================================================================================

                          PECO ENERGY TRANSITION TRUST,

                                     Issuer

                                       and


                              THE BANK OF NEW YORK,

                                  Bond Trustee



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


                                SERIES SUPPLEMENT

                              Dated as of [ ], 2000


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



================================================================================
<PAGE>

                                TABLE OF CONTENTS
<TABLE>
<CAPTION>
                                                                                 Page
                                                                                 -----
<S>          <C>                                                                 <C>
SECTION 1.  Definitions.............................................................2
SECTION 2.  Designation; Series Issuance Dates......................................4
SECTION 3.  Initial Principal Amount; Bond Rate; Expected
             Final Payment Date; Series Termination Date; Class
             Termination Dates......................................................4
SECTION 4.  Payment Dates; Expected Amortization Schedule
             for Principal; Interest; Overcollateralization
             Amount; Monthly Allocated Balances.....................................5
SECTION 5.  Authorized Initial Denominations........................................6
SECTION 6.  Redemption..............................................................6
SECTION 7.  Credit Enhancement......................................................7
SECTION 8.  Amendments to Indenture.................................................7
SECTION 9.  Delivery and Payment for the Series 1999-A
             Transition Bonds; Form of the Series 1999-A
             Transition Bonds.......................................................8
SECTION 10. Confirmation of Indenture...............................................8
SECTION 11. Counterparts............................................................8
SECTION 12. Governing Law...........................................................8
SECTION 13. Issuer Obligation.......................................................9



Schedule A    Expected Amortization Schedule
Schedule B    Monthly Allocated Balances

Exhibit A     Form of Transition Bond

</TABLE>


<PAGE>








                         SERIES SUPPLEMENT dated as of [ ], 2000 (this
                    "Supplement"), by and between PECO ENERGY TRANSITION TRUST,
                    a Delaware statutory business trust (the "Issuer"), and THE
                    BANK OF NEW YORK, a New York banking corporation (the "Bond
                    Trustee"), as Bond Trustee under the Indenture dated as of
                    March 1, 1999, between the Issuer and the Bond Trustee (the
                    "Indenture").


                              PRELIMINARY STATEMENT

     Section 9.01 of the Indenture provides, among other things, that the Issuer
and the Bond Trustee may at any time and from time to time enter into one or
more indentures supplemental to the Indenture for the purposes of authorizing
the issuance by the Issuer of a Series of Transition Bonds and specifying the
terms thereof and for modifying certain provisions of the Indenture. The Issuer
has duly authorized the execution and delivery of this Supplement and the
creation of a Series of Transition Bonds with an initial aggregate principal
amount of $[ ] to be known as the Issuer's Transition Bonds, Series [ ] (the
"Series [ ] Transition Bonds"). All acts and all things necessary to make the
Series [ ] Transition Bonds, when duly executed by the Issuer and authenticated
by the Bond Trustee as provided in the Indenture and this Supplement and issued
by the Issuer, the valid, binding and legal obligations of the Issuer and to
make this Supplement a valid and enforceable supplement to the Indenture have
been done, performed and fulfilled and the execution and delivery hereof have
been in all respects duly and lawfully authorized. The Issuer and the Bond
Trustee are executing and delivering this Supplement in order to provide for the
Series [ ] Transition Bonds and to modify certain provisions of the Indenture in
connection therewith.

     In order to secure the payment of principal of and interest on the Series
[ ] Transition Bonds issued and to be issued under the Indenture and/or any
Series Supplement, the Issuer hereby Grants to the Bond Trustee as trustee for
the benefit of the Holders of the Transition Bonds from time to time issued and
outstanding, all of the Issuer's right, title and interest in and to (a) the
Intangible Transition Property transferred by the Seller to the Issuer from time
to time pursuant to the Sale Agreement and all proceeds thereof, (b) the Sale
Agreement except for Section 5.01 thereof solely to the extent such Section
provides for indemnification of the Issuer, (c) all Bills of Sale delivered by
the Seller pursuant to the Sale Agreement,

<PAGE>

                                                                               2

(d) the Servicing Agreement except for Section 5.02(b) thereof solely to the
extent such Section provides for indemnification of the Issuer, (e) the
Collection Account and all amounts on deposit therein from time to time, (f) all
Swap Agreements with respect to the Series [ ] Transition Bonds, (g) all other
property of whatever kind owned from time to time by the Issuer including all
accounts, accounts receivable and chattel paper, (h) all present and future
claims, demands, causes and choses in action in respect of any or all of the
foregoing and (i) all payments on or under and all proceeds of every kind and
nature whatsoever in respect of any or all of the foregoing, including all
proceeds of the conversion, voluntary or involuntary, into cash or other liquid
property, all cash proceeds, accounts, accounts receivable, general intangibles,
notes, drafts, acceptances, chattel paper, checks, deposit accounts, insurance
proceeds, condemnation awards, rights to payment of any and every kind, and
other forms of obligations and receivables, instruments and other property which
at any time constitute all or part of or are included in the proceeds of any of
the foregoing (collectively, the "Collateral").

     To have and to hold in trust to secure the payment of principal of and
premium, if any, and interest on, and any other amounts (including all fees,
expenses, counsel fees and other amounts due and owing to the Bond Trustee)
owing in respect of, the Transition Bonds equally and ratably without prejudice,
preference, priority or distinction, except as expressly provided in the
Indenture or any Series Supplement and to secure performance by the Issuer of
all of the Issuer's obligations under the Indenture and all Series Supplements
with respect to the Transition Bonds, all as provided in the Indenture.

     The Bond Trustee, as trustee on behalf of the Holders of the Transition
Bonds, acknowledges such Grant, accepts the trusts hereunder in accordance with
the provisions hereof and agrees to perform its duties required in the Indenture
and this Supplement.

     SECTION 1. Definitions. (a) Article One of the Indenture provides that the
meanings of certain defined terms used in the Indenture shall, when applied to
the Transition Bonds of a particular Series, be as defined in Article One but
with such additional provisions as are specified in the related Series
Supplement. With respect to the Series [ ] Transition Bonds, the following
definitions shall apply:

<PAGE>

                                                                               3

     "Adjustment Date" shall mean initially each August 12th, until [ ] and on
such date and thereafter, the [ ]th day of each month.

     "Authorized Initial Denominations" shall mean $1,000 and integral multiples
thereof.

     "Bond Rate" has the meaning set forth in Section 3 of this Supplement.

     "Calculation Date" means initially each May 14th, until [ ] and on such
date and thereafter the [ ]th day of each month.

     "Class Termination Date" means, with respect to any Class of the Series [ ]
Transition Bonds, the termination date therefor, as specified in Section 3 of
this Supplement.

     "Expected Amortization Schedule" means Schedule A to this Supplement.

     "Expected Final Payment Date" means, with respect to any Class of the
Series [ ] Transition Bonds, the expected final payment date therefor, as
specified in Section 3 of this Supplement.

     "Interest Accrual Period" means, with respect to any Payment Date, the
period from and including the preceding Payment Date (or, in the case of the
first Payment Date, from and including the Series Issuance Date) to and
excluding such Payment Date.

     "Monthly Allocated Interest Balance" has the meaning set forth in Section
4(e) of this Supplement.

     "Monthly Allocated Principal Balance" has the meaning set forth in Section
4(e) of this Supplement.

     "Overcollateralization Amount" has the meaning set forth in Section 4(e) of
this Supplement.

     "Payment Date" has the meaning set forth in Section 4(a) of this
Supplement.

     "Record Date" shall mean, with respect to any Payment Date, the close of
business on the day prior to such Payment Date.

<PAGE>

                                                                               4

     "Series Issuance Date" has the meaning set forth in Section 2(b) of this
Supplement.

     "Series Termination Date" has the meaning set forth in Section 3 of this
Supplement.

     "Servicing Fee Rate" shall mean 0.25% per annum so long as ITC Charges are
included in electric bills otherwise sent to Customers or, if ITC Charges are
not included in such bills, 1.50% per annum.

     (b) All terms used in this Supplement that are defined in the Indenture,
either directly or by reference therein, have the meanings assigned to them
therein, except to the extent such terms are defined or modified in this
Supplement or the context clearly requires otherwise.

     SECTION 2. Designation; Series Issuance Dates. (a) Designation. The Series
[ ] Transition Bonds shall be designated generally as the Issuer's Transition
Bonds, Series [ ] and further denominated as Classes A-1 through A-[4].

     (b) Series Issuance Date. The Series [ ] Transition Bonds that are
authenticated and delivered by the Bond Trustee to or upon the order of the
Issuer on [ ], 2000 (the "Series Issuance Date") shall have as their date of
authentication [ ], 2000. Each other Series [ ] Transition Bond shall be dated
the date of its authentication.

     SECTION 3. Initial Principal Amount; Bond Rate; Expected Final Payment
Date; Series Termination Date; Class Termination Dates. The Transition Bonds of
each Class of the Series [ ] Transition Bonds shall have the initial principal
amounts, bear interest at the rates per annum and shall have Expected Final
Payment Dates and Class Termination Dates as set forth below:

<TABLE>
<CAPTION>
             Initial
            Principal              Bond                  Expected Final                  Class
Class         Amount               Rate                   Payment Date              Termination Date
-----       ---------              ----                  --------------             ----------------
<S>          <C>                   <C>                   <C>                        <C>
A-1
A-2
A-3
A-4

</TABLE>

<PAGE>

                                                                               5

     The Bond Rate for each Class shall be computed on the basis of a 360-day
year of twelve 30-day months.

     SECTION 4. Payment Dates; Expected Amortization Schedule for Principal;
Interest; Overcollateralization Amount; Monthly Allocated Balances. (a) Payment
Dates. The Payment Dates for each Class of the Series [ ] Transition Bonds are
March 1 and September 1 of each year or, if any such date is not a Business Day,
the next succeeding Business Day, commencing on [ , 2000] and continuing until
the earlier of repayment of such Class in full and the applicable Class
Termination Date.

     (b) Expected Amortization Schedule for Principal. Unless an Event of
Default shall have occurred and be continuing and the unpaid principal amount of
all Series of Transition Bonds has been declared to be due and payable together
with accrued and unpaid interest thereon, on each Payment Date, the Bond Trustee
shall distribute to the Series [ ] Transition Bondholders of record as of the
related Record Date amounts payable in respect of the Series [ ] Transition
Bonds pursuant to Section 8.02(e) of the Indenture as principal, in accordance
with the Expected Amortization Schedule. Available funds in the Series __
Subaccount will be allocated in a sequential manner, to the extent funds are
available, as follows: (1) to the holders of the Series __ Transition Bonds,
Class A-1, until this Class is retired in full, (2) to the holders of the Series
__ Transition Bonds, Class A-2, until this Class is retired in full, (3) to the
holders of the Series __ Transition Bonds, Class A-3, until this Class is
retired in full, and (4) to the holders of the Series __ Transition Bonds, Class
A-4, until this Class is retired in full. Other than in the event of an
acceleration of payments following an Event of Default or a redemption, in no
event shall a principal payment pursuant to this Section 4(b) on any Class on a
Payment Date be greater than the amount that reduces the Outstanding Amount of
such Class of Series [ ] Transition Bonds to the amount specified in the
Expected Amortization Schedule which is attached as Schedule A hereto for such
Class and Payment Date. In the event of an acceleration of payments following an
Event of Default on the Series __ Transition Bonds, principal payments on each
Class of Series __ Transition Bonds will be made on a pro rata basis based on
the respective Outstanding Amount of each Class as of the prior Payment Date.

     (c) Interest. Interest will be payable on each Class of the Series [ ]
Transition Bonds on each Payment Date in an amount equal to one-half of the
product of (i) the applicable Bond Rate and (ii) the Outstanding

<PAGE>

                                                                               6

Amount of the related Class of Transition Bonds as of the close of business on
the preceding Payment Date after giving effect to all payments of principal made
to the holders of the related Class of Series [ ] Transition Bonds on such
preceding Payment Date; and provided, further, that with respect to the initial
Payment Date or, if no payment has yet been made, interest on the outstanding
principal balance will accrue from and including the Series Issuance Date to,
but excluding, the following Payment Date.

     (d) Overcollateralization Amount. The Overcollateralization Amount for the
Series [ ] Transition Bonds shall be $[ ].

     (e) Monthly Allocated Balances. The Monthly Allocated Interest Balance and
Monthly Allocated Principal Balance for any Monthly Allocation Date and the
Series [ ] Transition Bonds shall be as set forth in Schedule B hereto.

     Not later than each Schedule Revision Date, the Issuer shall deliver to the
Bond Trustee replacement Schedules A and B hereto, adjusted to reflect the event
giving rise to such Schedule Revision Date and setting forth the Expected
Amortization Schedule for each Payment Date and the Monthly Allocated Interest
Balance and Monthly Allocated Principal Balance for each Monthly Allocation
Date; provided, however, that no such replacement schedules shall be required if
the event giving rise to such Schedule Revision Date is a redemption of the
Series [ ] Transition Bonds in whole.

     SECTION 5. Authorized Initial Denominations. The Series [ ] Transition
Bonds shall be issuable in the Authorized Initial Denominations.

     SECTION 6. Redemption. (a) Mandatory Redemption. The Series [ ] Transition
Bonds shall not be subject to mandatory redemption except as provided in Section
10.02 of the Indenture in the event that the Issuer receives Liquidated Damages.
If the Issuer receives Liquidated Damages from the Seller as a result of a
breach of a representation and warranty under the Sale Agreement which relates
to one of the Qualified Rate Orders, but not both of the Qualified Rate Orders,
then (i) only the Affected Transition Bonds will be redeemed and (ii) the
Redemption Price shall be equal to the then outstanding principal amount of the
Affected Transition Bonds as of the Liquidated Damages Redemption Date plus
accrued interest to such Redemption Date.

<PAGE>

                                                                               7

     (b) Optional Redemption. The Series [ ] Transition Bonds shall not be
subject to optional redemption by the Issuer except that the Series [ ]
Transition Bonds may be redeemed in whole at a Redemption Price equal to the
principal amount thereof plus interest at the applicable Bond Rate accrued to
the Redemption Date on any Payment Date on which the Outstanding Amount thereof
(after giving effect to payments that would otherwise be made on such Payment
Date) has been reduced to less than 5% of the initial principal balance thereof.

     SECTION 7. Credit Enhancement. No credit enhancement (other than the
Overcollateralization Amount) is provided for the Series [ ] Transition Bonds.

     SECTION 8. Amendments to Indenture. In connection with the issuance of the
Series [ ] Transition Bonds, the Indenture shall be amended as follows:

     (a) Section 1.01(a) of the Indenture shall be amended by (i) amending the
definition of "Liquidated Damages" by deleting the phrase "5.01(c)(ii) or" in
the second line thereof; (ii) amending the definition of "Liquidated Damages
Redemption Date" by adding the word "Affected" after the phrase "for the
redemption of" in the second line thereof; (iii) amending the definition of
"Sale Agreement" by replacing the phrase "Intangible Transition Property Sale
Agreement dated as of March 25, 1999" with the phrase "Amended and Restated
Intangible Transition Property Sale Agreement dated as of [ ], 2000"; and (iv)
amending the definition of "Servicing Agreement" by replacing the phrase "Master
Servicing Agreement dated as of March 25, 1999" with the phrase "Amended and
Restated Master Servicing Agreement dated as of [ ], 2000".

     (b) Section 1.01(b) of the Indenture shall be amended by (i) adding the
term "Affected Transition Bonds" in proper alphabetical order and (ii) replacing
the term "Qualified Rate Order" with the term "Qualified Rate Orders".

     (c) Section 3.10(vi) of the Indenture shall be amended by replacing the
term "Qualified Rate Order" with the term "Qualified Rate Orders" in each of the
second line and third line thereof.

     (d) Section 8.02(f) of the Indenture shall be amended by (i) adding the
following phrase at the end of clause (iv) thereof: "provided that if the Issuer
receives Liquidated Damages from the Seller as a result of a breach of a
representation and warranty under the Sale Agreement

<PAGE>

                                                                               8

which relates to one of the Qualified Rate Orders, but not both of the Qualified
Rate Orders, then only the Redemption Price and accrued interest for the
Affected Transition Bonds shall be paid to Transition Bondholders of such
Series, and any amounts due to any Counterparty pursuant to a Swap Agreement
entered into in connection with the issuance of the Affected Transition Bonds
shall be paid to such Counterparty;" and (ii) adding the following phrase at the
end of clause (vi) thereof: "provided that if the Issuer receives Liquidated
Damages from the Seller as a result of a breach of a representation and warranty
under the Sale Agreement which relates to one of the Qualified Rate Orders, but
not both of the Qualified Rate Orders, then the balance, if any, will remain in
the Collection Account".

     (e) Section 10.02(a) of the Indenture shall be amended by adding the
following phrase at the end of clause (ii) thereof: "; provided that if the
Issuer receives Liquidated Damages from the Seller as a result of a breach of a
representation and warranty under the Sale Agreement which relates to one of the
Qualified Rate Orders, but not both of the Qualified Rate Orders, then (1) only
the Affected Transition Bonds will be redeemed and (2) the Redemption Price
shall be equal to the then outstanding principal amount of the Affected
Transition Bonds as of the Liquidated Damages Redemption Date plus accrued
interest to such Redemption Date".

     SECTION 9. Delivery and Payment for the Series [ ] Transition Bonds; Form
of the Series [ ] Transition Bonds. The Bond Trustee shall deliver the Series
[ ] Transition Bonds to the Issuer when authenticated in accordance with Section
2.02 of the Indenture. The Series [ ] Transition Bonds of each Class shall be in
the form of Exhibits A-1 through A-[4] hereto.

     SECTION 10. Confirmation of Indenture. As supplemented by this Supplement,
the Indenture is in all respects ratified and confirmed and the Indenture, as so
supplemented by this Supplement, shall be read, taken, and construed as one and
the same instrument.

     SECTION 11. Counterparts. This Supplement may be executed in any number of
counterparts, each of which so executed shall be deemed to be an original, but
all of such counterparts shall together constitute but one and the same
instrument.

     SECTION 12. Governing Law. This Supplement shall be construed in accordance
with the laws of the Commonwealth of Pennsylvania, without reference to its
conflict of law

<PAGE>

                                                                               9

provisions, and the obligations, rights and remedies of the parties hereunder
shall be determined in accordance with such laws.

     SECTION 13. Issuer Obligation. No recourse may be taken, directly or
indirectly, with respect to the obligations of the Issuer or the Bond Trustee on
the Transition Bonds or under this Supplement or any certificate or other
writing delivered in connection herewith or therewith, against (i) any owner of
a beneficial interest in the Issuer or (ii) any partner, owner, beneficiary,
agent, officer, director or employee of the Bond Trustee, any holder of a
beneficial interest in the Issuer or the Bond Trustee or of any successor or
assign of the Bond Trustee, except as any such Person may have expressly agreed
(it being understood that none of the Bond Trustee's obligations are in its
individual capacity).

<PAGE>

                                                                              10

     IN WITNESS WHEREOF, the Issuer and the Bond Trustee have caused this
Supplement to be duly executed by their respective officers thereunto duly
authorized as of the first day of the month and year first above written.



                                     PECO ENERGY TRANSITION TRUST,

                                     by First Union Trust Company,
                                        National Association, not in
                                        its individual capacity but
                                        solely as Issuer Trustee,
                                        Delaware Trustee and
                                        Independent Trustee

                                       by
                                           ---------------------------
                                           Name:
                                           Title:


                                      THE BANK OF NEW YORK, not in
                                      its individual capacity but
                                      solely as Bond Trustee on
                                      behalf of the Transition
                                      Bondholders,

                                       by
                                           ----------------------------
                                           Name:
                                           Title:

<PAGE>



                                                                      SCHEDULE A


                         Expected Amortization Schedule


                          Outstanding Principal Balance

<TABLE>
<CAPTION>

Payment Date                Class A-1          Class A-2       Class A-3        Class A-4          Series 1999-A
----------------------      ---------          ---------       ---------        ---------          -------------
<S>                         <C>                <C>             <C>              <C>                <C>
Series Issuance Date..
September 1, 2000.....
March 1, 2001.........
September 1, 2001.....
March 1, 2002.........
September 1, 2002.....
March 1, 2003.........
September 1, 2003.....
March 1, 2004.........
September 1, 2004.....
March 1, 2005.........
September 1, 2005.....
March 1, 2006.........
September 1, 2006.....
March 1, 2007.........
September 1, 2007.....
March 1, 2008.........
September 1, 2008.....
March 1, 2009.........
September 1, 2009.....

</TABLE>

<PAGE>




                                                                      SCHEDULE B



                           Monthly Allocated Balances

<TABLE>
<CAPTION>
                                                   Monthly Allocated                          Monthly Allocated
Monthly Allocation Date                            Interest Balance                           Principal Balance
--------------------------------------             -----------------                          -----------------
<S>                                                <C>                                        <C>
May 1, 2000...........................
June 1, 2000..........................
July 1, 2000..........................
August 1, 2000........................
September 1, 2000.....................
October 1, 2000.......................
November 1, 2000......................
December 1, 2000......................
January 1, 2001.......................
February 1, 2001......................
March 1, 2001.........................
April 1, 2001.........................
May 1, 2001...........................
June 1, 2001..........................
July 1, 2001..........................
August 1, 2001........................
September 1, 2001.....................
October 1, 2001.......................
November 1, 2001......................
December 1, 2001......................
January 1, 2002.......................
February 1, 2002......................
March 1, 2002.........................
April 1, 2002.........................
May 1, 2002...........................
June 1, 2002..........................
July 1, 2002..........................
August 1, 2002........................
September 1, 2002.....................
October 1, 2002.......................
November 1, 2002......................
December 1, 2002......................
January 1, 2003.......................
February 1, 2003......................
March 1, 2003.........................
April 1, 2003.........................
May 1, 2003...........................
June 1, 2003..........................
July 1, 2003..........................
August 1, 2003........................
September 1, 2003.....................
October 1, 2003.......................
November 1, 2003......................
December 1, 2003......................
January 1, 2004.......................
February 1, 2004......................
March 1, 2004.........................
April 1, 2004.........................
May 1, 2004...........................
June 1, 2004..........................
July 1, 2004..........................
August 1, 2004........................

</TABLE>

<PAGE>


<TABLE>
<CAPTION>
                                                   Monthly Allocated                          Monthly Allocated
Monthly Allocation Date                            Interest Balance                           Principal Balance
--------------------------------------             -----------------                          -----------------
<S>                                                <C>                                        <C>
September 1, 2004.....................
October 1, 2004.......................
November 1, 2004......................
December 1, 2004......................
January 1, 2005.......................
February 1, 2005......................
March 1, 2005.........................
April 1, 2005.........................
May 1, 2005...........................
June 1, 2005..........................
July 1, 2005..........................
August 1, 2005........................
September 1, 2005.....................
October 1, 2005.......................
November 1, 2005......................
December 1, 2005......................
January 1, 2006.......................
February 1, 2006......................
March 1, 2006.........................
April 1, 2006.........................
May 1, 2006...........................
June 1, 2006..........................
July 1, 2006..........................
August 1, 2006........................
September 1, 2006.....................
October 1, 2006.......................
November 1, 2006......................
December 1, 2006......................
January 1, 2007.......................
February 1, 2007......................
March 1, 2007.........................
April 1, 2007.........................
May 1, 2007...........................
June 1, 2007..........................
July 1, 2007..........................
August 1, 2007........................
September 1, 2007.....................
October 1, 2007.......................
November 1, 2007......................
December 1, 2007......................
January 1, 2008.......................
February 1, 2008......................
March 1, 2008.........................
April 1, 2008.........................
May 1, 2008...........................
June 1, 2008..........................
July 1, 2008..........................
August 1, 2008........................
September 1, 2008.....................
October 1, 2008.......................
November 1, 2008......................

</TABLE>

<PAGE>



<TABLE>
<CAPTION>
                                                   Monthly Allocated                          Monthly Allocated
Monthly Allocation Date                            Interest Balance                           Principal Balance
--------------------------------------             -----------------                          -----------------
<S>                                                <C>                                        <C>
December 1, 2008......................
January 1, 2009.......................
February 1, 2009......................
March 1, 2009.........................
April 1, 2009.........................
May 1, 2009...........................
June 1, 2009..........................
July 1, 2009..........................
August 1, 2009........................
September 1, 2009.....................
October 1, 2009.......................
November 1, 2009......................
December 1, 2009......................
[                          ]..........

</TABLE>

<PAGE>

                                                                       EXHIBIT A


                             Form of Transition Bond

                                [To be provided]