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                                                                     Exhibit 4.3

                             DUQUESNE LIGHT COMPANY

                                       TO

                               JPMORGAN CHASE BANK

                                     TRUSTEE

                                   ----------

                           SUPPLEMENTAL INDENTURE NO.__


                          Dated as of __________, 200_


                    Supplemental to the Indenture of Mortgage

                   and Deed of Trust dated as of April 1, 1992

                                   ----------

                 Establishing a series of Securities designated
                         First Mortgage Bonds, Series __
                                       and
                       Amending certain provisions of said
                     Indenture of Mortgage and Deed of Trust

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     SUPPLEMENTAL INDENTURE NO. __ dated as of _____, 200_, between DUQUESNE
LIGHT COMPANY, a corporation duly organized and existing under the laws of the
Commonwealth of Pennsylvania (hereinafter sometimes called the "Company"), and
JPMORGAN CHASE BANK, a New York banking corporation and successor by merger to
The Chase Manhattan Bank, successor in trust to Mellon Bank, N.A., trustee
(hereinafter sometimes called the "Trustee"), under the Indenture of Mortgage
and Deed of Trust, dated as of April 1, 1992 (hereinafter called the "Original
Indenture"), this Supplemental Indenture No. __ being supplemental thereto. The
Original Indenture and any and all indentures and instruments supplemental
thereto are hereinafter sometimes collectively called the "Mortgage."

                             RECITALS OF THE COMPANY

     The Original Indenture was authorized, executed and delivered by the
Company to provide for the issuance from time to time of its Securities (such
term and all other capitalized terms used herein without definition having the
meanings assigned to them in the Original Indenture), to be issued in one or
more series as contemplated therein, and to provide security for the payment of
the principal of and premium, if any, and interest, if any, on the Securities.

     The Original Indenture has been recorded in the Recorders' Offices of the
various counties of Pennsylvania as follows:

     In Allegheny County in Mortgage Book Vol. 12068, page 8;
     In Beaver County in Mortgage Book Vol. 1208, page 520;
     In Greene County in Mortgage Book Vol. 100, page 174;
     In Washington County in Mortgage Book Vol. 1873, page 1;
     In Westmoreland County in Mortgage Book Vol. 2862, page 221;

and has also been recorded in the Office of the Clerk of County Commission of
Monongahela County, West Virginia, in Deed of Trust Book Vol. 672, page 129, the
Office of the Clerk of County Commission of Hancock County, West Virginia, in
Deed of Trust Book Vol. 293, page 46, the Recorder's Office of Belmont County,
Ohio, in Mortgage Book Vol. 586, page 273, the Recorder's Office of Columbiana
County, Ohio, in Mortgage Book Vol. 318, page 289, the Recorder's Office of
Jefferson County, Ohio, in Mortgage Book Vol. 65, page 675, the Recorder's
Office of Lake County, Ohio, in Mortgage Book Vol. 711, page 217, and the
Recorder's Office of Monroe County, Ohio, in Mortgage Book Vol. 129, page 301.

     The Company has heretofore executed and delivered to the Trustee
Supplemental Indentures for the purposes recited therein and for the purpose of
creating series of Securities as set forth in Schedule A hereto.

     The Company desires to establish a series of Securities to be designated
"First Mortgage Bonds, Series _", such series of Securities to be hereinafter
sometimes called "Series No. __."

     By virtue of Section 2 of Article Two of Supplemental Indenture No. 15,
dated as of November 1, 1999, the Holders of the Securities of Series Nos. 10
through 22 are deemed to have consented to the amendments to the Original
Indenture set forth therein, the Outstanding Securities of such series having an
aggregate principal amount of $417,985,000; by virtue of Article Two of
Supplemental Indenture No. 18, dated as of April 1, 2002, the Holders of the

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Securities of Series No. 23 are deemed to have consented to such amendments to
the Original Indenture, the Outstanding Securities of such series having an
aggregate principal amount of $200,000,000; by virtue of Article Two of
Supplemental Indenture No. 19, dated as of April 15, 2002, the Holders of the
Securities of Series No. 24 are deemed to have consented to such amendments to
the Original Indenture, the Outstanding Securities of such series having an
aggregate principal amount of $100,000,000; at the date of the execution and
delivery of this Supplemental Indenture No. 20, the aggregate principal amount
of Securities of all series Outstanding under the Indenture is $757,985,000; and
the aggregate principal amount of the Securities of Series Nos. 10 through 24 is
$717,985,000, which is more than a majority in principal amount of all
Securities Outstanding. Accordingly, the Company now desires to effect the
amendments to the Original Indenture set forth in Section 2 of Article Two of
Supplemental Indenture No. 15 in accordance with Sections 1402 and 1403 of the
Original Indenture.

     The Company has duly authorized the execution and delivery of this
Supplemental Indenture No. __ to establish the Securities of Series No. __ and
has duly authorized the issuance of such Securities and to make the amendments
to the Original Indenture referred to above; and all acts necessary to make this
Supplemental Indenture No. __ a valid agreement of the Company, and to make the
Securities of Series No. __ valid obligations of the Company, have been
performed.

     NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE NO. __ WITNESSETH, that, in
consideration of the premises and of the purchase of the Securities by the
Holders thereof, and in order to secure the payment of the principal of and
premium, if any, and interest, if any, on all Securities from time to time
Outstanding and the performance of the covenants contained therein and in the
Mortgage and to declare the terms and conditions on which such Securities are
secured, the Company hereby grants, bargains, sells, releases, conveys, assigns,
transfers, mortgages, pledges, sets over and confirms to the Trustee, and grants
to the Trustee a security interest in, the following:

                              GRANTING CLAUSE FIRST

          All right, title and interest of the Company in and to property (other
     than Excepted Property), real, personal and mixed and wherever situated, in
     any case used or to be used in or in connection with the generation,
     purchase, transmission, distribution or sale by the Company of electric
     energy (whether or not such use is the sole use of such property),
     including, without limitation, (a) all lands, easements, servitudes,
     licenses, permits, rights of way and other rights and interests in or
     relating to real property or the occupancy or use of the same; (b) all
     plants, generators, turbines, engines, boilers, fuel handling and
     transportation facilities, air and water pollution control and sewage and
     solid waste disposal facilities and other machinery and facilities for the
     generation of electric energy; (c) all switchyards, lines, towers,
     substations, transformers and other machinery and facilities for the
     transmission of electric energy; (d) all lines, poles, conduits,
     conductors, meters, regulators and other machinery and facilities for the
     distribution of electric energy; (e) all buildings, offices, warehouses and
     other structures; and (f) all pipes, cables, insulators, ducts, tools,
     computers and other data processing and/or storage equipment and other
     equipment, apparatus and

                                        2
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     facilities and all other property, of whatever kind and nature, ancillary
     to or otherwise used or to be used in conjunction with any or all of the
     foregoing or otherwise, directly or indirectly, in furtherance of the
     generation, purchase, transmission, distribution or sale by the Company of
     electric energy;

                             GRANTING CLAUSE SECOND

          Subject to the applicable exceptions permitted by Section 810, Section
     1303 and Section 1305 of the Original Indenture, all property (other than
     Excepted Property) of the kind and nature described in Granting Clause
     First which may be hereafter acquired by the Company, it being the
     intention of the Company that all such property acquired by the Company
     after the date of the execution and delivery of this Supplemental Indenture
     No. __ shall be as fully embraced within and subjected to the Lien hereof
     as if such property were owned by the Company as of the date of the
     execution and delivery of this Supplemental Indenture No. __;

                             GRANTING CLAUSE FOURTH

          All other property of whatever kind and nature subjected or intended
     to be subjected to the Lien of the Mortgage by any of the terms and
     provisions thereof;

                                EXCEPTED PROPERTY

          Expressly excepting and excluding, however, from the Lien and
     operation of the Mortgage all Excepted Property of the Company, whether now
     owned or hereafter acquired;

     TO HAVE AND TO HOLD all such property, real, personal and mixed, unto the
Trustee forever;

     SUBJECT, HOWEVER, to Permitted Liens and to Liens which have been granted
by the Company to other Persons prior to the date of the execution and delivery
of the Original Indenture and subject also, as to any property acquired by the
Company after the date of execution and delivery of the Original Indenture, to
vendors' Liens, purchase money mortgages and other Liens thereon at the time of
the acquisition thereof (including, but not limited to, the Lien of any Class
"A" Mortgage), it being understood that with respect to any of such property
which was at the date of execution and delivery of the Original Indenture or
thereafter became or hereafter becomes subject to the Lien of any Class "A"
Mortgage, the Lien of the Mortgage shall at all times be junior and subordinate
to the Lien of such Class "A" Mortgage;

     IN TRUST, NEVERTHELESS, for the equal and proportionate benefit and
security of the Holders from time to time of all Outstanding Securities without
any priority of any such Security over any other such Security;

     PROVIDED, HOWEVER, that if, after the right, title and interest of the
Trustee in and to the Mortgaged Property shall have ceased, terminated and
become void in accordance with Article Nine of the Original Indenture, the
principal of and premium, if any, and interest, if any,

                                        3
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on the Securities shall have been paid to the Holders thereof, or shall have
been paid to the Company pursuant to Section 603 of the Original Indenture, then
and in that case the Mortgage and the estate and rights thereby granted shall
cease, terminate and be void, and the Trustee shall cancel and discharge the
Mortgage and execute and deliver to the Company such instruments as the Company
shall require to evidence the discharge thereof; otherwise the Mortgage shall be
and remain in full force and effect; and

            THE PARTIES HEREBY FURTHER COVENANT AND AGREE as follows:

                                   ARTICLE ONE

                        TWENTY-_____ SERIES OF SECURITIES

     There is hereby created a series of Securities designated "First Mortgage
Bonds, Series _", which series shall constitute Series No. __. The form and
terms of the Securities of Series No. __ shall be established in or pursuant to
an Officer's Certificate. The Securities of Series No. __ shall be initially
authenticated and delivered in the aggregate principal amount of $_________, but
shall not be limited in aggregate principal amount.

                                   ARTICLE TWO

                                   AMENDMENTS

     The Original Indenture is hereby amended as set forth in Schedule B hereto.

                                  ARTICLE THREE

                            MISCELLANEOUS PROVISIONS

     This Supplemental Indenture No. __ is a supplement to the Mortgage. As
supplemented by this Supplemental Indenture No. __, the Mortgage is in all
respects ratified, approved and confirmed, and the Mortgage and this
Supplemental Indenture No. __ shall together constitute one and the same
instrument.

                                        4
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     IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture No. __ 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.

                                        DUQUESNE LIGHT COMPANY


                                        By:
                                            -----------------------------------
                                                 VICE PRESIDENT AND TREASURER

Attest:


-----------------------------
         SECRETARY


                                        JPMORGAN CHASE BANK, Trustee

                                        By:
                                            -----------------------------------
                                                 VICE PRESIDENT

Attest:


------------------------------
         AUTHORIZED OFFICER

                                        5
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COMMONWEALTH OF PENNSYLVANIA  )
                              )ss.:
COUNTY OF ALLEGHENY           )


     On the day of _____, 200_, before me personally came William F. Fields, to
me known, who, being by me duly sworn, did depose and say that he is a Vice
President and the Treasurer of Duquesne Light Company, the corporation 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.

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

COMMONWEALTH OF PENNSYLVANIA  )
                              ) ss.:
COUNTY OF ALLEGHENY           )


         On the day of _____, 200_, before me personally came Kent M. Christman,
to me known, who, being by me duly sworn, did depose and say that he is a Vice
President of JPMorgan Chase Bank, the banking corporation described in and which
executed the foregoing instrument; that he knows the seal of said banking
corporation; that the seal affixed to said instrument is the seal of said
banking corporation; that it was so affixed by authority of the Board of
Directors of said banking corporation, and that he signed his name thereto by
like authority.

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

                                        6
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                        CERTIFICATE OF PRECISE RESIDENCE

     I hereby certify that the precise residence of JPMorgan Chase Bank is One
Oxford Centre, Suite 1100, Pittsburgh, Allegheny County, Pennsylvania.


                    ---------------------------------------------------
                    Authorized Signatory of JPMorgan Chase Bank

                                                       _____ , 200__

                                        7
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                                                                      SCHEDULE A
<Table>
<Caption>
                                      Securities
Supplemental                              of            Series                                Principal Amount
Indenture No.       Dated as of       Series No.      Designation            Authorized           Issued(1)         Outstanding(1)
-------------     ----------------    -----------    ------------------    --------------     ----------------     -----------------
      <S>         <C>                    <C>         <C>                   <C>                <C>                  <C>
      1            April 1, 1992          1          Secured               $  400,000,000     $    400,000,000            None
                                                     Medium-Term
                                                     Notes, Series B

      2           October 1, 1992         2          First Collateral      $  400,000,000     $    400,000,000     $  40,000,000
                                                     Trust Bonds,
                                                     Series C

      3           December 1, 1992        3          First Collateral      $   47,925,000     $     47,925,000            None
                                                     Trust Bonds,
                                                     Pollution Control
                                                     Series D

      4            March 30, 1993        None        None                        None                 None                None
      5             June 1, 1993          4          First Collateral      $  300,000,000     $    300,000,000            None
                                                     Trust Bonds,
                                                     Series E
      6             June 1, 1993          5          First Collateral      $   25,000,000     $     25,000,000            None
                                                     Trust Bonds,
                                                     Pollution Control
                                                     Series F

      7            August 1, 1993         6          First Collateral      $   20,500,000     $     20,500,000            None
                                                     Trust Bonds,
                                                     Pollution Control
                                                     Series G

      8            March 21, 1994        None        None                         None                    None            None
      9           October 1, 1994         7          First Collateral      $   75,500,000     $     75,500,000            None
                                                     Trust Bonds,
                                                     Pollution Control
                                                     Series H
     10            March 22, 1995        None        None                   None              None                        None

     11             June 1, 1995          8          First Collateral      $  923,000,000     $    923,000,000            None
                                                     Trust Bonds,
                                                     Series I

     12          September 1, 1995        9          First Mortgage        $  685,000,000     $    685,000,000            None
                                                     Bonds, Series J
     13            March 22, 1996        None        None                   None              None                        None
     14            March 17, 1997        None        None                   None              None                        None
     15           November 1, 1999        10         First Mortgage        $   49,500,000     $     49,500,000     $   49,500,000
                                                     Bonds, Pollution
                                                     Control Series K1
     15           November 1, 1999        11         First Mortgage        $   13,500,000     $     13,500,000     $   13,500,000
                                                     Bonds, Pollution
                                                     Control Series K2
     15           November 1, 1999        12         First Mortgage        $   33,955,000     $     33,955,000     $   33,955,000
                                                     Bonds, Pollution
                                                     Control Series K3
</Table>

----------
(1)  As of December 31, 2003.

                                       A-1
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<Table>
<Caption>
                                      Securities
Supplemental                             of                Series                             Principal Amount
Indenture No.       Dated as of       Series No.         Designation          Authorized          Issued(1)         Outstanding(1)
-------------     ----------------    -----------    ------------------    --------------     ----------------     -----------------
<S>               <C>                    <C>          <C>                  <C>                <C>                  <C>
     15           November 1, 1999        13          First Mortgage       $   21,500,000     $     21,500,000     $   21,500,000
                                                      Bonds, Pollution
                                                      Control Series L1
     15           November 1, 1999        14          First Mortgage       $   20,500,000     $     20,500,000     $   20,500,000
                                                      Bonds, Pollution
                                                      Control Series L2
     15           November 1, 1999        15          First Mortgage       $    4,655,000     $      4,655,000     $    4,655,000
                                                      Bonds, Pollution
                                                      Control Series L3
     15           November 1, 1999        16          First Mortgage       $   25,000,000     $     25,000,000     $   25,000,000
                                                      Bonds, Pollution
                                                      Control Series M1
     15           November 1, 1999        17          First Mortgage       $   13,700,000     $     13,700,000     $   13,700,000
                                                      Bonds, Pollution
                                                      Control Series M2
     15           November 1, 1999        18          First Mortgage       $   18,000,000     $     18,000,000     $   18,000,000
                                                      Bonds, Pollution
                                                      Control Series M3
     15           November 1, 1999        19          First Mortgage       $   44,250,000     $     44,250,000     $   44,250,000
                                                      Bonds, Pollution
                                                      Control Series M4
     15           November 1, 1999        20          First Mortgage       $   75,500,000     $     75,500,000     $   75,500,000
                                                      Bonds, Pollution
                                                      Control Series M5
     15           November 1, 1999        21          First Mortgage       $   50,000,000     $     50,000,000     $   50,000,000
                                                      Bonds, Pollution
                                                      Control Series N1
     15           November 1, 1999        22          First Mortgage       $   47,925,000     $     47,925,000     $   47,925,000
                                                      Bonds, Pollution
                                                      Control Series N2
     16                                  None         None                       None                None                 None
     17            April 1, 2001         None         None                       None                None                 None
     18            April 1, 2002          23          First Mortgage       $  200,000,000     $    200,000,000     $   200,000,000
                                                      Bonds, Series O

     19            April 15, 2002         24          First Mortgage       $  100,000,000     $    100,000,000     $   100,000,000
                                                      Bonds Series P
                                                                  Totals   $3,594,910,000     $  3,594,910,000     $   757,985,000
</Table>

----------
(1)  As of December 31, 2003.

                                       A-2
<Page>

                                                                      SCHEDULE B

                        AMENDMENTS TO ORIGINAL INDENTURE

     SECTION 1. "STATED INTEREST RATE".

          The definition of "Stated Interest Rate" in Section 101 of the
     Original Indenture is hereby amended to read as follows:

          "STATED INTEREST RATE" means a rate (whether fixed or variable) at
     which an obligation by its terms is stated to bear simple interest. Any
     calculation or other determination to be made under this Indenture by
     reference to the Stated Interest Rate on an obligation shall be made (a) if
     the Company's obligations in respect of any other indebtedness shall be
     evidenced or secured in whole or in part by such obligation, by reference
     to the lower of the Stated Interest Rate on such obligation and the Stated
     Interest Rate on such other indebtedness and (b) without regard to the
     effective interest cost to the Company of such obligation or of any such
     other indebtedness.

     SECTION 2. "COST".

          The definition of "Cost" in Section 104 of the Original Indenture is
     hereby amended to read as follows:

          Except as otherwise provided in Section 803, the term "COST" with
     respect to Property Additions shall mean the sum of (i) any cash delivered
     in payment therefor or for the acquisition thereof, (ii) an amount
     equivalent to the fair market value in cash (as of the date of delivery) of
     any securities or other property delivered in payment therefor or for the
     acquisition thereof, (iii) the principal amount of any obligations secured
     by prior Lien (other than a Class A Mortgage) upon such Property Additions
     outstanding at the time of the acquisition thereof, (iv) the principal
     amount of any other obligations incurred or assumed in connection with the
     payment for such Property Additions or for the acquisition thereof and (v)
     any other amounts which, in accordance with generally accepted accounting
     principles, are properly charged or chargeable to the plant or other
     property accounts of the Company with respect to such Property Additions as
     part of the cost of construction or acquisition thereof, including, but not
     limited to, any allowance for funds used during construction or any similar
     or analogous amount; PROVIDED, HOWEVER, that, notwithstanding any other
     provision of this Indenture,

                (x)   with respect to Property Additions owned by a successor
          corporation immediately prior to the time it shall have become such by
          consolidation or merger or acquired by a successor corporation in or
          as a result of a consolidation or merger (excluding, in any case,
          Property Additions owned by the Company immediately prior to such
          time), Cost shall mean the amount or amounts at which such Property
          Additions are recorded in the plant or other property accounts of such
          successor corporation, or the predecessor corporation

                                       B-1
<Page>

          from which such Property Additions are acquired, as the case may be,
          immediately prior to such consolidation or merger;

                (y)   with respect to Property Additions which shall have been
          acquired (otherwise than by construction) by the Company without any
          consideration consisting of cash, securities or other property or the
          incurring or assumption of indebtedness, no determination of Cost
          shall be required, and, wherever in this Indenture provision is made
          for Cost or fair value, Cost with respect to such Property Additions
          shall mean an amount equal to the fair value to the Company thereof
          or, if greater, the aggregate amount reflected in the Company's books
          of account with respect thereto upon the acquisition thereof; and

                (z)   in no event shall the Cost of Property Additions be
          required to reflect any depreciation or amortization in respect of
          such Property Additions, or any adjustment to the amount or amounts at
          which such Property Additions are recorded in plant or other property
          accounts due to the non-recoverability of investment or otherwise.

     SECTION 3. "PURCHASE MONEY MORTGAGE".

          Section 101 of the Original Indenture is hereby amended to add a
     definition of the term "purchase money mortgage" as follows:

                "PURCHASE MONEY MORTGAGE" means, with respect to any property
          being acquired or disposed of by the Company or being released from
          the Lien of this Indenture, a Lien on such property which

                a.    is taken or retained by the transferor of such property to
          secure all or part of the purchase price thereof;

                b.    is granted to one or more Persons other than the
          transferor which, by making advances or incurring an obligation, gives
          value to enable the grantor of such Lien to acquire rights in or the
          use of such property;

                c.    is granted to any other Person in connection with the
          release of such property from the Lien of this Indenture on the basis
          of the deposit with the Trustee or the trustee or other holder of a
          Lien prior to the Lien of this Indenture of obligations secured by
          such Lien on such property (as well as any other property subject
          thereto);

                d.    is held by a trustee or agent for the benefit of one or
          more Persons described in clause (a), (b) and/or (c) above, provided
          that such Lien may be held, in addition, for the benefit of one or
          more other Persons which shall have theretofore given, or may
          thereafter give, value to or for the benefit or account of the grantor
          of such Lien for one or more other purposes; or

                e.    otherwise constitutes a purchase money mortgage or a
          purchase money security interest under applicable law;

                                       B-2
<Page>

     and, without limiting the generality of the foregoing, for purposes of this
     Indenture, the term "purchase money mortgage" shall be deemed to include
     any Lien described above whether or not such Lien (x) shall permit the
     issuance or other incurrence of additional indebtedness secured by such
     Lien on such property, (y) shall permit the subjection to such Lien of
     additional property and the issuance or other incurrence of additional
     indebtedness on the basis thereof and/or (z) shall have been granted prior
     to the acquisition, disposition or release of such property, shall attach
     to or otherwise cover property other than the property being acquired,
     disposed of or released and/or shall secure obligations issued prior and/or
     subsequent to the issuance of the obligations delivered in connection with
     such acquisition, disposition or release.

     SECTION 4. LIMITATIONS ON PURCHASE MONEY MORTGAGES.

                (a)   The proviso to clause (d) in Section 803 of the Original
     Indenture is hereby amended to:

                    (1)(A) delete therefrom clause (x) and

                       (B) redesignate clauses (y) and (z) therein as clauses
                (x) and (y), respectively; and

                    (2)    delete therefrom clause (y); and

                (b)   Section 803 is further amended in accordance with Section
     1401 of the Original Indenture, to:

                    (1)    add thereto a new clause (y) reading as follows:

                      "(y) no obligations secured by purchase money mortgage
                shall be used as a credit in connection with the release of
                property hereunder, if the aggregate credit in respect of such
                obligations to be used by the Company pursuant to subclause (i)
                and subclause (iv) of this clause (d) plus the aggregate credits
                used by the Company pursuant to said subclause (i) and subclause
                (iv) in connection with all previous releases of property from
                the Lien hereof on the basis of purchase money obligations
                theretofore delivered to and then held by the Trustee or the
                trustee or other holder of a Lien prior to the Lien of this
                Indenture shall, immediately after the release then being
                applied for, exceed forty per centum (40%) of the sum of (A) the
                aggregate principal amount of Securities then Outstanding and
                (B) the aggregate principal amount of Class "A" Bonds then
                Outstanding other than Class "A" Bonds delivered to and then
                held by the Trustee;" and

                    (2)    add the following paragraph immediately after the
     second full paragraph of such Section:

                      Anything herein to the contrary notwithstanding, there
                shall not be taken into account for purposes of the calculation
                contemplated in clause (y) in the proviso to clause (d) of the
                first paragraph of this Section any obligations secured

                                       B-3
<Page>

     by purchase money mortgage with respect to which there shall have been
     delivered to the Trustee:

                (x)   an Officer's Certificate (i) if any obligations shall then
          be outstanding under such purchase money mortgage and/or additional
          obligations are permitted to be issued thereunder, either (A) stating
          that the terms of such purchase money mortgage, as then in effect, do
          not permit the issuance of obligations thereunder on the basis of
          property additions in a principal amount exceeding seventy per centum
          (70%) of the balance of the cost or fair value of such property
          additions to the issuer thereof (whichever shall be less) after making
          deductions and additions similar to those provided for in Section 104,
          or (B) in the event that the statements contained in clause (A) above
          cannot be made, stating that such issuer has irrevocably waived its
          right to the authentication and delivery of obligations under such
          purchase money mortgage (1) on any basis, in a principal amount equal
          to the excess of (I) the aggregate principal amount of obligations, if
          any, then outstanding under such purchase money mortgage which were
          issued on the basis of property additions or on the basis of the
          retirement of obligations which were issued (whether directly or
          indirectly when considered in light of the successive issuance and
          retirement of obligations) on the basis of property additions over
          (II) an amount equal to seventy per centum (70%) of the aggregate
          Dollar amount of property additions certified as the basis for the
          issuance of such obligations then outstanding and (2) on the basis of
          property additions, in a principal amount exceeding seventy per centum
          (70%) of the balance of the cost or fair value thereof to such issuer
          (whichever shall be less) after making deductions and additions
          similar to those provided for in Section 104 and (ii) stating either
          (A) that the obligations secured by such purchase money mortgage
          delivered to the Trustee or to the trustee or other holder of a Lien
          prior to the Lien of this Indenture as the basis for such release of
          property contain a provision for mandatory redemption upon the
          acceleration of the maturity of all Outstanding Securities following
          an Event of Default (whether or not such redemption may be rescinded
          upon the rescission of such acceleration) or (B) that so long as such
          obligations are held by the Trustee or the trustee or other holder of
          such a prior Lien, an Event of Default under this Indenture
          constitutes a matured event of default under such purchase money
          mortgage (PROVIDED, HOWEVER, that the waiver or cure of such Event of
          Default hereunder and the rescission and annulment of the consequences
          thereof may constitute a cure of the corresponding event of default
          under such purchase money mortgage and a rescission and annulment of
          the consequences thereof); and

                (y)   an Opinion or Opinions of Counsel to the effect that (i)
          if any obligations shall then be outstanding under such purchase money
          mortgage and/or additional obligations are permitted to be issued
          thereunder, to the effect either (A) that the terms of such purchase
          money

                                       B-4
<Page>

          mortgage, as then in effect, do not permit the issuance of obligations
          thereunder upon the basis of property additions in a principal amount
          exceeding seventy per centum (70%) of the balance of the cost or the
          fair value thereof to the issuer of such obligations (whichever shall
          be less) after making deductions and additions similar to those
          provided for in Section 104, or, if such is not the case, (B) that the
          waivers contemplated by clause (x)(i)(B) above have been duly made and
          (ii) to the effect either (A) that the obligations secured by such
          purchase money mortgage delivered to the Trustee or to the trustee or
          other holder of a Lien prior to the Lien of this Indenture as the
          basis for such release of property contain a provision for mandatory
          redemption upon an acceleration) of the maturity of all Outstanding
          Securities following an Event of Default (whether or not such
          redemption may be rescinded upon the rescission of such acceleration)
          or (B) that, so long as such obligations are held by the Trustee or
          the trustee or other holder of such a prior Lien, an Event of Default
          under this Indenture constitutes a matured event of default under such
          purchase money mortgage (PROVIDED, HOWEVER, that the waiver or cure of
          such Event of Default hereunder and the rescission and annulment of
          the consequences thereof may constitute a cure of the corresponding
          event of default under such purchase money mortgage and a rescission
          and annulment of the consequences thereof).

                                       B-5
<Page>

     SECTION 5. "FAIR VALUE".

          Section 101 of Original Indenture is hereby amended to add a
     definition of the term "fair value" as follows:

          "FAIR VALUE", with respect to property, means the fair value of such
     property as may be determined by reference to (a) the amount which would be
     likely to be obtained in an arm's-length transaction with respect to such
     property between an informed and willing buyer and an informed and willing
     seller, under no compulsion, respectively, to buy or sell, (b) the amount
     of investment with respect to such property which, together with a
     reasonable return thereon, would be likely to be recovered through ordinary
     business operations or otherwise, (c) the Cost, accumulated depreciation
     and replacement cost with respect to such property and/or (d) any other
     relevant factors; PROVIDED, HOWEVER, that (x) the fair value of property
     shall be determined without deduction for any Liens on such property prior
     to the Lien of this Indenture (except as otherwise provided in Section 803)
     and (y) the fair value to the Company of Property Additions shall not
     reflect any reduction relating to the fact that such Property Additions may
     be of less value to a Person which is not the owner or operator of the
     Mortgaged Property or any portion thereof than to a Person which is such
     owner or operator. Fair value may be determined, without physical
     inspection, by the use of accounting and engineering records and other data
     maintained by the Company or otherwise available to the Engineer certifying
     the same.

     SECTION 6. LIMITATIONS ON REQUIREMENTS FOR NET EARNINGS CERTIFICATE.

     (i)  The proviso to clause (i) of subsection (b) of Section 404 of the
Original Indenture is hereby amended to read as follows:

          PROVIDED, HOWEVER, that no Net Earnings Certificate shall be required
          to be delivered; and

     (ii) The proviso to clause (ii) of subsection (b) of Section 402 of the
Original Indenture is hereby amended to read as follows:

          PROVIDED, HOWEVER, that no Net Earnings Certificate shall be required
          to be delivered if there shall be delivered an Officer's Certificate
          to the effect that such Class "A" Bonds were authenticated and
          delivered under the related Class "A" Mortgage on the basis of retired
          Class "A" Bonds; and

                                   ----------

                                       B-6
<Page>

                              RECORDING INFORMATION

                            Allegheny County, Pennsylvania
                            Office of Recorder of Deeds
                            Recorded
                            Mortgage Book Volume

                            Beaver County, Pennsylvania
                            Office of Recorder of Deeds
                            Recorded
                            Mortgage Book Volume

                            Greene County, Pennsylvania
                            Office of Recorder of Deeds
                            Recorded
                            Mortgage Book Volume

                            Washington County, Pennsylvania
                            Office of Recorder of Deeds
                            Recorded
                            Mortgage Book Volume

                            Westmoreland County, Pennsylvania
                            Office of Recorder of Deeds
                            Recorded
                            Mortgage Book Volume

                            Belmont County, Ohio
                            Office of Recorder
                            Received
                            Recorded
                            Mortgage Book Volume

                            Columbiana County, Ohio
                            Office of Recorder
                            Recorded
                            Official Records Volume

                            Jefferson County, Ohio
                            Office of Recorder
                            Received
                            Recorded
                            Official Records Volume

<Page>

                            Lake County, Ohio
                            Office of Recorder
                            Recorded
                            Official Records Volume

                            Monroe County, Ohio
                            Office of Recorder
                            Received
                            Recorded
                            Official Records Volume

                            Hancock County, West Virginia
                            Office of Clerk of County Commission
                            Recorded
                            Deed of Trust Book

                            Monongahela County, West Virginia
                            Office of Clerk of County Commission
                            Recorded
                            Deed of Trust Book