Exhibit 4 (a)







KANSAS GAS AND ELECTRIC COMPANY

TO

THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A.

(successor to BNY Midwest Trust Company)

and

JUDITH L.
BARTOLINI

(successor to W. A. Spooner, Henry A. Theis, Oliver R. Brooks,

Wesley L. Baker, Edwin F. McMichael and R. Amundsen)

as Trustees under Kansas Gas and Electric Companys

Mortgage and Deed of
Trust, Dated as of April 1, 1940

FIFTY-FIFTH SUPPLEMENTAL INDENTURE

Providing, among other things, for

First Mortgage Bonds, Burlington Series 2009 Due 2031

Dated as of
October 1, 2009









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FIFTY-FIFTH SUPPLEMENTAL INDENTURE

INDENTURE, dated as of October 1, 2009, between KANSAS GAS AND ELECTRIC COMPANY, a corporation of the State of Kansas (formerly named
KCA Corporation and successor by merger to Kansas Gas and Electric Company, a corporation of the State of Kansas, hereinafter sometimes called the Company-Kansas), whose post office address is 100 North Broadway Street, Suite 800,
Wichita, Kansas 67202 (hereinafter sometimes called the Company), and The Bank of New York Mellon Trust Company, N.A., a national banking association, whose post office address is 2 North LaSalle Street, Suite 1020, Chicago, Illinois
60602 (successor to BNY Midwest Trust Company (the Corporate Trustee)), and JUDITH L. BARTOLINI (successor to W.A. Spooner, Henry A. Theis, Oliver R. Brooks, Wesley L. Baker, Edwin F. McMichael and R. Amundsen, and being
hereinafter sometimes called the Individual Trustee), whose post office address is 2 North LaSalle Street, Suite 1020, Chicago, Illinois 60602 (the Corporate Trustee and the Individual Trustee being hereinafter together sometimes called
the Trustees), as Trustees under the Mortgage and Deed of Trust, dated as of April 1, 1940 (hereinafter called the Mortgage), which Mortgage was originally executed and delivered by Kansas Gas and Electric Company, a
corporation of the State of West Virginia to which the Company-Kansas was successor by merger (hereinafter sometimes called the Company-West Virginia), to secure the payment of bonds issued or to be issued under and in accordance with
the provisions of the Mortgage, reference to which Mortgage is hereby made, this Indenture (hereinafter sometimes called the Fifty-fifth Supplemental Indenture) being supplemental thereto;

WHEREAS, the Company-West Virginia caused the Mortgage to be filed for record as a mortgage of real property and as a chattel mortgage in
the offices of the Registers of Deeds in various counties in the State of Kansas, and on April 25, 1940 paid to the Register of Deeds of Sedgwick County, Kansas, that being the County in which the Mortgage was first filed for record, the sum of
$40,000 in payment of the Kansas mortgage registration tax as provided by Section 79-3101 et seq.,General Statutes of Kansas 1935; and

WHEREAS, by the Mortgage, the Company-West Virginia covenanted that it would execute and deliver such supplemental indenture or indentures and such further instruments and do such further acts as might be
necessary or proper to carry out more effectually the purposes of the Mortgage and to make subject to the lien of the Mortgage any property thereafter acquired, intended to be subject to the lien thereof; and

WHEREAS, an instrument, dated May 31, 1949, was executed by the Company-West Virginia appointing Oliver R. Brooks as Individual
Trustee in succession to said Henry A. Theis, resigned, under the Mortgage, and by Oliver R. Brooks accepting the appointment as Individual Trustee under the Mortgage in succession to said Henry A. Theis, which instrument was filed
for record in the offices of the Registers of Deeds in various counties in the State of Kansas; and

WHEREAS, an instrument,
dated March 3, 1958, was executed by the Company-West Virginia appointing Wesley L. Baker as Individual Trustee in succession to said Oliver R. Brooks, resigned, under the Mortgage, and by Wesley L. Baker accepting the appointment as
Individual Trustee under the Mortgage in succession to said Oliver R. Brooks, which instrument was filed for record in the offices of the Registers of Deeds in various counties in the State of Kansas; and

WHEREAS, an instrument, dated November 20, 1969, was executed by the Company-West Virginia appointing Edwin F. McMichael as Individual
Trustee in succession to said Wesley L. Baker, resigned, under the Mortgage, and by Edwin F. McMichael accepting the appointment as Individual Trustee under the Mortgage in succession to said Wesley L. Baker, which instrument was filed for record in
the offices of the Registers of Deeds in various counties in the State of Kansas; and

WHEREAS, by the Twenty-seventh
Supplemental Indenture mentioned below, the Company-Kansas, among other things, appointed R. Amundsen as Individual Trustee in succession to said Edwin F. McMichael, resigned, under the Mortgage, and by R. Amundsen accepting the appointment as
Individual Trustee under the Mortgage in succession to said Edwin F. McMichael; and



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WHEREAS, by the Thirty-second Supplemental Indenture mentioned below, the Company-Kansas,
among other things, appointed W. A. Spooner as Individual Trustee in succession to said R. Amundsen, resigned, under the Mortgage, and by W. A. Spooner accepting the appointment as Individual Trustee under the Mortgage in succession to said R.
Amundsen; and

WHEREAS, by the Fortieth Supplemental Indenture mentioned below, the Company-Kansas, among other things,
appointed Judith L. Bartolini as Individual Trustee in succession to said W.A. Spooner resigned, under the Mortgage, and by Judith L. Bartolini accepting the appointment as Individual Trustee under the Mortgage in succession to said W.A. Spooner;
and

WHEREAS, the Company-West Virginia executed and delivered to the Trustees a First Supplemental Indenture, dated as of
June 1, 1942 (which supplemental indenture is hereinafter sometimes called the First Supplemental Indenture); and

WHEREAS, the Company-West Virginia caused the First Supplemental Indenture to be filed for record as a mortgage of real property and as a chattel mortgage in the offices of the Registers of Deeds in various counties in the State of Kansas,
but paid no mortgage registration tax in connection with the recordation of the First Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-West Virginia executed and delivered to the Trustees the following supplemental indentures:



|                                |  |                 
|------------------------------- |  | ----------------
|Designation                     |  | Dated as of     
|Second Supplemental Indenture   |  | March 1, 1948   
|Third Supplemental Indenture    |  | December 1, 1949
|Fourth Supplemental Indenture   |  | June 1, 1952    
|Fifth Supplemental Indenture    |  | October 1, 1953 
|Sixth Supplemental Indenture    |  | March 1, 1955   
|Seventh Supplemental Indenture  |  | February 1, 1956
|Eighth Supplemental Indenture   |  | January 1, 1961 
|Ninth Supplemental Indenture    |  | May 1, 1966     
|Tenth Supplemental Indenture    |  | March 1, 1970   
|Eleventh Supplemental Indenture |  | May 1, 1971     
|Twelfth Supplemental Indenture  |  | March 1, 1972   

which supplemental indentures are hereinafter sometimes called the Second through Twelfth
Supplemental Indentures, respectively; and

WHEREAS, the Company-West Virginia caused the Second through Eighth Supplemental
Indentures to be filed for record as a mortgage of real property and as a chattel mortgage in the offices of the Registers of Deeds in various counties in the State of Kansas, and caused the Ninth through Twelfth Supplemental Indentures to be filed
for record as a mortgage of real property in the offices of the Registers of Deeds in various counties in the State of Kansas and as a chattel mortgage in the Office of the Secretary of State of Kansas, and on the following dates paid to the
Register of Deeds of Sedgwick County, Kansas, that being the County in which the Second through Twelfth Supplemental Indentures were first filed for record as a mortgage of real property, the following amounts:



|                 |  |        |       
|---------------- |  | ------ | ------
|Date             |  | Amount
|March 30, 1948   |  | $      | 12,500
|December 7, 1949 |  |        | 7,500 
|June 17, 1952    |  |        | 30,000
|October 21, 1953 |  |        | 25,000
|March 22, 1955   |  |        | 25,000
|March 5, 1956    |  |        | 17,500
|January 24, 1961 |  |        | 17,500
|May 17, 1966     |  |        | 40,000
|March 10, 1970   |  |        | 87,500
|May 19, 1971     |  |        | 87,500
|March 23, 1972   |  |        | 62,500



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such amounts being in payment of the Kansas mortgage registration tax as provided by the then currently
applicable sections of the statutes of the State of Kansas in effect on those dates; and

WHEREAS, the Company-West Virginia
was merged into the Company-Kansas on May 31, 1973; and

WHEREAS, in order to evidence the succession of the
Company-Kansas to the Company-West Virginia and the assumption by the Company-Kansas of the covenants and conditions of the Company-West Virginia in the bonds and in the Mortgage contained, and to enable the Company-Kansas to have and exercise the
powers and rights of the Company-West Virginia under the Mortgage in accordance with the terms thereof, the Company-Kansas executed and delivered to the Trustees a Thirteenth Supplemental Indenture, dated as of May 31, 1973 (which supplemental
indenture is hereinafter sometimes called the Thirteenth Supplemental Indenture); and

WHEREAS, the Company-Kansas
caused the Thirteenth Supplemental Indenture to be filed for record as a mortgage of real property in the offices of the Registers of Deeds in various counties in the State of Kansas and as a chattel mortgage in the Office of the Secretary of State
of Kansas, but paid no mortgage registration tax in connection with the recordation of the Thirteenth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas executed and delivered to the Trustees the following supplemental indentures:



|                                      |  |                  
|------------------------------------- |  | -----------------
|Designation                           |  | Dated as of      
|Fourteenth Supplemental Indenture     |  | July 1, 1975     
|Fifteenth Supplemental Indenture      |  | December 1, 1975 
|Sixteenth Supplemental Indenture      |  | September 1, 1976
|Seventeenth Supplemental Indenture    |  | March 1, 1977    
|Eighteenth Supplemental Indenture     |  | May 1, 1977      
|Nineteenth Supplemental Indenture     |  | October 1, 1977  
|Twentieth Supplemental Indenture      |  | March 15, 1978   
|Twenty-first Supplemental Indenture   |  | January 1, 1979  
|Twenty-second Supplemental Indenture  |  | April 1, 1980    
|Twenty-third Supplemental Indenture   |  | July 1, 1980     
|Twenty-fourth Supplemental Indenture  |  | October 1, 1980  
|Twenty-fifth Supplemental Indenture   |  | June 1, 1981     
|Twenty-sixth Supplemental Indenture   |  | December 1, 1981 
|Twenty-seventh Supplemental Indenture |  | May 1, 1982      
|Twenty-eighth Supplemental Indenture  |  | March 15, 1984   
|Twenty-ninth Supplemental Indenture   |  | September 1, 1984
|Thirtieth Supplemental Indenture      |  | September 1, 1984
|Thirty-first Supplemental Indenture   |  | February 1, 1985 
|Thirty-second Supplemental Indenture  |  | April 15, 1986   
|Thirty-third Supplemental Indenture   |  | June 1, 1991     
|Thirty-fourth Supplemental Indenture  |  | March 31, 1992   
|Thirty-fifth Supplemental Indenture   |  | December 17, 1992
|Thirty-sixth Supplemental Indenture   |  | October 12, 1993 
|Thirty-seventh Supplemental Indenture |  | January 15, 1994 
|Thirty-eighth Supplemental Indenture  |  | March 1, 1994    
|Thirty-ninth Supplemental Indenture   |  | April 15, 1994   
|Fortieth Supplemental Indenture       |  | June 28, 2000    



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|                                     |  |                  
|------------------------------------ |  | -----------------
|Forty-first Supplemental Indenture   |  | June 6, 2002     
|Forty-second Supplemental Indenture  |  | March 12, 2004   
|Forty-third Supplemental Indenture   |  | June 1, 2004     
|Forty-fourth Supplemental Indenture  |  | May 6, 2005      
|Forty-fifth Supplemental Indenture   |  | March 17, 2006   
|Forty-sixth Supplemental Indenture   |  | June 1, 2006     
|Forty-seventh Supplemental Indenture |  | March 16, 2007   
|Forty-eighth Supplemental Indenture  |  | July 10, 2007    
|Forty-ninth Supplemental Indenture   |  | October 12, 2007 
|Fiftieth Supplemental Indenture      |  | February 22, 2008
|Fifty-first Supplemental Indenture   |  | May 15, 2008     
|Fifty-second Supplemental Indenture  |  | August 1, 2008   
|Fifty-third Supplemental Indenture   |  | October 1, 2008  
|Fifty-fourth Supplemental Indenture  |  | June 11, 2009    

which supplemental indentures are hereinafter sometimes called the Fourteenth through Fifty-fourth
Supplemental Indentures, respectively; and

WHEREAS, the Company-Kansas caused the Fourteenth Supplemental Indenture to be
filed for record as a mortgage of real property in the offices of the Registers of Deeds in various counties in the State of Kansas and as a chattel mortgage in the Office of the Secretary of State of Kansas; and

WHEREAS, the Company-Kansas caused the Fifteenth Supplemental Indenture to be filed for record as a mortgage of real property in the office
of the Register of Deeds of Sedgwick County, Kansas (filed on December 10, 1975, Film 169, page 363), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on December 10, 1975 and indexed as No. 325,911);
and

WHEREAS, the Company-Kansas caused the Sixteenth Supplemental Indenture to be filed for record as a mortgage of real
property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on September 29, 1976, Film 21 1, page 363), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on September 29, 1976 and
indexed as No. 363,835); and

WHEREAS, the Company-Kansas caused the Seventeenth Supplemental Indenture to be filed for
record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on March 16, 1977, Film 234, page 492), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on
March 1, 1977 and indexed as No. 384,759); and

WHEREAS, the Company-Kansas caused the Eighteenth Supplemental
Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on May 26, 1977, Film 246, page 655), and as a chattel mortgage in the Office of the Secretary of State of
Kansas (filed on May 26, 1977 and indexed as No. 394,573); and

WHEREAS, the Company-Kansas caused the Nineteenth
Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on August 31, 1977, Film 263, page 882), and as a chattel mortgage in the Office of the
Secretary of State of Kansas (filed on September 1, 1977 and indexed as No. 406,577); and

WHEREAS, the
Company-Kansas caused the Twentieth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on March 29, 1978, Film 297, pages 635-656), and as a
chattel mortgage in the Office of the Secretary of State of Kansas (filed on March 30, 1978 and indexed as No. 434,072); and

WHEREAS, the Company-Kansas caused the Twenty-first Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on January 9, 1979, Film 345,
page 648), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on January 10, 1979 and indexed as No. 470,851); and

WHEREAS, the Company-Kansas caused the Twenty-second Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed
on April 2, 1980, Film 413, page 1,468), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on April 3, 1980 and indexed as No. 533,415); and



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WHEREAS, the Company-Kansas caused the Twenty-third Supplemental Indenture to be filed for
record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on July 1, 1980, Film 425, page 1,003), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on
July 2, 1980 and indexed as No. 546,185); and

WHEREAS, the Company-Kansas caused the Twenty-fourth Supplemental
Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on August 28, 1980, Film 435, page 266), and as a chattel mortgage in the Office of the Secretary of State
of Kansas (filed on August 29, 1980 and indexed as No. 554,543); and

WHEREAS, the Company-Kansas caused the
Twenty-fifth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on June 30, 1981, Film 483, page 1,512), and as a chattel mortgage in the Office
of the Secretary of State of Kansas (filed on June 30, 1981 and indexed as No. 601,270); and

WHEREAS, the
Company-Kansas caused the Twenty-sixth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on December 30, 1981, Film 510, page 300), and as a
chattel mortgage in the Office of the Secretary of State of Kansas (filed on December 31, 1981 and indexed as No. 628,293); and

WHEREAS, the Company-Kansas caused the Twenty-seventh Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed
on May 6, 1982, Film 526, page 1,141), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on May 7, 1982 and indexed as No. 650,115); and

WHEREAS, the Company-Kansas caused the Twenty-eighth Supplemental Indenture to be filed for record as a mortgage of real property in the
office of the Register of Deeds of Sedgwick County, Kansas (filed on March 22, 1984, Film 645, page 1,524), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on March 23, 1984 and indexed as
No. 796,449); and

WHEREAS, the Company-Kansas caused the Twenty-ninth Supplemental Indenture to be filed for record as a
mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on September 5, 1984, Film 681, page 763), and as a chattel mortgage in the Office of the Secretary of State of Kansas (filed on
September 6, 1984 and indexed as No. 852,425); and

WHEREAS, the Company-Kansas caused the Thirtieth Supplemental
Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on September 12, 1984, Film 682, page 1,087), and as a chattel mortgage in the Office of the Secretary of
State of Kansas (filed on September 13, 1984 and indexed as No. 854,284); and

WHEREAS, the Company-Kansas caused
the Thirty-third Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on June 18, 1991, Film 1 177, page 0876), and as a security agreement in the
Office of Secretary of State of Kansas (filed on June 18, 1991 and indexed as No. 1,693,446); and

WHEREAS, the
Company-Kansas caused the Fortieth Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on June 28, 2000, Film 2062, page 0053), and as a security
agreement in the Office of Secretary of State of Kansas (filed on June 28, 2000, and indexed as No. 3756913); and

WHEREAS, the Company-Kansas caused the Fifty-first Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on May 15, 2008, Film and Page
28975775), and as a security agreement in the office of Secretary of State of Kansas (filed on May 15, 2008, and indexed as No. 6489843); and



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WHEREAS, the Company-Kansas caused the Fifty-fourth Supplemental Indenture to be filed for
record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on June 11, 2009, Film and Page 29067265), and as a security agreement in the office of the Secretary of State of Kansas (filed on
June 11, 2009, and indexed as No. 6604136); and

WHEREAS, the Company on the following dates paid to the Register of
Deeds of Sedgwick County, Kansas, that being the County in which the Fourteenth through Thirtieth Supplemental Indentures, the Thirty-third Supplemental Indenture, the Fortieth Supplemental Indenture, the Fifty-first Supplemental Indenture and the
Fifty-fourth Supplemental Indenture were first filed for record as a mortgage of real property, the following amounts:



|                   |  |        |          
|------------------ |  | ------ | ---------
|Date               |  | Amount
|July 2, 1975       |  | $      | 100,000  
|December 10, 1975  |  |        | 48,750   
|September 29, 1976 |  |        | 62,500   
|March 16, 1977     |  |        | 62,500   
|May 26, 1977       |  |        | 25,000   
|August 31, 1977    |  |        | 6,100    
|March 29, 1978     |  |        | 62,500   
|January 9, 1979    |  |        | 36,250   
|April 2, 1980      |  |        | 67,500   
|July 1, 1980       |  |        | 37,500   
|August 28, 1980    |  |        | 63,750   
|June 30, 1981      |  |        | 75,000   
|December 30, 1981  |  |        | 62,500   
|May 6, 1982        |  |        | 100,000  
|March 22, 1984     |  |        | 93,750   
|September 5, 1984  |  |        | 75,000   
|September 12, 1984 |  |        | 50,000   
|June 18, 1991      |  |        | 334,100  
|June 28, 2000      |  |        | 1,780,539
|May 15, 2008       |  |        | 188,864  
|June 11, 2009      |  |        | 780,000  

such amounts being in payment of the Kansas mortgage registration tax as provided by the then
currently applicable sections of the statutes of the State of Kansas in effect on those dates; and

WHEREAS, the
Company-Kansas caused the Thirty-first Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on February 1, 1985, Film 707, page 378), and as a
chattel mortgage in the Office of the Secretary of State of Kansas (filed on February 4, 1985 and indexed as No. 895,468), but paid no mortgage registration tax in connection with the recordation of the Thirty-first Supplemental Indenture,
no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Thirty-second
Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on April 16, 1986, Film 791, page 1,336), and as a chattel mortgage in the Office of the
Secretary of State of Kansas (filed on April 17, 1986 and indexed as No. 1,048,212), but paid no mortgage registration tax in connection with the recordation of the Thirty-second Supplemental Indenture, no such tax having been payable in
connection with such recordation; and



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WHEREAS, in order to evidence the succession of the Company to the Company-Kansas and the
assumption by the Company of the covenants and conditions of the Company-Kansas in the bonds and in the Mortgage contained, and to enable the Company to have and exercise the powers and rights of the Company-Kansas under the Mortgage in accordance
with the terms thereof, the Company executed and delivered to the Trustees a Thirty-fourth Supplemental Indenture, dated as of March 31, 1992 (which supplemental indenture is hereinafter sometimes called the Thirty-fourth Supplemental
Indenture); and

WHEREAS, the Company-Kansas caused the Thirty-fourth Supplemental Indenture to be filed for record as a
mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on March 31, 1992, Film 1236, page 987), and as a security agreement in the Office of Secretary of State of Kansas (filed on March 31, 1992
and indexed as No. 1,780,893), but paid no mortgage registration tax in connection with the recordation of the Thirty-fourth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company caused the Thirty-fifth Supplemental Indenture to be filed for record as a mortgage of real property in the office of
the Register of Deeds of Sedgwick County, Kansas (filed on December 16, 1992, Film 301, page 0104), and as a security agreement in the Office of Secretary of State of Kansas (filed on December 16, 1992 and indexed as No. 1,861,886),
but paid no mortgage registration tax in connection with the recordation of the Thirty-fifth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Thirty-sixth Supplemental Indenture to be filed for record as a mortgage of real property in the
office of the Register of Deeds of Sedgwick County, Kansas (filed on August 10, 1993, Film 1364, page 0515), and as a security agreement in the Office of Secretary of State of Kansas (filed on August 11, 1993 and indexed as
No. 1,936,501), but paid no mortgage registration tax in connection with the recordation of the Thirty-sixth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Thirty-seventh Supplemental Indenture to be filed for record as a mortgage of real property in the
office of the Register of Deeds of Sedgwick County, Kansas (filed on January 18, 1994, Film 1411, page 0710), and as a security agreement in the Office of Secretary of State of Kansas (filed on January 18, 1994 and indexed as
No. 1,985,104), but paid no mortgage registration tax in connection with the recordation of the Thirty-seventh Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Thirty-eighth Supplemental Indenture to be filed for record as a mortgage of real property in the
office of the Register of Deeds of Sedgwick County, Kansas (filed on February 28, 1994, Film 1422, page 1046), and as a security agreement in the Office of Secretary of State of Kansas (filed on February 28, 1994 and indexed as
No. 1,997,743), but paid no mortgage registration tax in connection with the recordation of the Thirty-eighth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Thirty-ninth Supplemental Indenture to be filed for record as a mortgage of real property in the
office of the Register of Deeds of Sedgwick County, Kansas (filed on April 27, 1994, Film 1440, page 855), and as a security agreement in the Office of Secretary of State of Kansas (filed on April 27, 1994 and indexed as
No. 1,377,915), but paid no mortgage registration tax in connection with the recordation of the Thirty-ninth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-first Supplemental Indenture to be filed for record as a mortgage of real property in the
office of the Register of Deeds of Sedgwick County, Kansas (filed on June 6, 2002, Film 2460, page 1), and as a security agreement in the office of Secretary of State of Kansas (filed on June 6, 2002, and indexed as No. 5264221), but
paid no mortgage registration tax in connection with the recordation of the Forty-first Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-second Supplemental Indenture to be filed for record as a mortgage of real property in the
office of the Register of Deeds of Sedgwick County, Kansas (filed on March 12, 2004, Film 2854, page 8731), and as a security agreement in the office of Secretary of State of Kansas (filed on March 12, 2004, and indexed as
No. 5760673), but paid no mortgage registration tax in connection with the recordation of the Forty-second Supplemental Indenture, no such tax having been payable in connection with such recordation; and



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WHEREAS, the Company-Kansas caused the Forty-third Supplemental Indenture to be filed for
record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on June 10, 2004, Film and Page 28578510), and as a security agreement in the office of Secretary of State of Kansas (filed on
June 10, 2004, and indexed as No. 5820311), but paid no mortgage registration tax in connection with the recordation of the Forty-third Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-fourth Supplemental Indenture to be filed for record as a mortgage of real
property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on May 6, 2005, Film and Page 28671438), and as a security agreement in the office of Secretary of State of Kansas (filed on May 6, 2005, and indexed as
No. 5981824), but paid no mortgage registration tax in connection with the recordation of the Forty-fourth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-fifth Supplemental Indenture to be filed for record as a mortgage of real property in the
office of the Register of Deeds of Sedgwick County, Kansas (filed on March 17, 2006, Film and Page 28764552), and as a security agreement in the office of Secretary of State of Kansas (filed on March 17, 2006, and indexed as
No. 6122576), but paid no mortgage registration tax in connection with the recordation of the Forty-fifth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-sixth Supplemental Indenture to be filed for record as a mortgage of real property in the
office of the Register of Deeds of Sedgwick County, Kansas (filed on June 1, 2006, Film and Page 28785638), and as a security agreement in the office of Secretary of State of Kansas (filed on June 1, 2006, and indexed as No. 6168504),
but paid no mortgage registration tax in connection with the recordation of the Forty-sixth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-seventh Supplemental Indenture to be filed for record as a mortgage of real property in the
office of the Register of Deeds of Sedgwick County, Kansas (filed on March 16, 2007, Film and Page 28865277), and as a security agreement in the office of Secretary of State of Kansas (filed on March 16, 2007, and indexed as
No. 6326219), but paid no mortgage registration tax in connection with the recordation of the Forty-seventh Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-eighth Supplemental Indenture to be filed for record as a mortgage of real property in the
office of the Register of Deeds of Sedgwick County, Kansas (filed on July 13, 2007, Film and Page 28899558), and as a security agreement in the office of Secretary of State of Kansas (filed on July 13, 2007, and indexed as
No. 6385835), but paid no mortgage registration tax in connection with the recordation of the Forty-eighth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Forty-ninth Supplemental Indenture to be filed for record as a mortgage of real property in the
office of the Register of Deeds of Sedgwick County, Kansas (filed on October 12, 2007, Film and Page 28923805), and as a security agreement in the office of Secretary of State of Kansas (filed on October 12, 2007, and indexed as
No. 6417307), but paid no mortgage registration tax in connection with the recordation of the Forty-ninth Supplemental Indenture, no such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Fiftieth Supplemental Indenture to be filed for record as a mortgage of real property in the office
of the Register of Deeds of Sedgwick County, Kansas (filed on February 22, 2008, Film and Page 28953801), and as a security agreement in the office of Secretary of State of Kansas (filed on February 25, 2008, and indexed as
No. 6458236), but paid no mortgage registration tax in connection with the recordation of the Fiftieth Supplemental Indenture, no such tax having been payable in connection with such recordation; and



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WHEREAS, the Company-Kansas caused the Fifty-second Supplemental Indenture to be filed for
record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on August 26, 2008, Film and Page 29002339), and as a security agreement in the office of Secretary of State of Kansas (filed on
August 26, 2008, and indexed as No. 6521686, and refiled on October 2, 2008, and indexed as No. 6533509), but paid no mortgage registration tax in connection with the recordation of the Fifty-second Supplemental Indenture, no
such tax having been payable in connection with such recordation; and

WHEREAS, the Company-Kansas caused the Fifty-third
Supplemental Indenture to be filed for record as a mortgage of real property in the office of the Register of Deeds of Sedgwick County, Kansas (filed on October 10, 2008, Film and Page 29013036), and as a security agreement in the office of
Secretary of State of Kansas (filed on October 10, 2008, and indexed as No. 6535637), but paid no mortgage registration tax in connection with the recordation of the Fifty-third Supplemental Indenture, no such tax having been payable in
connection with such recordation; and

WHEREAS, the Company-West Virginia, the Company-Kansas or the Company has from time to
time caused to be filed in the respective offices of the above-mentioned Registers of Deeds and Secretary of State affidavits executed by the Trustees under the Mortgage, preserving and continuing the lien thereof either as a chattel mortgage in
accordance with the provisions of K.S.A. 58-303 (Section 58-303 of the General Statutes of Kansas 1935) or as a security agreement under the provisions of K.S.A. 84-9-401 et seq.;and

WHEREAS, in addition to the aforesaid filings for record in the respective offices of the above-mentioned Registers of Deeds, the
Company-West Virginia, the Company-Kansas or the Company has filed copies of the Mortgage and the First through Fifty-fourth Supplemental Indentures, certified as true by it, with the Secretary of State of Kansas; and

WHEREAS, the Company-West Virginia, the Company-Kansas or the Company has heretofore issued, in accordance with the provisions of the
Mortgage, as heretofore supplemented, the following series of First Mortgage Bonds:



|                       |  |                       |            |                            |     
|---------------------- |  | --------------------- | ---------- | -------------------------- | ----
|Series                 |  | PrincipalAmountIssued |            | PrincipalAmountOutstanding
|33/8% Series due 1970  |  | $                     | 16,000,000 |                            | None
|31/8% Series due 1978  |  |                       | 5,000,000  |                            | None
|23/4% Series due 1979  |  |                       | 3,000,000  |                            | None
|33/8% Series due 1982  |  |                       | 12,000,000 |                            | None
|35/8% Series due 1983  |  |                       | 10,000,000 |                            | None
|33/8% Series due 1985  |  |                       | 10,000,000 |                            | None
|33/8% Series due 1986  |  |                       | 7,000,000  |                            | None
|45/8% Series due 1991  |  |                       | 7,000,000  |                            | None
|55/8% Series due 1996  |  |                       | 16,000,000 |                            | None
|81/2% Series due 2000  |  |                       | 35,000,000 |                            | None
|81/8% Series due 2001  |  |                       | 35,000,000 |                            | None
|73/8% Series due 2002  |  |                       | 25,000,000 |                            | None
|95/8% Series due 2005  |  |                       | 40,000,000 |                            | None
|6% Series due 1985     |  |                       | 7,000,000  |                            | None
|73/4% Series due 2005  |  |                       | 12,500,000 |                            | None
|83/8% Series due 2006  |  |                       | 25,000,000 |                            | None
|81/2% Series due 2007  |  |                       | 25,000,000 |                            | None
|6% Series due 2007     |  |                       | 10,000,000 |                            | None
|57/8% Series due 2007  |  |                       | 21,940,000 |                            | None
|87/8% Series due 2008  |  |                       | 30,000,000 |                            | None
|6.80% Series due 2004  |  |                       | 14,500,000 |                            | None
|161/4% Series due 1987 |  |                       | 30,000,000 |                            | None



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|                                   |  |                       |  |                            |  
|---------------------------------- |  | --------------------- |  | -------------------------- | -
|Series                             |  | PrincipalAmountIssued |  | PrincipalAmountOutstanding |  
|61/2% Series due 1983              |  | 15,000,000            |  | None                       |  
|71/4% Series due 1983              |  | 25,500,000            |  | None                       |  
|147/8% Series due 1987-1991        |  | 30,000,000            |  | None                       |  
|16% Series due 1996                |  | 25,000,000            |  | None                       |  
|153/4% Series due 1989             |  | 40,000,000            |  | None                       |  
|131/2% Series due 1989             |  | 100,000,000           |  | None                       |  
|14.05% Series due 1991             |  | 30,000,000            |  | None                       |  
|141/8% Series due 1991             |  | 20,000,000            |  | None                       |  
|107/8% Series due 1987             |  | 30,000,000            |  | None                       |  
|93/4% Series due 2016              |  | 50,000,000            |  | None                       |  
|7.00% Series A due 2031            |  | 18,900,000            |  | None                       |  
|7.00% Series B due 2031            |  | 308,600,000           |  | None                       |  
|7.60% Series due 2003              |  | 135,000,000           |  | None                       |  
|61/2% Series due 2005              |  | 65,000,000            |  | None                       |  
|6.20% Series due 2006              |  | 100,000,000           |  | None                       |  
|5.10% Series due 2023              |  | 13,462,500            |  | 13,462,500                 |  
|71/2% Series A due 2032            |  | 14,500,000            |  | 14,500,000                 |  
|71/2% Series B due 2027            |  | 21,940,000            |  | 21,940,000                 |  
|71/2% Series C due 2032            |  | 10,000,000            |  | 10,000,000                 |  
|91/2% Series due 2003              |  | 702,200,000           |  | None                       |  
|8% Series due 2005                 |  | 735,000,000           |  | None                       |  
|31/2% Series due 2007              |  | 300,000,000           |  | None                       |  
|5.30% Series due 2031              |  | 18,900,000            |  | 18,900,000                 |  
|5.30% Series A due 2031            |  | 108,600,000           |  | 108,600,000                |  
|2.65% Series B due 2031            |  | 100,000,000           |  | None                       |  
|Variable Rate Series C due 2031    |  | 100,000,000           |  | 50,000,000                 | *
|4.60% Series due 2010              |  | 350,000,000           |  | None                       |  
|5.57% Series due 2011              |  | 500,000,000           |  | None                       |  
|Burlington Series 2004B-1 due 2031 |  | 50,000,000            |  | 50,000,000                 |  
|5.57% Series due 2012              |  | 500,000,000           |  | None                       |  
|6.53% Series due 2037              |  | 175,000,000           |  | 175,000,000                |  
|5.57% Series due 2012              |  | 750,000,000           |  | 750,000,000                |  
|6.15% Series A due 2023            |  | 50,000,000            |  | 50,000,000                 |  
|6.64% Series B due 2038            |  | 100,000,000           |  | 100,000,000                |  
|Burlington Series 2008 due 2031    |  | 50,000,000            |  | 50,000,000                 |  
|Burlington Series 2008A due 2031   |  | 50,000,000            |  | 50,000,000                 |  
|6.70% Series due 2019              |  | 300,000,000           |  | 300,000,000                |  



|* | Upon issuance of the bonds of the Sixty-first Series pursuant to this Supplemental Indenture, Variable Rate Series C due 2031 will be retired.
|- | ----------------------------------------------------------------------------------------------------------------------------------------------

hereinafter sometimes called Bonds of the First through Sixtieth Series; and

WHEREAS, Section 8 of the Mortgage provides that the form of each series of bonds (other than the First Series) issued thereunder and
of the coupons to be attached to the coupon bonds of such series shall be established by Resolution of the Board of Directors of the Company and that the form of such series, as established by said Board of Directors, shall specify the descriptive
title of the bonds and various other



---

terms thereof, and may also contain such provisions not inconsistent with the provisions of the Mortgage as the Board of Directors may, in its discretion, cause to be inserted therein expressing
or referring to the terms and conditions upon which such bonds are to be issued and/or secured under the Mortgage; and

WHEREAS, Section 120 of the Mortgage provides, among other things, that any power, privilege or right expressly or impliedly reserved to or in any way conferred upon the Company by any provision of the Mortgage whether such power,
privilege or right is in any way restricted or is unrestricted, may be in whole or in part waived or surrendered or subjected to any restriction if at the time unrestricted or to additional restriction if already restricted, and the Company may
enter into any further covenants, limitations or restrictions for the benefit of any one or more series of bonds issued thereunder, or the Company may cure any ambiguity contained therein or in any supplemental indenture, or may establish the terms
and provisions of any series of bonds other than said First Series, by an instrument in writing executed and acknowledged by the Company in such manner as would be necessary to entitle a conveyance of real estate to record in all of the states in
which any property at the time subject to the lien of the Mortgage shall be situated; and

WHEREAS, the Company now desires to
create a new series of bonds; and

WHEREAS, the execution and delivery by the Company of this Fifty-fifth Supplemental
Indenture, and the terms of the Bonds of the Sixty-first Series, hereinafter referred to, have been duly authorized by the Board of Directors of the Company by appropriate Resolutions of said Board of Directors;

NOW, THEREFORE, THIS INDENTURE WITNESSETH:

That Kansas Gas and Electric Company, in consideration of the premises and of One Dollar ($1) to it duly paid by the Trustees at or before the ensealing and delivery of these presents, the receipt whereof
is hereby acknowledged, and in further evidence of assurance of the estate, title and rights of the Trustees and in order further to secure the payment both of the principal of and interest and premium, if any, on the bonds from time to time issued
under the Mortgage, according to their tenor and effect and the performance of all the provisions of the Mortgage (including any instruments supplemental thereto and any modification made as in the Mortgage provided) and of said bonds, hereby
grants, bargains, sells, releases, conveys, assigns, transfers, mortgages, pledges, sets over and confirms (subject, however, to Excepted Encumbrances as defined in Section 6 of the Mortgage) unto The Bank of New York Mellon Trust Company, N.A.
and to Judith L. Bartolini, as Trustees under the Mortgage, and to their successor or successors in said trust, and to said Trustees and their successors and assigns forever, all property, real, personal and mixed, acquired by the Company after the
date of the execution and delivery of the Mortgage, in addition to property covered by the First through the Fifty-fourth Supplemental Indentures (except any herein or in the Mortgage, as heretofore supplemented, expressly excepted), now owned or,
subject to the provisions of Section 87 of the Mortgage, hereafter acquired by the Company and wheresoever situated, including (without in anywise limiting or impairing by the enumeration of the same the scope and intent of the foregoing or of
any general description contained in this Fifty-fifth Supplemental Indenture) all lands, flowage rights, water rights, flumes, raceways, dams, rights of way and roads; all steam and power houses, gas plants, street lighting systems, standards and
other equipment incidental thereto, telephone, radio and television systems, air-conditioning systems and equipment incidental thereto, water works, steam heat and hot water plants, lines, service and supply systems, bridges, culverts, tracks,
rolling stock, ice or refrigeration plants and equipment, street and interurban railway systems, offices, buildings and other structures and the equipment thereof; all machinery, engines, boilers, dynamos, electric and gas machines, regulators,
meters, transformers, generators, motors, electrical, gas and mechanical appliances, conduits, cables, water, steam heat, gas or other pipes, gas mains and pipes, service pipes, fittings, valves and connections, pole and transmission lines, wires,
cables, tools, implements, apparatus, furniture, chattels and chooses in action; all municipal and other franchises; all lines for the transmission and distribution of electric current, gas, steam heat or water for any purpose, including poles,
wires, cables, pipes, conduits, ducts and all apparatus for use in connection therewith; all real estate, lands, easements, servitudes, licenses, permits, franchises, privileges, rights of way and other rights in or relating to real estate or the
occupancy of the same and (except as herein or in the Mortgage, as heretofore supplemented, expressly excepted), all the right, title and interest of the Company in and to all other property of any kind or nature appertaining to and/or used and/or
occupied and/or enjoyed in connection with any property hereinbefore or in the Mortgage, as heretofore supplemented, described.



---

TOGETHER WITH all and singular the tenements, hereditarnents and appurtenances belonging or
in anywise appertaining to the aforesaid property or any part thereof, with the reversion and reversions, remainder and remainders and (subject to the provisions of Section 57 of the Mortgage) the tolls, rents, revenues, issues, earnings,
income, product and profits thereof, and all the estate, right, title and interest and claim whatsoever, at law as well as in equity, which the Company now has or may hereafter acquire in and to the aforesaid property and franchises and every part
and parcel thereof.

IT IS HEREBY AGREED by the Company that, subject to the provisions of Section 87 of the Mortgage,
all the property, rights and franchises acquired by the Company after the date hereof (except any herein or in the Mortgage, as heretofore supplemented, expressly excepted), shall be as fully embraced within the lien hereof and the lien of the
Mortgage, as if such property, rights and franchises were now owned by the Company and were specifically described herein and conveyed hereby.

PROVIDED that the following are not and are not intended to be now or hereafter granted, bargained, sold, released, conveyed, assigned, transferred, mortgaged, pledged, set over or confirmed hereunder and
are hereby expressly excepted from the lien and operation of this Fifty-fifth Supplemental Indenture and from the lien and operation of the Mortgage, viz.: (1) cash, shares of stock and obligations (including bonds, notes and other securities)
not hereafter specifically pledged, paid, deposited or delivered under the Mortgage or covenanted so to be; (2) merchandise, equipment, materials or supplies held for the purpose of sale in the usual course of business and fuel, oil and similar
materials and supplies consumable in the operation of any properties of the Company; vehicles and automobiles; (3) bills, notes and accounts receivable, and all contracts, leases and operating agreements not specifically pledged under the
Mortgage or covenanted so to be; and (4) electric energy, and other materials or products generated, manufactured, produced or purchased by the Company for sale, distribution or use in the ordinary course of its business; provided, however,
that the property and rights expressly excepted from the lien and operation of the Mortgage and this Fifty-fifth Supplemental Indenture in the above subdivisions (2) and (3) shall (to the extent permitted by law) cease to be so excepted in
the event that either or both of the Trustees or a receiver or trustee shall enter upon and take possession of the Mortgaged and Pledged Property in the manner provided in Article XII of the Mortgage by reason of the occurrence of a Default as
defined in said Article XII.

THERE is expressly excepted from the lien of the Mortgage and from the lien hereof all property
of the Company located in the State of Missouri now owned or hereafter acquired unless such property in the State of Missouri shall be subjected to the lien of the Mortgage by an indenture or indentures supplemental thereto, pursuant to
authorization by the Board of Directors of the Company.

TO HAVE AND TO HOLD all such properties, real, personal and mixed,
granted, bargained, sold, released, conveyed, assigned, transferred, mortgaged, pledged, set over or confirmed by the Company as aforesaid, or intended so to be, unto the Trustees, their successors and assigns forever.

IN TRUST NEVERTHELESS, for the same purposes and upon the same terms, trusts and conditions and subject to and with the same provisos and
covenants as are set forth in the Mortgage, as supplemented, this Fifty-fifth Supplemental Indenture being supplemental thereto.

AND IT IS HEREBY COVENANTED by the Company that all the terms, conditions, provisos, covenants and provisions contained in the Mortgage, as supplemented, shall affect and apply to the property hereinbefore described and conveyed and to the
estate, rights, obligations and duties of the Company and Trustees and the beneficiaries of the trust with respect to said property, and to the Trustees and their successors as Trustees of said property in the same manner and with the same effect as
if the said property had been owned by the Company at the time of the execution of the Mortgage, and had been specifically and at length described in and conveyed to the Trustees by the Mortgage as a part of the property therein stated to be
conveyed.



---

The Company further covenants and agrees to and with the Trustees and their successors in
said trust under the Mortgage, as follows:

ARTICLE I

SIXTY-FIRST SERIES OF BONDS

SECTION 1. (I) There shall
be a series of bonds designated Burlington Series 2009 due 2031 (herein sometimes referred to as the Sixty-first Series), each of which shall also bear the descriptive title, First Mortgage Bond, and the form thereof, which
is established by Resolution of the Board of Directors of the Company, shall contain suitable provisions with respect to the matters hereinafter in this Article I specified. Bonds of the Sixty-first Series shall be limited to $50,000,000 in
aggregate principal amount, except as provided in Section 16 of the Mortgage, shall mature on June 1, 2031, and shall be issued as fully registered bonds in denominations of Five Thousand Dollars and in any multiple or multiples of Five
Thousand Dollars. Bonds of the Sixty-first Series shall bear interest from time to time at a rate equal to the interest rate then borne by the City of Burlington, Kansas, Pollution Control Refunding Revenue Bonds (Kansas Gas and Electric Company
Project), Series 2009 (hereinafter referred to as the Burlington Bonds Series 2009), issued under the Indenture of Trust, dated as of October 1, 2009 (hereinafter referred to as the Burlington Indenture), of the
City of Burlington, Kansas, which rate shall initially be 5.0% per annum, payable at the same times as interest is payable on the Burlington Bonds Series 2009, the first payment to be made on December 1, 2009 for the period from
October 15, 2009 to, but not including, December 1, 2009. The principal of and interest on bonds of the Sixty-first Series shall be payable at the office or agency of the Company in the Borough of Manhattan, 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 public and private debts. Bonds of the Sixty-first Series shall be dated as in Section 10 of the Mortgage provided.

(II) Upon the redemption, in whole or in part, of the Burlington Bonds Series 2009, bonds of the Sixty-first Series shall be redeemed in
whole or in like part. To effect the redemption of bonds of the Sixty-first Series, the trustee under the Burlington Indenture (hereinafter referred to as the Burlington Trustee) shall deliver to the Corporate Trustee (and mail a copy
thereof to the Company) a written demand (hereinafter referred to as a Burlington Redemption Demand) for the redemption of bonds of the Sixty-first Series equal in principal amount to the principal amount of the Burlington Bonds Series
2009 to be redeemed. The Burlington Redemption Demand shall be signed by the President, a Vice President, an Assistant Vice President or a Trust Officer of the Burlington Trustee and shall state: (1) the aggregate principal amount of the
Burlington Bonds Series 2009 then outstanding under the Burlington Indenture; (2) the principal amount of the Burlington Bonds Series 2009 to be redeemed; (3) the interest thereon and premium, if any, to be payable on the redemption date;
(4) the redemption date and that notice thereof has been given as required in the Burlington Indenture; (5) that the Corporate Trustee is thereby instructed to call for redemption bonds of the Sixty-first Series equal in principal amount
to the principal amount of the Burlington Bonds Series 2009 specified in (2) above and on the same date and at the same price as the Burlington Bonds Series 2009. The Burlington Redemption Demand shall also contain a waiver of notice of such
redemption by the Burlington Trustee, as holder of all bonds of the Sixty-first Series then outstanding. The Corporate Trustee may conclusively presume the statements contained in the Burlington Redemption Demand to be correct. Redemption of the
bonds of the Sixty-first Series shall be at the principal amount of the bonds to be redeemed, together with premium, if any, and the accrued interest to the redemption date and such amount shall become and be due and payable on the redemption date.

In the event of a defeasance of all or any portion of Burlington Bonds Series 2009, the delivery of a Burlington Redemption
Demand to the Corporate Trustee shall not be required. Upon receipt by the Corporate Trustee from the Burlington Trustee of the principal amount of bonds of the Sixty-first Series equal to the principal amount of Burlington Bonds Series 2009
defeased, the Corporate Trustee shall (1) cancel such bonds of the Sixty-first Series as of the date of defeasance of the Burlington Bonds Series 2009 and (2) promptly provide evidence of such cancellation to the Company.

If the Burlington Trustee has declared the principal of and accrued interest on the Burlington Bonds Series 2009 to be immediately due and
payable pursuant to Section 7.2 of the Burlington Indenture as a result of an Event of Default under Section 7.1 of the Burlington Indenture (except 7.1(f) thereof), and if the Burlington Trustee shall deliver to the Corporate Trustee (and
mail a copy thereof to the Company) a written demand (hereinafter referred to as a Burlington Bonds Acceleration Notice) for the immediate redemption of bonds of the Sixty-first Series in whole, the bonds of the Sixty-first Series shall
be immediately redeemed at the principal amount thereof and accrued interest thereon. The Burlington Bonds



---

Acceleration Notice shall be signed by the President, a Vice President, an Assistant Vice President or a Trust Officer of the Burlington Trustee and shall state: (1) the aggregate principal
amount of the Burlington Bonds Series 2009 then outstanding under the Burlington Indenture; (2) that the entire principal amount of the Burlington Bonds Series 2009 has been declared by the Burlington Trustee to be immediately due and payable
pursuant to Section 7.2 of the Burlington Indenture; (3) that the Corporate Trustee is thereby instructed to call for immediate redemption bonds of the Sixty-first Series in whole; and (4) that the Burlington Trustee, as holder of all
bonds of the Sixty-first Series, waives notice of such redemption.

The Company hereby covenants that if a Burlington
Redemption Demand or a Burlington Bonds Acceleration Notice shall be delivered to the Corporate Trustee, the Company, subject to subdivision (III) of this Article I, will deposit, on or before the redemption date, with the Corporate Trustee, in
accordance with Article X of the Mortgage, an amount in cash sufficient to redeem the bonds of the Sixty-first Series so called for redemption.

The bonds of the Sixty-first Series shall not be subject to redemption prior to maturity except as provided in this Section 1(II).

(III) All bonds of the Sixty-first Series shall be issued and pledged by the Company with the Burlington Trustee to secure the payment of
the principal of, and interest on the Burlington Bonds Series 2009. The obligation of the Company to make payments with respect to the principal of and interest on bonds of the Sixty-first Series shall be fully or partially, as the case may be,
satisfied and discharged to the extent that, at the time that any such payment shall be due, the then due principal of and interest on the Burlington Bonds Series 2009 shall have been fully or partially paid, or there shall be in the Bond Fund
established pursuant to the Burlington Indenture sufficient available funds to fully or partially pay the then due principal of and interest on the Burlington Bonds Series 2009. The Corporate Trustee may conclusively presume that the obligation of
the Company to make payments with respect to the principal of and interest on bonds of the Sixty-first Series shall have been fully satisfied and discharged unless and until the Corporate Trustee shall have received a written notice from the
Burlington Trustee, signed by its President, a Vice President, or a Trust Officer, stating (i) that timely payment of the principal of or interest on the Burlington Bonds Series 2009 required to be made by the Company has not been made,
(ii) that there are not sufficient available funds held in the Bond Fund to make such payment and (iii) the amount of funds, in addition to available funds held in the Bond Fund, required to make such payment. For the avoidance of doubt,
notwithstanding anything to the contrary provided in the Mortgage, the Company shall not be obligated to make interest payments on overdue interest or principal to the extent such payments are not contemplated in the Burlington Indenture.

(IV) At the option of the registered owner, any bonds of the Sixty-first Series, upon surrender thereof, for cancellation, at
the office or agency of the Company in the Borough of Manhattan, The City of New York, shall be exchangeable for a like aggregate principal amount of bonds of the same series of other authorized denominations. The bonds of the Sixty-first Series may
bear such legends as may be necessary to comply with any law or with any rules or regulations made pursuant thereto or with the rules or regulations of any stock exchange or to conform to usage with respect thereto.

(V) Bonds of the Sixty-first Series shall be transferable upon the surrender thereof, for cancellation, together with a written instrument
of transfer in form approved by the registrar duly executed by the registered owner or by his duly authorized attorney, at the office or agency of the Company in the Borough of Manhattan, The City of New York.

(VI) The Company may deliver to the Burlington Trustee in substitution for any bonds of the Sixty-first Series, mortgage bonds or other
similar instruments of the Company or any successor entity, whether by merger, combination or acquisition of all or substantially all of the assets of the Company, or otherwise, issued under the Mortgage in the event of a reallocation of the
Burlington Bonds Series 2009 in connection with a change in Mode as provided in Section 2.1 of the Burlington Indenture or under a mortgage and deed of trust or similar instrument of the Company or any successor entity, in each case, in like
principal amount of like term and bearing interest from time to time at a rate equal to the interest rate then borne by the Burlington Bonds Series 2009 (such substituted bonds hereinafter being referred to as the Substituted Mortgage
Bonds). The Substituted Mortgage Bonds may only be delivered to the Burlington Trustee upon receipt by the Burlington Trustee of (i) if not delivered under the Mortgage, a letter from Moodys (as



---

hereinafter defined), dated within ten days prior to the date of delivery of the Substituted Mortgage Bonds, stating that its rating of the Substituted Mortgage Bonds is at least equal to its
then current rating on the bonds of the Sixty-first Series, (ii) if not delivered under the Mortgage, a letter from S&P (as hereinafter defined), dated within ten days prior to the date of delivery of the Substituted Mortgage Bonds, stating
that its rating of the Substituted Mortgage Bonds is at least equal to its then current rating on the bonds of the Sixty-first Series, (iii) an opinion of counsel which may be in-house counsel or counsel to the Company or any successor entity,
to the effect that the Substituted Mortgage Bonds shall have been duly and validly authorized, executed, authenticated, and delivered and shall constitute the valid, legally binding and enforceable obligations of the Company or any successor entity
enforceable in accordance with their terms, except as limited by bankruptcy, insolvency or other laws affecting the enforcement of mortgagees and other creditors rights and shall be entitled to the benefit of the Mortgage or the mortgage
and deed of trust or similar instrument pursuant to which they shall have been issued, (iv) an opinion of Bond Counsel, as defined in the Burlington Indenture, to the effect that the substitution of the Substituted Mortgage Bonds will not
adversely affect the exclusion from gross income for federal income tax purposes of interest on the Burlington Bonds Series 2009 and (v) such other certificates and documents with respect to the issuance and delivery of the Substituted Mortgage
Bonds as may be required by law or as the Burlington Trustee may reasonably request.

Moodys means
Moodys Investor Services, Inc., a corporation organized and existing under the laws of the State of Delaware, its successors and their assigns, except that if such corporation shall be dissolved or liquidated or shall no longer perform the
functions of a securities rating agency, then the term Moodys shall be deemed to refer to any other nationally recognized securities rating agency selected by the Company.

S&P means Standard & Poors Ratings Services, a division of The McGraw Hill Companies, Inc., duly organized
and existing under and by virtue of the laws of the State of New York, and its successors and assigns, except that if such rating agency shall be dissolved or liquidated or shall no longer perform the functions of a securities rating agency, then
the term S&P shall be deemed to refer to any other nationally recognized securities rating agency selected by the Company.

ARTICLE II

AMENDMENTS TO THE MORTGAGE AND RESERVATION OF RIGHTS

SECTION 1. The Company reserves the right, subject to appropriate action, but without any consent or other action by holders of Bonds of the
Sixty-first Series, or of any subsequent series of bonds, to clarify the ability of the Company to issue variable rate bonds under the Mortgage, notwithstanding any provision of the Mortgage to the contrary. The Company may make such other
amendments to the Mortgage as may be necessary or desirable in the opinion of the Company to effect the foregoing.

SECTION 2.
The Company reserves the right, subject to appropriate action, but without any consent or other action by holders of Bonds of the Sixty-first Series, or of any subsequent series of bonds, to amend the Mortgage to eliminate the requirements for the
provision by the Company of a Net Earning Certificate by deleting Section 27, Section 28(6) and Section 30(3) and deleting the following language from the end of Section 26: and, in case the bonds are to be authenticated
and delivered under the provisions of the next preceding paragraph of this Section by reason of an increase in the aggregate principal amount of bonds authenticated and delivered under this Indenture having increased the aggregate principal amount
of bonds which may be authenticated and delivered within the limitations prescribed by this Section, a Net Earning Certificate showing the Net Earnings of the Company to be as required by Section 27 hereof. The Company may make such other
amendments to the Mortgage as may be necessary or desirable in the opinion of the Company to effect the foregoing.



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SECTION 3. The Company reserves the right, subject to appropriate action, but without any
consent or other action by holders of Bonds of the Sixty-first Series, or of any subsequent series of bonds, to amend the Mortgage to add the following new section:

This Indenture shall be deemed to be a contract made under the laws of the State of Kansas and for all purposes shall be construed in accordance with the laws of the State of Kansas, without regard
to conflicts of laws principles thereof.

SECTION 4. The Company reserves the right, subject to appropriate action, but
without any consent or other action by holders of Bonds of the Sixty-first Series, or of any subsequent series of bonds, to amend the Mortgage to:

(I) Simplify the provisions for release of obsolete property, de minimis property releases and substitution of property and unfunded property;

(II) Permit additional terms of bonds or forms of bond in supplemental indentures, including terms for uncertificated and global securities
and medium-term notes;

(III) Make any changes necessary to conform the Mortgage with the requirements of the Trust Indenture
Act;

(IV) Eliminate the requirement to have an individual trustee under the Mortgage; and

(V) Replace the phrase two and one-half (21/2) in Section 27 of the Mortgage with two (2).

ARTICLE III

MISCELLANEOUS PROVISIONS

SECTION 1. All Bonds of the Sixty-first Series acquired
by the Company shall forthwith be delivered to the Corporate Trustee for cancellation.

SECTION 2. Subject to the amendments
provided for in this Fifty-fifth Supplemental Indenture, the terms defined in the Mortgage, as heretofore supplemented, shall, for all purposes of this Fifty-fifth Supplemental Indenture, have the meanings specified in the Mortgage, as heretofore
supplemented.

SECTION 3. The Trustees hereby accept the trusts herein declared, provided, created or supplemented and agree
to perform the same upon the terms and conditions set forth herein and in the Mortgage, as heretofore amended and supplemented, and upon the following terms and conditions:

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

SECTION 4. Subject to the provisions of
Article XV and Article XVI of the Mortgage, as heretofore amended and supplemented, whenever in this Fifty-fifth Supplemental Indenture any of the parties hereto is named or referred to, this shall be deemed to include the successors or assigns of
such party, and all the covenants and agreements in this Fifty-fifth Supplemental Indenture contained by or on behalf of the Company or by or on behalf of the Trustees shall bind and inure to the benefit of the respective successors and assigns of
such parties whether so expressed or not.

SECTION 5. Nothing in this Fifty-fifth Supplemental Indenture, expressed or
implied, is intended, or shall be construed, to confer upon, or to give to, any person, firm or corporation, other than the parties hereto and the holders of the bonds and coupons Outstanding under the Mortgage, any right, remedy or claim under or
by reason of this Fifty-fifth Supplemental Indenture or any covenant, condition, stipulation, promise or agreement hereof, and all the covenants, conditions, stipulations, promises and agreements in this Fifty-fifth Supplemental Indenture contained
by or on behalf of the Company shall be for the sole and exclusive benefit of the parties hereto, and of the holders of the bonds and of the coupons Outstanding under the Mortgage.

SECTION 6. This Fifty-fifth Supplemental Indenture shall be executed in several counterparts, each of which shall be an original and all of
which shall constitute but one and the same instrument.



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IN WITNESS WHEREOF, KANSAS GAS AND ELECTRIC COMPANY has caused its corporate name to be
hereunto affixed, and this instrument to be signed and sealed by Anthony D. Somma, Assistant Treasurer, and its corporate seal to be attested by Larry D. Irick, its Secretary for and on its behalf, The Bank of New York Mellon Trust Company, N.A. has
caused its corporate name to be hereunto affixed, and this instrument to be signed and sealed by one of its duly authorized officers and its corporate seal to be attested by one of its Assistant Secretaries for and on its behalf, and D. G. Donovan
has hereunto set his hand and all as of the day and year first above written.

[REMAINDER OF PAGE LEFT BLANK INTENTIONALLY]



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KANSAS GAS AND ELECTRIC COMPANYBy:

/s/ Anthony D. SommaAnthony D. SommaAssistant Treasurer




|                   |  |  |  |                 
|------------------ |  |  |  | ----------------
|Attest:            |  |  |  |                 
|                   |  | 
|/s/ Larry D. Irick |  |  |  | (corporate seal)
|Larry D. Irick     |  |  |  |                 
|Secretary          |  |  |  |                 

Executed, sealed and delivered by

KANSAS GAS AND ELECTRIC COMPANY,

in the presence of:

|                    
|--------------------
|                    
|/s/ Sally Wilson    
|                    
|/s/ Peter L. Sumners



THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A., as TrusteeBy:

/s/ L. GarciaVice President




|                |  |  |  |                 
|--------------- |  |  |  | ----------------
|Attest:         |  |  |  |                 
|                |  | 
|/s/ M. Callahan |  |  |  | (corporate seal)
|Vice President  |  |  |  |                 



/s/ D.G. Donovan(D. G. Donovan)


Executed, sealed and delivered by

THE BANK OF NEW YORK MELLON TRUST

COMPANY, N.A.

and D. G. DONOVAN, in the

presence of:

|                    
|--------------------
|                    
|/s/ Robert Cafarelli
|                    
|/s/ Julie Meadors   



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|                   |  |       
|------------------ |  | ------
|STATE OF KANSAS    |  | )     
|                   |  | : ss.:
|COUNTY OF SEDGWICK |  | )     

BE IT REMEMBERED, that on this 15thday of October, A.D. 2009, before me, the undersigned, a Notary
Public within and for the County and State aforesaid, came Anthony D. Somma, the Assistant Treasurer of KANSAS GAS AND ELECTRIC COMPANY, a corporation duly organized, incorporated and existing under the laws of the State of Kansas, who is personally
known to me to be such officer, and who is personally known to me to be the same person who executed, as such officer, the within instrument of writing, and such person duly acknowledged the execution of the same to be the act and deed of said
corporation and that said instrument of writing was so executed by order of the Board of Directors of said corporation.

On this 15thday of October, 2009, before me appeared Larry D. Irick, to me personally known, who being by me duly sworn did say that he is the Secretary of KANSAS GAS AND ELECTRIC COMPANY, and that the seal affixed to the foregoing instrument is the corporate
seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation by authority of its Board of Directors, and said Larry D. Irick acknowledged said instrument to be the free act and deed of said corporation.

On the 15thday of October in the year 2009, before me personally appeared Anthony D. Somma to me known, who, being by me duly
sworn, did depose and say that he is the Assistant Treasurer of KANSAS GAS AND ELECTRIC COMPANY; that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of
said corporation by authority of its Board of Directors, and said Anthony D. Somma acknowledged said instrument to be the free act and of said corporation.

IN WITNESS WHEREOF, I have hereunto subscribed my name and affixed my official seal on the day and year above written.



|              |  |  |  |                                
|------------- |  |  |  | -------------------------------
|              |  | 
|              |  |  |  | /s/ Patti Beasley              
|              |  | 
|(notary seal) |  |  |  |                                
|              |  | 
|              |  |  |  | NOTARY PUBLIC - STATE OF KANSAS
|              |  |  |  | MY APPOINTMENT EXPIRES        



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|                  |  |       
|----------------- |  | ------
|STATE OF ILLINOIS |  | )     
|                  |  | : ss.:
|COUNTY OF COOK    |  | )     

BE IT REMEMBERED, that on this 13thday of October, A.D. 2009, before me, the undersigned, a Notary
Public within and for the County and State aforesaid, came L. Garcia, a Vice President of The Bank of New York Mellon Trust Company, N.A., as trustee, a national banking association, who is personally known to me to be such officer, and who is
personally known to me to be the same person who executed, as such officer, the within instrument of writing, and such person duly acknowledged the execution of the same to be the act and deed of said corporation and that said instrument of writing
was so executed by authority of the Board of Directors of said corporation.

On this 13thday of October, 2009, before me appeared M. Callahan, to me
personally known, who being by me duly sworn did say that she is a Vice President of The Bank of New York Mellon Trust Company, N.A., and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said
instrument was signed and sealed in behalf of said corporation by authority of its Board of Directors, and said M. Callahan acknowledged said instrument to be the free act and deed of said corporation.

On the 13thday of October in the year 2009, before me personally came L. Garcia, to me known, who, being by me duly sworn, did
depose and say that she resides at 2 N. LaSalle Street, Chicago, Illinois, that she is a Vice President of The Bank of New York Mellon Trust Company, N.A., one of the corporations described in and which executed the above 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.

IN WITNESS WHEREOF, I have hereunto subscribed my name and affixed my official seal on the day and year above written.



/s/ Julie MeadorsNOTARY PUBLIC, STATE OF ILLINOISCOMMISSION EXPIRES / /


(notary seal)



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|                  |  |       
|----------------- |  | ------
|STATE OF ILLINOIS |  | )     
|                  |  | : ss.:
|COUNTY OF COOK    |  | )     

On this 13thday of October in the year 2009, before me, the undersigned, a Notary Public in and for the State of
Illinois, in the County of Cook, personally appeared and came D. G. Donovan, to me known and known to me to be the person described in and who executed the within and foregoing instrument and whose name is subscribed thereto and acknowledged to me
that she executed the same.

IN WITNESS WHEREOF, I have hereunto subscribed my name and affixed my official seal the day and
year in this certificate first above written.



/s/ Julie MeadorsNOTARY PUBLIC, STATE OF ILLINOISCOMMISSION EXPIRES / /


(notary seal)