Supplemental Indenture



 Exhibit 4.1 
 This instrument was prepared by, 
 and when recorded should be 

returned to: 
 Richard W. Astle 

Sidley Austin LLP 
 One South Dearborn Street

 Chicago, Illinois 60603 
  

 
 SUPPLEMENTAL
INDENTURE 
 Dated as of January 4, 2011 

COMMONWEALTH EDISON COMPANY 

to 
 BNY
MELLON TRUST COMPANY OF ILLINOIS 
 and

 D.G. DONOVAN 
 Trustees Under Mortgage Dated July 1, 1923, 
 and Certain 

Indentures Supplemental Thereto 
 Providing for Issuance of 
 FIRST MORTGAGE 1.625% BONDS, SERIES 110 

Due January 15, 2014 
  

 







 THIS SUPPLEMENTAL INDENTURE, dated as of
January 4, 2011, between COMMONWEALTH EDISON COMPANY, a corporation organized and existing under the laws of the State of Illinois (hereinafter called the “Company”) having an
address at 440 South LaSalle Street, Suite 3300, Chicago, Illinois 60605, party of the first part, BNY MELLON TRUST COMPANY OF ILLINOIS, a trust company organized and
existing under the laws of the State of Illinois having an address at 2 North LaSalle Street, Suite 1020, Chicago, Illinois 60602, and D.G. DONOVAN, an individual having an address at 2 North LaSalle Street, Suite 1020, Chicago,
Illinois 60602, as Trustee and Co-Trustee, respectively, under the Mortgage of the Company dated July 1, 1923, as amended and supplemented by Supplemental Indenture dated August 1, 1944 and the subsequent supplemental indentures
hereinafter mentioned, parties of the second part (said Trustee being hereinafter called the “Trustee”, the Trustee and said Co-Trustee being hereinafter together called the “Trustees”, and said Mortgage dated
July 1, 1923, as amended and supplemented by said Supplemental Indenture dated August 1, 1944 and subsequent supplemental indentures, being hereinafter called the “Mortgage”), 

W I T N E S S E T H: 
 WHEREAS, the Company duly executed and delivered the Mortgage to provide for the issue of, and to secure, its bonds, issuable in series and without limit as to principal amount except as provided in the
Mortgage; and 
 WHEREAS, the Company from time to time has executed and delivered supplemental indentures to the Mortgage to
provide for (i) the creation of additional series of bonds secured by the Mortgage, (ii) the amendment of certain of the terms and provisions of the Mortgage and (iii) the confirmation of the lien of the Mortgage upon property of the
Company, such supplemental indentures that are currently effective and the respective dates, parties thereto and purposes thereof, being as follows: 
  

					
	Supplemental
Indenture Date	  	Parties	  	Providing For
			
	 August 1, 1944
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Edmond B. Stofft, as Trustee and Co-Trustee	  	Amendment and restatement of
Mortgage dated July 1, 1923
			
	 August 1, 1946
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Edmond B. Stofft, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 April 1, 1953
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Edmond B. Stofft, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 March 31, 1967
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Edward J. Friedrich, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 April 1, 1967
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Edward J. Friedrich, as Trustee and Co-Trustee	  	Amendment of Sections 3.01,
3.02, 3.05 and 3.14 of the
Mortgage and issuance of First
Mortgage 5-3/8% Bonds, Series Y
			
	 February 28, 1969
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien


  
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	Supplemental
Indenture Date	  	Parties	  	Providing For
			
	 May 29, 1970
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 June 1, 1971
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 April 1, 1972
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 May 31, 1972
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 June 15, 1973
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 May 31, 1974
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 June 13, 1975
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 May 28, 1976
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 June 3, 1977
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 May 17, 1978
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 August 31, 1978
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 June 18, 1979
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 June 20, 1980
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 April 16, 1981
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 April 30, 1982
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien


  
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	Supplemental
Indenture Date	  	Parties	  	Providing For
			
	 April 15, 1983
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 April 13, 1984
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 April 15, 1985
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and Donald W. Alfvin, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 April 15, 1986
	  	Company to Continental Illinois National Bank and Trust Company of Chicago and M.J. Kruger, as Trustee and Co-Trustee	  	Confirmation of mortgage lien
			
	 April 15, 1993
	  	Company to Continental Bank, National Association and M.J. Kruger, as Trustee and Co-Trustee	  	Issuance of First Mortgage 7-
5/8% Bonds, Series 92
			
	 June 15, 1993
	  	Company to Continental Bank, National Association and M.J. Kruger, as Trustee and Co-Trustee	  	Issuance of First Mortgage
7% Bonds, Series 93 and First
Mortgage 7-1/2% Bonds,
Series 94
			
	 January 15, 1994
	  	Company to Continental Bank, National Association and M.J. Kruger, as Trustee and Co-Trustee	  	Issuance of First Mortgage
Bonds, Pollution Control
Series 1994A, 1994B and
1994C
			
	 March 1, 2002
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Issuance of unregistered First
Mortgage 6.15% Bonds,
Series 98
			
	 June 1, 2002
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Issuance of additional
unregistered First Mortgage
6.15% Bonds, Series 98
			
	 October 7, 2002
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Issuance of registered First
Mortgage 6.15% Bonds,
Series 98 in exchange for
unregistered First Mortgage
6.15% Bonds, Series 98
			
	 January 13, 2003
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Issuance of First Mortgage
3.700% Bonds, Series 99 and
First Mortgage 5.875%
Bonds, Series 100
			
	 March 14, 2003
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Issuance of First Mortgage
4.70% Bonds, Series 101
			
	 August 13, 2003
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Issuance of First Mortgage
4.74% Bonds, Series 102
			
	 February 22, 2006
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Issuance of First Mortgage
5.90% Bonds, Series 103
			
	 August 1, 2006
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Issuance of First Mortgage
5.95% Bonds, Series 104


  
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	Supplemental
Indenture Date	  	Parties	  	Providing For
			
	 September 15, 2006
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Issuance of additional First
Mortgage 5.95% Bonds, Series
104
			
	 December 1, 2006
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Issuance of First Mortgage 5.40%
Bonds, Series 105
			
	 March 1, 2007
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Issuance of additional First
Mortgage 5.90% Bonds, Series
103
			
	 August 30, 2007
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Issuance of First Mortgage
6.15% Bonds, Series 106
			
	 December 20, 2007
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Issuance of First Mortgage
6.45% Bonds, Series 107
			
	 March 10, 2008
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Amendment of Section 15.06
of the Mortgage and issuance
of First Mortgage 5.80%
Bonds, Series 108
			
	 April 23, 2008
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Amendment of Section 15.06
of the Mortgage and issuance
of First Mortgage Bonds,
Pollution Control Series 2008D
and Series 2008F
			
	 June 12, 2008
	  	Company to BNY Midwest Trust Company and D.G. Donovan, as Trustee and Co-Trustee	  	Amendment of Section 15.06
of the Mortgage and issuance
of First Mortgage Bonds,
Pollution Control Series 2008E
			
	 July 12, 2010
	  	Company to BNY Mellon Trust Company of Illinois and D.G. Donovan, as Trustee and Co-Trustee	  	Amendment of Section 15.06
of the Mortgage and issuance
of First Mortgage 4.00%
Bonds, Series 109


WHEREAS, the respective designations, maturity dates and stated principal amounts of the bonds of each series presently outstanding
under, and secured by, the Mortgage and the several supplemental indentures above referred to, are as follows: 
  

							
	Designation	  	Maturity Date	  	Principal Amount	 
			
	 First Mortgage 7-5/8% Bonds, Series 92
	  	April 15, 2013	  	$	125,000,000	  
			
	 First Mortgage 7-1/2% Bonds, Series 94
	  	July 1, 2013	  	 	127,000,000	  
			
	 First Mortgage 5.85% Bonds, Pollution Control Series 1994C
	  	January 15, 2014	  	 	17,000,000	  
			
	 First Mortgage 6.15% Bonds, Series 98
	  	March 15, 2012	  	 	450,000,000	  
			
	 First Mortgage 5.875% Bonds, Series 100
	  	February 1, 2033	  	 	253,600,000	  
			
	 First Mortgage 4.70% Bonds, Series 101
	  	April 15, 2015	  	 	260,000,000	  
			
	 First Mortgage 5.90% Bonds, Series 103
	  	March 15, 2036	  	 	625,000,000	  
			
	 First Mortgage 5.95% Bonds, Series 104
	  	August 15, 2016	  	 	415,000,000	  


  
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	Designation	  	Maturity Date	  	Principal Amount	 
			
	 First Mortgage 5.40% Bonds, Series 105
	  	December 15, 2011	  	 	345,000,000	  
			
	 First Mortgage 6.15% Bonds, Series 106
	  	September 15, 2017	  	 	425,000,000	  
			
	 First Mortgage 6.45% Bonds, Series 107
	  	January 15, 2038	  	 	450,000,000	  
			
	 First Mortgage 5.80% Bonds, Series 108
	  	March 15, 2018	  	 	700,000,000	  
			
	 First Mortgage Bonds, Pollution Control Series 2008D
	  	March 1, 2020	  	 	50,000,000	  
			
	 First Mortgage Bonds, Pollution Control Series 2008F
	  	March 1, 2017	  	 	91,000,000	  
			
	 First Mortgage Bonds, Pollution Control Series 2008E
	  	May 1, 2021	  	 	49,830,000	  
			
	 First Mortgage 4.00% Bonds, Series 109
	  	August 1, 2020	  	 	500,000,000	  
		  		  	 	 	 
		  	Total	  	$	4,883,430,000	  
		  		  	 	 	 

 WHEREAS, the Mortgage provides for the issuance from time to time thereunder, in series, of bonds of the
Company for the purposes and subject to the limitations therein specified; and 
 WHEREAS, the Company desires, by this
Supplemental Indenture, to create an additional series of bonds to be issuable under the Mortgage, such bonds to be designated “First Mortgage 1.625% Bonds, Series 110 (hereinafter called the “bonds of Series 110”) and the
terms and provisions to be contained in the bonds of Series 110 or to be otherwise applicable thereto to be as set forth in this Supplemental Indenture; and 
 WHEREAS, the bonds of Series 110 and the Trustee’s certificate to be endorsed thereon shall be substantially in the form of the General Form of Registered Bond Without Coupons and the form of the
General Form of Trustee’s Certificate set forth in Section 3.05 of the Supplemental Indenture dated August 1, 1944 to the Mortgage with such appropriate insertions, omissions and variations in order to express the designation, date,
maturity date, annual interest rate, record dates for, and dates of, payment of interest, denominations, terms of redemption and redemption prices, and other terms and characteristics authorized or permitted by the Mortgage or not inconsistent
therewith; and 
 WHEREAS, the Company is legally empowered and has been duly authorized by the necessary corporate action and
by an order or orders of the Illinois Commerce Commission to make, execute and deliver this Supplemental Indenture, and to create, as an additional series of bonds of the Company, the bonds of Series 110, and all acts and things whatsoever necessary
to make this Supplemental Indenture, when executed and delivered by the Company and the Trustees, a valid, binding and legal instrument, and to make the bonds of Series 110, when authenticated by the Trustee and issued as in the Mortgage and in this
Supplemental Indenture provided, the valid, binding and legal obligations of the Company, entitled in all respects to the security of the Mortgage, as amended and supplemented, have been done and performed; 

NOW, THEREFORE, in consideration of the premises and of the sum of one dollar duly paid by the Trustees to the Company, and for other
good and valuable consideration, the receipt of which is hereby acknowledged, the parties hereto do hereby agree as follows: 

SECTION 1. Designation and Issuance of Bonds of Series 110. The bonds of Series 110 shall, as hereinbefore
recited, be designated as the Company’s “First Mortgage 1.625% Bonds, Series 110,” and shall be issued in the original aggregate principal amount of $600,000,000. Subject to the provisions of


  
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the Mortgage, additional bonds of Series 110 may be issued without limitation as to the aggregate principal amount thereof. 

SECTION 2. Form, Date, Maturity Date, Interest Rate and Interest Payment Dates of Bonds of Series 110.
(a) The definitive bonds of Series 110 shall be in engraved, lithographed, printed or typewritten form and shall be registered bonds without coupons; and such bonds and the Trustee’s certificate to be endorsed thereon shall be
substantially in the forms hereinbefore recited, respectively. The bonds of Series 110 shall be dated as provided in Section 3.01 of the Mortgage, as amended by Supplemental Indenture dated April 1, 1967. 

(b) The bonds of Series 110 shall mature on January 15, 2014. 

(c) The bonds of Series 110 shall bear interest at the rate of 1.625% per annum until the principal thereof shall be paid.

 (d) Interest on the bonds of Series 110 shall be payable semi-annually on the fifteenth day of January and the fifteenth day
of July in each year, commencing July 15, 2011. January 1 and July 1 in each year are hereby established as record dates for the payment of interest payable on the next succeeding interest payment dates, respectively. The
interest on each bond of Series 110 so payable on any interest payment date shall, subject to the exceptions provided in Section 3.01 of the Mortgage, as amended by said Supplemental Indenture dated April 1, 1967, be paid to the person in
whose name such bond is registered at the close of business on January 1 or July 1, as the case may be, next preceding such interest payment date. 
 SECTION 3. Execution of Bonds of Series 110. The bonds of Series 110 shall be executed on behalf of the Company by its President or one of its Vice Presidents, manually or by
facsimile signature, and shall have its corporate seal affixed thereto or a facsimile of such seal imprinted thereon, attested by its Secretary or one of its Assistant Secretaries, manually or by facsimile signature, all as may be provided by
resolution of the Board of Directors of the Company. In case any officer or officers whose signature or signatures, manual or facsimile, shall appear upon any bond of Series 110 shall cease to be such officer or officers before such bond shall have
been actually authenticated and delivered, such bond nevertheless may be issued, authenticated and delivered with the same force and effect as though the person or persons whose signature or signatures, manual or facsimile, appear thereon had not
ceased to be such officer or officers of the Company. 
 SECTION 4. Medium and Places of Payment of Principal of
and Interest on Bonds of Series 110; Transferability and Exchangeability. Both the principal of and interest on the bonds of Series 110 shall be payable in any coin or currency of the United States of America which at the time of
payment is legal tender for the payment of public and private debts, and both such principal and interest shall be payable at the office or agency of the Company in the City of Chicago, State of Illinois, or, at the option of the registered owner,
at the office or agency of the Company in the Borough of Manhattan, The City of New York, State of New York, and such bonds shall be transferable and exchangeable, in the manner provided in Sections 3.09 and 3.10 of the Mortgage, at said office or
agency. No charge shall be made by the Company to the registered owner of any bond of Series 110 for the transfer of such bond or for the exchange thereof for bonds of other authorized denominations, except, in the case of transfer, a charge
sufficient to reimburse the Company for any stamp or other tax or governmental charge required to be paid by the Company or the Trustee. 
 SECTION 5. Denominations and Numbering of Bonds of Series 110. The bonds of Series 110 shall be issued in the denomination of $1,000 and in such multiples of $1,000 as shall
from time to time hereafter be determined and authorized by the Board of Directors of the Company or by any officer or 

  
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officers of the Company authorized to make such determination, the authorization of the denomination of any bond of Series 110 to be conclusively evidenced by the execution thereof on behalf of
the Company. Bonds of Series 110 shall be numbered R-1 and consecutively upwards. 
 SECTION 6. Temporary Bonds of
Series 110. Until definitive bonds of Series 110 are ready for delivery, there may be authenticated and issued in lieu of any thereof and subject to all of the provisions, limitations and conditions set forth in Section 3.11 of
the Mortgage, temporary registered bonds without coupons of Series 110. 
 SECTION 7. Redemption of Bonds of Series
110. (a) The bonds of Series 110 shall be redeemable, at the option of the Company, as a whole or in part, at any time upon notice sent by the Company through the mail, postage prepaid, at least thirty (30) days and not more
than forty-five (45) days prior to the date fixed for redemption, to the registered holder of each bond to be redeemed in whole or in part, addressed to such holder at his address appearing upon the registration books, at a redemption price
equal to the greater of 
 (1) 100% of the principal amount of the bonds of Series 110 to be redeemed, plus
accrued and unpaid interest up to but excluding the redemption date, or 
 (2) as determined by the Quotation
Agent (as hereinafter defined), the sum of the present values of the remaining scheduled payments of principal and interest on the bonds of Series 110 to be redeemed (not including any portion of payments of interest accrued as of the redemption
date) discounted to the redemption date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the Adjusted Treasury Rate (as hereinafter defined) plus ten (10) basis points, plus accrued and unpaid interest up
to but excluding the redemption date. 
 Unless the Company defaults in payment of the redemption price, on and after the redemption date,
interest will cease to accrue on the bonds of Series 110 or portions of the bonds of Series 110 called for redemption. 
 (b)
For purposes of the foregoing Section 7(a), the following terms shall have the respective meanings set forth below: 
 “Adjusted Treasury Rate” means, with respect to any redemption date, the rate per year equal to the semi-annual equivalent yield to maturity of the Comparable Treasury Issue, assuming a
price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for the redemption date. 
 “Business Day” means any day that is not a day on which banking institutions in New York City are authorized or required by law or regulation to close. 

“Comparable Treasury Issue” means the United States Treasury security selected by the Quotation Agent as
having a maturity comparable to the remaining term of the bonds of Series 110 to be redeemed that would be used, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of
comparable maturity to the remaining term of the bonds of Series 110. 
 “Comparable Treasury
Price” means, with respect to any redemption date: 

  
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 (i) the average of the Reference Treasury Dealer Quotations for that
redemption date, after excluding the highest and lowest of the Reference Treasury Dealer Quotations; or 
 (ii)
if the Trustee obtains fewer than three Reference Treasury Dealer Quotations, the average of all Reference Treasury Dealer Quotations so received. 
 “Quotation Agent” means the Reference Treasury Dealer appointed by the Company. 
 “Reference Treasury Dealer” means (1) each of Credit Suisse Securities (USA) LLC, J.P. Morgan Securities LLC and Morgan Stanley & Co. Incorporated, or any of their
affiliates, and their respective successors, unless any of them ceases to be a primary U.S. Government securities dealer in the United States of America (“Primary Treasury Dealer”), in which case the Company shall substitute another
Primary Treasury Dealer; and (2) any other Primary Treasury Dealer selected by the Company. 

“Reference Treasury Dealer Quotations” means, with respect to each Reference Treasury Dealer and any
redemption date, the average, as determined by the Trustee, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Trustee by that Reference Treasury
Dealer at 3:30 p.m., New York City time, on the third Business Day preceding that redemption date. 
 (c) In case the Company
shall desire to exercise such right to redeem and pay off all or any part of such bonds of Series 110 as hereinbefore provided, it shall comply with all the terms and provisions of Article V of the Mortgage applicable thereto, and such redemption
shall be made under and subject to the terms and provisions of Article V and in the manner and with the effect therein provided, but at the time or times and upon mailing of notice, all as hereinbefore set forth in this Section 7. No
publication of notice of any redemption of any bonds of Series 110 shall be required under Section 5.03(a) of the Mortgage. 
 SECTION 8. Book-Entry Only System. It is intended that the bonds of Series 110 be registered so as to participate in the securities depository system (the “DTC
System”) with The Depository Trust Company (“DTC”), as set forth herein. The bonds of Series 110 shall be initially issued in the form of a fully registered bond or bonds in the name of Cede & Co., or any successor
thereto, as nominee for DTC. The Company and the Trustees are authorized to execute and deliver such letters to or agreements with DTC as shall be necessary to effectuate the DTC System, including the Letter of Representations from the Company and
the Trustees to DTC relating to the bonds of Series 110 (the “Representation Letter”). In the event of any conflict between the terms of the Representation Letter and the Mortgage, the terms of the Mortgage shall control. DTC may
exercise the rights of a bondholder only in accordance with the terms hereof applicable to the exercise of such rights. 
 With
respect to bonds of Series 110 registered in the name of DTC or its nominee, the Company and the Trustees shall have no responsibility or obligation to any broker-dealer, bank or other financial institution for which DTC holds such bonds from time
to time as securities depository (each such broker-dealer, bank or other financial institution being referred to herein as a “Depository Participant”) or to any person on behalf of whom such a Depository Participant holds an
interest in such bonds (each such person being herein referred to as an “Indirect Participant”). Without limiting the immediately preceding sentence, the Company and the Trustees shall have no responsibility or obligation with
respect to: 
 (i) the accuracy of the records of DTC, its nominee or any Depository Participant with respect to
any ownership interest in the bonds of Series 110, 

  
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 (ii) the delivery to any Depository Participant or any Indirect Participant
or any other person, other than a registered owner of a bond of Series 110, of any notice with respect to the bonds of Series 110, including any notice of redemption, 

(iii) the payment to any Depository Participant or Indirect Participant or any other person, other than a registered owner
of a bond of Series 110, of any amount with respect to principal of, redemption premium, if any, on, or interest on, the bonds of Series 110, or 
 (iv) any consent given by DTC as registered owner. 
 So long as certificates for the bonds of
Series 110 are not issued as hereinafter provided, the Company and the Trustees may treat DTC or any successor securities depository as, and deem DTC or any successor securities depository to be, the absolute owner of such bonds for all purposes
whatsoever, including, without limitation, (1) the payment of principal and interest on such bonds, (2) giving notice of matters (including redemption) with respect to such bonds and (3) registering transfers with respect to such
bonds. While a bond of Series 110 is in the DTC System, no person other than DTC or its nominee shall receive a certificate with respect to such bond. 
 In the event that: 
 (a) DTC notifies the Company that it is
unwilling or unable to continue as depositary or if DTC ceases to be a clearing agency registered under applicable law and a successor depositary is not appointed by the Company within 90 days, 

(b) the Company determines that the beneficial owners of the bonds of Series 110 should be able to obtain certificated
bonds and so notifies the Trustees in writing or 
 (c) there shall have occurred and be continuing a completed
default or any event which after notice or lapse of time or both would be a completed default with respect to the bonds of Series 110, 
 the
bonds of Series 110 shall no longer be restricted to being registered in the name of DTC or its nominee. In the case of clause (a) of the preceding sentence, the Company may determine that the bonds of Series 110 shall be registered in the name
of and deposited with a successor depository operating a securities depository system, as may be acceptable to the Company and the Trustees, or such depository’s agent or designee, and if the Company does not appoint a successor securities
depository system within 90 days, then the bonds may be registered in whatever name or names registered owners of bonds transferring or exchanging such bonds shall designate, in accordance with the provisions hereof. 

Notwithstanding any other provision of the Mortgage to the contrary, so long as any bond of Series 110 is registered in the name of DTC
or its nominee, all payments with respect to principal of and interest on such bond and all notices with respect to such bond shall be made and given, respectively, in the manner provided in the Representation Letter. 

SECTION 9. Legends. So long as the bonds of Series 110 are held by DTC, such bonds of Series 110 shall bear the
following legend: 
 Unless this bond is presented by an authorized representative of the Depository Trust
Company, a New York corporation (“DTC”), to the Company or its agent for registration of transfer, exchange or payment, and any bond 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 

  
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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 a person is
wrongful inasmuch as the registered owner hereof, Cede & Co., has an interest herein. 
 SECTION 10.
Confirmation of Lien. The Company, for the equal and proportionate benefit and security of the holders of all bonds at any time issued under the Mortgage, hereby confirms the lien of the Mortgage upon, and hereby grants, bargains,
sells, transfers, assigns, pledges, mortgages, warrants and conveys unto the Trustees, all property of the Company and all property hereafter acquired by the Company, other than (in each case) property which, by virtue of any of the provisions of
the Mortgage, is excluded from such lien, and hereby confirms the title of the Trustees (as set forth in the Mortgage) in and to all such property. Without in any way limiting or restricting the generality of the foregoing, there is specifically
included within the confirmation of lien and title hereinabove expressed the property of the Company legally described on Exhibit A attached hereto and made a part hereof. 

SECTION 11. Amendment of Provision of Mortgage. (a) Section 15.06 of the Mortgage shall be amended and
restated to read in its entirety as follows: 
 SECTION 15.06. The Trustee and any successor to the Trustee may
resign and be discharged from the trusts created by this Mortgage by giving notice thereof in writing to the Company, specifying the date when such resignation shall take effect, and by giving notice thereof to the bondholders in the manner and to
the extent provided under Section 15.10(c), and by publishing such notice at least once a week for three successive calendar weeks (the first such publication to be not less than thirty days nor more than sixty days prior to the effective date
of such resignation) in one authorized newspaper in the City of Chicago, State of Illinois, and in one authorized newspaper in the Borough of Manhattan, The City of New York, State of New York. Subject to the provisions of Sections 15.04 and 15.05,
such resignation shall take effect on the date specified in such notice unless previously a successor Trustee shall have been appointed as hereinafter provided, in which event such resignation shall take effect upon the appointment of such successor
Trustee. The Co-Trustee and any successor to the Co-Trustee may resign at any time and be discharged from the trusts hereby created by giving the Trustee and the Company notice in writing of such resignation, specifying a date when such resignation
shall take effect, which shall be at least thirty days after the giving of such notice. Such resignation shall, subject to the provisions of Sections 15.04 and 15.05, take effect on the date specified in such notice unless previously a successor
trustee shall have been appointed as hereinafter provided, in which event such resignation shall take effect immediately upon the appointment of such a successor trustee. 

Either of the Trustees or any successor trustee may be removed at any time by the holders of a majority in principal
amount of the bonds issued hereunder and at the time outstanding, upon payment to the trustee so removed of all moneys then due to it or him hereunder, by an instrument or concurrent instruments in writing, signed in duplicate by such holders. One
copy shall be filed with the Company and the other with the trustee so removed. 
 The Co-Trustee and any
successor to the Co-Trustee may be removed at any time by an instrument in writing signed in duplicate by the Trustee, one copy of which shall be filed with the Company and the other delivered to the Co-Trustee so removed. 

In case at any time either of the Trustees or any successor trustee shall resign, die, be dissolved or be removed or
otherwise shall become disqualified to act or incapable of acting, or in case control of the Trustee or of any successor trustee, or of its officers shall be taken over by any public officer or officers, a successor trustee may be appointed by the
holders of a majority in 

  
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principal amount of the bonds issued hereunder and at the time outstanding by an instrument or concurrent instruments in writing signed in duplicate by such holders, and filed, one copy with the
retiring trustee and the other with the successor trustee, notification thereof being given to the Company by such successor trustee; but until a successor trustee shall be so appointed by the bondholders as herein authorized, the Company, by an
instrument in writing, executed by order of the Board of Directors, shall in any such case appoint a successor to the Trustee and the Trustee shall, by an instrument in writing in any such case, appoint a successor to the Co-Trustee. Every such
successor to the Trustee so appointed by the bondholders, by a court of competent jurisdiction or by the Company shall be a bank or trust company in good standing organized and doing business under the laws of the United States or of any State,
having an office in the United States of America, and (a) which shall be a corporation having a combined capital and surplus of not less than $5,000,000, (b) which shall be authorized under the laws of the jurisdiction of incorporation to
exercise corporate trust powers, and (c) which shall be subject to supervision or examination by a Federal or State authority. If such successor Trustee publishes reports of condition at least annually, pursuant to law or to the requirements of
such supervising or examining authority, the combined capital and surplus of such successor Trustee shall be deemed to be its combined capital and surplus as set forth in its most recent report of condition so published. Every such successor trustee
appointed by the bondholders or by the Trustee in succession to the Co-Trustee shall always be an individual, a citizen of the United States of America, unless otherwise required by law. 

Anything hereinabove to the contrary notwithstanding, in case at any time the Co-Trustee, or any successor thereto, shall
die, become incapable of acting, resign or be removed, all the estates, properties, rights, powers, trusts, duties and obligations of the Trustees hereunder shall, to the extent permitted by law, vest in and be exercised by the Trustee, without the
appointment of a successor Co-Trustee. 
 If in a proper case no appointment of a successor to the Trustee or of
a successor to the Co-Trustee shall be made pursuant to the foregoing provisions of this Article XV within six months after a vacancy shall have occurred in the office of trustee, the holder of any bond or the retiring Trustee or Co-Trustee may
apply to any court, State or Federal having jurisdiction to appoint a successor trustee, and such court may thereupon, after such notice, if any, as such court may deem proper and prescribe, appoint a successor to the Trustee or to the Co-Trustee,
as the case may be. 
 (b) The holders of the Series 110 Bonds shall be deemed to have approved the foregoing amendment;
however, the foregoing amendment shall not become effective until such time as it shall have received the requisite approvals under the provisions of the Mortgage. 
 SECTION 12. Miscellaneous. The terms and conditions of this Supplemental Indenture shall be deemed to be a part of the terms and conditions of the Mortgage for any and all
purposes. The Mortgage, as supplemented by said indentures supplemental thereto dated subsequent to August 1, 1944 and referred to in the recitals of this Supplemental Indenture, and as further supplemented by this Supplemental Indenture, is in
all respects hereby ratified and confirmed. 
 This Supplemental Indenture shall bind and, subject to the provisions of Article
XIV of the Mortgage, inure to the benefit of the respective successors and assigns of the parties hereto. 
 Although this
Supplemental Indenture is dated as of January 4, 2011, it shall be effective only from and after the actual time of its execution and delivery by the Company and the Trustees on the date indicated by their respective acknowledgments hereto
annexed. 

  
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 Notwithstanding anything to the contrary contained in the Mortgage, the maximum amount of
indebtedness secured by the Mortgage shall not exceed 200% of the aggregate stated principal amount of the bonds of each series presently outstanding under, and secured by, the Mortgage, as set forth in the Recitals to this Supplemental Indenture,
except to the extent such maximum amount may be adjusted by a subsequent recorded supplemental indenture (which adjustment, and the corresponding supplemental indenture, shall not require the consent or approval of the holders of any bonds then
outstanding under the Mortgage, including the holders of the bonds of Series 110). 
 This Supplemental Indenture may be
simultaneously executed in any number of counterparts, and all such counterparts executed and delivered, each as an original, shall constitute but one and the same instrument. 

  
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 IN WITNESS WHEREOF, Commonwealth Edison Company has caused this Supplemental Indenture to be
executed in its name by its Senior Vice President, Chief Financial Officer and Treasurer, and attested by its Secretary, and BNY Mellon Trust Company of Illinois, as Trustee under the Mortgage, has caused this Supplemental Indenture to be executed
in its name by one of its Vice Presidents, and attested by one of its Vice Presidents, and D.G. Donovan, as Co-Trustee under the Mortgage, has hereunto affixed his signature, all as of the day and year first above written. 

 

							
		 		 	COMMONWEALTH EDISON COMPANY
				
		 		 	By:	 	 /s/ Joseph R. Trpik, Jr.

		 		 		 	Joseph R. Trpik, Jr.
		 		 		 	 Senior Vice President,

Chief Financial Officer and Treasurer

	ATTEST:	 		 		 	
				
	 /s/ Donna Massey
	 		 		 	
	Donna Massey	 		 		 	
	Secretary	 		 		 	
		 		 	BNY MELLON TRUST COMPANY OF ILLINOIS
				
		 		 	By:	 	 /s/ M. Callahan

		 		 		 	M. Callahan
		 		 		 	Vice President
	ATTEST:	 		 		 	
				
	 /s/ Lawrence M. Kusch
	 		 		 	
	Lawrence M. Kusch	 		 		 	
	Vice President	 		 		 	
		 		 	 /s/ D.G. Donovan

		 		 	D.G. Donovan


  
 13 









  

			
	STATE OF ILLINOIS	 	)
		 	)
	COUNTY OF COOK	 	)

 I, MARY E. NOLAN, a Notary Public in
and for said County, in the State aforesaid, DO HEREBY CERTIFY that Joseph R. Trpik, Jr., Senior Vice President, Chief Financial Officer and Treasurer of Commonwealth Edison Company, an Illinois corporation, one of the parties described in and which
executed the foregoing instrument, and Donna Massey, Secretary of said corporation, who are both personally known to me to be the same persons whose names are subscribed to the foregoing instrument as such Senior Vice President, Chief Financial
Officer and Treasurer and Secretary, respectively, and who are both personally known to me to be Senior Vice President, Chief Financial Officer and Treasurer and Secretary, respectively, of said corporation, appeared before me this day in person and
severally acknowledged that they signed, executed and delivered said instrument as their free and voluntary act as such Senior Vice President, Chief Financial Officer and Treasurer and Secretary, respectively, of said corporation, and as the free
and voluntary act of said corporation, for the uses and purposes therein set forth. 
 GIVEN under my hand
and notarial seal this 7th day of January, A.D. 2011.

  

	
	 /s/ Mary E. Nolan

	Mary E. Nolan
	Notary Public


 (NOTARIAL SEAL) 

My Commission expires April 23, 2013. 

  
 14 









  

			
	STATE OF ILLINOIS	 	)
		 	)
	COUNTY OF COOK	 	)

 I, T. MOSTERD, a Notary Public in and
for said County, in the State aforesaid, DO HEREBY CERTIFY that M. CALLAHAN, Vice President of BNY Mellon Trust Company of Illinois, an Illinois trust company, one of the parties described in and which executed the foregoing instrument, and LAWRENCE
M. KUSCH, Vice President of said trust company, who are both personally known to me to be the same persons whose names are subscribed to the foregoing instrument as such Vice Presidents, and who are both personally known to me to be Vice Presidents
of said trust company, appeared before me this day in person and severally acknowledged that they signed, executed and delivered said instrument as their free and voluntary act as such Vice Presidents of said trust company, and as the free and
voluntary act of said trust company, for the uses and purposes therein set forth. 
 GIVEN under my hand and
notarial seal this 5th day of January, A.D. 2011.

  

	
	 /s/ T. Mosterd

	T. Mosterd
	Notary Public


 (NOTARIAL SEAL) 

My Commission expires January 22, 2013. 

  
 15 









  

			
	STATE OF ILLINOIS	 	)
		 	)
	COUNTY OF COOK	 	)

 I, T. MOSTERD, a Notary Public in and
for said County, in the State aforesaid, DO HEREBY CERTIFY that D.G. DONOVAN, one of the parties described in and which executed the foregoing instrument, who is personally known to me to be the same person whose name is subscribed to the foregoing
instrument, appeared before me this day in person and acknowledged that he signed, executed and delivered said instrument as his free and voluntary act for the uses and purposes therein set forth. 

GIVEN under my hand and notarial seal this 5th day of January, A.D. 2011. 

 

	
	 /s/ T. Mosterd

	T. Mosterd
	Notary Public


 (NOTARIAL SEAL) 

My Commission expires January 22, 2013. 

  
 16 









 EXHIBIT A 
 LEGAL DESCRIPTIONS 
 Omitted