Interest Payment Date
or the Maturity of the Notes Due 2001, as the case may be.

     SECTION 104. The Company,  at its option,  may redeem all, or, from time to
time any part of the Notes Due 2001,  on any  Interest  Payment Date on or after
November  15,  2000,  upon notice as provided in the  Indenture  at a Redemption
Price equal to the  principal  amount of the Notes Due 2001 to be redeemed  plus
interest (if any) accrued to the Redemption Date.

     SECTION 105. The Notes Due 2001 shall not be defeasible pursuant to Section
1302 or 1303 of the Indenture.

                                   ARTICLE TWO

                             FORM OF NOTES DUE 2001

     SECTION  201.  The  Notes  Due  2001  and  the  Trustee's   certificate  of
authentication  to be endorsed  thereon are to be substantially in the following
forms:

Form of Face of Security:

UNLESS THIS  CERTIFICATE  IS PRESENTED BY AN  AUTHORIZED  REPRESENTATIVE  OF THE
DEPOSITORY  TRUST COMPANY,  A NEW YORK  CORPORATION  ("DTC"),  TO ARIZONA PUBLIC
SERVICE COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE, OR PAYMENT,
AND ANY  CERTIFICATE  ISSUED IS  REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH
OTHER  NAME AS IS  REQUESTED  BY AN  AUTHORIZED  REPRESENTATIVE  OF DTC (AND ANY
PAYMENT  IS MADE TO CEDE & CO. OR TO SUCH  OTHER  ENTITY AS IS  REQUESTED  BY AN
AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR
VALUE OR  OTHERWISE BY OR TO ANY PERSON IS WRONGFUL  INASMUCH AS THE  REGISTERED
OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

                                        5

                         ARIZONA PUBLIC SERVICE COMPANY

                           Floating Rate Note Due 2001

No. _________                                                       $250,000,000
                                                             CUSIP No. 040555BZ6

     Arizona Public Service  Company,  a corporation duly organized and existing
under the laws of Arizona (herein called the "Company",  which term includes any
successor  Person  under  the  Indenture  hereinafter  referred  to),  for value
received,  hereby  promises to pay to Cede & Co.,  or  registered  assigns,  the
principal sum of Two Hundred Fifty Million  Dollars on November 15, 2001, and to
pay  interest  thereon  from  November 8, 1999 or from the most recent  Interest
Payment Date to which interest has been paid or duly provided for,  quarterly in
arrears  on  February  15,  May 15,  August  15 and  November  15 in each  year,
commencing  February  15,  2000,  at the rate of LIBOR  plus  0.72%,  until  the
principal hereof is paid or made available for payment.

     The calculation  agent,  initially The Chase Manhattan Bank, will calculate
the interest  rate on this  Security.  The interest  rate will be equal to LIBOR
plus 0.72%.  The interest rate in effect for the period from November 8, 1999 to
February 15, 2000, the initial Interest Reset Date, will be LIBOR, as determined
on November 4, 1999, plus 0.72% (the "Initial  Interest Rate").  The calculation
agent will reset the interest rate on each Interest  Payment Date (each such day
an "Interest Reset Date").  The second London Business Day preceding an Interest
Reset Date will be the "Interest  Determination  Date" for that  Interest  Reset
Date. The interest rate in effect on each day that is not an Interest Reset Date
will be the  interest  rate  determined  as of the Interest  Determination  Date
pertaining to the immediately  preceding  Interest Reset Date. The interest rate
in effect on any day that is an Interest  Reset Date will be the  interest  rate
determined  as of the Interest  Determination  Date  pertaining to that Interest
Reset  Date,  except  that the  interest  rate in effect for the period from and
including  November 8, 1999 to the first Interest Reset Date will be the Initial
Interest Rate. The amount of interest payable for any period will be computed on
the basis of a  360-day  year for the  actual  number  of days  elapsed.  If any
Interest  Payment  Date (other than the Stated  Maturity  hereof or a Redemption
Date herefor) would  otherwise be a day that is not a Business Day, the Interest
Payment Date will be postponed to the next succeeding  Business Day, except that
if such Business Day falls in the next succeeding  calendar month, such Interest
Payment  Date shall be the  immediately  preceding  Business  Day. If the Stated
Maturity  hereof or any  Redemption  Date  herefor is not a Business  Day,  then
payment of principal and interest  payable on such date will be made on the next
succeeding  day which is a  Business  Day (and  without  any  interest  or other
payment  in  respect  of any such  delay),  in each case with the same force and
effect as if made on such date.  A "Business  Day" shall mean any day,  except a
Saturday,  a Sunday or a legal  holiday in The City of New York on which banking
institutions are authorized or required by law, regulation or executive order to
close;  provided that the day is also a London  Business Day.  "London  Business
Day" means any day on which  dealings in United States dollars are transacted in
the London interbank market.

     The  calculation  agent  will  determine  "LIBOR"  in  accordance  with the
following provisions:

                                        6

     (i) With respect to any Interest Determination Date, LIBOR will be the rate
     for  deposits in United  States  dollars  having a maturity of three months
     commencing on the first day of the applicable  Interest Period that appears
     on  Telerate  Page 3750 as of 11:00 A.M.,  London  time,  on that  Interest
     Determination Date. If no rate appears,  LIBOR, in respect to that Interest
     Determination  Date,  will be determined in accordance  with the provisions
     described in (ii) below.

     (ii)  With  respect  to an  Interest  Determination  Date on  which no rate
     appears on Telerate Page 3750, as specified in (i) above,  the  calculation
     agent  will  request  the  principal  London  offices of each of four major
     reference  banks  in  the  London  interbank  market,  as  selected  by the
     calculation  agent,  to provide  the  calculation  agent  with its  offered
     quotation  for  deposits in United  States  dollars for the period of three
     months,  commencing on the first day of the applicable  Interest Period, to
     prime banks in the London  interbank  market at  approximately  11:00 A.M.,
     London time, on that Interest  Determination Date and in a principal amount
     that is representative for a single transaction in United States dollars in
     that market at that time. If at least two  quotations  are  provided,  then
     LIBOR on that Interest  Determination  Date will be the arithmetic  mean of
     those quotations.  If fewer than two quotations are provided, then LIBOR on
     the Interest  Determination  Date will be the arithmetic  mean of the rates
     quoted  at  approximately  11:00  A.M.,  in The  City of New  York,  on the
     Interest  Determination  Date by three  major banks in The City of New York
     selected by the  calculation  agent for loans in United  States  dollars to
     leading  European banks,  having a three-month  maturity and in a principal
     amount that is  representative  for a single  transaction  in United States
     dollars in that market at that time; provided,  however,  that if the banks
     selected  by the  calculation  agent are not  providing  quotations  in the
     manner  described by this  sentence,  LIBOR  determined as of that Interest
     Determination  Date will be LIBOR in effect on that Interest  Determination
     Date.

     "Telerate Page 3750" means the display  designated as "Page 3750" on Bridge
Telerate,  Inc., or any  successor  service,  for the purpose of displaying  the
London interbank rates of major banks for United States dollars.

     "Interest Period" means the period from and including November 8, 1999, to,
and  excluding,  the first Interest  Payment Date  thereafter and then from, and
including, the immediately preceding Interest Payment Date to which interest has
been paid or duly provided for to, but excluding, the next Interest Payment Date
or the Maturity hereof, as the case may be.

     The interest so payable,  and punctually  paid or duly provided for, on any
Interest Payment Date will, as provided in such Indenture, be paid to the Person
in  whose  name  this  Security  (or  one or  more  Predecessor  Securities)  is
registered  at the  close  of  business  on the  Regular  Record  Date  for such
interest,  which shall be the fifteenth  calendar day immediately  preceding the
Interest  Payment Date (whether or not a Business Day). Any such interest not so
punctually  paid or duly provided for will forthwith  cease to be payable to the
Holder on such Regular Record Date and may either be paid to the Person in whose
name this Security (or one or more Predecessor  Securities) is registered at the
close of  business on a Special  Record  Date for the payment of such  Defaulted
Interest to be fixed

                                        7

by the Trustee,  notice  whereof shall be given to Holders of Securities of this
series not less than 10 days prior to such Special  Record  Date,  or be paid at
any time in any other lawful manner not  inconsistent  with the  requirements of
any  securities  exchange on which the  Securities of this series may be listed,
and upon such  notice as may be  required  by such  exchange,  all as more fully
provided in said Indenture.

     Payment of the principal of (and premium,  if any) and any interest on this
Security will be made at the office or agency of the Company maintained for that
purpose in The City of New York,  in such coin or currency of the United  States
of America as at the time of payment is legal  tender for  payment of public and
private debts;  provided,  however, that at the option of the Company payment of
interest  may be made by check  mailed to the  address  of the  Person  entitled
thereto as such address shall appear in the Security Register.

     Reference  is hereby made to the further  provisions  of this  Security set
forth on the reverse  hereof,  which further  provisions  shall for all purposes
have the same effect as if set forth at this place.

     Unless the  certificate of  authentication  hereon has been executed by the
Trustee  referred to on the reverse  hereof by manual  signature,  this Security
shall  not be  entitled  to any  benefit  under  the  Indenture  or be  valid or
obligatory for any purpose.

     IN WITNESS  WHEREOF,  the  Company has caused  this  instrument  to be duly
executed under its corporate seal.

                                        ARIZONA PUBLIC SERVICE COMPANY


                                        By
                                           -------------------------------------

Attest:


- ----------------------------
Form of Reverse of Security.

     This  Security  is one of a duly  authorized  issue  of  securities  of the
Company (herein called the "Securities"), issued and to be issued in one or more
series  under an  Indenture,  dated as of January  15, 1998  (herein  called the
"Indenture",  which  term  shall  have  the  meaning  assigned  to  it  in  such
instrument),  between  the  Company  and The Chase  Manhattan  Bank,  as Trustee
(herein  called the "Trustee",  which term includes any successor  trustee under
the Indenture), and reference is hereby made to the Indenture for a statement of
the respective rights,  limitations of rights,  duties and immunities thereunder
of the Company, the Trustee and the Holders of the Securities and of the

                                        8

terms upon which the Securities are, and are to be, authenticated and delivered.
This  Security is one of the series  designated  on the face hereof,  limited in
aggregate principal amount to $250,000,000.

     The Securities of this series are subject to redemption  upon not less than
30 days' notice by mail at the option of the Company,  in whole or in part, from
time to time on any  Interest  Payment  Date on or after  November 15, 2000 at a
Redemption  Price equal to the principal amount of the Securities of this series
to be redeemed plus interest  accrued to the  Redemption  Date (the  "Redemption
Price").

     If notice has been given as  provided  in the  Indenture  and funds for the
redemption of any  Securities  (or any portion  thereof)  called for  redemption
shall  have been made  available  on the  Redemption  Date  referred  to in such
notice,  such Securities (or any portion thereof) will cease to bear interest on
the date fixed for such  redemption  specified in such notice and the only right
of the Holders of such  Securities  will be to receive payment of the Redemption
Price.

     Notice of any  optional  redemption  of  Securities  of this series (or any
portion  thereof) will be given to Holders at their  addresses,  as shown in the
Security  Register for such  Securities,  not more than 60 nor less than 30 days
prior to the date fixed for  redemption.  The notice of redemption will specify,
among  other  items,  the  Redemption  Price  and the  principal  amount  of the
Securities  of this series held by such Holder to be redeemed.  If less than all
of the  Securities  of this  series  are to be  redeemed  at the  option  of the
Company,  the  Trustee  shall  select,  in such manner as it shall deem fair and
appropriate, the portion of such Securities to be redeemed in whole or in part.

     The Securities of this series will not be subject to any sinking fund.

     In the event of redemption of this Security in part only, a new Security or
Securities of this series and of like tenor for the  unredeemed  portion  hereof
will be issued in the name of the Holder hereof upon the cancellation hereof.

     If an Event of Default  with  respect to  Securities  of this series  shall
occur and be  continuing,  the principal of the Securities of this series may be
declared  due and  payable in the manner  and with the  effect  provided  in the
Indenture.

     The Indenture  permits,  with certain  exceptions as therein provided,  the
amendment  thereof and the  modification  of the rights and  obligations  of the
Company  and the rights of the  Holders of the  Securities  of each series to be
affected under the Indenture at any time by the Company and the Trustee  without
the consent of such Holders in certain limited circumstances or with the consent
of the  Holders of 66-2/3% in  principal  amount of the  Securities  at the time
Outstanding  of  each  series  to  be  affected.  The  Indenture  also  contains
provisions  permitting the Holders of specified  percentages in principal amount
of the  Securities  of each  series  at the time  Outstanding,  on behalf of the
Holders of all  Securities  of such series,  to waive  compliance by the Company
with certain  provisions of the  Indenture  and certain past defaults  under the
Indenture  and their  consequences.  Any such consent or waiver by the Holder of
this  Security  shall be  conclusive  and binding  upon such Holder and upon all
future Holders of this Security and of any Security issued upon the registration

                                        9

of transfer  hereof or in  exchange  herefor or in lieu  hereof,  whether or not
notation of such consent or waiver is made upon this Security.

     As provided in and subject to the provisions of the  Indenture,  the Holder
of this  Security  shall not have the right to  institute  any  proceeding  with
respect to the Indenture or for the  appointment of a receiver or trustee or for
any other remedy thereunder,  unless such Holder shall have previously given the
Trustee  written  notice of a  continuing  Event of Default  with respect to the
Securities of this series,  the Holders of not less than 25% in principal amount
of the Securities of this series at the time Outstanding shall have made written
request to the  Trustee  to  institute  proceedings  in respect of such Event of
Default as Trustee and offered the Trustee reasonable indemnity, and the Trustee
shall not have  received  from the Holders of a majority in principal  amount of
Securities of this series at the time Outstanding a direction  inconsistent with
such  request,  and shall have failed to institute any such  proceeding,  for 60
days after receipt of such notice, request and offer of indemnity. The foregoing
shall not apply to any suit  instituted  by the Holder of this  Security for the
enforcement of any payment of principal hereof or any premium or interest hereon
on or after the respective due dates expressed herein.

     No reference  herein to the  Indenture and no provision of this Security or
of the Indenture  shall alter or impair the obligation of the Company,  which is
absolute and unconditional, to pay the principal of and any premium and interest
on this  Security  at the times,  place and rate,  and in the coin or  currency,
herein prescribed.

     As provided in the Indenture and subject to certain limitations therein set
forth,  the transfer of this Security is registrable  in the Security  Register,
upon  surrender of this Security for  registration  of transfer at the office or
agency of the  Company in any place where the  principal  of and any premium and
interest on this  Security are payable,  duly endorsed by, or  accompanied  by a
written  instrument  of  transfer  in form  satisfactory  to the Company and the
Security  Registrar  duly  executed by, the Holder  hereof or his attorney  duly
authorized in writing,  and thereupon one or more new  Securities of this series
and of like  tenor,  of  authorized  denominations  and for the  same  aggregate
principal amount, will be issued to the designated transferee or transferees.

     The Securities of this series are issuable only in registered  form without
coupons  in  denominations  of $1,000  and any  integral  multiple  thereof.  As
provided in the Indenture and subject to certain  limitations therein set forth,
Securities of this series are exchangeable for a like aggregate principal amount
of  Securities  of this  series  and of like  tenor  of a  different  authorized
denomination, as requested by the Holder surrendering the same.

     No service  charge shall be made for any such  registration  of transfer or
exchange,  but the Company may require  payment of a sum sufficient to cover any
tax or other governmental charge payable in connection therewith.

     Prior to due presentment of this Security for registration of transfer, the
Company,  the  Trustee and any agent of the Company or the Trustee may treat the
Person in whose name this

                                       10

Security is registered as the owner hereof for all purposes, whether or not this
Security be overdue,  and  neither the  Company,  the Trustee nor any such agent
shall be affected by notice to the contrary.

     All terms used in this Security  which are defined in the  Indenture  shall
have the meanings assigned to them in the Indenture.

Form of Trustee's Certificate of Authentication.

                          CERTIFICATE OF AUTHENTICATION

     This is one of the Securities of the series designated  therein referred to
in the within-mentioned Indenture.

                                        THE CHASE MANHATTAN BANK
                                                                      AS TRUSTEE


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

                                  ARTICLE THREE

                        ORIGINAL ISSUE OF NOTES DUE 2001

     SECTION  301.  Notes  Due  2001  in  the  aggregate   principal  amount  of
$250,000,000 may, upon execution of this Third Supplemental  Indenture,  or from
time to time thereafter, be executed by the Company and delivered to the Trustee
for  authentication,  and the Trustee shall thereupon  authenticate  and deliver
said Notes Due 2001 in accordance  with a Company Order delivered to the Trustee
by the Company, without any further action by the Company.

                                  ARTICLE FOUR

                           PAYING AGENT AND REGISTRAR

     SECTION 401. The Chase Manhattan Bank will be the Paying Agent and Security
Registrar for the Notes Due 2001.

                                       11

                                  ARTICLE FIVE

                                SUNDRY PROVISIONS

     SECTION 501. For all purposes relating to this Third Supplemental Indenture
and  the  Notes  Due  2001,  the  term  Assistant  Secretary,  when  used in the
Indenture, will include an Associate Secretary of the Company.

     SECTION  502.  Except  as  otherwise   expressly  provided  in  this  Third
Supplemental  Indenture  or in the form of Notes Due 2001 or  otherwise  clearly
required by the context hereof or thereof, all terms used herein or in said form
of Notes Due 2001 that are  defined  in the  Indenture  shall  have the  several
meanings respectively assigned to them thereby.

     SECTION 503. The Indenture,  as heretofore supplemented and amended, and as
supplemented by this Third Supplemental  Indenture,  is in all respects ratified
and confirmed, and this Third Supplemental Indenture shall be deemed part of the
Indenture in the manner and to the extent herein and therein provided.

     SECTION  504.  The  Trustee  hereby  accepts  the trusts  herein  declared,
provided, created,  supplemented, or amended and agrees to perform the same upon
the terms and conditions herein and in the Indenture, as heretofore supplemented
and amended, set forth and upon the following terms and conditions:

     The Trustee shall not be  responsible  in any manner  whatsoever  for or in
respect of the validity or sufficiency of this Third  Supplemental  Indenture or
for or in respect of the recitals  contained  herein,  all of which recitals are
made by the  Company  solely.  In  general,  each and every  term and  condition
contained in Article Six of the Indenture shall apply to and form a part of this
Third Supplemental  Indenture with the same force and effect as if the same were
herein set forth in full with such omissions,  variations,  and  insertions,  if
any, as may be  appropriate  to make the same conform to the  provisions of this
Third Supplemental Indenture.

                                   ----------

     This  instrument  may be  executed in any number of  counterparts,  each of
which so executed shall be deemed to be an original,  but all such  counterparts
shall together constitute but one and the same instrument.

                                       12

     IN WITNESS WHEREOF,  the parties hereto have caused this Third Supplemental
Indenture  to be duly  executed,  and  their  respective  corporate  seals to be
hereunto affixed and attested, all as of the day and year first above written.

                                        ARIZONA PUBLIC SERVICE COMPANY


                                        By: Barbara M. Gomez
                                            ------------------------------------
                                            Barbara M. Gomez
                                            Treasurer


Attest:

Betsy A. Pregulman
- ------------------------------
     Associate Secretary

                                        THE CHASE MANHATTAN BANK, as Trustee


                                        By: T. J. Foley
                                            ------------------------------------


Attest:

R. Lorenzen
- ------------------------------

                                       13

STATE OF ARIZONA     )
                     )  ss.:
COUNTY OF MARICOPA   )

     On the 5th day of  November,  1999,  before me  personally  came Barbara M.
Gomez, to me known,  who, being by me duly sworn, did depose and say that she is
the  Treasurer  of  Arizona  Public  Service  Company,  one of the  corporations
described in and which  executed the  foregoing  instrument;  that she knows the
seal of said  corporation;  that the seal  affixed  to said  instrument  is such
corporate seal; that it was so affixed by authority of the Board of Directors of
said corporation; and that she signed her name thereto by like authority.

                                            Debra L. Blondin
                                            ------------------------------------
                                            Notary Public

My Commission Expires:
June 7, 2000
- ----------------------


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

     On the 4th day of November, 1999, before me personally came T. J. Foley, to
me  known,  who,  being by me duly  sworn,  did  depose  and say that he is Vice
President of The Chase Manhattan Bank, one of the corporations  described in and
which  executed  the  foregoing  instrument;  that  he  knows  the  seal of said
corporation;  that the seal affixed to said  instrument is such corporate  seal;
that  it was so  affixed  by  authority  of  the  Board  of  Directors  of  said
corporation; and that he signed his name thereto by like authority.

                                            Annabelle DeLuca
                                            ------------------------------------
                                            Notary Public

My Commission Expires:
July 15, 2001
- ----------------------

                                       14