<PAGE>
 
UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), TO ISSUER 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.

THIS SECURITY IS A BOOK-ENTRY SECURITY WITHIN THE MEANING OF THE INDENTURE
HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITORY OR A
NOMINEE OF A DEPOSITORY.  THIS SECURITY IS EXCHANGEABLE FOR SECURITIES
REGISTERED IN THE NAME OF A PERSON OTHER THAN THE DEPOSITORY OR ITS NOMINEE ONLY
IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE INDENTURE, AND NO TRANSFER OF THIS
SECURITY (OTHER THAN A TRANSFER OF THIS SECURITY AS A WHOLE BY THE DEPOSITORY TO
A NOMINEE OF THE DEPOSITORY OR BY A NOMINEE OF THE DEPOSITORY TO THE DEPOSITORY
OR ANOTHER NOMINEE OF THE DEPOSITORY) MAY BE REGISTERED EXCEPT IN SUCH LIMITED
CIRCUMSTANCES.

                              ENSERCH CORPORATION
                               7% Notes Due 1999

No. 1                                                               $150,000,000
CUSIP No. 293567 AU 7

     ENSERCH Corporation, a corporation duly organized and existing under the
laws of the State of Texas (herein called the "Company", which term includes any
successor corporation under the Indenture hereinafter referred to), for value
received, hereby promises to pay to CEDE & CO., or registered assigns, the
principal sum of ONE HUNDRED FIFTY MILLION DOLLARS on August 15, 1999 and to pay
interest thereon from August 15, 1992 or from the most recent Interest Payment
Date to which interest has been paid or duly provided for, semi-annually on
August 15 and February 15 (each an "Interest Payment Date") in each year,
commencing February 15, 1993 at the rate of 7% per annum, until the principal
hereof is paid or made available for payment, and (to the extent that the
payment of such interest shall be legally enforceable) at the rate of 7% per
annum on any overdue principal and on any overdue installment of interest.  The
amount of interest payable on any Interest Payment Date shall be computed on the
basis of a 360-day year of twelve 30-day months. 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 August 1 or
February 1 (whether or not a Business Day), as the case may be, next preceding
such Interest Payment Date.  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 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 any such 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.

                                  ENSERCH CORPORATION

Dated: August 18, 1992                      By /s/ Jerry W. Pinkerton
                                                     Vice President

[CORPORATE SEAL]                            By /s/ A. E. Gallatin
                                                     Treasurer

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

                                THE FIRST NATIONAL BANK OF CHICAGO,
                                            as Trustee

                                            By /s/ Donne Fanning
                                                     Authorized Officer
<PAGE>
 
     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 February 15, 1992 (herein called the
"Indenture"), between the Company and The First National Bank of Chicago, as
Trustee (herein called the "Trustee", which term includes any successor trustee
under the Indenture), to which Indenture and all indentures supplemental thereto
reference is hereby made 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 terms upon which the Securities are, and
are to be, authenticated and delivered.  This Security is a global Book-Entry
Security representing $150,000,000 principal amount of the series of Securities
designated on the face hereof, limited in aggregate principal amount to
$150,000,000.

     The Securities of this series are not redeemable in whole or in part at any
time prior to maturity.

     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 contains provisions for defeasance at any time of (a) the
entire indebtedness of this Security and (b) certain restrictive covenants, in
each case upon compliance by the Company with certain conditions set forth
therein, which provisions apply to this Security.

     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 with the
consent of the Holders of at least a majority 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 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.

     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 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 herein and
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 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, of authorized
denominations and for the same aggregate principal amount, will be issued to the
designated transferee or transferees.

     This global Book-Entry Security is exchangeable for Securities in
definitive form only under certain limited circumstances set forth in the
Indenture. Securities of this series so issued 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 herein
and therein set forth, Securities of this series so issued are exchangeable for
a like aggregate principal amount of Securities of this series 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 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.

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

                                 ABBREVIATIONS

     The following abbreviations, when used in the inscription on the face of
the within Security, shall be construed as though they were written out in full
according to applicable laws or regulations.

 
TEN COM - as tenants in common                 
TEN ENT - as tenants by the entireties         
JT TEN  - as joint tenants with right of       
          survivorship and not as tenants
          in common                                 

UNIF GIFT MIN ACT -  ...................   Custodian ........................
                          (Cust)                               (Minor)
                                 
                            under Uniform Gifts to Minors Act 

                     ........................................................
                                            (State)

    Additional abbreviations may also be used though not in the above list.

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

  FOR VALUE RECEIVED, the undersigned hereby sells, assigns and transfers unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
   IDENTIFYING NUMBER OF ASSIGNEE

[________________________________]

(PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE)

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the within Security of ENSERCH CORPORATION and hereby does irrevocably
constitute and appoint

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                                                                        Attorney
------------------------------------------------------------------------
to transfer the said Security on the books of the within-named Corporation, with
full power of substitution in the premises.

Dated
     --------------------------------------------------------

Signature Guaranteed by: