Exhibit
      4(a)




















**PPL
      ENERGY SUPPLY, LLC,**


**Issuer**




**TO**




**JPMORGAN
      CHASE BANK, N.A.**


**(formerly
      known as The Chase Manhattan Bank),**


**Trustee**




**_________**




**Supplemental
      Indenture No. 4**




**Dated
      as of May 1, 2006**




**Supplemental
      to the Indenture**


**dated
      as of October 1, 2001**




**Establishing
      a series of Securities designated**


**Senior
      Notes, 6.20% Series due 2016**


**limited
      in aggregate principal amount to $300,000,000**





**SUPPLEMENTAL
      INDENTURE NO. 4** ,
      dated
      as of May 1, 2006 between **PPL
      ENERGY SUPPLY, LLC** ,
      a
      limited liability company duly organized and existing under the laws of the
      State of Delaware (herein called the “Company”), and **JPMORGAN
      CHASE BANK, N.A.** ,
      a
      national banking association (formerly known as The Chase Manhattan Bank),
      as
      Trustee (herein called the “Trustee”), under the Indenture dated as of October
      1, 2001 (hereinafter called the “Original Indenture”), this Supplemental
      Indenture No. 4 being supplemental thereto. The Original Indenture and any
      and
      all indentures and instruments supplemental thereto are hereinafter sometimes
      collectively called the “Indenture.”




**Recitals
      of the Company**




The
      Original Indenture was authorized, executed and delivered by the Company to
      provide for the issuance by the Company from time to time of its Securities
      (such term and all other capitalized terms used herein without definition having
      the meanings assigned to them in the Original Indenture), to be issued in one
      or
      more series as contemplated therein.




As
      contemplated by Sections 301 and 1201(f) of the Original Indenture, the Company
      wishes to establish a series of Securities to be designated “Senior Notes, 6.20%
      Series due 2016” to be limited in aggregate principal amount (except as
      contemplated in Section 301(b) and the last paragraph of Section 301 of the
      Original Indenture) to $300,000,000, such series of Securities to be hereinafter
      sometimes called “Series No. 5.”




The
      Company has duly authorized the execution and delivery of this Supplemental
      Indenture No. 4 to establish the Securities of Series No. 5 and has duly
      authorized the issuance of such Securities. All acts necessary to make this
      Supplemental Indenture No. 4 a valid agreement of the Company and to make the
      Securities of Series No. 5 valid obligations of the Company have been
      performed.




**NOW,
      THEREFORE, THIS SUPPLEMENTAL INDENTURE NO. 4
      WITNESSETH** :




For
      and
      in consideration of the premises and of the purchase of the Securities by the
      Holders thereof, it is mutually covenanted and agreed, for the equal and
      proportionate benefit of all Holders of the Securities of Series No. 5, as
      follows:




**ARTICLE
      ONE**




**Fifth
      Series of Securities**




**Section
      1.**  There
      is
      hereby created a series of Securities designated “Senior Notes, 6.20% Series due
      2016” and limited in aggregate principal amount (except as contemplated in
      Section 301(b) and the last paragraph of Section 301 of the Original Indenture)
      to $300,000,000. The form and terms of the Securities of Series No. 5 shall
      be established in an Officer’s Certificate of the Company, as contemplated by
      Section 301 of the Original Indenture.




**Section
      2.**  The
      Company hereby agrees that, if the Company shall make any deposit of money
      and/or Eligible Obligations with respect to any Securities of Series No. 5,
      or any portion of the principal amount thereof, as contemplated by Section
      701
      of the Indenture, the Company shall not deliver an Officer’s Certificate
      described in clause (z) in the first paragraph of said Section 701 unless the
      Company shall also deliver to the Trustee, together with such Officer’s
      Certificate, either:




(A)  an
      instrument wherein the Company, notwithstanding the satisfaction and discharge
      of its indebtedness in respect of such Securities, shall assume the obligation
      (which shall be absolute and unconditional) to irrevocably deposit with the
      Trustee or Paying Agent such additional sums of money, if any, or additional
      Eligible Obligations (meeting the requirements of Section 701), if any, or
      any
      combination thereof, at such time or times, as shall be necessary, together
      with
      the money and/or Eligible Obligations theretofore so deposited, to pay when
      due
      the principal of and premium, if any, and interest due and to become due on
      such
      Securities or portions thereof, all in accordance with and subject to the
      provisions of said Section 701; provided , however ,
      that
      such instrument may state that the obligation of the Company to make additional
      deposits as aforesaid shall arise only upon the delivery to the Company by
      the
      Trustee of a notice asserting the deficiency and showing the calculation thereof
      and shall continue only until the Company shall have delivered to the Trustee
      an
      opinion of an independent public accountant of nationally recognized standing
      to
      the effect that no such deficiency exists and showing the calculation of the
      sufficiency of the deposits then held by the Trustee; or




(B)  an
      Opinion of Counsel to the effect that the Holders of such Securities, or
      portions of the principal amount thereof, will not recognize income, gain or
      loss for United States federal income tax purposes as a result of the
      satisfaction and discharge of the Company’s indebtedness in respect thereof and
      will be subject to United States federal income tax on the same amounts, at
      the
      same times and in the same manner as if such satisfaction and discharge had
      not
      been effected.




**Section
      3.**  The
      Company agrees that for so long as any Securities of Series No. 5 shall
      remain Outstanding, without consent of the Holders of a majority in principal
      amount of the Outstanding Securities of such series, the Company shall not
      create, incur or assume any Lien (other than Permitted Liens) upon any property
      of the Company, whether now owned or hereafter acquired, in order to secure
      any
      Debt of the Company. The foregoing agreement shall not restrict the ability
      of
      Subsidiaries or Affiliates of the Company to create, incur or assume any Lien
      upon their properties or assets.




**Section
      4.**  The
      provisions of Section 3 above shall not prohibit the creation, issuance,
      incurrence or assumption of any Lien if either




(A)  the
      Company shall make effective provision whereby all Securities of Series
      No. 5 then Outstanding shall be secured equally and ratably with all other
      Debt then outstanding under such Lien; or




(B)  the
      Company shall deliver to the Trustee bonds, notes or other evidences of
      indebtedness secured by the Lien which secures such Debt (hereinafter called
      “Secured Obligations”) (I) in an aggregate principal amount equal to the
      aggregate principal amount of the Securities of Series No. 5 then Outstanding,
      (II) maturing (or being subject to mandatory redemption) on such dates and
      in
      such principal amounts that, at each Stated Maturity of the Outstanding
      Securities of Series No. 5, there shall mature (or be redeemed) Secured
      Obligations equal in principal amount to such Securities then to mature and
      (III) containing, in addition to any mandatory redemption provisions applicable
      to all Secured Obligations outstanding under such Lien and any mandatory
      redemption provisions contained therein pursuant to clause (II) above, mandatory
      redemption provisions correlative to the provisions, if any, for the mandatory
      redemption (pursuant to a sinking fund or otherwise) of the Securities of Series
      No. 5 or for the redemption thereof at the option of the Holder, as well as
      a provision for mandatory redemption upon an acceleration of the maturity of
      all
      Outstanding Securities of Series No. 5 following an Event of Default (such
      mandatory redemption to be rescinded upon the rescission of such acceleration);
      it being expressly understood that such Secured Obligations (X) may, but need
      not, bear interest, (Y) may, but need not, contain provisions for the redemption
      thereof at the option of the issuer, any such redemption to be made at a
      redemption price or prices not less than the principal amount thereof and (Z)
      shall be held by the Trustee for the benefit of the Holders of all Securities
      of
      Series No. 5 from time to time Outstanding subject to such terms and
      conditions relating to surrender to the Company, transfer restrictions, voting,
      application of payments of principal and interest and other matters as shall
      be
      set forth in an indenture supplemental hereto specifically providing for the
      delivery to the Trustee of such Secured Obligations.




**Section
      5.**  If
      the
      Company shall elect either of the alternatives described in Section 4 above,
      the
      Company shall deliver to the Trustee:




(A)  an
      indenture supplemental to the Original Indenture (I) together with any
      appropriate inter-creditor arrangements, whereby such Securities of Series
      No. 5 then Outstanding shall be secured by the Lien referred to in Section
      4 above equally and ratably with all other indebtedness secured by such Lien
      or
      (II) providing for the delivery to the Trustee of Secured Obligations;
      and




(B)  an
      Officer’s Certificate (I) stating that, to the knowledge of the signer, (1) no
      Event of Default has occurred and is continuing and (2) no event has occurred
      and is continuing which entitles the secured party under such Lien to accelerate
      the maturity of the indebtedness outstanding thereunder and (II) stating the
      aggregate principal amount of indebtedness issuable, and then proposed to be
      issued, under and secured by such Lien; and




(C)  an
      Opinion of Counsel (I) if the Securities of Series No. 5 then Outstanding
      are to be secured by such Lien, to the effect that all such Securities then
      Outstanding are entitled to the benefit of such Lien equally and ratably with
      all other indebtedness outstanding under such Lien or (II) if Secured
      Obligations are to be delivered to the Trustee, to the effect that such Secured
      Obligations have been duly issued under such Lien and constitute valid
      obligations, entitled to the benefit of such Lien equally and ratably with
      all
      other indebtedness then outstanding under such Lien.






**Section
      6.**  The
      Company agrees that for so long as any Securities of Series No. 5 shall remain
      Outstanding, and except for the sale of the properties and assets of the Company
      substantially as an entirety pursuant to Article Eleven of the Original
      Indenture, and other than assets required to be sold to conform with
      governmental requirements, the Company shall not, and shall not permit any
      of
      its Subsidiaries to, consummate any Asset Sale, if the aggregate net book value
      of all such Asset Sales consummated during the four calendar quarters
      immediately preceding any date of determination would exceed 15% of the
      consolidated assets of the Company and its consolidated Subsidiaries as of
      the
      beginning of the Company’s most recently ended full fiscal quarter; provided , however ,
      that
      any such Asset Sale will be disregarded for purposes of the 15% limitation
      specified above (i) if any such Asset Sale is in the ordinary course of
      business, (ii) to the extent that such assets are worn out or are no longer
      useful or necessary in connection with the operation of the business of the
      Company or its Subsidiaries, (iii) to the extent such assets are being
      transferred to a wholly-owned Subsidiary of the Company, (iv) to the extent
      any
      such assets subject to any such Asset Sale involve transfers of assets of or
      equity interests in connection with (a) the formation of any joint venture
      between the Company or any of its Subsidiaries and any other entity, or (b)
      any
      project development and acquisition activities, and (v) if the proceeds thereof
      (a) are, within 12 months of such Asset Sale, invested or reinvested by the
      Company or any Subsidiary in a Permitted Business, (b) are used by the Company
      or a Subsidiary to repay Debt of the Company or such Subsidiary, or (c) are
      retained by the Company or its Subsidiaries. Additionally, if prior to any
      Asset
      Sale that otherwise would cause the 15% limitation to be exceeded, Moody’s and
      S&P confirm the then current long term debt rating of such Securities of
      Series No. 5 after giving effect to such Asset Sale, such Asset Sale shall
      also be disregarded for purposes of the foregoing limitations.




**Section
      7.**  So
      long
      as any Securities of Series No. 5 shall remain Outstanding, the following
      event shall be an Event of Default with respect to the Securities of Series
      No.
      5: the occurrence of a matured event of default, as defined in any instrument
      of
      the Company under which there may be issued or evidenced any Debt of the
      Company, that has resulted in the acceleration of such Debt in excess of
      $25,000,000, or any default in payment of Debt in excess of $25,000,000 at
      final
      maturity, after the expiration of any applicable grace or cure periods; provided , however ,
      that
      the waiver or cure of any such default under any such instrument or Debt shall
      constitute a waiver and cure of the corresponding Event of Default under the
      Indenture and the rescission and annulment of the consequences thereof shall
      constitute a rescission and annulment of the corresponding consequences under
      the Indenture.




**Section
      8.**  So
      long
      as any Securities of Series No. 5 shall remain Outstanding, for purposes of
      Section 1101(a) of the Indenture, “corporation” shall be deemed to refer to a
      corporation or limited liability company. For all other purposes, the definition
      of “corporation” in Section 101 of the Original Indenture shall
      govern.




**Section
      9.**  For
      the
      purposes of this Article One, except as otherwise expressly provided or unless
      the context otherwise requires:




(A)  “Asset
      Sale” shall mean any sale of any assets of the Company or its Subsidiaries
      including by way of the sale by the Company or any of its Subsidiaries of equity
      interests in such Subsidiaries.




(B)  “Debt”,
      with respect to any Person, means (A) indebtedness of such Person for borrowed
      money evidenced by a bond, debenture, note or other similar written instrument
      or agreement by which such Person is obligated to repay such borrowed money
      and
      (B) any guaranty by such Person of any such indebtedness of another Person.
      “Debt” does not include, among other things, (W) indebtedness of such Person
      under any installment sale or conditional sale agreement or any other agreement
      relating to indebtedness for the deferred purchase price of property or
      services, (X) any trade obligations (including obligations under agreements
      relating to the purchase and sale of any commodity, including power purchase
      or
      sale agreements, and any commodity hedges or derivatives regardless or whether
      such transaction is a “financial” or physical transaction) or other obligations
      of such Person in the ordinary course of business, (Y) obligations of such
      Person under any lease agreement (including any lease intended as security),
      whether or not such obligations are required to be capitalized on the balance
      sheet of such Person under generally accepted accounting principles, or (Z)
      liabilities secured by any Lien on any property owned by such Person if and
      to
      the extent that such Person has not assumed or otherwise become liable for
      the
      payment thereof.


(C)  “Lien”
      means any lien, mortgage, deed of trust, pledge or security interest, in each
      case, intended to secure the repayment of Debt, except for any Permitted
      Lien.




(D)  “Material
      Subsidiary” means PPL Global, LLC, a Delaware limited liability company, PPL
      EnergyPlus, LLC, a Delaware limited liability company, or PPL Generation, LLC,
      a
      Delaware limited liability company.




(E)  “Moody’s”
      means Moody’s Investors Service, Inc. and its successors and assigns, or absent
      a successor, or if such entity ceases to rate the Securities of Series
      No. 5, such other nationally recognized statistical rating organization as
      the Company may designate by notice to the Trustee.




(F)  “Permitted
      Business” means a business that is the same or similar to the business of the
      Company or any Subsidiary as of the date that Securities of Series No. 5 are
      first authenticated hereunder, or any business reasonably related
      thereto.




(G)  “Permitted
      Liens” means




(i)  any
      Liens
      existing at May 18, 2006;




(ii)  any
      vendors’ Liens, purchase money Liens and other Liens on property at the time of
      acquisition thereof by the Company and Liens to secure or provide for the
      construction or improvement of property provided that no such Lien shall extend
      to or cover any other property of the Company;




(iii)  any
      Liens
      on cash or securities (other than limited liability company interests issued
      by
      any Material Subsidiary), including any cash or securities on hand or in banks
      or other financial institutions, deposit accounts and interests in general
      or
      limited partnerships;




(iv)  any
      Liens
      on the equity interest of any Subsidiary that is not a Material
      Subsidiary;




(v)  any
      Liens
      on property or shares of capital stock, or arising out of any Debt of any
      corporation existing at the time the corporation becomes or is merged or
      consolidated into the Company;




(vi)  any
      Liens
      in connection with the issuance of tax-exempt industrial development or
      pollution control bonds or other similar bonds issued pursuant to Section 103(b)
      of the Internal Revenue Code of 1986, as amended (or any successor provision),
      to finance all or any part of the purchase price of or the cost of constructing,
      equipping or improving property, provided that such Liens are limited to the
      property acquired or constructed or improved and to substantially unimproved
      real property on which such construction or improvement is located; provided , further ,
      that
      the Company may further secure all or any part of such purchase price or the
      cost of construction or improvement by an interest on additional property of
      the
      Company only to the extent necessary for the construction, maintenance and
      operation of, and access to, such property so acquired or constructed or such
      improvement;




(vii)  any
      Liens
      on contracts, leases and other agreements of whatsoever kind and nature; any
      Liens on contract rights, bills, notes and other instruments; any Liens on
      revenues, income and earnings, accounts, accounts receivable and unbilled
      revenues, claims, credits, demands and judgments; any Liens on governmental
      and
      other licenses, permits, franchises, consents and allowances; and any Liens
      on
      patents, patent licenses and other patent rights, patent applications, trade
      names, trademarks, copyrights, claims, credits, choses in action and other
      intangible property and general intangibles including, but not limited to,
      computer software;




(viii)  any
      Liens
      securing Debt which matures less than one year from the date of issuance or
      incurrence thereof and is not extendible at the option of the issuer, and any
      refundings, refinancings and/or replacements of any such Debt by or with similar
      secured Debt;




(ix)  any
      Liens
      on automobiles, buses, trucks and other similar vehicles and movable equipment;
      vessels, boats, barges and other marine equipment; airplanes, helicopters,
      aircraft engines and other flight equipment; parts, accessories and supplies
      used in connection with any of the foregoing;




(x)  any
      Liens
      on furniture and furnishings, and computers, data processing, data storage,
      data
      transmission, telecommunications and other equipment and facilities, equipment
      and apparatus, which, in any case, are used primarily for administrative or
      clerical purposes;




(xi)  any
      Liens
      on property which is the subject of a lease agreement designating the Company
      as
      lessee and all right, title and interest of the Company in and to such property
      and in, to and under such lease agreement, whether or not such lease agreement
      is intended as security;




(xii)  other
      Liens securing Debt the principal amount of which does not exceed 10% of the
      total assets of the Company and its consolidated Subsidiaries as shown on the
      Company’s most recent audited consolidated balance sheet; and




(xiii)  any
      Liens
      granted in connection with extending, renewing, replacing or refinancing, in
      whole or in part, the Debt secured by liens described in the foregoing clauses
      (i) through (xii), to the extent of such Debt so extended, renewed, replaced
      or
      refinanced.




(H)  “S&P”
      means Standard & Poor’s Ratings Services, a division of The McGraw-Hill
      Companies, Inc. and its successors and assigns, or absent a successor, or if
      such entity ceases to rate the Securities of Series No. 5, such other nationally
      recognized statistical rating organization as the Company may designate by
      notice to the Trustee.




(I)  “Subsidiary”
      means any corporation a majority of the outstanding Voting Stock of which is
      owned, directly or indirectly, by the Company or by one or more other
      Subsidiaries of the Company.




(J)  “Voting
      Stock” means stock (or other interests) of a corporation having voting power for
      the election of directors, managers or trustees thereof, whether at all times
      or
      only so long as no senior class of stock has such voting power by reason of
      any
      contingency.




**ARTICLE
      TWO**




**Miscellaneous
      Provisions**




**Section
      1.**  This
      Supplemental Indenture No. 4 is a supplement to the Original Indenture. As
      supplemented by this Supplemental Indenture No. 4, the Indenture is in all
      respects ratified, approved and confirmed, and the Original Indenture and this
      Supplemental Indenture No. 4 shall together constitute one and the same
      instrument.




**Section
      2.**  The
      recitals contained in this Supplemental Indenture No. 4 shall be taken as the
      statements of the Company and the Trustee assumes no responsibility for their
      correctness and makes no representations as to the validity or sufficiency
      of
      this Supplemental Indenture No. 4.




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





**IN
      WITNESS WHEREOF** ,
      the
      parties hereto have caused this Supplemental Indenture No. 4 to be duly
      executed, and their respective seals to be hereunto affixed and attested, all
      as
      of the day and year first written above.




**PPL
      ENERGY SUPPLY, LLC**




By:
      ________________________________________________


Name:
      James E. Abel


Title:
      Vice President and Treasurer


[SEAL]




ATTEST:




________________________________________________




**JPMORGAN
      CHASE BANK, N.A.,**


as
      Trustee




By:
      ________________________________________________


Name:


Title:


[SEAL]




ATTEST:




________________________________________________