Document:

Exhibit 4.2

 

MIDAMERICAN ENERGY COMPANY

 

and

 

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

as Trustee

________________

 

THIRD SUPPLEMENTAL INDENTURE

 

Dated as of October 15, 2015

________________

 

ESTABLISHING AND CREATING

 

4.25% FIRST MORTGAGE BONDS
DUE 2046

________________

    	 

    	

    

THIRD SUPPLEMENTAL INDENTURE, dated as of October
15, 2015 (herein called the “Third Supplemental Indenture”), between MIDAMERICAN ENERGY COMPANY, a corporation
duly organized and existing under the laws of the State of Iowa (herein called the “Company”), and THE BANK
OF NEW YORK MELLON TRUST COMPANY, N.A., a national banking association duly organized and existing under the laws of the United
States of America, as Trustee (herein called the “Trustee”), under the Base Indenture referred to below. Capitalized
terms used but not defined herein shall have the meaning assigned to such term in the Base Indenture.

 

W I T N E S S E T H :

 

WHEREAS, the Company has heretofore executed
and delivered to the Trustee an indenture dated as of September 9, 2013 as amended by the first supplemental indenture thereto
dated September 19, 2013, as supplemented by the second supplemental indenture thereto dated April 3, 2014, as amended by amendment
number 1 to the second supplemental indenture, dated as of October 15, 2015 (herein called the “Base Indenture”),
to provide for the issuance from time to time of its first mortgage bonds, the form and terms of which are to be established as
set forth in Section 2.01 of the Base Indenture;

 

WHEREAS, Section 15.01 of the Base Indenture
provides, among other things, that the Company and the Trustee may enter into indentures supplemental to the Base Indenture for,
among other things, the purpose establishing the form and terms of the Bonds (as defined in the Base Indenture) of any series as
permitted by Section 2.01 of the Base Indenture;

 

WHEREAS, the Company desires to create an individual
series of its first mortgage bonds upon the basis of Bondable Property (as defined in the Base Indenture) pursuant to Article III
of the Base Indenture in aggregate principal amount of $450,000,000 to be designated the “4.25% First Mortgage Bonds due
2046” (the “Bonds”), and all action on the part of the Company necessary to authorize the issuance of
the Bonds under the Base Indenture and this Third Supplemental Indenture has been duly taken;

 

WHEREAS, the execution and delivery by the Company
of this Third Supplemental Indenture, and the terms of the Bonds herein referred to, have been duly authorized by the Board in
or pursuant to appropriate resolutions; and

 

WHEREAS, all acts and things necessary to make
the Bonds, when executed by the Company and authenticated and delivered by the Trustee as provided in the Base Indenture, the valid
and binding obligations of the Company and to constitute these presents a valid and binding supplemental indenture and agreement
according to its terms, have been done and performed.

 

NOW, THEREFORE, THIS THIRD SUPPLEMENTAL INDENTURE
WITNESSETH:

 

That in consideration of the premises and of
the acceptance and purchase of the Bonds by the holders thereof and of the acceptance of this trust by the Trustee, the Company
covenants and agrees with the Trustee, for the equal benefit of the holders of the Bonds, as follows:

    	2

    	

    

ARTICLE I

DEFINITIONS

 

Unless otherwise defined herein, the use of the
terms and expressions herein is in accordance with the definitions, uses and constructions contained in the Base Indenture and
the form of Bonds attached hereto as Exhibit A.

 

ARTICLE II

TERMS AND ISSUANCE OF THE BONDS

 

Section 2.01. Issue of Bonds. A series
of first mortgage bonds, which shall be designated the “4.25% First Mortgage Bonds due 2046” shall be executed, authenticated
and delivered in accordance with the provisions of, and shall in all respects be subject to, the terms, conditions and covenants
of the Base Indenture and this Third Supplemental Indenture (including the form of Bonds set forth in Exhibit A).

 

Section 2.02. Optional Redemption. The
Bonds may be redeemed, in whole or in part, at the option of the Company pursuant to the terms set forth in Annex 1. The
provisions of Article IX of the Base Indenture shall also apply to any optional redemption of Bonds by the Company.

 

Section 2.03. Defeasance and Discharge.
The provisions of Article XVIII of the Base Indenture shall be applicable to the Bonds.

 

Section 2.04. Place of Payment. The Place
of Payment in respect of the Bonds will be initially at the Corporate Trust Office of The Bank of New York Mellon Trust Company,
N.A. (which as of the date hereof is located at 2 N. LaSalle Street, Suite 1020, Chicago, Illinois 60602, Attention: Corporate
Trust Administration).

 

Section 2.05. Form of Bonds; Incorporation
of Terms. The form of the Bonds shall be substantially in the form of Exhibit A, the terms of which are herein incorporated
by reference and which are part of this Third Supplemental Indenture. The Bonds shall be issued in global form as permitted by
Section 2.01(c)(xviii) of the Base Indenture. The Bonds issued in global form shall be delivered by the Trustee to the Depositary,
as the Holder thereof, or a nominee or custodian therefor, to be held by or on behalf of the Depositary in accordance with the
Base Indenture.

 

Section 2.06. Exchange of the Bonds Issued
in Global Form. The Bonds issued in global form shall be exchangeable for definitive Bonds only as provided in Section 2.06
of the Base Indenture.

 

Section 2.07. Regular Record Date for the
Bonds. The Regular Record Date for the Bonds shall be the April 15 or October 15 (whether or not a Business Day) immediately
prior to each Interest Payment Date.

 

Section 2.08. Authorized Denominations. Beneficial
interests in the Bonds issued in global form, as well as definitive Bonds, may be held only in denominations of $2,000 and integral
multiples of $1,000 in excess thereof.

    	3

    	

    

Section 2.09. Additional Bonds. The Company
may from time to time, without the consent of the Holders of the Bonds, create and issue further securities having the same terms
and conditions as the Bonds in all respects, except for the original issue date, offering price and, in some circumstances, the
initial interest accrual date and initial interest payment date. Additional Bonds issued in this manner will be consolidated with,
and form a single series with, the Bonds and shall thereafter be deemed Bonds of such series for all purposes.

 

ARTICLE III

DEPOSITARY

 

Section 3.01. Depositary. The Depository
Trust Company, and their respective successors are hereby appointed Depositary with respect to the Bonds issued in global form.

 

ARTICLE IV

MISCELLANEOUS

 

Section 4.01. Execution as Supplemental Indenture.
This Third Supplemental Indenture is executed and shall be construed as an indenture supplemental to the Base Indenture and, as
provided in the Base Indenture, this Third Supplemental Indenture forms a part thereof.

 

Section 4.02. Effect of Headings. The
Article and Section headings herein are for convenience only and shall not affect the construction hereof.

 

Section 4.03. Successors and Assigns.
All covenants and agreements contained in this Third Supplemental Indenture made by the Company shall bind its successors and assigns,
whether so expressed or not.

 

Section 4.04. Separability Clause. In
case any provision in this Third Supplemental Indenture or in the Bonds shall be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not in any way be affected or impaired thereby.

 

Section 4.05. Benefits of Second Supplemental
Indenture. Nothing in this Third Supplemental Indenture or in the Bonds, express or implied, shall give to any person, other
than the parties hereto and their successors hereunder and the Holders of the Bonds, any benefit or any legal or equitable right,
remedy or claim under this Second Supplemental Indenture.

 

Section 4.06. Execution and Counterparts.
This Third Supplemental Indenture may be executed in any number of counterparts, each of which shall be deemed to be an original,
but all such counterparts shall together constitute but one and the same instrument.

 

Section 4.07. Trustee Not Responsible for
Recitals. The recitals herein contained are made by the Company and not by the Trustee, and the Trustee assumes no responsibility
for the correctness thereof. The Trustee makes no representation as to the validity or sufficiency of this Third Supplemental Indenture
or of the Bonds. The Trustee shall not be accountable for the use or application by the Company of the Bonds or the proceeds thereof.

    	4

    	

    

Section 4.08. Governing Law. This Third
Supplemental Indenture and the Bonds shall be governed by and construed in accordance with the law of New York (including without limitation Section 5-1401 of the New York General Obligations Law or any successor to such statute), except to the extent that
the TIA, shall be applicable and except to the extent that the law of any jurisdiction wherein any portion of the Mortgaged Property
is located shall mandatorily govern the creation of a mortgage lien on and security interest in, or perfection, priority or enforcement
of the Lien of the Mortgage or exercise of remedies with respect to, such portion of the Mortgaged Property.

 

[SIGNATURE PAGE FOLLOWS]

    	5

    	

    

IN WITNESS WHEREOF, the parties hereof have caused
this Third Supplemental Indenture to be duly executed by their respective officers or directors duly authorized thereto, all as
of the day and year first above written.

 

	 	MIDAMERICAN ENERGY COMPANY
	 	 	 	 
	 	By:	/s/ James C. Galt
	 	 	Name:	James C. Galt
	 	 	Title:	Treasurer
	 	 	 	 
	 	THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A., as
    Trustee
	 	 	 	 
	 	By:	/s/ R. Tarnas
	 	 	Name:	R. Tarnas
	 	 	Title:	Vice President

 

[Third Supplemental Indenture]

    	 

    	

    

EXHIBIT
A

 

Form of 4.25% First Mortgage
Bonds due 2046

    	 

    	

    

	REGISTERED	No. 

 

ILL.C.C. No.              ($                issued pursuant to Illinois
Commerce Commission Docket No.           )

 

MIDAMERICAN ENERGY COMPANY

___________

 

4.25% First Mortgage Bond due 2046

___________

 

Unless this certificate is presented by an authorized
representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company (as defined below) or
its agent for registration of transfer, exchange or payment, and any certificate issued is registered in the name of Cede &
Co., or in such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or
to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE
OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein.

 

The following summary of terms is subject to
the provisions set forth below:

 

CUSIP: 595620 AP0

ORIGINAL ISSUE DATE: October 15, 2015

PRINCIPAL AMOUNT: $

MATURITY DATE: May 1, 2046 (“Maturity”)

INTEREST RATE: 4.25%

INTEREST PAYMENT DATES: May 1 and
November 1, commencing May 1, 2016.

RECORD DATES: April 15 and October 15.

OPTIONAL REDEMPTION:             x
Yes             o No

 

MidAmerican Energy Company, an Iowa corporation
(herein called the “Company”, which term includes any successor Person under the Indenture referred to on the reverse
hereof), for value received, hereby promises to pay to CEDE & CO. or registered assigns the principal amount of                     ($                  ), in such
coin or currency of the United States of America as at the time of payment is legal tender for payment of public and private debts,
on the Maturity Date specified above and to pay interest thereon, in such coin or currency, from and including the Original Issue
Date specified above, or from and including the most recent Interest Payment Date specified above to which interest has been paid
or duly provided for, as the case may be. Interest shall be paid in arrears semiannually on each Interest Payment Date in each
year commencing on May 1, 2016, at the per annum Interest Rate set forth above until Maturity and the principal hereof is paid
or made available for payment. The interest so payable and punctually paid or duly provided for on any Interest Payment Date will,
as provided in the Indenture, be paid to the Person in whose name this global Bond is registered at the close of business on the
Record Date specified above (whether or not a Business Day) next preceding such Interest Payment Date; provided, however,
that interest payable on the Maturity Date or, if applicable, upon redemption, shall be payable to the Person to whom principal
shall be payable. Payment of the principal of and any premium and interest on this global Bond shall be made on or before 10:30
A.M., New York City time or such other time as shall be agreed upon between the Trustee and the Depositary, of the day on which
such payment is due, by wire transfer into the account specified by the Depositary; provided, however, that as a
condition to the payment at the Maturity Date or upon redemption of any part of the principal of and any applicable premium on
this global Bond, the Depositary shall surrender, or cause to be surrendered, this global Bond to the Trustee. The Company will
pay any administrative costs imposed by banks in connection with making payments by wire transfer, but not any tax or other governmental
charge imposed on the Holder of this global Bond.

    	 

    	

    

Under certain circumstances, this global Bond
is exchangeable in whole or from time to time in part for a definitive individual Bond or Bonds, with the same Original Issue Date,
Maturity Date, Interest Rate and redemption and other provisions as provided herein or in the Indenture.

 

REFERENCE IS HEREBY MADE TO THE FURTHER PROVISIONS
OF THIS GLOBAL BOND SET FORTH IN FULL ON THE REVERSE HEREOF, WHICH FURTHER PROVISIONS SHALL FOR ALL PURPOSES HAVE THE SAME EFFECT
AS IF SET FORTH IN FULL AT THIS PLACE.

 

Unless the certificate of authentication hereon
has been executed by the Trustee referred to on the reverse hereof, directly or through an Authenticating Agent, by manual signature
of an authorized signatory, this global Bond shall not be entitled to any benefit under the Indenture or be valid or obligatory
for any purpose.

    	ii

    	

    

IN WITNESS WHEREOF, the Company has caused this
instrument to be duly executed.

 

Dated: October 15, 2015

 

	 	MIDAMERICAN ENERGY COMPANY
	 	 

	 	By:	 	 

	 	 	Name:	 
	 	 	Title:	 

 

Attest:

 

	By:	 	 
	 	Name:	Paul J. Leighton	 
	 	Title:	Vice President, Secretary and	 
	 	 	Assistant General Counsel	 

 

TRUSTEE’S CERTIFICATE OF AUTHENTICATION

 

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

 

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

	 	By:	 	 

	 	Name:
	 	Authorized Signatory

    	iii

    	

    

[REVERSE OF NOTE]

 

MIDAMERICAN ENERGY COMPANY

4.25% First Mortgage Bond due 2046

 

This global Bond is one of, and a global security
which represents Bonds which are part of, the duly authorized 4.25% First Mortgage Bonds due 2046 of the Company (herein called
the “Bonds”), issued under an Indenture dated as of September 9, 2013, as amended and supplemented (herein called the
“Indenture”), between the Company and The Bank of New York Mellon Trust Company, N.A., as Trustee (herein called the
“Trustee,” which term includes any successor Trustee under the Indenture), to which Indenture and all indentures supplemental
thereto reference is hereby made for a statement of the respective rights, limitations of rights, duties and immunities thereunder
of the Company, the Trustee and the Holders, and of the terms upon which the Bonds are, and are to be, authenticated and delivered.

 

Interest on this global Bond will be payable
on the Interest Payment Date or Interest Payment Dates as specified on the face hereof and, in either case, at Maturity. Unless
otherwise specified on the face hereof, payments on this global Bond with respect to any particular Interest Payment Date, redemption
date or the Maturity Date will include interest accrued from and including the applicable Original Issue Date, or from and including
the most recent Interest Payment Date to which interest has been paid or duly provided for, to but excluding the particular Interest
Payment Date, redemption date or the Maturity Date. Interest on this global Bond will be computed and paid on the basis of a 360-day
year of twelve 30-day months.

 

All percentages resulting from any calculation
with respect to this global Bond will be rounded, if necessary, to the nearest one hundred-thousandth of a percentage point (with
five one-millionths of a percentage point rounded upward) and all dollar amounts used in or resulting from any such calculation
with respect to this global Bond will be rounded to the nearest cent (with one-half cent being rounded upward).

 

“Business Day” means, unless otherwise
specified on the face hereof, any Monday, Tuesday, Wednesday, Thursday or Friday that in the City of New York, New York is not
a day on which banking institutions are authorized or obligated by law or executive order to close. In any case when any Interest
Payment Date, redemption date, or Maturity Date of any Bond shall not be a Business Day at any Place of Payment, then (notwithstanding
any other provision of the Indenture or of the Bonds) payment of interest or principal (and premium, if any) need not be made on
such date, but may be made on the next succeeding Business Day with the same force and effect as if made on the Interest Payment
Date, redemption date or at the Maturity Date, provided that no interest shall accrue for the period from and after such Interest
Payment Date, redemption date or Maturity Date, as the case may be.

 

This global Bond is secured under the Company’s
Mortgage, Security Agreement, Fixture Filing and Financing Statement between the Company and The Bank of New York Mellon Trust
Company, N.A., as amended and supplemented from time to time (the “Mortgage”). Reference is made to the Mortgage for
a description of the property mortgaged and pledged and the nature and extent of the security and to the Intercreditor and Collateral
Trust Agreement among the Company, the Trustee and The Bank of New York Mellon Trust Company, N.A., as collateral trustee, and
the Indenture for the rights of the holders of the Bonds and of the Trustee in respect thereof. Reference is made to the Indenture
and the Mortgage for the terms and conditions upon which the Bonds are secured and the circumstances under which additional bonds
may be issued.

    	 

    	

    

This global Bond will be subject to redemption
at the option of the Company on any date in whole or from time to time in part in increments of $2,000 or integral multiples of
$1,000 in excess thereof, at the redemption prices specified in an annex attached to this global Bond, plus accrued interest on
the principal amount thereof to be redeemed to the redemption date, but payments due with respect to this global Bond prior to
the redemption date will be paid to the Person in whose name this global Bond is registered at the close of business on the relevant
Record Date specified on the face hereof, all as provided in the Indenture. The Company may exercise such option by causing the
Trustee to mail a notice of such redemption, not less than 30 nor more than 60 days prior to the redemption date, in accordance
with the provisions of the Indenture. In the event of redemption of this global Bond in part only, this global Bond will be cancelled
and a new global Bond representing the unredeemed portion hereof will be issued in the name of the Holder hereof. This global Bond
is not subject to a sinking fund.

 

The Indenture permits, with certain exceptions
as therein provided, the amendment thereof and the modification of the rights and obligations of the Company and the rights of
the Holders to be affected under the Indenture at any time by the Company and the Trustee with the consent of the Holders of not
less than a majority in principal amount of the Outstanding Bonds of all series that would be affected thereby. The Indenture also
provides that the Holders of not less than a majority in principal amount of the Outstanding Bonds of all affected series may on
behalf of the Holders of all Bonds of such series waive certain existing Events of Default and their consequences. Any such consent
or waiver of the Holder of any Bond shall bind every future Holder of the same Bond and the Holder of every Bond issued upon the
registration of transfer thereof or in exchange therefor or in lieu thereof in respect of anything done, omitted or suffered to
be done by the Trustee or the Company in reliance thereon, whether or not notation of such action is made upon such Bond.

 

As set forth in, and subject to, the provisions
and limitations set forth in the Indenture, the Holders of at least a majority in principal amount of the Outstanding Bonds of
all series shall have any right to direct the time, method and place of conducting any proceeding for any remedy available to the
Trustee, or exercising any trust or power conferred on the Trustee.

 

THIS GLOBAL BOND IS A GLOBAL BOND REGISTERED
IN THE NAME OF THE DEPOSITARY OR A NOMINEE THEREOF AND, UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR THE INDIVIDUAL
SECURITIES REPRESENTED HEREBY, THIS GLOBAL BOND MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE
DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY OR BY THE DEPOSITARY OR ANY
SUCH NOMINEE TO A SUCCESSOR DEPOSITARY OR A NOMINEE OF SUCH SUCCESSOR DEPOSITARY.

    	2

    	

    

If at any time the Depositary for this global
Bond notifies the Company that it is unwilling or unable to continue as Depositary for this global Bond or if at any time the Depositary
for this global Bond shall no longer be registered or in good standing under the Securities Exchange Act of 1934, as amended, or
other applicable statute or regulation, the Company shall appoint a successor Depositary with respect to this global Bond. If a
successor Depositary for this global Bond is not appointed by the Company within 90 days after the Company receives such notice
or becomes aware of such condition, the Company shall execute, and the Trustee, upon receipt of a Company Order for the authentication
and delivery of definitive Bonds of this series, shall authenticate and deliver Bonds of this series in definitive form in an aggregate
principal amount equal to the principal amount of this global Bond in exchange for this global Bond.

 

The Company may at any time and in its sole discretion
and subject to the procedures of the Depositary determine that the Bonds of this series shall no longer be represented by a global
Bond. In such event the Company shall execute, and the Trustee, upon receipt of a Company Order for the authentication and delivery
of definitive Bonds of this series, shall authenticate and deliver, Bonds of this series in definitive registered form without
coupons, in any authorized denominations, in an aggregate principal amount equal to the principal amount of this global Bond, in
exchange for this global Bond.

 

The Company may from time to time, without the
consent of Holders of the Bonds, create and issue further Bonds having the same terms and conditions as the Bonds in all respects,
except for the Original Issue Date, issue price and, in some circumstances, the initial interest accrual date and initial interest
payment date. Additional Bonds issued in this manner will be consolidated with, and form a single series with, the Bonds and shall
thereafter be deemed Bonds for all purposes.

 

No reference herein to the Indenture and no provision
of this global Bond or of the Indenture shall alter or impair the obligation of the Company, which is absolute and unconditional,
to pay the principal of and any premium and interest on this global Bond at the times, places and rate, and in the coin or currency,
herein prescribed.

 

The Indenture contains provisions for the satisfaction
and discharge of the Indenture upon compliance by the Company with certain conditions specified therein, which provisions apply
to this global Bond.

 

The Indenture contains provisions for the defeasance
and discharge of the Indenture upon compliance by the Company with certain conditions specified therein, which provisions apply
to this global Bond.

 

The Company, the Trustee and any agent of the
Company or the Trustee may treat the Person in whose name this global Bond is registered as the owner of this global Bond for the
purpose of receiving payment of principal of (and premium, if any) and interest on this global Bond and for all other purposes
whatsoever, whether or not this global Bond be overdue, and neither the Company, the Trustee nor any agent of the Company or the
Trustee shall be affected by notice to the contrary.

    	3

    	

    

The Indenture and the Bonds are governed by and
construed in accordance with the law of the State of New York (including without limitation Section 5-1401 of the New York General
Obligations Law or any successor to such statute), except to the extent that the TIA shall be applicable and except to the extent
that the law of any jurisdiction wherein any portion of the Mortgaged Property is located shall mandatorily govern the creation
of a mortgage lien on and security interest in, or perfection, priority or enforcement of the Lien of the Mortgage or exercise
of remedies with respect to, such portion of the Mortgaged Property.

 

All terms used in this global Bond which are
defined in the Indenture but are not defined in this global Bond shall have the meanings assigned to them in the Indenture.

    	4

    	

    

ANNEX 1

 

OPTIONAL REDEMPTION PROVISIONS

 

The Bonds will be redeemable, in whole or in
part, at the Company’s option at any time or from time to time prior to maturity. Prior to November 1, 2045 (the “2046
Par Call Date”), the Bonds will be redeemable, in whole at any time or in part from time to time, at a redemption price equal
to the greater of (i) 100% of the principal amount of the Bonds being redeemed and (ii) as determined by the Quotation Agent, the
sum of the present values of the remaining scheduled payments of principal and interest on the Bonds being redeemed that would
be due if the Maturity Date of such Bonds were the 2046 Par Call Date (not including any portion of any payments of interest accrued
to, but not including, 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 Treasury Rate, plus 25 basis points (the “2046 Make-Whole Amount”); plus,
in either case, accrued and unpaid interest on the principal amount of the Bonds being redeemed to the redemption date.

 

On or after the 2046 Par Call Date, the Bonds
will be redeemable at a redemption price equal to 100% of the principal amount of the Bonds being redeemed, plus accrued and unpaid
interest on the principal amount of the Bonds being redeemed to the redemption date.

 

“Comparable Treasury Issue” means
the United States Treasury security selected by an Independent Investment Banker as having a maturity comparable to the remaining
term of the Bonds to be redeemed (assuming that the Bonds matured on the 2046 Par Call Date) that would be utilized, 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 Bond.

 

“Comparable Treasury Price” means,
the Reference Treasury Dealer Quotation for such redemption date.

 

“Independent Investment Banker” means
an investment banking institution of international standing appointed by the Company.

 

“Quotation Agent” means the Reference
Treasury Dealer.

 

“Reference Treasury Dealer” means
a primary United States government securities dealer in New York City appointed by the Company.

 

“Reference Treasury Dealer Quotation”
means, with respect to the Reference Treasury Dealer and any redemption date, the average, as determined by the Company, of the
bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount and quoted
in writing to the Company by such Reference Treasury Dealer at 5:00 p.m. on the third Business Day in New York City preceding such
redemption date).

    	5

    	

    

“Treasury Rate” means the rate per
annum equal to the semi-annual equivalent or interpolated (on a day-count basis) 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 that redemption date.

 

Notice of any redemption will be mailed (or as
long as the Bonds are represented by one or more global Bonds, transmitted in accordance with DTC’s standard procedures therefor)
at least 30 days but not more than 60 days before the redemption date to each holder of the Bonds to be redeemed. If, at the time
notice of redemption is given, the redemption moneys are not held by the Trustee, the redemption may be made subject to their receipt
on or before the redemption date and such notice shall be of no effect unless such moneys are so received. Upon payment of the
redemption price, on and after the redemption date interest will cease to accrue on the Bonds or portions thereof called for redemption.

 

The Company shall give the Trustee notice of
the redemption price with respect to a redemption pursuant to the first paragraph of this Annex 1 promptly after the calculation
thereof and the Trustee shall not be responsible for such calculation.

    	6

    	

    

ABBREVIATIONS

 

The following abbreviations, when used in the
inscription of the face of this instrument, shall be construed as though they were written out in full according to applicable
laws or regulations:

 

	 	TEN COM –	 	as tenants in common
	 	TEN ENT –	 	as tenants by the entireties
	 	JT TEN –	 	as joint tenants with right of survivorship and
	 	 	 	not as tenants in common
	 	UNIT GIFT MIN ACT –	 	_________________ (Cust) Custodian
	 	 	 	_________________ (Minor) under Uniform
	 	 	 	Gifts to Minors Act
	 	 	 	 
	 	 	 	 
	 	 	 	(State)

 

 

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

 

FOR VALUE RECEIVED the undersigned hereby sell(s),
assign(s) and transfer(s) unto

 

PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING
NUMBER OF ASSIGNEE:

 

__________________________________

 

__________________________________

 

 

 

Please print or typewrite name and address

including postal zip code of assignee

 

 

 

 

the within Bond and all rights thereunder, hereby irrevocably constituting
and appointing _____________________ attorney to transfer said Bond on the books of the Company, with full power of substitution
in the premises.

 

Dated:____________________

 

	 	 
	 	NOTICE:  The signature to this assignment must correspond with the name as written upon the face of the within instrument in every particular, without alteration or enlargement or any change whatever. The signature must be guaranteed by a commercial bank, a trust company or a member of the New York Stock Exchange.

    	7Exhibit 4.3

 

	 	REGISTERED	No.

 

ILL.C.C. No.          ($            issued
pursuant to Illinois Commerce Commission Docket No.        )

 

MIDAMERICAN
ENERGY COMPANY

________________

 

3.50%
First Mortgage Bond due 2024

________________

 

Unless this certificate is presented by an authorized
representative of The Depository Trust Company, a New York corporation (“DTC”), to the Company (as defined below) or
its agent for registration of transfer, exchange or payment, and any certificate issued is registered in the name of Cede &
Co., or in such other name as is requested by an authorized representative of DTC (and any payment is made to Cede & Co. or
to such other entity as is requested by an authorized representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE
OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein.

 

The following summary of terms is subject to
the provisions set forth below:

 

CUSIP: 595620 AM7

ORIGINAL ISSUE DATE: October 15, 2015

PRINCIPAL AMOUNT: $

MATURITY DATE: October 15, 2024

INTEREST RATE: 3.50%

INTEREST PAYMENT DATES: April 15
and October 15, commencing April 15, 2016.

RECORD DATES: April 1 and October 1.

OPTIONAL REDEMPTION:                      x   Yes                o   No

 

MidAmerican Energy Company, an Iowa corporation
(herein called the “Company”, which term includes any successor Person under the Indenture referred to on the reverse
hereof), for value received, hereby promises to pay to CEDE & CO. or registered assigns the principal amount of                        ($                 ),
in such coin or currency of the United States of America as at the time of payment is legal tender for payment of public and private
debts, on the Maturity Date specified above and to pay interest thereon, in such coin or currency, from and including the Original
Issue Date specified above, or from and including the most recent Interest Payment Date specified above to which interest has been
paid or duly provided for, as the case may be. Interest shall be paid in arrears semiannually on each Interest Payment Date in
each year commencing on April 15, 2016, at the per annum Interest Rate set forth above until Maturity and the principal hereof
is paid or made available for payment. The interest so payable and punctually paid or duly provided for on any Interest Payment
Date will, as provided in the Indenture, be paid to the Person in whose name this global Bond is registered at the close of business
on the Record Date specified above next preceding such Interest Payment Date; provided, however, that interest
payable on the Maturity Date or, if applicable, upon redemption, shall be payable to the Person to whom principal shall be payable.
Payment of the principal of and any premium and interest on this global Bond shall be made on or before 10:30 A.M., New York City
time or such other time as shall be agreed upon between the Trustee and the Depositary, of the day on which such payment is due,
by wire transfer into the account specified by the Depositary; provided, however, that as a condition to the payment
at the Maturity Date of any part of the principal of and any applicable premium on this global Bond, the Depositary shall surrender,
or cause to be surrendered, this global Bond to the Trustee. The Company will pay any administrative costs imposed by banks in
connection with making payments by wire transfer, but not any tax or other governmental charge imposed on the Holder of this global
Bond.

    	 

    	

    

Under certain circumstances, this global Bond
is exchangeable in whole or from time to time in part for a definitive individual Bond or Bonds, with the same Original Issue Date,
Maturity Date, Interest Rate and redemption and other provisions as provided herein or in the Indenture.

 

REFERENCE IS HEREBY MADE TO THE FURTHER PROVISIONS
OF THIS GLOBAL BOND SET FORTH IN FULL ON THE REVERSE HEREOF, WHICH FURTHER PROVISIONS SHALL FOR ALL PURPOSES HAVE THE SAME EFFECT
AS IF SET FORTH IN FULL AT THIS PLACE.

 

Unless the certificate of authentication hereon
has been executed by the Trustee referred to on the reverse hereof, directly or through an Authenticating Agent, by manual signature
of an authorized signatory, this global Bond shall not be entitled to any benefit under the Indenture or be valid or obligatory
for any purpose.

 

ii

    	 

    	

    

IN WITNESS WHEREOF, the Company has caused this
instrument to be duly executed.

 

Dated: October 15, 2015

 

	 	MIDAMERICAN ENERGY COMPANY
	 	 	 	 

	 	By:	 	 

	 	 	Name:	Calvin D. Haack
	 	 	Title:	Vice President and Treasurer

 

Attest:

 

	By:	 	 	 
	 	Name:	Paul J. Leighton	 
	 	Title:	Vice President, Secretary and	 
	 	 	Assistant General Counsel	 

 

TRUSTEE’S
CERTIFICATE OF AUTHENTICATION

 

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

 

	 	THE BANK OF NEW YORK MELLON TRUST 

COMPANY, N.A., as Trustee
	 	 	 	 

	 	By:	 	 

	 	Name:
	 	Authorized Officer

 

iii

    	 

    	

    

[REVERSE OF
NOTE]

 

MIDAMERICAN
ENERGY COMPANY

3.50% First Mortgage Bonds due 2024

 

This global Bond is one of, and a global security
which represents Bonds which are part of, the duly authorized 3.50% First Mortgage Bonds due 2024 of the Company (herein called
the “Bonds”), issued under an Indenture dated as of September 9, 2013, as amended and supplemented (herein called the
“Indenture”), between the Company and The Bank of New York Mellon Trust Company, N.A., as Trustee (herein called the
“Trustee,” which term includes any successor Trustee under the Indenture), to which Indenture and all indentures supplemental
thereto reference is hereby made for a statement of the respective rights, limitations of rights, duties and immunities thereunder
of the Company, the Trustee and the Holders, and of the terms upon which the Bonds are, and are to be, authenticated and delivered.

 

Interest on this global Bond will be payable
on the Interest Payment Date or Interest Payment Dates as specified on the face hereof and, in either case, at Maturity. Unless
otherwise specified on the face hereof, payments on this global Bond with respect to any particular Interest Payment Date or the
Maturity Date will include interest accrued from and including the applicable Original Issue Date, or from and including the most
recent Interest Payment Date to which interest has been paid or duly provided for, to but excluding the particular Interest Payment
Date or the Maturity Date. Interest on this global Bond will be computed and paid on the basis of a 360-day year of twelve 30-day
months.

 

All percentages resulting from any calculation
with respect to this global Bond will be rounded, if necessary, to the nearest one hundred-thousandth of a percentage point (with
five one-millionths of a percentage point rounded upward) and all dollar amounts used in or resulting from any such calculation
with respect to this global Bond will be rounded to the nearest cent (with one-half cent being rounded upward).

 

“Business Day” means, unless otherwise
specified on the face hereof, any Monday, Tuesday, Wednesday, Thursday or Friday that in the City of New York, New York is not
a day on which banking institutions are authorized or obligated by law or executive order to close. In any case when any Interest
Payment Date, Redemption Date, or stated maturity of any Bond shall not be a Business Day at any Place of Payment, then (notwithstanding
any other provision of the Indenture or of the Bonds) payment of interest or principal (and premium, if any) need not be made on
such date, but may be made on the next succeeding Business Day with the same force and effect as if made on the Interest Payment
Date, Redemption Date or at the stated maturity, provided that no interest shall accrue for the period from and after such Interest
Payment Date, Redemption Date or stated maturity, as the case may be.

 

This global Bond is secured under the Company’s
Mortgage, Security Agreement, Fixture Filing and Financing Statement between the Company and The Bank of New York Mellon Trust
Company, N.A., as amended and supplemented from time to time (the “Mortgage”). Reference is made to the Mortgage for
a description of the property mortgaged and pledged and the nature and extent of the security and to the Intercreditor and Collateral
Trust Agreement among the Company, the Trustee and The Bank of New York Mellon Trust Company, N.A., as collateral trustee, and the
Indenture for the rights of the holders of the Bonds and of the Trustee in respect thereof. Reference is made to the Indenture
and the Mortgage for the terms and conditions upon which the Bonds are secured and the circumstances under which additional bonds
may be issued.

    	 

    	

    

This global Bond will be subject to redemption
at the option of the Company on any date in whole or from time to time in part in increments of $2,000 or integral multiples of
$1,000 in excess thereof, at the redemption prices specified in an annex attached to this global Bond, plus accrued interest on
the principal amount thereof to the Redemption Date, but payments due with respect to this global Bond prior to the Redemption
Date will be paid to the Person in whose name this global Bond is registered at the close of business on the relevant Record Date
specified on the face hereof, all as provided in the Indenture. The Company may exercise such option by causing the Trustee to
mail a notice of such redemption, not less than 30 nor more than 60 days prior to the Redemption Date, in accordance with the provisions
of the Indenture. In the event of redemption of this global Bond in part only, this global Bond will be cancelled and a new global
Bond representing the unredeemed portion hereof will be issued in the name of the Holder hereof. This global Bond is not subject
to a sinking fund.

 

The Indenture permits, with certain exceptions
as therein provided, the amendment thereof and the modification of the rights and obligations of the Company and the rights of
the Holders to be affected under the Indenture at any time by the Company and the Trustee with the consent of the Holders of not
less than a majority in principal amount of the Outstanding Bonds of each series that would be affected thereby. The Indenture
also provides that the Holders of not less than a majority in principal amount of the Outstanding Bonds of any affected series
may on behalf of the Holders of all Bonds of such series waive certain existing Events of Default and their consequences. Any such
consent or waiver of the Holder of any Bond shall bind every future Holder of the same Bond and the Holder of every Bond issued
upon the registration of transfer thereof or in exchange therefor or in lieu thereof in respect of anything done, omitted or suffered
to be done by the Trustee or the Company in reliance thereon, whether or not notation of such action is made upon such Bond.

 

As set forth in, and subject to, the provisions
and limitations set forth in the Indenture, the Holders of at least a majority in principal amount of the Outstanding Bonds of
each series shall have any right to direct the time, method and place of conducting any proceeding for any remedy available to
the Trustee, or exercising any trust or power conferred on the Trustee, with respect to the Securities of such series.

 

THIS GLOBAL BOND IS A GLOBAL BOND REGISTERED
IN THE NAME OF THE DEPOSITARY OR A NOMINEE THEREOF AND, UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE OR IN PART FOR THE INDIVIDUAL
SECURITIES REPRESENTED HEREBY, THIS GLOBAL BOND MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE
DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY OR BY THE DEPOSITARY OR ANY
SUCH NOMINEE TO A SUCCESSOR DEPOSITARY OR A NOMINEE OF SUCH SUCCESSOR DEPOSITARY.

    	2

    	

    

If at any time the Depositary for this global
Bond notifies the Company that it is unwilling or unable to continue as Depositary for this global Bond or if at any time the Depositary
for this global Bond shall no longer be registered or in good standing under the Securities Exchange Act of 1934, as amended, or
other applicable statute or regulation, the Company shall appoint a successor Depositary with respect to this global Bond. If a
successor Depositary for this global Bond is not appointed by the Company within 90 days after the Company receives such notice
or becomes aware of such condition, the Company shall execute, and the Trustee, upon receipt of a Company Order for the authentication
and delivery of definitive Bonds of this series, shall authenticate and deliver Bonds of this series in definitive form in an aggregate
principal amount equal to the principal amount of this global Bond in exchange for this global Bond.

 

The Company may at any time and in its sole discretion
determine that the Bonds of this series shall no longer be represented by a global Bond. In such event the Company shall execute,
and the Trustee, upon receipt of a Company Order for the authentication and delivery of definitive Bonds of this series, shall
authenticate and deliver, Bonds of this series in definitive registered form without coupons, in any authorized denominations,
in an aggregate principal amount equal to the principal amount of this global Bond, in exchange for this global Bond.

 

The Company may from time to time, without the
consent of Holders of the Securities, create and issue further notes having the same terms and conditions as the Bonds in all respects,
except for the Original Issue Date, issue price and, in some circumstances, the initial interest accrual date and initial interest
payment date. Additional Bonds issued in this manner will be consolidated with, and form a single series with, the Bonds and shall
thereafter be deemed Bonds for all purposes.

 

No reference herein to the Indenture and no provision
of this global Bond or of the Indenture shall alter or impair the obligation of the Company, which is absolute and unconditional,
to pay the principal of and any premium and interest on this global Bond at the times, places and rates, and in the coin or currency,
herein prescribed.

 

The Indenture contains provisions for the satisfaction
and discharge of the Indenture upon compliance by the Company with certain conditions specified therein, which provisions apply
to this global Bond.

 

The Indenture contains provisions for the defeasance
and discharge of the Indenture upon compliance by the Company with certain conditions specified therein, which provisions apply
to this global Bond.

 

The Company, the Trustee and any agent of the
Company or the Trustee may treat the Person in whose name this global Bond is registered as the owner of this global Bond for the
purpose of receiving payment of principal of (and premium, if any) and interest on this global Bond and for all other purposes
whatsoever, whether or not this global Bond be overdue, and neither the Company, the Trustee nor any agent of the Company or the
Trustee shall be affected by notice to the contrary.

    	3

    	

    

The Indenture and the Bonds are governed by and
construed in accordance with the laws of the State of New York and for all purposes shall be governed by and construed in accordance
with the laws of said state without regard to the conflicts of laws rules of said state.

 

All terms used in this global Bond which are
defined in the Indenture but are not defined in this global Bond shall have the meanings assigned to them in the Indenture.

    	4

    	

    

ANNEX 1

 

OPTIONAL REDEMPTION
PROVISIONS

 

The Bonds will be redeemable as a whole at any
time or in part, from time to time, at the option of the Company, at a redemption price equal to the sum of (a) the greater of
(i) 100% of the principal amount of the Bonds being redeemed and (ii) the sum of the present values of the remaining scheduled
payments of principal and interest thereon from the redemption date to the maturity date, computed by discounting such payments,
in each case, to the redemption date on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the
Treasury Rate plus 15 basis points, plus (b) accrued interest on the principal amount thereof to the redemption date.

 

On and after July 15, 2024, the Company may redeem
all or any part of the Bonds, at the option of the Company, at any time or from time to time, at a redemption price equal to 100%
of the principal amount of the Bonds to be redeemed, plus accrued and unpaid interest thereon to the redemption date.

 

“Comparable Treasury Issue” means
the United States Treasury security selected by an Independent Investment Banker as having a maturity comparable to the remaining
term of the Bonds to be redeemed that would be utilized, 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 Bond.

 

“Comparable Treasury Price” means,
with respect to any redemption date, (i) the average of the bid and asked prices for the Comparable Treasury Issue (expressed in
each case as a percentage of its principal amount) on the third business day in New York City preceding such redemption date, as
set forth in the daily statistical release (or any successor release) published by the Federal Reserve Bank of New York and designated
“Composite 3:30 p.m. Quotations for U.S. Government Securities” or (ii) if such release (or any successor release)
is not published or does not contain such prices on such business day, the Reference Treasury Dealer Quotation for such redemption
date.

 

“Independent Investment Banker” means
an investment banking institution of international standing appointed by the Company.

 

“Reference Treasury Dealer” means
a primary United States government securities dealer in New York City appointed by the Company.

 

“Reference Treasury Dealer Quotation”
means, with respect to the Reference Treasury Dealer and any Redemption Date, the average, as determined by the Company, of the
bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount and quoted
in writing to the Company by such Reference Treasury Dealer at 5:00 p.m. on the third Business Day in New York City preceding such
redemption date).

    	5

    	

    

“Treasury Rate” means the rate per
annum equal to the semi-annual equivalent or interpolated (on a day-count basis) 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 that Redemption Date.

 

Notice of any redemption will be mailed at least
30 days but not more than 60 days before the redemption date to each holder of the Bonds to be redeemed. If, at the time notice
of redemption is given, the redemption moneys are not held by the Trustee, the redemption may be made subject to their receipt
on or before the redemption date and such notice shall be of no effect unless such moneys are so received. Upon payment of the
redemption price, on and after the redemption date interest will cease to accrue on Bonds or portions thereof called for redemption.

    	6

    	

    

ABBREVIATIONS

 

The following abbreviations, when used in the
inscription of the face of this instrument, shall be construed as though they were written out in full according to applicable
laws or regulations:

 

	 	TEN COM –	as tenants in common
	 	TEN ENT –	as tenants by the entireties
	 	JT TEN –	as joint tenants with right of survivorship and
	 	 	not as tenants in common
	 	UNIT GIFT MIN ACT –	_________________ (Cust) Custodian
	 	 	_________________ (Minor) under Uniform
	 	 	Gifts to Minors Act
	 	 	 
	 	 	 
	 	 	(State)

 

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

 

FOR VALUE RECEIVED the undersigned hereby sell(s),
assign(s) and transfer(s) unto

 

PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING
NUMBER OF ASSIGNEE:

	 	 	 
	 	 	 
	 	 	 
	 	 	 
	 	 	 
	 	 	 

Please print
or typewrite name and address

including postal zip code of assignee

	 	 	 

 

the within Bond and all rights thereunder, hereby
irrevocably constituting and appointing _____________________ attorney to transfer said Bond on the books of the Company, with
full power of substitution in the premises.

 

Dated:____________________

	 	 	 
	 	NOTICE: The signature to this assignment must correspond with the name as written upon the face of the within instrument in every particular, without alteration or enlargement or any change whatever. The signature must be guaranteed by a commercial bank, a trust company or a member of the New York Stock Exchange.

    	7

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