<PAGE>

                                                                   EXHIBIT 10(A)

================================================================================

                                 $500,000,000

                               CREDIT AGREEMENT

                                  dated as of

                                 June 24, 1999

                                     among

                           SIERRA PACIFIC RESOURCES,

                              MELLON BANK, N.A.,

                           as Administrative Agent,

                           FIRST UNION NATIONAL BANK

                                      and

                            WELLS FARGO BANK, N.A.,

                            as Syndication Agents,

                                      and

                  the LENDERS party hereto from time to time,


                                  Arranged By

                               MELLON BANK, N.A.

================================================================================


                                       1
<PAGE>

          CREDIT AGREEMENT, dated as of June 24, 1999, among SIERRA PACIFIC
RESOURCES, a Nevada corporation, MELLON BANK, N.A., as Administrative Agent,
FIRST UNION NATIONAL BANK and WELLS FARGO BANK, N.A., as Syndication Agents, the
LENDERS party hereto from time to time and MELLON BANK, N.A., as Arranger.

                             W I T N E S S E T H:
                             -------------------

          WHEREAS, the Borrower (as defined below) has requested, and Lenders
(as defined below) have agreed to make available, the credit facilities
described below upon the terms and conditions contained herein.

          NOW, THEREFORE, in consideration of the premises and of the mutual
covenants herein contained and intending to be legally bound hereby, the parties
hereto agree as follows:

                                   ARTICLE I
                           DEFINITIONS; CONSTRUCTION

          SECTION 1.01  Defined Terms.
                        -------------

          As used in this Agreement, the following terms have the following
meanings:

          "ABR", when used in reference to any Loan or Borrowing, refers to
           ---
whether such Loan, or the Loans comprising such Borrowing, are bearing interest
at a rate determined by reference to the Alternate Base Rate.

          "Acquisition" means any transaction, or any series of related
           -----------
transactions, consummated after the Effective Date, by which the Borrower and/or
any of its Subsidiaries directly or indirectly (a) acquires any ongoing business
or all or substantially all of the assets of any Person engaged in any ongoing
business, whether through purchase of assets, merger or otherwise, (b) acquires
control of securities of a Person engaged in an ongoing business representing
more than 50% of the ordinary voting power for the election of directors or
other governing position if the business affairs of such Person are managed by a
board of directors or other governing body or (c) acquires control of more than
50% of the ownership interest in any partnership, joint venture, limited
liability company, business trust or other Person engaged in an ongoing business
that is not managed by a board of directors or other governing body.

          "Adjusted LIBO Rate" means, with respect to any Eurodollar Revolving
           ------------------
Borrowing for any Interest Period, an interest rate per annum (rounded upwards,
if necessary, to the nearest 1/100 of 1%) equal to (a) the LIBO Rate for such
Interest Period multiplied by (b) the Statutory Reserve Rate.

          "Administrative Agent" means Mellon Bank, N.A., in its capacity as
           --------------------
administrative agent for the Lenders hereunder and any successor appointed
pursuant to Section 8.10.

                                       2
<PAGE>

          "Affiliate" means, any Person that directly or indirectly Controls, or
           ---------
is under common Control with, or is Controlled by, another Person, provided
that, in any event, any Person that owns directly or indirectly securities
having 20% or more of the voting power for the election of directors or other
governing body of a corporation or 20% or more of the partnership or other
ownership interests of any other Person (other than as a limited partner of such
other Person) will be deemed to Control such corporation or other Person.

          "AFUDC-Debt" means, for any period, the allowance for borrowed funds
           ----------
used during construction for such period as calculated in accordance with the
rules of the Public Utilities Commission of Nevada.

          "AFUDC-Equity" means, for any period, the allowance for funds other
           ------------
than borrowed funds used during construction for such period as calculated in
accordance with the rules of the Public Utilities Commission of Nevada.

          "Agents" means, collectively, the Administrative Agent, the Arranger
           ------
and the Syndication Agents.

          "Alternate Base Rate" means, for any day, a rate per annum equal to
           -------------------
the greater of (a) the Prime Rate in effect on such day and (b) the Federal
Funds Effective Rate in effect on such day plus 1/2 of 1%. Any change in the
Alternate Base Rate due to a change in the Prime Rate or the Federal Funds
Effective Rate shall be effective from and including the effective date of such
change in the Prime Rate or the Federal Funds Effective Rate, respectively.

          "Applicable Percentage" means, with respect to any Lender as of any
           ---------------------
date of determination, the percentage of the total Commitments as of such date
represented by such Lender's Commitments as of such date.  If the Commitments
have terminated or expired, the Applicable Percentages shall be determined, as
of any date of determination, based upon the percentage of the total Loans
outstanding as of such date represented by such Lender's Loans outstanding as of
such date.

          "Applicable Rate" means, for any day, with respect to the facility
           ---------------
fees payable hereunder, with respect to any Eurodollar Revolving Loan or with
respect to any usage fees payable hereunder, as the case may be, the applicable
rate per annum set forth below under the caption "Facility Fee",  "Eurodollar
Spread" or "Usage Fee", as the case may be, based on the ratings by S&P and
Moody's, respectively, applicable on such day to the Index Debt:

<TABLE>
                                           Facility Fee         Eurodollar
                                             (364-Day         Spread (364-Day
                                          Facility/3-Year    Facility/3-             Usage Fee
Index Debt rating: S&P/Moody's               Facility)       Year Facility)         (*33%/*66%)
------------------------------               ---------       --------------         ----------
<S>                                       <C>                <C>                    <C>
Ratings greater than A-/A3                 .1500/.2000%        .3500/.3000%         .0250/.0750%

Ratings equal to A-/A3                     .1500/.2000%        .4000/.3500%         .0250/.0750%

Ratings equal to BBB+/Baa1                 .2000/.2500%        .4250/.3750%         .0250/.0750%
</TABLE>

* greater than

                                       3
<PAGE>

<TABLE>
<S>                                        <C>                 <C>                   <C>
Ratings equal to BBB/Baa2                  .2250/.2750%        .5250/.4750%         .0500/.1250%

Ratings equal to BBB-/Baa3                 .2500/.3000%        .7500/.7000%         .0500/.1250%

Ratings less than BBB-/Baa3                .3750/.4250%        .8750/.8250%         .1250/.2500%
</TABLE>

For purposes of the foregoing, (i) if either Moody's or S&P shall not have in
effect a rating for the Index Debt (other than by reason of the circumstances
referred to in the last sentence of this definition), then such rating agency
shall be deemed to have established a rating in its lowest rating category, (ii)
if the ratings established or deemed to have been established by Moody's and S&P
for the Index Debt shall be changed (other than as a result of a change in the
rating system of Moody's or S&P), such change shall be effective as of two
Business Days after it is first announced by the applicable rating agency and
(iii) if the rating assigned by Moody's and the rating assigned by S&P shall
differ (a) by one level (e.g., Moody's rating of A3 and S&P rating of BBB+),
then the higher rating level shall apply (i.e., A3) and (b) by more than one
level (e.g., Moody's rating of A3 and S&P rating of BBB-), then the rating level
above the lower rating level shall apply (i.e., BBB/Baa2). Each change in the
Applicable Rate shall apply during the period commencing two Business Days after
the effective date of such change and ending on the date immediately preceding
the effective date of the next such change. If the rating system of Moody's or
S&P shall change, or if either such rating agency shall cease to be in the
business of rating corporate debt obligations, the Borrower and the Lenders
shall negotiate in good faith to amend this definition to reflect such changed
rating system or the unavailability of ratings from such rating agency and,
pending the effectiveness of any such amendment, the Applicable Rate shall be
determined by reference to the rating most recently in effect prior to such
change or cessation.

          "Arranger" means Mellon Bank, N.A. in its capacity as arranger
           --------
hereunder.

          "Assignment and Acceptance" means an assignment and acceptance entered
           -------------------------
into by a Lender and an assignee (with the consent of any party whose consent is
required by Section 9.12), and accepted by the Administrative Agent, in the form
of Exhibit A or any other form approved by the Administrative Agent.

          "Bankruptcy Code" means Title 11 of the United States Code entitled
           ---------------
"Bankruptcy," as now or hereafter in effect, or any successor thereto.

          "Board" means the Board of Governors of the Federal Reserve System of
           -----
the United States of America.

          "Borrower" means Sierra Pacific Resources, a Nevada corporation.
           --------

          "Borrowing" means Loans of the same Type under a Facility, made,
           ---------
converted or continued on the same date and, in the case of Eurodollar Loans, as
to which a single Interest Period is in effect.

          "Borrowing Request" means a request by the Borrower for a Borrowing
           -----------------
made in accordance with Section 2.03.

                                       4
<PAGE>

          "Business Day" means any day that is not a Saturday, Sunday or other
           ------------
day on which commercial banks in Pittsburgh, Pennsylvania are authorized or
required by Law to remain closed; provided that, when used in connection with a
Eurodollar Loan, the term "Business Day" shall also exclude any day on which
banks are not open for dealings in dollar deposits in the London interbank
market.

          "Capital Lease Obligations" of any Person means all obligations of
           -------------------------
such Person to pay rent or other amounts under a lease of (or other agreement
conveying the right to use) Property to the extent such obligations are required
to be classified and accounted for as a capital lease on a balance sheet of such
Person under GAAP (including Statement of Financial Accounting Standards No. 13
of the Financial Accounting Standards Board), and, for purposes of this
Agreement, the amount of such obligations shall be the capitalized amount
thereof, determined in accordance with GAAP (including such Statement No. 13).

          "Change in Control" means (a) the acquisition of ownership, directly
           -----------------
or indirectly, beneficially or of record, by any Person or group (within the
meaning of the Securities Exchange Act of 1934 and the rules of the Securities
and Exchange Commission thereunder as in effect on the date hereof) of shares
representing more than 20% of the aggregate ordinary voting power represented by
the issued and outstanding capital stock of the Borrower; (b) for any period of
12 consecutive calendar months, a majority of the Board of Directors of the
Borrower shall no longer be composed of individuals (i) who were members of said
Board on the first day of such period, (ii) whose election or nomination to said
Board was approved by individuals referred to in clause (i) above constituting
at the time of such election or nomination at least a majority of said Board or
(iii) whose election or nomination to said Board was approved by individuals
referred to in clauses (i) and (ii) above constituting at the time of such
election or nomination at least a majority of said Board; (c) the failure of the
Borrower to own, legally and beneficially, 100% of the aggregate ordinary voting
power represented by the issued and outstanding capital stock of either NPC or
SPPC; or (d) any reduction in Borrower's ownership, either legal or beneficial,
of a Significant Subsidiary.

          "Change in Law" means (a) the adoption of any Law after the date of
           -------------
this Agreement, (b) any change in any Law or in the interpretation or
application thereof by any Governmental Authority after the date of this
Agreement or (c) compliance by any Lender (or, for purposes of Section 2.13(b),
by any lending office of such Lender or by such Lender's Parent, if any) with
any request, guideline or directive (whether or not having the force of Law) of
any Governmental Authority made or issued after the date of this Agreement.

          "Class", when used in reference to any Loan or Borrowing under the
           -----
364-Day Facility, refers to whether such Loan, or the Loans comprising such
Borrowing, are Revolving Loans or Term Loans.

          "Code" means the Internal Revenue Code of 1986 and the regulations
           ----
promulgated and rulings issued thereunder.  Section references to the Code are
to the Code, as in effect at the date of this Agreement and any subsequent
provisions of the Code, amendatory thereof, supplemental thereto or substituted
therefor.

                                       5
<PAGE>

          "Commitment" means, with respect to each Lender at any time, the 364-
           ----------
Day Commitment and/or 3-Year Commitment of such Lender, as the context may
require, in each case as of such time.

          "Consolidated Earnings Available For Fixed Charges" means, for any
           -------------------------------------------------
period, Consolidated Net Income Available to Common less AFUDC-Debt less AFUDC-
Equity plus Consolidated Fixed Charges, in each case for the Borrower for such
period.

          "Consolidated Fixed Charges" means, for any period, the sum of (i) the
           --------------------------
total consolidated cash interest paid by the Borrower and its consolidated
Subsidiaries for such period, (ii) lease payments made or accrued by the
Borrower and its consolidated Subsidiaries, on a consolidated basis, for such
period and (iii) preferred dividends paid by the Borrower and its consolidated
Subsidiaries for such period.

          "Consolidated Net Income Available to Common" means, for any period,
           -------------------------------------------
the consolidated net income of the Borrower and its consolidated Subsidiaries
less consolidated preferred dividends accrued by the Borrower and its
consolidated Subsidiaries, in each case for such period.

          "Control" of a Person (including, with its correlative meanings,
           -------
"Controlled by" and "under common Control with") means possession, directly or
indirectly, of the power to direct or cause the direction of management or
policies (whether through ownership of securities or partnership or other
ownership interests, by contract or otherwise) of such Person.

          "Default" means any event, act or condition which upon notice, lapse
           -------
of time or both would, unless cured or waived, become an Event of Default.

          "Default Interest" has the meaning assigned to such term in Section
           ----------------
2.11(c).

          "Dollars" or "$" refers to freely transferable lawful money of the
           -------      -
United States of America.

          "Effective Date" means the date on which the conditions specified in
           --------------
Section 4.01 are satisfied (or waived in accordance with Section 9.01).

          "Environmental Claims" means any and all administrative, regulatory or
           --------------------
judicial actions, suits, demands, demand letters, directives, claims, liens,
notices of noncompliance or violation, investigations or proceedings relating in
any way to any Environmental Law or any permit issued, or any approval given,
under any such Environmental Law (hereafter, "Claims"), including, without
                                              ------
limitation, (a) any and all Claims by governmental or regulatory authorities for
enforcement, cleanup, removal, response, remedial or other actions or damages
pursuant to any applicable Environmental Law, and (b) any and all Claims by any
third party seeking damages, contribution, indemnification, cost recovery,
compensation or injunctive relief in connection with alleged injury or threat of
injury to health, safety or the environment due to the presence of Hazardous
Materials.

          "Environmental Law" means any Federal, state, foreign or local
           -----------------
statute, Law, rule, regulation, ordinance, code, guideline, written policy and
rule of common law now or

                                       6
<PAGE>

hereafter in effect and in each case as amended, and any judicial or
administrative interpretation thereof, including any judicial or administrative
order, consent decree or judgment, relating to the environment, employee health
and safety or Hazardous Materials, including, without limitation, CERCLA; RCRA;
the Federal Water Pollution Control Act, 33 U.S.C. (S) 1251 et seq.; the Toxic
                                                            -- ---
Substances Control Act, 15 U.S.C. (S) 2601 et seq.; the Clean Air Act, 42 U.S.C.
                                           -- ---
(S) 7401 et seq.; the Safe Drinking Water Act, 42 U.S.C. (S) 3803 et seq.; the
         -- ---                                                   -- ---
Oil Pollution Act of 1990, 33 U.S.C. (S) 2701 et seq.; the Emergency Planning
                                              -- ---
and the Community Right-to-Know Act of 1986, 42 U.S.C. (S) 11001 et seq.; the
                                                                 -- ---
Hazardous Material Transportation Act, 49 U.S.C. (S) 1801 et seq. and the
                                                          -- ---
Occupational Safety and Health Act, 29 U.S.C. (S) 651 et seq.; and any state and
                                                      -- ---
local or foreign counterparts or equivalents, in each case as amended from time
to time.

          "ERISA" means the Employee Retirement Income Security Act of 1974 and
           -----
the regulations promulgated and rulings issued thereunder.  Section references
to ERISA are to ERISA, as in effect at the date of this Agreement, and to any
subsequent provisions of ERISA, amendatory thereof, supplemental thereto or
substituted therefor.

          "ERISA Affiliate" means any corporation or trade or business that is a
           ---------------
member of any group of organizations described in Section 414(b) or (c) of the
Code of which the Borrower is a member.

          "Eurodollar", when used in reference to any Loan or Borrowing, refers
           ----------
to whether such Loan, or the Loans comprising such Borrowing, are bearing
interest at a rate determined by reference to the Adjusted LIBO Rate.

          "Event of Default" has the meaning assigned to such term in Section
           ----------------
7.01.

          "Excluded Taxes" means, with respect to the Administrative Agent, any
           --------------
Lender or any other recipient of any payment to be made by or on account of any
obligation of the Borrower hereunder, (a) income or franchise taxes imposed on
(or measured by) its net income by the United States of America, or by the
jurisdiction under the Laws of which such recipient is organized or in which its
principal office is located or, in the case of any Lender, in which its
applicable lending office is located, (b) any branch profits taxes imposed by
the United States of America or any similar tax imposed by any other
jurisdiction in which the Borrower is located and (c) in the case of a Foreign
Lender (other than an assignee pursuant to a request by the Borrower under
Section 2.17(b)), any withholding tax that is imposed on amounts payable to such
Foreign Lender at the time such Foreign Lender becomes a party to this Agreement
or is attributable to such Foreign Lender's failure or inability to comply with
Section 2.15(e), except to the extent that such Foreign Lender's assignor (if
any) was entitled, at the time of assignment, to receive additional amounts from
the Borrower with respect to such withholding tax pursuant to Section 2.15(a).

          "Existing Indebtedness" has the meaning assigned to such term in
           ---------------------
Section 3.23.

          "Extension Request" has the meaning assigned to such term in Section
           -----------------
2.06(f).

          "Extension Request Notice" has the meaning assigned to such term in
           ------------------------
Section 2.06(f).

                                       7
<PAGE>

          "Extension Request Period" has the meaning assigned to such term in
           ------------------------
Section 2.06(f).

          "Facility" means either the 364-Day Facility or the 3-Year Facility,
           --------
as the context may require, and "Facilities" means the 364-Day Facility and the
                                 ----------
3-Year Facility.

          "Federal Funds Effective Rate" means, for any day, the weighted
           ----------------------------
average (rounded upwards, if necessary, to the next 1/100 of 1%) of the rates on
overnight Federal funds transactions with members of the Federal Reserve System
arranged by Federal funds brokers, as published on the next succeeding Business
Day by the Federal Reserve Bank of New York, or, if such rate is not so
published for any day that is a Business Day, the average (rounded upwards, if
necessary, to the next 1/100 of 1%) of the quotations for such day for such
transactions received by the Administrative Agent from three Federal funds
brokers of recognized standing selected by it.

          "Final Fee Payment Date" has the meaning assigned to such term in
           ----------------------
Section 2.10(a).

          "Final Repayment Date" means the earliest to occur of (a) the date
           --------------------
that is one year after the Term Loan Conversion Date and (b) the date on which
the Obligations under this Agreement terminate, whether by prepayment,
cancellation, acceleration or otherwise.

          "Fixed Charge Coverage Ratio" means, as of the last day of a fiscal
           ---------------------------
quarter, the ratio of Consolidated Earnings Available For Fixed Charges to
Consolidated Fixed Charges, in each case, for the four consecutive fiscal
quarter period of the Borrower ended on such last day.  For each fiscal quarter
ended on or prior to the consummation of the Mergers that is included in any
four consecutive fiscal quarter test period, notwithstanding the definitions
thereof, Consolidated Earnings Available For Fixed Charges and Consolidated
Fixed Charges for such fiscal quarter shall be calculated as if the Mergers had
been consummated prior to such fiscal quarter and accounted for by the pooling
of interests method using, for this purpose, the Borrower's and NPC's respective
reports on Form 10-Q that were filed with the Securities and Exchange Commission
(or, in the case of the fiscal quarter ended December 31, 1998, the Borrower's
and NPC's unaudited financial statements for that fiscal quarter).  For each
fiscal quarter ended after the consummation of the Mergers but before October 1,
1999 that is included in any four consecutive fiscal quarter test period,
notwithstanding the definitions thereof, Consolidated Earnings Available For
Fixed Charges and Consolidated Fixed Charges for such fiscal quarter shall be
calculated as if the Mergers were to be accounted for by the pooling of
interests method using, for this purpose, the Borrower's unaudited internally
prepared financial statements and not the Borrower's reports on Form 10-Q that
were filed with the Securities and Exchange Commission.

          "Foreign Lender" means any Lender that is organized under the Laws of
           --------------
a jurisdiction other than the United States of America, each State thereof and
the District of Columbia.

          "Foreign Pension Plan" means any plan, fund (including, without
           --------------------
limitation, any superannuation fund) or other similar program established or
maintained outside the United

                                       8
<PAGE>

States of America by the Borrower or any one or more of its Subsidiaries
primarily for the benefit of employees of the Borrower or such Subsidiaries
residing outside the United States of America, which plan, fund or other similar
program provides, or results in, retirement income, a deferral of income in
contemplation of retirement or payments to be made upon termination of
employment, and which plan is not subject to ERISA or the Code.

          "GAAP" means generally accepted accounting principles in the United
           ----
States of America applied in a consistent manner.

          "Governmental Action" means any authorization, approval, order,
           -------------------
decree, ruling or other action by, or notice to or filing with, any Governmental
Authority.

          "Governmental Authority" means the government of the United States of
           ----------------------
America, any other nation or any political subdivision thereof, whether state or
local, and any agency, authority, bureau, instrumentality, regulatory body,
court, tribunal, central bank or other entity exercising executive, legislative,
judicial, taxing, regulatory or administrative powers or functions of or
pertaining to government.

          "Hazardous Materials" means (a) any petroleum or petroleum products,
           -------------------
radioactive materials, asbestos in any form that is friable, urea formaldehyde
foam insulation, transformers or other equipment that contain dielectric fluid
containing levels of polychlorinated biphenyls, and radon gas; (b) any
chemicals, materials or substances defined as or included in the definition of
"hazardous substances," "hazardous waste," "hazardous materials," "extremely
hazardous substances," "restricted hazardous waste," "toxic substances," "toxic
pollutants," "contaminants," or "pollutants," or words of similar import, under
any applicable Environmental Law; and (c) any other chemical, material or
substance, the Release of which is prohibited, limited or regulated by any
governmental authority.

          "Indebtedness" of any Person means, (a) obligations created, issued or
           ------------
incurred by such Person for borrowed money (whether by loan, the issuance and
sale of debt securities or the sale of Property to another Person subject to an
understanding or agreement, contingent or otherwise, to repurchase such Property
from such Person); (b) obligations of such Person to pay the deferred purchase
or acquisition price of Property or services, other than trade accounts payable
(other than for borrowed money) arising, and accrued expenses incurred, in the
ordinary course of business; (c) Indebtedness of others secured by a Lien on the
Property of such Person, whether or not the respective indebtedness so secured
has been assumed by such Person; (d) obligations of such Person in respect of
letters of credit or similar instruments issued or accepted by banks and other
financial institutions for account of such Person; (e) Capital Lease Obligations
of such Person; and (f) any guarantee or other arrangement by which such Person
guarantees or is otherwise liable for the Indebtedness of others; provided,
                                                                  --------
however, that "Indebtedness" shall not include Secured Nonrecourse Obligations.
-------

          "Indebtedness to be Refinanced" means all Indebtedness that is listed
           -----------------------------
on Schedule VII.

          "Indemnified Parties" means each Agent, the Lenders, their respective
           -------------------
Affiliates, and the directors, officers, employees, attorneys and agents of each
of the foregoing.

                                       9
<PAGE>

          "Indemnified Taxes" means all Taxes other than Excluded Taxes.
           -----------------

          "Index Debt" means the senior, unsecured, long-term indebtedness for
           ----------
borrowed money of the Borrower that is not guaranteed by any other Person or
subject to any credit enhancement.

          "Interest Election Request" means a request by the Borrower to convert
           -------------------------
or continue a Borrowing in accordance with Section 2.05.

          "Interest Payment Date" means (a) with respect to any ABR Loan, each
           ---------------------
Quarterly Date, and (b) with respect to any Eurodollar Loan, the last day of the
Interest Period applicable to the Borrowing of which such Loan is a part and, in
the case of a Eurodollar Borrowing with an Interest Period of more than three
months' duration, each day prior to the last day of such Interest Period that
occurs at intervals of three months' duration after the first day of such
Interest Period.

          "Interest Period" means, with respect to any Eurodollar Borrowing, the
           ---------------
period commencing on the date of such Borrowing and ending on the numerically
corresponding day in the calendar month that is one, two, three or six months
thereafter, as the Borrower may elect; provided, that (a) if any Interest Period
would end on a day other than a Business Day, such Interest Period shall be
extended to the next succeeding Business Day unless such next succeeding
Business Day would fall in the next calendar month, in which case such Interest
Period shall end on the next preceding Business Day and (b) any Interest Period
that commences on the last Business Day of a calendar month (or on a day for
which there is no numerically corresponding day in the last calendar month of
such Interest Period) shall end on the last Business Day of the last calendar
month of such Interest Period.  For purposes hereof, the date of a Borrowing
initially shall be the date on which such Borrowing is made and, thereafter
shall be the effective date of the most recent conversion or continuation of
such Borrowing.

          "Investment" means, when used in connection with any Person, any
           ----------
investment by or of that Person, whether by means of purchase or other
acquisition of stock or other securities of any other Person or by means of a
loan, advance creating a debt, capital contribution, guaranty or other debt or
equity participation or interest in any other Person, including any partnership
                                                      ---------
and joint venture interests of such Person but excluding  any Wholly-Owned
                                               ---------
Subsidiary of such Person.  The amount of any Investment shall be the amount
actually invested (minus any return of capital with respect to such Investment
                   -----
which has actually been received in cash or has been converted into cash),
without adjustment for subsequent increases or decreases in the value of such
Investment.

          "Law" shall mean any law (including common law), constitution,
           ---
statute, treaty, convention, regulation, rule, ordinance, order, injunction,
writ, decree or award of any Governmental Authority.

          "Lenders" means the Persons listed on Schedule I and any other Person
           -------
that shall have become a party hereto pursuant to an Assignment and Acceptance.

          "LIBO Rate" means, with respect to any Eurodollar Borrowing for any
           ---------
Interest Period, the average of the offered rates for Dollar deposits for the
applicable Interest Period

                                       10
<PAGE>

which appear on the Telerate Page 3750, British Bankers Association Interest
Settlement Rates, with maturities comparable to the Interest Period to be
applicable to such Eurodollar Loan, determined as of 10:00 A.M. (Pittsburgh,
Pennsylvania time) on the date which is two Business Days prior to the
commencement of such Interest Period.

          "Lien" means, with respect to any Property, any mortgage, lien,
           ----
pledge, charge, security interest or encumbrance of any kind in respect of such
Property. For purposes of this Agreement, a Person shall be deemed to own
subject to a Lien any Property that it has acquired or holds subject to the
interest of a vendor or lessor under any conditional sale agreement, capital
lease or other title retention agreement (other than an operating lease)
relating to such Property.

          "Loan Documents" means this Agreement, each Borrowing Request, each
           --------------
Interest Election Request, each Note and the Notice of Term Loan Conversion.

          "Loans" means (a) 364-Day Revolving Loans, (b) 3-Year Revolving Loans,
           -----
(c) Term Loans or (d) 364-Day Revolving Loans, 3-Year Revolving Loans and Term
Loans, as the context may require.

          "Material Adverse Effect" means a material adverse effect on (a) the
           -----------------------
Property, business, operations, financial condition, prospects, liabilities or
capitalization of the Borrower and its Subsidiaries taken as a whole, (b) the
ability of the Borrower to perform its obligations hereunder, (c) the validity
or enforceability of this Agreement, (d) the rights and remedies of the Lenders
and the Administrative Agent hereunder or (e) the timely payment of the
principal of or interest on the Loans or other amounts payable in connection
therewith.

          "Mergers" means the merger of (a) LAKE Merger Sub, Inc., a wholly-
           -------
owned Subsidiary of Sierra Pacific Resources, with and into Sierra Pacific
Resources and (b) NPC with and into DESERT Merger Sub, Inc., a wholly-owned
Subsidiary of Sierra Pacific Resources, in each case pursuant to the Agreement
and Plan of Merger, dated as of April 29, 1998, among NPC, Sierra Pacific
Resources, DESERT Merger Sub, Inc. and LAKE Merger Sub, Inc.

          "Moody's" means Moody's Investors Service, Inc.; provided that if such
           -------
corporation (or its successors and assigns) shall for any reason no longer
perform the functions of a securities rating agency, "Moody's" shall be deemed
to refer to any other nationally recognized securities rating agency approved
for purposes hereof by the Required Lenders and the Borrower.

          "Multiemployer Plan" means a multiemployer plan defined as such in
           ------------------
Section 3(37) of ERISA to which contributions have been made by the Borrower or
any ERISA Affiliate and which is covered by Title IV of ERISA.

          "NPC" means Nevada Power Co., a Nevada corporation.
           ---

          "NPC Credit Agreement" means that certain Credit Agreement of even
           --------------------
date herewith among NPC, as borrower, Mellon Bank, N.A., as administrative
agent, First Union National Bank and Wells Fargo Bank, N.A., as syndication
agents, and the lenders from time to time party thereto.

                                       11
<PAGE>

          "NPC First Mortgage Bonds" means obligations issued from time to time
           ------------------------
under, and secured by, the NPC First Mortgage Indenture.

          "NPC First Mortgage Indenture" means the Indenture of Mortgage, dated
           ----------------------------
as of October 1, 1953, from NPC to Bankers Trust Company (successor to First
Interstate Bank of Nevada, N.A. formerly First National Bank of Nevada, Reno
Nevada), as trustee, as modified, amended or supplemented at any time or from
time to time by supplemental indentures.

          "Note" means either a 364-Day Note or a 3-Year Note, as the context
           ----
may require, and "Notes" means 364-Day Notes and 3-Year Notes.
                  -----

          "Notice of Term Loan Conversion" has the meaning assigned to such term
           ------------------------------
in Section 2.07(a).

          "Obligations" means all Indebtedness, obligations and liabilities of
           -----------
the Borrower to any Lender or any Agent from time to time arising under or in
connection with or related to or evidenced by or secured by this Agreement or
any other Loan Document, and all extensions, renewals or refinancings thereof,
whether such Indebtedness, obligations or liabilities are direct or indirect,
otherwise secured or unsecured, joint or several, absolute or contingent, due or
to become due, whether for payment or performance, now existing or hereafter
arising. Without limitation of the foregoing, such Indebtedness, obligations and
liabilities shall include the principal amount of all Loans, all interest, fees,
indemnities or expenses under or in connection with this Agreement or any other
Loan Document, and all extensions, renewals and refinancings thereof, whether or
not such Loans were made in compliance with the terms and conditions of this
Agreement or in excess of the obligation of the Lenders to lend. Obligations
shall remain obligations notwithstanding any assignment or transfer or any
subsequent assignment or transfer of any of the Obligations or any interest
therein.

          "Other Taxes" means any and all present or future stamp or documentary
           -----------
taxes or any other excise or Property taxes, charges or similar levies arising
from any payment made hereunder or from the execution, delivery or enforcement
of, or otherwise with respect to, this Agreement.

          "Parent" means any Person that Controls a Lender.
           ------

          "Participant" has the meaning assigned to Section 9.12(b).
           -----------

          "PBGC" means the Pension Benefit Guaranty Corporation or any entity
           ----
succeeding to any or all of its functions under ERISA.

          "Permitted Liens" has the meaning assigned to such term in Section
           ---------------
6.02.

          "Person" means any natural person, corporation, limited liability
           ------
company, trust, joint venture, association, company, partnership, Governmental
Authority or other entity.

          "Plan" means an employee benefit or other plan established or
           ----
maintained by the Borrower or any ERISA Affiliate and that is covered by Title
IV of ERISA, other than a Multiemployer Plan.

                                       12
<PAGE>

          "Prime Rate" means the rate of interest per annum publicly announced
           ----------
from time to time by Mellon Bank, N.A. as its prime rate, the Prime Rate to
change when and as such prime rate changes.  The Prime Rate is a reference rate
and does not necessarily represent the lowest or best rate actually charged to
any customer.  Mellon Bank, N.A. may make commercial loans or other loans at
rates of interest at, above or below the Prime Rate.

          "Principal Office" means the principal office of Mellon Bank, N.A.,
           ----------------
located on the date hereof at One Mellon Bank Center, Pittsburgh, Pennsylvania
15258.

          "Property" means any right or interest in or to property of any kind
           --------
whatsoever, whether real, personal or mixed and whether tangible or intangible.

          "Purchasing Lender" has the meaning assigned to Section 9.12(c).
           -----------------

          "Quarterly Dates" means the last day of March, June, September and
           ---------------
December in each year, the first of which shall be the first such day after the
date hereof; provided that if any such day is not a Business Day, then such
Quarterly Date shall be the next succeeding Business Day (unless such succeeding
Business Day falls in a subsequent calendar month, in which event such Quarterly
Date shall be the next preceding Business Day).

          "Register" has the meaning assigned to Section 9.12(d).
           --------

          "Related Parties" means, with respect to any specified Person, such
           ---------------
Person's Affiliates and the respective directors, officers, employees, agents
and advisors of such Person and such Person's Affiliates.

          "Release" means the disposing, discharging, injecting, spilling,
           -------
pumping, leaking, leaching, dumping, emitting, escaping, emptying, pouring or
migrating, into or upon any land or water or air, or otherwise entering into the
environment.

          "Reportable Event" means an event described in Section 4043(c) of
           ----------------
ERISA with respect to a Plan that is subject to Title IV of ERISA other than
those events as to which the 30-day notice period is waived under subsection
 .22, .23, .25, .27 or .28 of PBGC Regulation Section 4043 (provided that a
failure to meet the minimum funding standard of Section 412 of the Code or
Section 302 of ERISA, including, without limitation, the failure to make on or
before its due date a required installment under Section 412(m) of the Code or
Section 302(e) of ERISA, shall be a reportable event regardless of the issuance
of any waivers in accordance with Section 412(d) of the Code).

          "Required Lenders" means (a) so long as any Commitments remain in
           ----------------
effect, Lenders having Commitments representing 51% or more of the sum of the
total Commitments at such time, or (b) if all of the Commitments have
terminated, Lenders holding 51% or more of the aggregate principal amount of the
Loans outstanding at such time.

          "Responsible Officer" means the Treasurer, the Assistant Treasurer,
           -------------------
the Chief Financial Officer or the Controller.

                                       13
<PAGE>

          "Revolving Credit Exposure" means, with respect to any Lender at any
           -------------------------
time, either such Lender's 364-Day Revolving Credit Exposure or such Lender's 3-
Year Revolving Credit Exposure, in each case, at such time.

          "Revolving Loan" means either a 364-Day Revolving Loan or a 3-Year
           --------------
Revolving Loan, as the context may require, and "Revolving Loans" means 364-Day
                                                 ---------------
Revolving Loans and 3-Year Revolving Loans.

          "Revolving Termination Date" means (i) in the case of the 364-Day
           --------------------------
Facility, the 364-Day Revolving Termination Date and (ii) in the case of the 3-
Year Facility, the 3-Year Revolving Termination Date.

          "Secured Nonrecourse Obligations" means and includes (a) secured
           -------------------------------
obligations of the Borrower taken on a consolidated basis where recourse of the
payee of such obligations is expressly limited to an assigned lease or loan
receivable and the Property related thereto and (b) liabilities of the Borrower
taken on a consolidated basis to manufacturers of leased equipment where such
liabilities are payable solely out of revenues derived from the leasing or sale
of such equipment.

          "Securities Issuance" has the meaning assigned to such term in Section
           -------------------
2.06(d).

          "Shareholders' Equity" means, as of any date of determination, the
           --------------------
amount which is shown as "shareholders' equity" (which shall include both common
and preferred equity) in the consolidated balance sheet of the Borrower at such
date.

          "Significant Subsidiary" has the meaning given to such term in
           ----------------------
Regulation S-X under the Securities Act of 1934, as amended.

          "SPPC" means Sierra Pacific Power Company, a Nevada corporation.
           ----

          "SPPC Credit Agreement" means that certain Credit Agreement of even
           ---------------------
date herewith among SPPC, as borrower, Mellon Bank, N.A., as administrative
agent, First Union National Bank and Wells Fargo Bank, N.A., as syndication
agents, and the lenders from time to time party thereto.

          "SPPC First Mortgage Bonds" means obligations issued from time to time
           -------------------------
under, and secured by, the SPPC First Mortgage Indenture.

          "SPPC First Mortgage Indenture" means the Indenture of Mortgage, dated
           -----------------------------
as of December 1, 1940, from SPPC to State Street Bank and Trust Company
(successor to The New England Trust Company), as trustee, and Gerald R. Wheeler
(successor to Leo W. Huegle), as co-Trustee, as modified, amended or
supplemented at any time or from time to time by supplemental indentures.

          "S&P" means Standard & Poor's Ratings Group, a division of The McGraw
           ---
Hill Companies, Inc., and its successor and assigns; provided that if such
corporation (or its successors and assigns) shall for any reason no longer
perform the functions of a securities rating

                                       14
<PAGE>

agency, "S&P" shall be deemed to refer to any other nationally recognized
securities rating agency approved for purposes hereof by the Required Lenders
and the Borrower.

          "Statutory Reserve Rate" means a fraction (expressed as a decimal),
           ----------------------
the numerator of which is the number one and the denominator of which is the
number one minus the aggregate of the maximum reserve percentages (including any
marginal, special, emergency or supplemental reserves) expressed as a decimal
established by the Board to which the Administrative Agent is subject for
eurocurrency funding (currently referred to as "Eurocurrency liabilities" in
Regulation D of the Board). Such reserve percentages shall include those imposed
pursuant to such Regulation D. Eurodollar Loans shall be deemed to constitute
eurocurrency funding and to be subject to such statutory reserve rates without
benefit of or credit for proration, exemptions or offsets that may be available
from time to time to any Lender under such Regulation D or any comparable
regulation. The Statutory Reserve Rate shall be adjusted automatically on and as
of the effective date of any change in any reserve percentage.

          "Subsidiary" shall mean, as to any Person, (i) any corporation more
           ----------
than 50% of whose stock of any class or classes having by the terms thereof
ordinary voting power to elect a majority of the directors of such corporation
(irrespective of whether or not at the time stock of any class or classes of
such corporation shall have or might have voting power by reason of the
happening of any contingency) is at the time owned by such Person and/or one or
more Subsidiaries of such Person and (ii) any partnership, limited liability
company, association, joint venture or other entity in which such Person and/or
one or more Subsidiaries of such Person has more than a 50% equity interest at
the time.

          "Substitute Lender" has the meaning assigned to such term in Section
           -----------------
2.06(g).

          "Syndication Agents" means First Union National Bank and Wells Fargo
           ------------------
Bank, N.A.

          "Tangible Net Worth" shall mean Shareholders' Equity exclusive of any
           ------------------
value attributable to licenses, patents, patent applications, copyrights,
trademarks, trade names, goodwill, experimental or organizational expense and
other like intangibles, treasury stock and unamortized debt discount and
expense.

          "Taxes" means any and all present or future taxes, levies, imposts,
           -----
duties, deductions, charges or withholdings imposed by any Governmental
Authority.

          "Term Loan" has the meaning assigned to such term in Section 2.01(b).
           ---------

          "Term Loan Conversion Date" means the date set forth in the Notice of
           -------------------------
Term Loan Conversion; provided, however, that the Term Loan Conversion Date
                      --------  -------
shall not be a date that occurs later than the 364-Day Revolving Termination
Date.

          "364-Day Availability" means, for any Lender as of any time, the 364-
           --------------------
Day Commitment of such Lender less the 364-Day Revolving Credit Exposure of such
Lender, in each case, as of such time.

                                       15
<PAGE>

          "364-Day Availability Period" means the period from and including the
           ---------------------------
Effective Date to but excluding the earlier of the 364-Day Revolving Termination
Date and the date on which the 364-Day Commitments terminate.

          "364-Day Commitment" means, with respect to each Lender, the
           ------------------
commitment of such Lender to make 364-Day Revolving Loans hereunder, expressed
as an amount representing the maximum aggregate amount of such Lender's 364-Day
Revolving Credit Exposure hereunder, as such commitment may be (a) reduced from
time to time pursuant to Section 2.06 and (b) reduced or increased from time to
time pursuant to assignments by or to such Lender pursuant to Section 9.12. The
initial amount of each Lender's 364-Day Commitment is set forth on Schedule I
under the caption "364-Day Commitments" or in the Assignment and Acceptance
pursuant to which such Lender shall have assumed its 364-Day Commitment, as
applicable. The initial aggregate amount of the Lenders' 364-Day Commitments is
$150,000,000.

          "364-Day Facility" means the several agreement of the Lenders
           ----------------
contained in Section 2.01(a) to make 364-Day Loans.

          "364-Day Note" has the meaning assigned to such term in Section
           ------------
2.08(f).

          "364-Day Revolving Credit Exposure" means, with respect to any Lender
           ---------------------------------
at any time, the aggregate outstanding principal amount of such Lender's 364-Day
Revolving Loans at such time.

          "364-Day Revolving Loan" has the meaning assigned to such term in
           ----------------------
Section 2.01(a).

          "364-Day Revolving Termination Date" means the date which is 364 days
           ----------------------------------
after the Effective Date, as such termination date may be extended from time to
time in accordance with Section 2.06(f).

          "3-Year Availability" means, for any Lender as of any time, the 3-Year
           -------------------
Commitment of such Lender less the 3-Year Revolving Credit Exposure of such
Lender, in each case, as of such time.

          "3-Year Availability Period" means the period from and including the
           --------------------------
Effective Date to but excluding the earlier of the 3-Year Revolving Termination
Date and the date on which the 3-Year Commitments terminate.

          "3-Year Commitment" means, with respect to each Lender, the commitment
           -----------------
of such Lender to make 3-Year Revolving Loans hereunder, expressed as an amount
representing the maximum aggregate amount of such Lender's 3-Year Revolving
Credit Exposure hereunder, as such commitment may be (a) reduced from time to
time pursuant to Section 2.06 and (b) reduced or increased from time to time
pursuant to assignments by or to such Lender pursuant to Section 9.12. The
initial amount of each Lender's 3-Year Commitment is set forth on Schedule I
under the caption "3-Year Commitments" or in the Assignment and Acceptance
pursuant to which such Lender shall have assumed its 3-Year Commitment, as
applicable. The initial aggregate amount of the Lenders' 3-Year Commitments is
$350,000,000.

                                       16
<PAGE>

          "3-Year Facility" means the several agreement of the Lenders contained
           ---------------
in Section 2.01(c) to make 3-Year Loans.

          "3-Year Note" has the meaning assigned to such term in Section
           -----------
2.08(f).

          "3-Year Revolving Credit Exposure" means, with respect to any Lender
           --------------------------------
at any time, the aggregate outstanding principal amount of such Lender's 3-Year
Revolving Loans at such time.

          "3-Year Revolving Loan" has the meaning assigned to such term in
           ---------------------
Section 2.01(c).

          "3-Year Revolving Termination Date" means the date which is the three
           ---------------------------------
year anniversary of the Effective Date.

          "Total Credit Exposure" means, at any time, (a) if the 364-Day
           ---------------------
Commitments have not terminated, the sum of (i) all 364-Day Availability, (ii)
all 364-Day Revolving Credit Exposures, (iii) all 3-Year Availability and (iv)
all 3-Year Revolving Credit Exposures, (b) if the 364-Day Commitments have
terminated and Term Loans are outstanding, the sum of (i) the unpaid balance of
all Term Loans, (ii) all 3-Year Availability and (iii) all 3-Year Revolving
Credit Exposures or (c) if the 364-Day Commitments have terminated and no Term
Loans are outstanding, the sum of (i) all 3-Year Availability and (ii) all 3-
Year Revolving Credit Exposures.

          "Total Indebtedness" means, as of any date of determination, the sum
           ------------------
of all Indebtedness of the Borrower and its consolidated Subsidiaries as of such
date.

          "Type", when used in reference to any Loan or Borrowing, refers to
           ----
whether the rate of interest on such Loan, or on the Loans comprising such
Borrowing, is determined by reference to the Adjusted LIBO Rate or the Alternate
Base Rate.

          "Unfunded Current Liability" of any Plan means the amount, if any, by
           --------------------------
which the value of the accumulated plan benefits under the Plan determined on a
plan termination basis in accordance with actuarial assumptions at such time
consistent with those prescribed by the PBGC for purposes of Section 4044 of
ERISA, exceeds the fair market value of all plan assets allocable to such
liabilities under Title IV of ERISA (excluding any accrued but unpaid
contributions).

          "Wholly-Owned Subsidiary" shall mean, as to any Person, (i) any
           -----------------------
corporation 100% of whose stock of any class or classes having by the terms
thereof ordinary voting power to elect a majority of the directors of such
corporation (irrespective of whether or not at the time stock of any class or
classes of such corporation shall have or might have voting power by reason of
the happening of any contingency) is at the time owned by such Person and/or one
or more Subsidiaries of such Person and (ii) any partnership, limited liability
company, association, joint venture or other entity in which such Person and/or
one or more Subsidiaries of such Person has a 100% equity interest at the time.

          "Year 2000 Compliant" has the meaning assigned to such term in Section
           -------------------
3.21.

                                       17
<PAGE>

          "Year 2000 Plan" has the meaning assigned to such term in Section
           --------------
3.21.

          SECTION 1.02.  Classification of Loans and Borrowings.
                         ---------------------------------------

          For purposes of this Agreement, Loans may be classified and referred
to by Class (e.g., a Revolving Loan or a Term Loan) or by Type (e.g., a
Eurodollar Loan or an ABR Loan) or by Class and Type (e.g., a Eurodollar
Revolving Loan).  Borrowings also may be classified and referred to by Class
(e.g., a "Revolving Borrowing") or by Type (e.g., a "Eurodollar Borrowing") or
by Class and Type (e.g., a "Eurodollar Revolving Borrowing").

          SECTION 1.03  Terms Generally.
                        ---------------

          The definitions of terms herein shall apply equally to the singular
and plural forms of the terms defined.  Whenever the context may require, any
pronoun shall include the corresponding masculine, feminine and neuter forms.
The words "include", "includes" and "including" shall be deemed to be followed
by the phrase "without limitation". The word "will" shall be construed to have
the same meaning and effect as the word "shall".  Unless the context requires
otherwise (a) any definition of or reference to any agreement, instrument or
other document herein shall be construed as referring to such agreement,
instrument or other document as from time to time amended, supplemented or
otherwise modified (subject to any restrictions on such amendments, supplements
or modifications set forth herein), (b) any reference herein to any Person shall
be construed to include such Person's successors and assigns, (c) the words
"herein", "hereof" and "hereunder", and words of similar import, shall be
construed to refer to this Agreement in its entirety and not to any particular
provision hereof and (d) all references herein to Articles, Sections, Exhibits
and Schedules shall be construed to refer to Articles and Sections of, and
Exhibits and Schedules to, this Agreement.

          SECTION 1.04  Accounting Terms; GAAP.
                        ----------------------

          Except as otherwise expressly provided herein, all terms of an
accounting or financial nature shall be construed in accordance with GAAP, as in
effect from time to time.

                                  ARTICLE II
                                  THE CREDITS

          SECTION 2.01  The Commitments.
                        ---------------

          (a)  Subject to the terms and conditions set forth herein, each Lender
agrees to make loans (each such loan, a "364-Day Revolving Loan") to the
                                         ----------------------
Borrower from time to time on any Business Day during the 364-Day Availability
Period in an aggregate principal amount that will not result in (i) such
Lender's 364-Day Revolving Credit Exposure (after giving effect to such 364-Day
Revolving Loans) exceeding such Lender's 364-Day Commitment or (ii) the sum of
the 364-Day Revolving Credit Exposures of all Lenders exceeding the total 364-
Day Commitments.  Within the foregoing limits and subject to the terms and
conditions set forth herein, the Borrower may borrow, prepay and reborrow 364-
Day Revolving Loans.

          (b)  Subject to the terms and conditions set forth herein, each Lender
agrees, so long as no Default or Event of Default has occurred and is
continuing, to consolidate on the

                                       18
<PAGE>

Term Loan Conversion Date all of such Lender's 364-Day Revolving Loans that are
outstanding on the Term Loan Conversion Date (after giving effect to any payment
or prepayment of such 364-Day Revolving Loans made by the Borrower on such date)
into a single loan (each such loan, a "Term Loan") in an amount not to exceed
                                       ---------
the aggregate principal amount of such 364-Day Revolving Loans. 364-Day
Revolving Loans that are consolidated into a Term Loan shall be deemed paid.
Term Loans which are repaid or prepaid may not be reborrowed.

          (c)  Subject to the terms and conditions set forth herein, each Lender
agrees to make loans (each such loan, a "3-Year Revolving Loan") to the Borrower
                                         ---------------------
from time to time on any Business Day during the 3-Year Availability Period in
an aggregate principal amount that will not result in (i) such Lender's 3-Year
Revolving Credit Exposure (after giving effect to such 3-Year Revolving Loans)
exceeding such Lender's 3-Year Commitment or (ii) the sum of the 3-Year
Revolving Credit Exposures of all Lenders exceeding the total 3-Year
Commitments.  Within the foregoing limits and subject to the terms and
conditions set forth herein, the Borrower may borrow, prepay and reborrow 3-Year
Revolving Loans.

          SECTION 2.02  Loans and Borrowings.
                        --------------------

          (a)  Obligations of Lenders. Each Revolving Loan shall be made as part
               ----------------------
of a Borrowing consisting of Loans of the same Type under the same Facility made
by the Lenders ratably in accordance with their respective Commitments for that
Facility. Each Term Loan shall be made in accordance with the procedures set
forth in Section 2.07. The failure of any Lender to make any Loan required to be
made by it shall not relieve any other Lender of its obligations hereunder. The
Commitments of the Lenders are several and no Lender shall be responsible for
any other Lender's failure to make Loans as required.

          (b)  Type of Loans.  Subject to Section 2.12, each Borrowing shall be
               -------------
comprised entirely of ABR Loans or Eurodollar Loans.  Each Lender may, at its
option, make any Eurodollar Loan by causing any domestic or foreign branch or
Affiliate of such Lender to make such Loan; provided that any exercise of such
option shall not affect the obligation of the Borrower to repay such Loan in
accordance with the terms of this Agreement.

          (c)  Minimum Amounts; Limitation on Number of Borrowings.  Each
               ---------------------------------------------------
Revolving Borrowing (whether an ABR Borrowing or a Eurodollar Borrowing) shall
be in an aggregate amount equal to $5,000,000 or a multiple of $1,000,000 in
excess thereof, provided that an ABR Borrowing may be made in an aggregate
amount that is equal to the entire unused balance of the total Commitments of a
Facility. The Borrower may thereafter, upon irrevocable notice to the
Administrative Agent in accordance with Section 2.05(b), (i) elect, as of any
Business Day, in the case of ABR Loans of a Facility, to convert any such ABR
Loans or any part thereof, in an aggregate amount equal to $5,000,000 or a
multiple of $1,000,000 in excess thereof, into Eurodollar Loans, and (ii) elect,
as of the last day of the applicable Interest Period, to continue any Eurodollar
Loans of a Facility having Interest Periods expiring on such day or any part
thereof in an aggregate amount of $5,000,000 or a multiple of $1,000,000 in
excess thereof; provided that, if at any time the aggregate amount of Eurodollar
Loans of a Facility in respect of any Borrowing is reduced by payment,
prepayment or conversion of part thereof to be less than $5,000,000, such
Eurodollar Loans shall automatically convert into ABR Loans. Borrowings of more
than one Type may be outstanding at the same time; provided that there

                                       19
<PAGE>

shall not at any time be more than a total of (x) five Eurodollar Borrowings
outstanding under the 364-Day Facility and (y) five Eurodollar Borrowings
outstanding under the 3-Year Facility.

          (d)  Maximum Duration of Interest Periods.  Notwithstanding any other
               ------------------------------------
provision of this Agreement, until the Term Loan Conversion Date shall have
occurred, the Borrower shall not be entitled to request, or to elect to convert
or continue, any Eurodollar Borrowing under the 364-Day Facility if the Interest
Period requested with respect thereto would end after the 364-Day Revolving
Termination Date. From and after the Term Loan Conversion Date (if any), the
Borrower shall not be entitled to elect to convert or continue any Borrowing if
the Interest Period requested with respect thereto would end after the Final
Repayment Date. Notwithstanding any other provision of this Agreement, the
Borrower shall not be entitled to request, or to elect to convert or continue,
any Eurodollar Borrowing under the 3-Year Facility if the Interest Period
requested with respect thereto would end after the 3-Year Revolving Termination
Date.

          SECTION 2.03  Requests for Revolving Borrowings.
                        ---------------------------------

          To request a Revolving Borrowing under a Facility, the Borrower shall
notify the Administrative Agent of such request by telephone (a) in the case of
a Eurodollar Revolving Borrowing, not later than 12:00 noon., Pittsburgh,
Pennsylvania time, three Business Days before the date of the proposed
Borrowing, or (b) in the case of an ABR Borrowing, not later than 12:00 noon,
Pittsburgh, Pennsylvania time, one Business Day before the date of the proposed
Borrowing.  Each such telephonic Borrowing Request shall be irrevocable and
shall be confirmed promptly by hand delivery or telecopy to the Administrative
Agent of a written Borrowing Request in the form attached hereto as Exhibit B
and signed by the Borrower.  Each such telephonic and written Borrowing Request
shall specify the following information in compliance with Section 2.02:

               (i)   the Facility pursuant to which such Borrowing is to be
     made;

               (ii)  the aggregate amount of the requested Borrowing;

               (iii) the date of such Borrowing, which shall be a Business Day;

               (iv)  whether such Borrowing is to be an ABR Borrowing or a
     Eurodollar Borrowing;

               (v)   in the case of a Eurodollar Borrowing, the initial Interest
     Period to be applicable thereto, which shall be a period contemplated by
     the definition of the term "Interest Period"; and

               (vi)  the location and number of the Borrower's account to which
     funds are to be disbursed, which shall comply with the requirements of
     Section 2.04.

          If no election as to the Type of Revolving Borrowing is specified,
then the requested Revolving Borrowing shall be an ABR Borrowing.  If no
Interest Period is specified with respect to any Eurodollar Revolving Borrowing,
then the Borrower shall be deemed to have selected an Interest Period of one
month's duration.  Promptly following receipt of a Borrowing

                                       20
<PAGE>

Request in accordance with this Section, the Administrative Agent shall advise
each Lender of the details thereof and of the amount of such Lender's Loan to be
made as part of the requested Borrowing.

          SECTION 2.04  Funding of Borrowings.
                        ---------------------

          (a)  Funding by Lenders.  No later than 12:00 noon, Pittsburgh,
               ------------------
Pennsylvania time, on the date specified in each Borrowing Request, each Lender
will make available its Applicable Percentage of each Revolving Borrowing
requested to be made on such date, in Dollars and in immediately available funds
at the account of the Administrative Agent most recently designated by it for
such purpose by notice to the Lenders. The Administrative Agent will make such
Loans available to the Borrower by promptly crediting the amounts so received,
in like funds, to an account of the Borrower maintained with Mellon Bank, N.A.
at the Principal Office and designated by the Borrower in the applicable
Borrowing Request.

          (b)  Presumption by the Administrative Agent.  Unless the
               ---------------------------------------
Administrative Agent shall have received notice from a Lender prior to the
proposed date of any Borrowing that such Lender will not make available to the
Administrative Agent such Lender's share of such Borrowing, the Administrative
Agent may assume that such Lender has made such share available on such date in
accordance with paragraph (a) of this Section and may, in reliance upon such
assumption, make available to the Borrower a corresponding amount.  In such
event, if a Lender has not in fact made its share of the applicable Borrowing
available to the Administrative Agent, then the applicable Lender and the
Borrower severally agree to pay to the Administrative Agent forthwith on demand
such corresponding amount with interest thereon, for each day from and including
the date such amount is made available to the Borrower to but excluding the date
of payment to the Administrative Agent, at (i) in the case of such Lender, the
Federal Funds Effective Rate or (ii) in the case of the Borrower, the interest
rate applicable to the Loans of such Borrowing.  If such Lender pays such amount
to the Administrative Agent, then such amount shall constitute such Lender's
Loan included in such Borrowing.

          SECTION 2.05  Interest Elections.
                        ------------------

          (a)  Elections by the Borrower for Borrowings.  Each Borrowing
               ----------------------------------------
initially shall be of the Type specified in the applicable Borrowing Request
and, in the case of a Eurodollar Borrowing, shall have an initial Interest
Period as specified in such Borrowing Request.  Thereafter, the Borrower may
elect to convert such Borrowing to a different Type or to continue such
Borrowing and, in the case of a Eurodollar Borrowing, may elect Interest Periods
therefor, all as provided in this Section but subject to Section 2.02.  Once
Loans have been made pursuant to a Borrowing, the Borrower may elect to convert
or continue different portions of such Borrowing, in which case each such
portion shall be allocated ratably among the Lenders holding the Loans
comprising such Borrowing, and the Loans comprising each such portion shall be
considered a separate Borrowing.

          (b)  Notice of Elections.  To make an election pursuant to this
               -------------------
Section, the Borrower shall notify the Administrative Agent of such election by
telephone by the time that a Borrowing Request would be required under Section
2.03 if the Borrower were requesting a Revolving Borrowing of the Type resulting
from such election to be made on the effective date

                                       21
<PAGE>

of such election. Each such telephonic Interest Election Request shall be
irrevocable and shall be confirmed promptly by hand delivery or telecopy to the
Administrative Agent of a written Interest Election Request in a form approved
by the Administrative Agent and signed by the Borrower.

          (c)  Information in Interest Election Requests.  Each telephonic and
               -----------------------------------------
written Interest Election Request shall specify the following information in
compliance with Section 2.02:

               (i)   the Borrowing and Facility to which such Interest Election
     Request applies and, if different options are being elected with respect to
     different portions thereof, the portions thereof to be allocated to each
     resulting Borrowing (in which case the information to be specified pursuant
     to clauses (iii) and (iv) of this paragraph shall be specified for each
     resulting Borrowing);

               (ii)  the effective date of the election made pursuant to such
     Interest Election Request, which shall be a Business Day;

               (iii) whether the resulting Borrowing is to be an ABR Borrowing,
     or a Eurodollar Borrowing; and

               (iv)  if the resulting Borrowing is a Eurodollar Borrowing, the
     Interest Period to be applicable thereto after giving effect to such
     election, which shall be a period contemplated by the definition of the
     term "Interest Period".

          If any such Interest Election Request requests a Eurodollar Borrowing
but does not specify an Interest Period, then the Borrower shall be deemed to
have selected an Interest Period of one month's duration.

          (d)  Notice by the Administrative Agent to Lenders. Promptly following
               ---------------------------------------------
receipt of an Interest Election Request, the Administrative Agent shall advise
each Lender of the details thereof and of such Lender's portion of each
resulting Borrowing.

          (e)  Failure to Elect; Events of Default.  If the Borrower fails to
               -----------------------------------
deliver a timely Interest Election Request with respect to a Eurodollar
Borrowing prior to the end of the Interest Period applicable thereto, then,
unless such Borrowing is repaid as provided herein, at the end of such Interest
Period such Borrowing shall be converted to an ABR Borrowing.  Notwithstanding
any contrary provision hereof, if an Event of Default has occurred and is
continuing and the Administrative Agent, at the request of the Required Lenders,
so notifies the Borrower, then, so long as an Event of Default is continuing (i)
no outstanding Borrowing may be converted to or continued as a Eurodollar
Borrowing and (ii) unless repaid, each Eurodollar Borrowing shall be converted
to an ABR Borrowing at the end of the Interest Period applicable thereto.

                                       22
<PAGE>

          SECTION 2.06  Termination, Reduction and Extension of Commitments.
                        ---------------------------------------------------

          (a)  Scheduled Termination. Unless previously terminated, the 364-Day
               ---------------------
Commitments shall terminate on the 364-Day Revolving Termination Date.  Unless
previously terminated, the 3-Year Commitments shall terminate on the 3-Year
Revolving Termination Date.

          (b)  Voluntary Termination or Reduction.  The Borrower may at any time
               ----------------------------------
prior to the Revolving Termination Date of a Facility terminate, or from time to
time reduce, the Commitments under that Facility; provided that (i) each
reduction of the Commitments shall be in an amount that is $10,000,000 or a
multiple of $5,000,000 in excess thereof and (ii) the Borrower shall not
terminate or reduce the Commitments of a Facility if, after giving effect to any
concurrent prepayment of the Loans under that Facility in accordance with
Section 2.09, the sum of the total Revolving Credit Exposures under a Facility
would exceed the total Commitments of that Facility.

          (c)  Notice of Voluntary Termination or Reduction.  The Borrower shall
               --------------------------------------------
notify the Administrative Agent of any election to terminate or reduce the
Commitments under a Facility in accordance with paragraph (b) of this Section at
least three Business Days prior to the effective date of such termination or
reduction, specifying such election and the effective date thereof.  Promptly
following receipt of any such notice, the Administrative Agent shall advise the
Lenders of the contents thereof. Each notice delivered by the Borrower pursuant
to this subsection shall be irrevocable; provided that a notice of termination
of the Commitments of a Facility delivered by the Borrower may state that such
notice is conditioned upon the effectiveness of other credit facilities, in
which case such notice may be revoked by the Borrower (by notice to the
Administrative Agent on or prior to the specified effective date) if such
condition is not satisfied.

          (d)  Mandatory Reduction. So long as the Total Credit Exposure exceeds
               -------------------
$300,000,000 at any time, the 3-Year Commitments shall be permanently reduced
until the Total Credit Exposure (after giving effect to any prepayment of 3-Year
Revolving Loans required by Section 2.09(c)) is less than or equal to
$300,000,000 at such time, by the net proceeds received by the Borrower at such
time from the issuance of securities (whether debt, equity or some variation or
combination thereof) of the Borrower or, if the Borrower is primarily
responsible for the payment thereof, any other Person (a "Securities Issuance").
                                                          -------------------
The Borrower shall, where possible, notify the Administrative Agent of any
Securities Issuance that will trigger a reduction of 3-Year Commitments at least
three Business Days prior to the effective date of such reduction, specifying
the expected effective date thereof.  Promptly following receipt of any such
notice, the Administrative Agent shall advise the Lenders of the contents
thereof.

          (e)  Effect of Termination or Reduction.  Any termination or reduction
               ----------------------------------
of the Commitments of a Facility shall be permanent.  Each reduction of the
Commitments of a Facility shall be made ratably among the Lenders under that
Facility in accordance with their Applicable Percentages.

                                       23
<PAGE>

          (f)  Extension of 364-Day Commitments.
               --------------------------------

               (i)   Not earlier than the date which is 60 days (but not later
than 30 days) prior to the then existing 364-Day Revolving Termination Date (the
"Extension Request Notice Date"), the Borrower may deliver to the Administrative
------------------------------
Agent (which shall promptly transmit the same to each Lender) a notice (an
"Extension Request") requesting that the 364-Day Revolving Termination Date be
 -----------------
extended for an additional 364 days commencing on the then existing 364-Day
Revolving Termination Date.  Not earlier than the date which is 30 days (but not
later than 20 days) prior to the then existing 364-Day Revolving Termination
Date (the period from the Extension Request Notice Date to such date, the
"Extension Request Period"), each Lender (in its sole and absolute discretion
 ------------------------
and after conducting an internal credit review of the Borrower) shall notify the
Administrative Agent of such Lender's willingness or unwillingness to so extend
the 364-Day Revolving Termination Date.  Any Lender which shall fail to so
notify the Administrative Agent within such period shall be deemed to have
declined to extend the 364-Day Revolving Termination Date.  If Lenders having
364-Day Commitments totaling an amount equal to at least 51% of the aggregate
amount of the 364-Day Commitments then in effect agree to such extension by
notice to the Administrative Agent, then (A) subject to clause (iii) below, the
364-Day Revolving Termination Date shall be extended for an additional 364 days
with respect to the 364-Day Commitments of the Lenders so agreeing, and (B)
subject to Section 2.06(g) hereof, the 364-Day Commitment of each Lender not so
agreeing shall expire on the then expiring 364-Day Revolving Termination Date
and the Borrower shall pay or prepay on such day without premium or penalty all
principal of such Lender's 364-Day Revolving Loans together with accrued
interest thereon and all accrued facility and usage fees and other amounts
payable to such Lender hereunder (including, without limitation, amounts payable
pursuant to Section 2.14 hereof as a result of such payment or prepayment);
provided, however, that
--------  -------

               (x)   if Lenders having 364-Day Commitments totaling an amount
          equal to at least 51% of the aggregate amount of the 364-Day
          Commitments then in effect do not agree as contemplated by Section
          2.06(f)(i), then the 364-Day Revolving Termination Date shall not be
          extended pursuant to this Section 2.06(f) and the 364-Day Commitments
          of all of the Lenders shall remain in effect until the 364-Day
          Revolving Termination Date except as otherwise provided in this
          Agreement; and

               (y)   the Borrower may not request any extension of the 364-Day
          Revolving Termination Date pursuant to this Section 2.06(f)(i) more
          frequently than once in any calendar year.

               (ii)  Any 364-Day Revolving Loan by any Lender the 364-Day
     Commitment of which is to terminate pursuant to Section 2.06(f)(i) hereof
     that would otherwise be made or converted by such Lender as a Eurodollar
     Loan having an Interest Period ending after the date such 364-Day
     Commitment is to terminate shall be made or continued as an ABR Loan and
     all ABR Loans of such Lender that would otherwise be converted into
     Eurodollar Loans having such Interest Periods shall remain as ABR Loans.

                                       24
<PAGE>

               (iii)  It shall be a condition precedent to any extension of the
     364-Day Revolving Termination Date that: (a) on the date of such extension
     no Default or Event of Default shall have occurred and be continuing; (b)
     the representations and warranties made by the Borrower in Article III
     shall be true and complete on and as of the date of such extension (or if
     any such representation or warranty is expressly stated to have been made
     as of a specific date, as of such specific date); and (c) except for the
     Mergers, on the date of such extension there shall have been no material
     adverse change in the consolidated financial condition, operations,
     business or prospects taken as a whole of the Borrower and its Subsidiaries
     from that set forth in its financial statements as of December 31, 1998
     referred to in Section 3.06 hereof or, if the Borrower has delivered its
     financial statements for any fiscal year to the Lenders and the
     Administrative Agent pursuant to Section 5.01(a) hereof, as of the date of
     the most recent such financial statements. Each request for an extension of
     the 364-Day Revolving Termination Date pursuant to Section 2.06(f) shall
     constitute a certification by the Borrower to the effect set forth in the
     preceding sentence (both as of the date of such request and, unless the
     Borrower notifies the Administrative Agent prior to the date of such
     extension, as of the date of such extension).

          (g)  Substitute Lenders. In the event any Lender does not agree to any
               ------------------
extension by the date provided pursuant to Section 2.06(f) hereof, then, unless
a Default or an Event of Default shall have occurred and be continuing, the
Borrower may, not later than 10 days following the expiration of the Extension
Request Period, designate one or more other banks (each such bank being herein
called a "Substitute Lender"), which may include any of the Lenders, acceptable
          -----------------
to the Administrative Agent (which acceptance will not be unreasonably
withheld), to assume such non-consenting Lender's 364-Day Commitment hereunder
and to purchase, on or before the date such Lender's 364-Day Revolving Loans
would otherwise be required to be paid or prepaid hereunder, the 364-Day
Revolving Loans and 364-Day Notes of such Lender and such Lender's rights
hereunder in respect thereof, without recourse to or representation or warranty
by, or expense to, such Lender.  In such event, the purchase price shall be
equal to the outstanding principal amount of the 364-Day Revolving Loans and
364-Day Notes payable to such Lender plus any accrued but unpaid interest on
such Loans and Notes and accrued but unpaid facility and usage fees in respect
of such Lender's 364-Day Commitment.  Upon such assumption and purchase and the
receipt by such Lender of any other amounts payable to it by the Borrower under
this Agreement, and subject to the execution and delivery to the Administrative
Agent and such Lender by the Substitute Lender of documentation reasonably
satisfactory to the Administrative Agent and such Lender pursuant to which such
Substitute Lender shall assume the obligations of such original Lender under
this Agreement in respect of its 364-Day Revolving Loans, 364-Day Notes and 364-
Day Commitment and agree to become a "Lender" hereunder (if not already a
Lender) to the extent of the Commitments, Loans and Notes assumed and purchased,
the Substitute Lender shall succeed to the rights, obligations and benefits of
such Lender hereunder in such respect (except for such rights, obligations and
benefits of the Lender as have accrued (other than principal, accrued interest
or facility and usage fees ) or are required to be performed by it on or prior
to the date of such assumption and purchase) (and such Lender shall be released
from its 364-Day Commitment except for any liability arising or relating to any
event occurring prior to the date of such assumption and purchase) and the
Substitute Lender shall be deemed to have agreed to the relevant extension of
the 364-Day Revolving Termination Date and, anything in Section 2.06(f) to the
contrary

                                       25
<PAGE>

notwithstanding, whether such extension is effective shall be determined
accordingly; provided that following any such assumption and purchase the 364-
Day Commitment of each Substitute Lender (including any 364-Day Commitment
theretofore held by it) shall be not less than $10,000,000.

          SECTION 2.07  Term Loan Conversion Option.
                        ----------------------------

          (a)  In the event the Borrower desires to have all of its 364-Day
Revolving Loans consolidated into Term Loans, the Borrower shall deliver written
notice thereof (the "Notice of Term Loan Conversion") to the Administrative
                     ------------------------------
Agent at least 10 days prior to the Term Loan Conversion Date.  Once delivered,
the Notice of Term Loan Conversion shall be irrevocable.

          (b)  The Notice of Term Loan Conversion shall specify:

               (i)   the Term Loan Conversion Date, which shall be a date (A) no
     sooner than 5 days after the date on which the Notice of Term Loan
     Conversion is delivered to the Administrative Agent, (B) no later than the
     364-Day Revolving Termination Date and (C) that is a Business Day;

               (ii)  the principal amount of 364-Day Revolving Loans that are to
     be consolidated into Term Loans on the Term Loan Conversion Date, which
     amount shall be the aggregate principal amount of all 364-Day Revolving
     Loans that will be outstanding on the Term Loan Conversion Date after
     giving effect to all payments or prepayments to be made prior to such date;

               (iii) whether the Term Loans are to be ABR Loans or Eurodollar
     Loans on the Term Loan Conversion Date; and

               (iv)  if the Terms Loans are to be Eurodollar Loans on the Term
     Loan Conversion Date, the duration of the Interest Period applicable
     thereto, provided that if the Notice of Term Loan Conversion fails to
     specify the duration of the Interest Period for any Borrowing comprised of
     Eurodollar Loans, such Interest Period shall be three months.

          (c)  The Administrative Agent will promptly notify each Lender of its
receipt of the Notice of Term Loan Conversion from the Borrower and of the
contents of such notice.

          (d)  If the Borrower requests that Term Loans be made available on the
Term Loan Conversion Date, each Lender shall, on the Term Loan Conversion Date,
be deemed to have made available to the Borrower its Applicable Percentage of
the Term Loans requested and the Borrower shall be deemed to have applied the
full amount of such proceeds to the repayment of the 364-Day Revolving Loans
previously made by such Lender to such Borrower.

          (e)  Unless all the Lenders otherwise consent, (i) the Borrower may
not deliver any Notice of Term Loan Conversion so long as any Default or Event
of Default has occurred and is continuing and (ii) no consolidation of 364-Day
Revolving Loans into Term Loans pursuant to any validly given Notice of Term
Loan Conversion shall be permitted if on the Term

                                       26
<PAGE>

Loan Conversion Date specified a Default or an Event of Default shall have
occurred and is continuing.

          SECTION 2.08  Repayment of Loans; Evidence of Debt.
                        ------------------------------------

          (a)  Repayment. The Borrower hereby unconditionally promises to pay to
               ---------
the Administrative Agent for account of the Lenders (i) the outstanding
principal amount of the 364-Day Revolving Loans on the 364-Day Revolving
Termination Date, unless the Borrower elects to consolidate all of such 364-Day
Revolving Loans into Term Loans on or before such date; (ii) the outstanding
principal amount of all Term Loans made to the Borrower on the Final Repayment
Date and (iii) the outstanding principal amount of the 3-Year Revolving Loans on
the 3-Year Revolving Termination Date.

          (b)  Manner of Payment.  Prior to any repayment or prepayment of any
               -----------------
Borrowings hereunder, the Borrower shall select the Borrowing or Borrowings to
be paid and shall notify the Administrative Agent by telephone (confirmed by
telecopy) of such selection not later than 12:00 noon, Pittsburgh, Pennsylvania
time, three Business Days before the scheduled date of such repayment or
prepayment; provided that each repayment or prepayment of Borrowings shall be
applied to repay or prepay any outstanding ABR Borrowings before any other
Borrowings. If the Borrower fails to make a timely selection of the Borrowing or
Borrowings to be repaid or prepaid, such payment shall be applied, first, to pay
any outstanding ABR Borrowings and, second, to other Borrowings in the order of
the remaining duration of their respective Interest Periods (the Borrowing with
the shortest remaining Interest Period to be repaid first). Each payment of a
Revolving Borrowing shall be applied ratably to the Loans included in such
Borrowing.

          (c)  Maintenance of Loan Accounts by Lenders.  Each Lender shall
               ---------------------------------------
maintain in accordance with its usual practice an account or accounts evidencing
the indebtedness of the Borrower to such Lender resulting from each Loan made by
such Lender, including the amounts of principal and interest payable and paid to
such Lender from time to time hereunder.

          (d)  Maintenance of Loan Accounts by the Administrative Agent.  The
               --------------------------------------------------------
Administrative Agent shall maintain accounts in which it shall record (i) the
amount of each Loan made hereunder, the Facility pursuant to which such Loan was
made, the Class and Type thereof and the Interest Period applicable thereto,
(ii) the amount of any principal or interest due and payable or to become due
and payable from the Borrower to each Lender hereunder and (iii) the amount of
any sum received by the Administrative Agent hereunder for the account of the
Lenders and each Lender's share thereof.

          (e)  Effect of Entries.  The entries made in the accounts maintained
               ------------------
pursuant to paragraph (c) and (d) of this Section shall be prima facie evidence
of the existence and amounts of the obligations recorded therein; provided that
the failure of any Lender or the Administrative Agent to maintain such accounts
or any error therein shall not in any manner affect the obligation of the
Borrower to repay the Loans in accordance with the terms of this Agreement.

          (f)  Notes.  Any Lender may request that 364-Day Revolving Loans and
               -----
Term Loan made by it be evidenced by a promissory note (each a "364-Day Note")
                                                                ------------
in substantially the

                                       27
<PAGE>

form of Exhibit C-1. In such event, the Borrower shall prepare, execute and
deliver to such Lender a 364-Day Note payable to the order of such Lender (or,
if requested by such Lender, to such Lender and its registered assigns) and in
the form of Exhibit C-1. Thereafter, the 364-Day Revolving Loans and Term Loans
evidenced by such 364-Day Note and interest thereon shall at all times
(including after assignment pursuant to Section 9.12) be represented by one or
more 364-Day Notes in such form payable to the order of the payee named therein
(or, if such 364-Day Note is a registered note, to such payee and its registered
assigns). Any Lender may request that 3-Year Revolving Loans made by it be
evidenced by a promissory note (each a "3-Year Note") in substantially the form
                                        -----------
of Exhibit C-2. In such event, the Borrower shall prepare, execute and deliver
to such Lender a 3-Year Note payable to the order of such Lender (or, if
requested by such Lender, to such Lender and its registered assigns) and in the
form of Exhibit C-2. Thereafter, the 3-Year Revolving Loans evidenced by such 3-
Year Note and interest thereon shall at all times (including after assignment
pursuant to Section 9.12) be represented by one or more 3-Year Notes in such
form payable to the order of the payee named therein (or, if such 3-Year Note is
a registered note, to such payee and its registered assigns)

          SECTION 2.09  Prepayment of Loans.
                        -------------------

          (a)  Optional Prepayments Right to Prepay Borrowings.  The Borrower
               -----------------------------------------------
shall have the right at any time and from time to time to prepay any Borrowing
in whole or in part, subject to the requirements of this Section.

          (b)  Notices, Etc.  The Borrower shall notify the Administrative Agent
               -------------
by telephone (confirmed by telecopy) of any optional prepayment hereunder (i) in
the case of prepayment of a Eurodollar Borrowing, not later than 12:00 noon,
Pittsburgh, Pennsylvania time, three Business Days before the date of
prepayment, or (ii) in the case of prepayment of an ABR Borrowing, not later
than 12:00 noon, Pittsburgh, Pennsylvania time, one Business Day before the date
of prepayment. Each such notice shall be irrevocable and shall specify the
prepayment date and the principal amount of each Borrowing or portion thereof to
be prepaid; provided that, if a notice of prepayment is given in connection with
a conditional notice of termination of the Commitments as contemplated by
Section 2.06(c), then such notice of prepayment may be revoked if such notice of
termination is revoked in accordance with Section 2.06(d). Promptly following
receipt of any such notice relating to a Borrowing, the Administrative Agent
shall advise the Lenders of the contents thereof. Each partial prepayment of any
Borrowing shall be in an aggregate principal amount equal to $5,000,000 or a
multiple of $1,000,000 in excess thereof, provided that if any prepayment of
Eurodollar Loans made pursuant to a single Borrowing shall reduce the
outstanding 364-Day Revolving Loans made pursuant to such Borrowing to an amount
less than $5,000,000, such outstanding Loans shall immediately be converted into
ABR Loans. Each prepayment of a Borrowing shall be applied ratably to the Loans
included in the prepaid Borrowing. Prepayments shall be accompanied by accrued
interest to the extent required by Section 2.11 and shall be made in the manner
specified in this Section 2.09(b).

          (c)  Mandatory Prepayments.  If at any time, the sum of the 364-Day
               ---------------------
Revolving Credit Exposures exceeds the sum of the 364-Day Commitments, the
Borrower shall prepay 364-Day Revolving Loans by the amount of such excess.  If
at any time, the sum of the 3-Year Revolving Credit Exposures exceeds the sum of
the 3-Year Commitments, the Borrower shall prepay 3-Year Revolving Loans by the
amount of such excess.  If at the time of any

                                       28
<PAGE>

Securities Issuance the Total Credit Exposure exceeds $300,000,000, the Borrower
shall apply the net proceeds of such Securities Issuance to prepay 3-Year
Revolving Loans until such time as the Total Credit Exposure is reduced to
$300,000,000. With respect to each prepayment of Loans required by this Section
2.09(c), the Borrower may designate the Types of 3-Year Revolving Loans which
are to be prepaid and, in the case of Eurodollar Loans, the specific Borrowing
or Borrowings pursuant to which such Eurodollar Loans were made, provided that:
(i) if any prepayment of Eurodollar Loans made pursuant to a single Borrowing
shall reduce the outstanding 3-Year Revolving Loans made pursuant to such
Borrowing to an amount less than $5,000,000, such outstanding Loans shall
immediately be converted into ABR Loans; and (ii) each prepayment of any 3-Year
Revolving Loans made pursuant to a Borrowing shall be applied pro rata among
                                                              --- ----
such Loans. In the absence of a designation by the Borrower as described in the
preceding sentence, the Administrative Agent shall, subject to the above, make
such designation in its sole discretion.

          SECTION 2.10  Fees.
                        ----

          (a)  Facility Fee. The Borrower shall pay the Administrative Agent for
               ------------
the account of each Lender a facility fee for the period from and including the
Effective Date to but excluding the later of (i) the 364-Day Revolving
Termination Date and (ii) the 3-Year Revolving Termination Date (or such earlier
date on which the total Commitments shall have been terminated) (the "Final Fee
                                                                      ---------
Payment Date") computed at a rate per annum equal to the Applicable Rate on each
------------
Lender's daily average Commitment, such fee to be paid quarterly in arrears on
each Quarterly Date and on the Final Fee Payment Date.  The facility fee shall
be calculated on the basis of the actual number of days elapsed in a year of 360
days.

          (b)  Usage Fee.  The Borrower shall pay the Administrative Agent for
               ---------
the account of each Lender a usage fee for each day during the period from and
including the date hereof to but excluding the Final Fee Payment Date on which
the aggregate principal amount of the then outstanding Revolving Loans exceeds
33% or 66%, as the case may be, of the total Commitments hereunder computed at a
rate per annum equal to the Applicable Rate for such percentage of usage on the
daily average aggregate principal amount of the Revolving Loans then
outstanding, such fee to be paid quarterly in arrears on each Quarterly Date and
on the Final Fee Payment Date.  The usage fee shall be calculated on the basis
of the actual number of days elapsed in a year of 360 days.

          (c)  Payment of Fees.  All fees payable hereunder shall be paid on the
               ---------------
dates due, in immediately available funds, to the Administrative Agent for
distribution, in the case of facility and usage fees, to the Lenders entitled
thereto.

          SECTION 2.11  Interest.
                        --------

          (a)  ABR Loans.  The Loans comprising each ABR Revolving Borrowing
               ---------
shall bear interest at a rate per annum equal to the Alternate Base Rate.

          (b)  Eurodollar Loans.  The Loans comprising each Eurodollar Borrowing
               ----------------
shall bear interest at a rate per annum equal to the Adjusted LIBO Rate for the
Interest Period in effect for such Borrowing plus the Applicable Rate.

                                       29
<PAGE>

          (c)  Default Interest. Notwithstanding the foregoing, if any principal
               ----------------
of or interest on any Loan or any fee or other amount payable by the Borrower
hereunder is not paid when due, whether at stated maturity, upon acceleration or
otherwise, such overdue amount shall bear interest, after as well as before
judgment, at a rate per annum equal to (i) in the case of overdue principal of
any Loan, 2% plus the rate otherwise applicable to such Loan as provided above
or (ii) in the case of any other amount, 2% plus the rate applicable to ABR
Loans as provided in paragraph (a) of this Section.

          (d)  Payment of Interest.  Accrued interest on each Loan shall be
               -------------------
payable in arrears on each Interest Payment Date for such Loan and (i) in the
case of Revolving Loans of a Facility, upon termination of the Commitments under
that Facility and (ii) in the case of Term Loans, on the Final Repayment Date;
provided that (x) interest accrued pursuant to paragraph (c) of this Section
shall be payable on demand, (y) in the event of any repayment or prepayment of
any Loan (other than a prepayment of an ABR Revolving Loan prior to the 364-Day
Revolving Termination Date or 3-Year Revolving Terminate Date, as the case may
be), accrued interest on the principal amount repaid or prepaid shall be payable
on the date of such repayment or prepayment and (z) in the event of any
conversion of any Eurodollar Borrowing prior to the end of the current Interest
Period therefor, accrued interest on such Borrowing shall be payable on the
effective date of such conversion.

          (e)  Computation.  All interest hereunder shall be computed on the
               -----------
basis of a year of 360 days, except that interest computed by reference to the
Alternate Base Rate at times when the Alternate Base Rate is based on the Prime
Rate shall be computed on the basis of a year of 365 days (or 366 days in a leap
year), and in each case shall be payable for the actual number of days elapsed
(including the first day but excluding the last day).  The applicable Alternate
Base Rate, Adjusted LIBO Rate or LIBO Rate shall be determined by the
Administrative Agent, and such determination shall be conclusive, absent
manifest error.

          SECTION 2.12  Alternate Rate of Interest.  If prior to the
                        --------------------------
commencement of any Interest Period for a Eurodollar Borrowing:

          (a)  the Administrative Agent determines (which determination shall be
conclusive, absent manifest error) that adequate and reasonable means do not
exist for ascertaining the Adjusted LIBO Rate or the LIBO Rate, as applicable,
for such Interest Period; or

          (b)  the Administrative Agent is advised by the Required Lenders that
the Adjusted LIBO Rate or the LIBO Rate, as applicable, for such Interest Period
will not adequately and fairly reflect the cost to such Lenders (or Lender) of
making or maintaining their Loans (or its Loan) included in such Borrowing for
such Interest Period;

then the Administrative Agent shall give notice thereof to the Borrower and the
Lenders by telephone or telecopy as promptly as practicable thereafter and,
until the Administrative Agent notifies the Borrower and the Lenders that the
circumstances giving rise to such notice no longer exist, (i) any Interest
Election Request that requests the conversion of any Borrowing to, or
continuation of any Borrowing as, a Eurodollar Borrowing shall be ineffective,
and (ii) if any Borrowing Request requests a Eurodollar Revolving Borrowing,
such Borrowing shall be made as an ABR Revolving Borrowing.

                                       30
<PAGE>

          SECTION 2.13  Increased Costs.
                        ---------------

          (a)  Increased Costs Generally.  If any Change in Law shall:
               -------------------------

               (i)  impose, modify or deem applicable any reserve, special
     deposit or similar requirement against assets of, deposits with or for the
     account of, or credit extended by, any Lender or its Parent (except any
     such reserve requirement reflected in the Adjusted LIBO Rate); or

               (ii) impose on any Lender or its Parent or the London interbank
     market any other condition affecting this Agreement or Eurodollar Loans
     made by such Lender;

and the result of any of the foregoing shall be to increase the cost to such
Lender or its Parent of making or maintaining any Eurodollar Loan (or of
maintaining its obligation to make any such Loan) or to reduce the amount of any
sum received or receivable by such Lender hereunder (whether of principal,
interest or otherwise), then the Borrower will pay to such Lender such
additional amount or amounts as will compensate such Lender or its Parent, as
the case may be, for such additional costs incurred or reduction suffered.

          (b)  Capital Requirements. If any Lender determines that any Change in
               --------------------
Law regarding capital requirements has or would have the effect of reducing the
rate of return on such Lender's capital or on the capital of its Parent as a
consequence of this Agreement or the Loans made by such Lender to a level below
that which such Lender or its Parent could have achieved but for such Change in
Law (taking into consideration such Lender's policies and the policies of its
Parent with respect to capital adequacy), then from time to time the Borrower
will pay to such Lender such additional amount or amounts as will compensate
such Lender or its Parent for any such reduction suffered.

          (c)  Certificates from Lenders.  A certificate of a Lender setting
               -------------------------
forth the amount or amounts necessary to compensate such Lender or its Parent,
as the case may be, as specified in paragraph (a) or (b) of this Section shall
be delivered to the Borrower and shall be conclusive, absent manifest error.
The Borrower shall pay such Lender the amount shown as due on any such
certificate within 10 days after receipt thereof.

          (d)  Delay in Requests.  Failure or delay on the part of any Lender to
               -----------------
demand compensation pursuant to this Section shall not constitute a waiver of
such Lender's right to demand such compensation.

          SECTION 2.14  Break Funding Payments.  In the event of (a) the payment
                        ----------------------
of any principal of any Eurodollar Loan other than on the last day of an
Interest Period applicable thereto (including as a result of an Event of
Default), (b) the conversion of Eurodollar Loan other than on the last day of
the Interest Period applicable thereto, (c) the failure to borrow, convert,
continue or prepay any Revolving Loan on the date specified in any notice
delivered pursuant hereto (regardless of whether such notice is permitted to be
revocable under Section 2.09(b) and is revoked in accordance herewith), or (d)
the assignment of any Eurodollar Loan other than on the last day of the Interest
Period applicable thereto as a result of a request by the Borrower pursuant to
Section 2.17, then, in any such event, the Borrower shall compensate each Lender
for the loss, cost and expense attributable to such event. In the case of a
Eurodollar Loan, the loss to

                                       31
<PAGE>

any Lender attributable to any such event shall be deemed to include an amount
determined by such Lender to be equal to the excess, if any, of (i) the amount
of interest that such Lender would pay for a deposit equal to the principal
amount of such Loan for the period from the date of such payment, conversion,
failure or assignment to the last day of the then current Interest Period for
such Loan (or, in the case of a failure to borrow, convert or continue, the
duration of the Interest Period that would have resulted from such borrowing,
conversion or continuation) if the interest rate payable on such deposit were
equal to the Adjusted LIBO Rate for such Interest Period, over (ii) the amount
of interest that such Lender would earn on such principal amount for such period
if such Lender were to invest such principal amount for such period at the
interest rate that would be bid by such Lender (or an Affiliate of such Lender)
for dollar deposits from other banks in the eurodollar market at the
commencement of such period. A certificate of any Lender setting forth any
amount or amounts that such Lender is entitled to receive pursuant to this
Section shall be delivered to the Borrower and shall be conclusive, absent
manifest error. The Borrower shall pay such Lender the amount shown as due on
any such certificate within 10 days after receipt thereof.

          SECTION 2.15  Taxes.
                        -----

          (a)  Payments Free of Taxes.  Any and all payments by or on account of
               ----------------------
any obligation of the Borrower hereunder shall be made free and clear of and
without deduction for any Indemnified Taxes or Other Taxes; provided that if the
Borrower shall be required to deduct any Indemnified Taxes or Other Taxes from
such payments, then (i) the sum payable shall be increased as necessary so that
after making all required deductions (including deductions applicable to
additional sums payable under this Section) the Administrative Agent, Arranger,
Syndication Agent or Lender (as the case may be) receives an amount equal to the
sum it would have received had no such deductions been made, (ii) the Borrower
shall make such deductions and (iii) the Borrower shall pay the full amount
deducted to the relevant Governmental Authority in accordance with applicable
Law.

          (b)  Payment of Other Taxes by the Borrower. In addition, the Borrower
               --------------------------------------
shall pay any Other Taxes to the relevant Governmental Authority in accordance
with applicable Law.

          (c)  Indemnification by the Borrower. The Borrower shall indemnify the
               -------------------------------
Administrative Agent, the Arranger, each Syndication Agent  and each Lender,
within 10 days after written demand therefor, for the full amount of any
Indemnified Taxes or Other Taxes (including Indemnified Taxes or Other Taxes
imposed or asserted on or attributable to amounts payable under this Section)
paid by the Administrative Agent, Arranger, such Syndication Agent or such
Lender, as the case may be, and any penalties, interest and reasonable expenses
arising therefrom or with respect thereto, whether or not such Indemnified Taxes
or Other Taxes were correctly or legally imposed or asserted by the relevant
Governmental Authority. A certificate as to the amount of such payment or
liability delivered to the Borrower by a Lender, the Arranger, a Syndication
Agent or by the Administrative Agent (on its own behalf or on behalf of a
Lender, the Arranger or a Syndication Agent) shall be conclusive, absent
manifest error.

          (d)  Evidence of Payments. As soon as practicable after any payment of
               ---------------------
Indemnified Taxes or Other Taxes by the Borrower to a Governmental Authority,
the Borrower shall deliver to the Administrative Agent the original or a
certified copy of a receipt issued by

                                       32
<PAGE>

such Governmental Authority evidencing such payment, a copy of the return
reporting such payment or other evidence of such payment reasonably satisfactory
to the Administrative Agent.

          (e)  Foreign Lenders. Any Foreign Lender that is entitled to an
               ----------------
exemption from or reduction of withholding tax under the Law of the jurisdiction
in which the Borrower is located, or any treaty to which such jurisdiction is a
party, with respect to payments under this Agreement shall deliver to the
Borrower (with a copy to the Administrative Agent), at the time or times
prescribed by applicable Law or reasonably requested by the Borrower, such
properly completed and executed documentation prescribed by applicable Law as
will permit such payments to be made without withholding or at a reduced rate.

          SECTION 2.16  Payments Generally; Pro Rata Treatment; Sharing of Set-
                        ------------------------------------------------------
offs.
----

          (a)  Payments by the Borrower.  The Borrower shall make each payment
               ------------------------
required to be made by it hereunder (whether of principal, interest or fees, or
under Section 2.13, 2.14 or 2.15, or otherwise) prior to 1:00 PM, Pittsburgh,
Pennsylvania time, on the date when due, in immediately available funds, without
set-off or counterclaim. Any amounts received after such time on any such date
shall be deemed to have been received on the next succeeding Business Day for
purposes of calculating interest thereon. All such payments shall be made to the
Administrative Agent at its Principal Office and to such account at its
Principal Office as the Administrative Agent shall specify to the Borrower,
except that payments pursuant to Sections 2.13, 2.14, 2.15 and 9.04 shall be
made directly to the Persons entitled thereto. The Administrative Agent shall
distribute any such payments received by it for account of any other Person to
the appropriate recipient promptly following receipt thereof. If any payment
hereunder shall be due on a day that is not a Business Day, the date for payment
shall be extended to the next succeeding Business Day and, in the case of any
payment accruing interest, interest thereon shall be payable for the period of
such extension. All payments hereunder shall be made in Dollars.

          (b)  Application of Insufficient Payments. If at any time insufficient
               ------------------------------------
funds are received by and available to the Administrative Agent to pay fully all
amounts of principal, interest and fees then due hereunder, such funds shall be
applied (i) first, to pay interest and fees then due hereunder, ratably among
the parties entitled thereto in accordance with the amounts of interest and fees
then due to such parties and ratably between the 364-Day Facility and 3-Year
Facility, and (ii) second, to pay principal then due hereunder, ratably among
the parties entitled thereto in accordance with the amounts of principal then
due to such parties and ratably between the 364-Day Facility and 3-Year
Facility.

          (c)  Pro Rata Treatment.  Except to the extent otherwise provided
               ------------------
herein:  (i) each Revolving Borrowing shall be made from the Lenders, each
payment of facility and usage fees under Section 2.10 shall be made for account
of the Lenders, and each termination or reduction of the amount of the
Commitments under a Facility pursuant to Section 2.06 shall be applied to the
respective Commitments of the Lenders under the applicable Facility, pro rata
according to the amounts of their respective Commitments under such Facility;
(ii) each Borrowing under a Facility shall be allocated pro rata among the
Lenders according to the amounts of their respective Commitments (in the case of
the making of Revolving Loans) under such Facility or their respective Loans (in
the case of conversions and continuations of Loans);

                                       33
<PAGE>

(iii) each payment or prepayment of principal of Loans by the Borrower shall be
made for account of the Lenders pro rata in accordance with the respective
unpaid principal amounts of the Loans held by them; and (iv) each payment of
interest on Loans by the Borrower shall be made for account of the Lenders pro
rata in accordance with the amounts of interest on such Loans then due and
payable to the respective Lenders.

          (d)  Sharing of Payments by Lenders.  If any Lender shall, by
               ------------------------------
exercising any right of set-off or counterclaim or otherwise, obtain payment in
respect of any principal of or interest on any of its Loans resulting in such
Lender receiving payment of a greater proportion of the aggregate amount of its
Loans and accrued interest thereon then due than the proportion received by any
other Lender, then the Lender receiving such greater proportion shall purchase
(for cash at face value) participations in the Loans of other Lenders to the
extent necessary so that the benefit of all such payments shall be shared by the
Lenders ratably in accordance with the aggregate amount of principal of and
accrued interest on their respective Loans; provided that (i) if any such
participations are purchased and all or any portion of the payment giving rise
thereto is recovered, such participations shall be rescinded and the purchase
price restored to the extent of such recovery, without interest, and (ii) the
provisions of this paragraph shall not be construed to apply to any payment made
by the Borrower pursuant to and in accordance with the express terms of this
Agreement or any payment obtained by a Lender as consideration for the
assignment of or sale of a participation in any of its Loans to any assignee or
participant, other than to the Borrower or any Subsidiary or Affiliate thereof
(as to which the provisions of this paragraph shall apply). The Borrower
consents to the foregoing and agrees, to the extent it may effectively do so
under applicable Law, that any Lender acquiring a participation pursuant to the
foregoing arrangements may exercise against the Borrower rights of set-off and
counterclaim with respect to such participation as fully as if such Lender were
a direct creditor of the Borrower in the amount of such participation.

          (e)  Presumptions of Payment.  Unless the Administrative Agent shall
               -----------------------
have received notice from the Borrower prior to the date on which any payment is
due to the Administrative Agent for account of the Lenders hereunder that the
Borrower will not make such payment, the Administrative Agent may assume that
the Borrower has made such payment on such date in accordance herewith and may,
in reliance upon such assumption, distribute to the Lenders the amount due.  In
such event, if the Borrower has not in fact made such payment, then each of the
Lenders severally agrees to repay to the Administrative Agent forthwith on
demand the amount so distributed to such Lender with interest thereon, for each
day from and including the date such amount is distributed to it to but
excluding the date of payment to the Administrative Agent, at the Federal Funds
Effective Rate.

          (f)  Certain Deductions by the Administrative Agent.  If any Lender
               ----------------------------------------------
shall fail to make any payment required to be made by it pursuant to Section
2.04(b) or 2.16(e), then the Administrative Agent may, in its discretion
(notwithstanding any contrary provision hereof), apply any amounts thereafter
received by the Administrative Agent for account of such Lender to satisfy such
Lender's obligations under such Sections until all such unsatisfied obligations
are fully paid.

                                       34
<PAGE>

          SECTION 2.17  Mitigation Obligations; Replacement of Lenders.
                        ----------------------------------------------

          (a) Designation of a Different Lending Office.  If any Lender requests
              -----------------------------------------
compensation under Section 2.13, or if the Borrower is required to pay any
additional amount to any Lender or any Governmental Authority for account of any
Lender pursuant to Section 2.15, then such Lender shall use reasonable efforts
to designate a different lending office for funding or booking its Loans
hereunder or to assign its rights and obligations hereunder to another of its
offices, branches or affiliates, if, in the judgment of such Lender, such
designation or assignment (i) would eliminate or reduce amounts payable pursuant
to Section 2.13 or 2.15, as the case may be, in the future and (ii) would not
subject such Lender to any unreimbursed cost or expense and would not otherwise
be disadvantageous to such Lender.  The Borrower hereby agrees to pay all
reasonable costs and expenses incurred by any Lender in connection with any such
designation or assignment.

          (b) Replacement of Lenders.  If any Lender requests compensation under
              ----------------------
Section 2.13, or if the Borrower is required to pay any additional amount to any
Lender or any Governmental Authority for account of any Lender pursuant to
Section 2.15, or if any Lender defaults in its obligation to fund Loans
hereunder, then the Borrower may, at its sole expense and effort, upon notice to
such Lender and the Administrative Agent, require such Lender to assign and
delegate, without recourse (in accordance with and subject to the restrictions
contained in Section 9.12), all its interests, rights and obligations under this
Agreement to an assignee that shall assume such obligations (which assignee may
be another Lender, if a Lender accepts such assignment); provided that (i) the
Borrower shall have received the prior consent of the Administrative Agent,
which consent shall not unreasonably be withheld, (ii) such Lender shall have
received payment of an amount equal to the outstanding principal of its Loans,
accrued interest thereon, accrued fees and all other amounts payable to it
hereunder, from the assignee (to the extent of such outstanding principal and
accrued interest and fees) or the Borrower (in the case of all other amounts)
and (iii) in the case of any such assignment resulting from a claim for
compensation under Section 2.13 or payments required to be made pursuant to
Section 2.15, such assignment will result in a reduction in such compensation or
payments.  A Lender shall not be required to make any such assignment and
delegation if, prior thereto, as a result of a waiver by such Lender or
otherwise, the circumstances entitling the Borrower to require such assignment
and delegation cease to apply.

                                  ARTICLE III
                        REPRESENTATIONS AND WARRANTIES

          The Borrower hereby represents and warrants to the Administrative
Agent and each Lender as follows:

          SECTION 3.01  Corporate Status.
                        ----------------

          The Borrower and each Subsidiary of the Borrower is a corporation,
trust or limited liability company duly organized, validly existing and in good
standing under the Laws of its jurisdiction of organization.  The Borrower and
each Subsidiary of the Borrower has the corporate power and authority to own its
Property and to transact the business in which it is engaged or presently
proposes to engage.  The Borrower and each Subsidiary of the Borrower is

                                       35
<PAGE>

duly qualified to do business as a foreign corporation, trust or limited
liability company and is in good standing in all jurisdictions in which the
ownership of its properties or the nature of its activities or both makes such
qualification necessary or advisable. Schedule II states as of the date hereof
the jurisdiction of organization of the Borrower and each Subsidiary of the
Borrower, and the jurisdictions in which the Borrower and each Subsidiary of the
Borrower is qualified to do business as a foreign corporation, trust or limited
liability company.

          SECTION 3.02  Corporate Power and Authorization.
                        ---------------------------------

          The Borrower has the corporate power and authority to execute,
deliver, perform, and take all actions contemplated by, each of the Loan
Documents to which it is a party, and all such action has been duly and validly
authorized by all necessary corporate proceedings on its part.  Without limiting
the foregoing, the Borrower has the corporate power and authority to borrow
pursuant to the Loan Documents to the fullest extent permitted hereby and
thereby from time to time, and has taken all necessary corporate action to
authorize such borrowings.

          SECTION 3.03  Execution and Binding Effect.
                        ----------------------------

          This Agreement and each of the other Loan Documents to which the
Borrower is a party and which is required to be delivered on or before the
Effective Date pursuant to Section 4.01 has been duly and validly executed and
delivered by the Borrower.  This Agreement and each such other Loan Document
constitutes, and when executed and delivered by the Borrower will constitute,
the legal, valid and binding obligation of the Borrower, enforceable against the
Borrower in accordance with its terms, except as the enforceability hereof or
thereof may be limited by bankruptcy, insolvency or other similar laws of
general application affecting the enforcement of creditors' rights or by general
principles of equity limiting the availability of equitable remedies.

          SECTION 3.04  Governmental Approvals and Filings.
                        ----------------------------------

          No Governmental Action is required for the due execution, delivery and
performance by the Borrower of this Agreement or any of the other Loan Documents
to which it is a party.  All Governmental Actions required to be taken in order
the effect the Mergers have been taken.

          SECTION 3.05  Absence of Conflicts.
                        --------------------

          Neither the execution and delivery of any of the Loan Documents by the
Borrower, nor the consummation of the transactions herein or therein
contemplated by the Borrower, nor the performance of or the compliance with the
terms and conditions hereof or thereof by the Borrower, nor the consummation of
the Mergers, does or will:

          (a) violate or conflict with any Law; or

          (b) violate, conflict with or result in a breach of any term or
condition of, or constitute a default under, or result in (or give rise to any
              --                             --
right, contingent or otherwise, of any Person to cause) any termination,
cancellation, prepayment or acceleration of performance of, or result in the
                                                            --
creation or imposition of (or give rise to any obligation, contingent or
otherwise, to

                                       36
<PAGE>

create or impose) any Lien upon any of the Property of the Borrower or any of
the Borrower pursuant to, or otherwise result in (or give rise to any right,
                          --
contingent or otherwise, of any Person to cause) any change in any right, power,
privilege, duty or obligation of the Borrower or any Subsidiary of the Borrower
under or in connection with,

               (i)   the articles of incorporation or by-laws (or other
     constituent documents) of the Borrower or any Subsidiary of the Borrower;

               (ii)  any agreement or instrument creating, evidencing or
     securing any Indebtedness to which the Borrower or any Subsidiary of the
     Borrower is a party or by which any of them or any of their respective
     properties (now owned or hereafter acquired) may be subject or bound; or

               (iii) any other material agreement or instrument to which the
     Borrower or any Subsidiary of the Borrower is a party or by which any of
     them or any of their respective properties (now owned or hereafter
     acquired) may be subject or bound.

          SECTION 3.06  Audited Financial Statements.
                        ----------------------------

          The Borrower has heretofore furnished to each of the Agents and each
of the Lenders consolidated balance sheets of the Borrower, its consolidated
Subsidiaries and NPC as of December 31, 1996, 1997 and 1998 and the related
consolidated statements of income, retained earnings and changes in cash flows
for the fiscal years then ended, as examined and reported on by independent
certified public accountants for the Borrower, who delivered an unqualified
opinion in respect thereof.  Such financial statements (including the notes
thereto) present fairly the financial condition of the Borrower and its
consolidated Subsidiaries as of the end of each such fiscal year and the results
of their operations and their retained earnings and changes in cash flows for
the fiscal years then ended, all in conformity with GAAP.

          SECTION 3.07  Interim Financial Statements.
                        ----------------------------

          The Borrower has heretofore furnished to each of the Agents and each
of the Lenders an interim consolidated balance sheet of the Borrower, its
consolidated Subsidiaries and NPC as of the end of the first fiscal quarter of
the fiscal year beginning January 1, 1999, together with the related
consolidated statements of income, retained earnings and changes in cash flows
for the applicable fiscal period ending on such date.  Such financial statements
(including the notes thereto) present fairly the financial condition of the
Borrower and its consolidated Subsidiaries as of the end of such fiscal quarter
and the results of their operations and their retained earnings and changes in
cash flows for the fiscal periods then ended, all in conformity with GAAP,
subject to normal and recurring year-end audit adjustments.

          SECTION 3.08  Absence of Undisclosed Liabilities.
                        ----------------------------------

          Neither the Borrower nor any Subsidiary of the Borrower has any
liability or obligation of any nature whatever (whether absolute, accrued,
contingent or otherwise, whether or not due), forward or long-term commitments
or unrealized or anticipated losses from unfavorable commitments, except (a) as
disclosed in the financial statements referred to in Sections 3.06 and 3.07, and
(b) liabilities, obligations, commitments and losses incurred after

                                       37
<PAGE>

March 31, 1999, in the ordinary course of business and consistent with past
practices.

          SECTION 3.09   Absence of Material Adverse Change.
                         ----------------------------------

          Except for the Mergers, since December 31, 1998, there has been no
material adverse change in the business, operations, condition (financial or
otherwise), or prospects of the Borrower and its Subsidiaries taken as a whole.

          SECTION 3.10  Accurate and Complete Disclosure.
                        --------------------------------

          All information heretofore, contemporaneously or hereafter provided by
or on behalf of the Borrower to any Agent or any Lender pursuant to or in
connection with any Loan Document or any transaction contemplated hereby or
thereby is or will be (as the case may be) true and accurate in all material
respects on the date as of which such information is dated (or, if not dated,
when received by such Agent or such Lender) and does not or will not (as the
case may be) omit to state any material fact necessary to make such information
not misleading at such time in light of the circumstances in which it was
provided.  The Borrower has disclosed to each Agent and each Lender in writing
every fact or circumstance which has, or which so far as the Borrower can
reasonably foresee is reasonably likely and is reasonably likely to have, a
Material Adverse Effect.

          SECTION 3.11  Margin Regulations.
                        ------------------

          No part of the proceeds of any Loan hereunder will be used for the
purpose of buying or carrying any "margin stock", as such term is used in
Regulation U of the Board of Governors of the Federal Reserve System, as amended
from time to time, or to extend credit to others for the purpose of buying or
carrying any "margin stock".  Neither the Borrower nor any Subsidiary of the
Borrower is engaged in the business of extending credit to others for the
purpose of buying or carrying "margin stock".  Neither the Borrower nor any
Subsidiary of the Borrower owns any "margin stock".  Neither the making of any
Loan nor any use of proceeds of any such Loan will violate or conflict with the
provisions of Regulation T, U or X of the Board, as amended from time to time.

          SECTION 3.12  Litigation.
                        ----------

          There is no pending or (to the Borrower's knowledge after due inquiry)
threatened action, suit, proceeding or investigation (including any
Environmental Claim) by or before any Governmental Authority against or
affecting the Borrower or any Subsidiary of the Borrower which, if adversely
decided, individually or in the aggregate, would reasonably be expected to have
a Material Adverse Effect, except for (a) matters described in the financial
statements referred to in Section 3.06 and (b) matters set forth in Schedule
III.

          SECTION 3.13  Absence of Events of Default.
                        ----------------------------

          No event has occurred and is continuing and no condition exists which
constitutes a Default or an Event of Default.

                                       38
<PAGE>

          SECTION 3.14  Absence of Other Conflicts.
                        --------------------------

          Neither the Borrower nor any Subsidiary of the Borrower is in
violation of or conflict with, or is subject to any contingent liability on
account of any violation of or conflict with:

          (a) any Law (including ERISA, the Code, any applicable occupational
     health, safety or welfare Law or any applicable Environmental Law);

          (b) its articles of incorporation or by-laws (or other constituent
     documents); or

          (c) any agreement or instrument to which it is party or by which it or
     any of its properties (now owned or hereafter acquired) may be subject or
     bound;

except for matters which, individually or in the aggregate, would not reasonably
be expected to have a Material Adverse Effect.

          SECTION 3.15  Insurance.
                        ---------

          The Borrower and each Subsidiary of the Borrower maintains with
financially sound and reputable insurers insurance with respect to its
properties and business and against at least such liabilities, casualties and
contingencies and in at least such types and amounts as is customary in the case
of corporations engaged in the same or a similar business or having similar
properties similarly situated.

          SECTION 3.16  Title to Property; No Liens.
                        ---------------------------

          The Borrower and each Subsidiary of the Borrower has good and
marketable title in fee simple to all real Property owned or purported to be
owned by it and good title to all other Property of whatever nature owned or
purported to be owned by it, including but not limited to all Property reflected
in the most recent audited balance sheet referred to in Section 3.06 or
submitted pursuant to Section 5.01(b), as the case may be (except as sold or
otherwise disposed of in the ordinary course of business after the date of such
balance sheet).  Except for (i) Liens reflected in the most recent audited
balance sheet referred to in Section 3.06 or submitted pursuant to Section
5.01(b), as the case may be, (ii) Liens consisting of zoning or planning
restrictions, easements, permits and other restrictions or limitations on the
use of real Property or irregularities in title thereto which do not materially
detract from the value of, or impair the use of, such Property by the Borrower
or any Subsidiary of the Borrower in the operation of its business, (iii) Liens
for current Taxes not yet due and delinquent and (iv) Liens set forth on
Schedule IV, no Property owned by the Borrower or any Subsidiary of the Borrower
is subject to any Lien.

          SECTION 3.17  Taxes.
                        -----

          All tax and information returns required to be filed by or on behalf
of the Borrower or any Subsidiary of the Borrower have been properly prepared,
executed and filed.  All Taxes upon the Borrower or any Subsidiary of the
Borrower or upon any of their respective Properties, incomes, sales or
franchises which are due and payable have been paid, other than those not yet
delinquent and payable without premium or penalty, and except for those being
diligently

                                       39
<PAGE>

contested in good faith by appropriate proceedings, and in each case adequate
reserves and provisions for Taxes have been made on the books of the Borrower
and each Subsidiary of the Borrower. The reserves and provisions for Taxes on
the books of the Borrower and each Subsidiary of the Borrower are adequate for
all open years and for its current fiscal period. Neither the Borrower nor any
Subsidiary of the Borrower knows of any proposed additional assessment or basis
for any material assessment for additional Taxes (whether or not reserved
against).

          SECTION 3.18  Borrower Not An Investment Company or a Registered
                        --------------------------------------------------
Public Utility Holding Company.
------------------------------

          Neither the Borrower nor any Subsidiary of the Borrower is an
"investment company" or a company controlled by an "investment company" within
the meaning of the Investment Company Act of 1940.  The Borrower is not a
"holding company" within the meaning of the Public Utility Holding Company Act
of 1935 which is subject to registration.

          SECTION 3.19  Environmental Matters.
                        ---------------------

          (a) The Borrower and each of its Subsidiaries have complied with and
are in compliance with, all applicable Environmental Laws and the requirements
of any permits issued under such Environmental Laws.  Except as disclosed on
Schedule V, there are no pending or threatened Environmental Claims against the
Borrower or any of its Subsidiaries (including any such claim arising out of the
ownership, lease or operation by the Borrower or any of its Subsidiaries of any
real Property no longer owned, leased or operated by the Borrower or any of its
Subsidiaries) or any real Property owned, leased or operated by the Borrower or
any of its Subsidiaries.  Except as disclosed on Schedule V, there are no facts,
circumstances, conditions or occurrences with respect to the business or
operations of the Borrower or any of its Subsidiaries, or any real Property
owned, leased or operated by the Borrower or any of its Subsidiaries (including
any real Property formerly owned, leased or operated by the Borrower or any of
its Subsidiaries but no longer owned, leased or operated by the Borrower or any
of its Subsidiaries) or any Property adjoining or adjacent to any such real
Property that could be expected (i) to form the basis of an Environmental Claim
against the Borrower or any of its Subsidiaries or any real Property owned,
leased or operated by the Borrower or any of its Subsidiaries or (ii) to cause
any real Property owned, leased or operated by the Borrower or any of its
Subsidiaries to be subject to any restrictions on the ownership, occupancy or
transferability of such real Property by the Borrower or any of its Subsidiaries
under any applicable Environmental Law.

          (b) Hazardous Materials have not at any time been generated, used,
treated or stored on, or transported to or from, any real Property owned, leased
or operated by the Borrower or any of its Subsidiaries where such generation,
use, treatment or storage has violated or could be expected to violate any
Environmental Law.  Hazardous Materials have not at any time been Released on or
from any real Property owned, leased or operated by Borrower or any of its
Subsidiaries where such Release has violated or would be expected to violate any
applicable Environmental Law.

          (c) Notwithstanding anything to the contrary in this Section, the
representations made in this Section shall not be untrue unless the effect of
all violations, claims,

                                       40
<PAGE>

restrictions, failures and noncompliances of the types described in this Section
would reasonably be expected to, individually or in the aggregate, have a
Material Adverse Effect on the Borrower.

          SECTION 3.20  ERISA.
                        -----

          (a) Each Plan (and each related trust, insurance contract or fund) is
in substantial compliance with its terms and with all applicable Laws, including
without limitation ERISA and the Code; each Plan (and each related trust, if
any) which is intended to be qualified under Section 401(a) of the Code has
received a determination letter from the Internal Revenue Service to the effect
that it meets the requirements of Sections 401(a) and 501(a) of the Code; no
Reportable Event has occurred; no Multiemployer Plan is insolvent or in
reorganization; no Plan has an Unfunded Current Liability; no Plan which is
subject to Section 412 of the Code or Section 302 of ERISA has an accumulated
funding deficiency within the meaning of such sections of the Code or ERISA or
has applied for or received a waiver of an accumulated funding deficiency or an
extension of any amortization period within the meaning of Section 412 of the
Code or Section 303 or 304 of ERISA; all contributions required to be made with
respect to a Plan have been timely made; neither the Borrower nor any Subsidiary
of the Borrower nor any ERISA Affiliate has incurred any material liability
(including any indirect, contingent or secondary liability) to or on account of
a Plan pursuant to Section 409, 502(i), 502(l), 515, 4062, 4063, 4064, 4069,
4201, 4204 or 4212 of ERISA or Section 401(a)(29), 4971 or 4975 of the Code or
expects to incur any such liability under any of the foregoing sections with
respect to any Plan; no condition exists which presents a material risk to the
Borrower or any Subsidiary of the Borrower or any ERISA Affiliate of incurring a
liability to or on account of a Plan pursuant to the foregoing provisions of
ERISA and the Code; no proceedings have been instituted to terminate or appoint
a trustee to administer any Plan; no action, suit, proceeding, hearing, audit or
investigation with respect to the administration, operation or the investment of
assets of any Plan (other than routine claims for benefits) is pending, expected
or threatened; using actuarial assumptions and computation methods consistent
with Part 1 of subtitle E of Title IV of ERISA, the aggregate liabilities of the
Borrower and its Subsidiaries and its ERISA Affiliates to all Multiemployer
Plans in the event of a complete withdrawal therefrom, as of the close of the
most recent fiscal year of each such Plan ended prior to the date of the most
recent Borrowing, would not have a Material Adverse Effect; each group health
plan (as defined in Section 607(1) of ERISA or Section 4980B(g)(2) of the Code)
which covers or has covered employees or former employees of the Borrower, any
Subsidiary of the Borrower, or any ERISA Affiliate has at all times been
operated in compliance with the provisions of Part 6 of subtitle B of Title I of
ERISA and Section 4980B of the Code; no Lien imposed under the Code or ERISA on
the assets of the Borrower or any Subsidiary of the Borrower or any ERISA
Affiliate exists or is likely to arise on account of any Plan; and the Borrower
and its Subsidiaries may cease contributions to or terminate any Plan maintained
by any of them without incurring any material liability.

          (b) Each Foreign Pension Plan, if any, has been maintained in
substantial compliance with its terms and with the requirements of any and all
applicable Laws, statutes, rules, regulations and orders and has been
maintained, where required, in good standing with applicable regulatory
authorities.  All contributions required to be made with respect to a Foreign
Pension Plan have been timely made.  Neither the Borrower nor any of its
Subsidiaries has incurred any obligation in connection with the termination of
or withdrawal from any Foreign Pension Plan.  The present value of the accrued
benefit liabilities (whether or not vested) under

                                       41
<PAGE>

each Foreign Pension Plan, determined as of the end of the Borrower's most
recently ended Fiscal Year on the basis of actuarial assumptions, each of which
is reasonable, did not exceed the current value of the assets of such Foreign
Pension Plan allocable to such benefit liabilities.

          SECTION 3.21  Year 2000 Issues.
                        ----------------

          The Borrower has (i) initiated a detailed review and assessment of all
areas within its business and operations and the business and operations of its
Subsidiaries, including those affected by suppliers and vendors, that could be
adversely impacted by the "Year 2000 Problem", i.e., the risk that computer
applications used by the Borrower, its Subsidiaries, or their suppliers and
vendors, may be unable to recognize and perform properly date-sensitive
functions involving certain dates prior to and any date after December 31, 1999,
(ii) developed a detailed plan and timetable for addressing the Year 2000
Problem on a timely basis (the "Year 2000 Plan"), and (iii) to date, implemented
this plan in accordance with the timetable.  The Borrower reasonably believes
that all computer applications, including those of its suppliers and vendors,
that are material to its business, operations or conditions (financial or
otherwise) will, on a timely basis, be able to perform properly date-sensitive
functions for all dates before and after January 1, 2000, that is, be "Year 2000
Compliant", except to the extent that a failure to do so could not reasonably be
expected to have a Material Adverse Effect.

          SECTION 3.22  Pari Passu Status.
                        -----------------

          The claims and rights of the Lenders against the Borrower hereunder
are not subordinated to, and rank at least pari passu with, the claims and
rights of other holders of its unsecured indebtedness except to the extent
otherwise provided by Law (including without limitation the Bankruptcy Code and
the provisions of 31 U.S.C. (S)3713).

          SECTION 3.23  Indebtedness.
                        ------------

          Schedule VI contains a true and complete list of all Indebtedness of
the Borrower and its Subsidiaries that is, or will be, outstanding on the
Effective Date ("Existing Indebtedness").
                 ---------------------

                                  ARTICLE IV
                                  CONDITIONS

          SECTION 4.01  Effective Date.
                        --------------

          This Agreement and the other Loan Documents shall become effective as
against the Lenders and the Agents on the first date on which all of the
following conditions shall be satisfied or waived:

          (a) Agreement; Notes.  The Administrative Agent shall have received an
              ----------------
     executed counterpart of this Agreement for each Lender, duly executed by
     the Borrower, and, to the extent any Lender has requested a Note pursuant
     to Section 2.08(f), a Note conforming to the requirements hereof, duly
     executed on behalf of the Borrower.

                                       42
<PAGE>

          (b) Corporate Proceedings.  The Administrative Agent shall have
              ---------------------
     received, with a counterpart for each Lender, certificates by the Secretary
     or Assistant Secretary of the Borrower dated as of the Effective Date as to
     (i) true copies of the articles of incorporation and by-laws (or other
     constituent documents) of the Borrower as in effect on such date (which, in
     the case of articles of incorporation or other constituent documents filed
     or required to be filed with the Secretary of State or other Governmental
     Authority in its jurisdiction of incorporation, shall be certified to be
     true, correct and complete by such Secretary of State or other Governmental
     Authority not more than 30 days before the date hereof), (ii) true copies
     of all corporate action taken by the Borrower relative to this Agreement
     and the other Loan Documents, and (iii) the incumbency and signatures of
     the respective officers of the Borrower executing this Agreement and the
     other Loan Documents to which the Borrower is a party, together with
     satisfactory evidence of the incumbency of such Secretary or Assistant
     Secretary.  The Administrative Agent shall have received, with a copy for
     each Lender, certificates from the Secretary of State of Nevada (or other
     applicable Governmental Authority) dated not more than 30 days before the
     Effective Date showing the good standing of the Borrower in Nevada and in
     each state in which the Borrower does business.

          (c) Legal Opinion of Counsel to the Borrower.  The Administrative
              ----------------------------------------
     Agent shall have received, with an executed counterpart for each Lender, an
     opinion addressed to the Administrative Agent and each Lender, dated
     Effective Date, of Choate, Hall & Stewart, counsel to the Borrower, as to
     such matters as may be requested by the Administrative Agent and in form
     and substance satisfactory to the Lenders.

          (d) Financial Statements.  The Administrative Agent shall have
              --------------------
     received for each Lender a true and correct copy of the (i) audited
     consolidated financial statements, including balance sheets, income
     statements and cash flow statements, for the Borrower, NPC, SPPC and their
     respective consolidated Subsidiaries for the years ended December 31, 1998,
     1997 and 1996, (ii) unaudited interim consolidated financial statements,
     including a balance sheet, income statement and statement of cash flows,
     for the Borrower, NPC, SPPC and their respective consolidated Subsidiaries
     for the three month period ended March 31, 1999, and (iii) unaudited pro
     forma (giving effect to the Mergers) consolidated financial statements,
     including a balance sheet, income statement and statement of cash flows,
     for the Borrower and its consolidated Subsidiaries for the years ended
     December 31, 1998 and 1997.

          (e) No Material Adverse Effect.  Nothing shall have occurred (and
              --------------------------
     neither the Administrative Agent nor the Lenders shall have become aware of
     any facts or conditions not previously known) which the Lenders shall
     determine (i) has had, or could reasonably be expected to have, a Material
     Adverse Effect. The Administrative Agent shall have received a certificate
     of a senior financial officer of the Borrower, dated the Effective Date, to
     the effect that, as of the Effective Date, there has been no Material
     Adverse Effect since December 31, 1998.

          (f) Mergers.  The Mergers shall have been consummated prior to
              -------
     September 1, 1999, or such later date as the Lenders and the Administrative
     Agent shall agree upon in writing, on terms satisfactory to the Lenders and
     the Administrative Agent shall have

                                       43
<PAGE>

     received copies of all documentation related there, including, without
     limitation, the order(s) of the Federal Energy Regulatory Commission and
     the Securities and Exchange Commission approving the Mergers.

          (g) Governmental Approvals.  All necessary and material Governmental
              ----------------------
     Actions (domestic and foreign) and third party approvals and/or consents in
     connection with the Mergers and the transactions contemplated in this
     Agreement shall have been obtained and remain in effect and all applicable
     waiting periods with respect thereto shall have expired without any action
     being taken by any competent authority which restrains, prevents or imposes
     materially adverse conditions upon, the consummation of the Mergers or the
     transactions contemplated hereby or otherwise referred to herein or
     therein.  The Administrative Agent shall have received documentation
     reasonably acceptable to it that the Federal Energy Regulatory Commission
     and the Securities and Exchange Commission have duly approved the Mergers.

          (h) No Injunctions.  There shall not exist any judgment, order,
              --------------
     injunction or other restraint issued or filed or a hearing seeking
     injunctive relief or other restraint pending or notified prohibiting or
     imposing materially adverse conditions upon the consummation of the Mergers
     or the other transactions contemplated hereby or otherwise referred to
     herein.

          (i) Litigation, Proceedings and Investigations.  There shall be no
              ------------------------------------------
     actions, arbitrations, suits, investigations or proceedings pending or
     threatened with respect to this Agreement or the Mergers or which the
     Administrative Agent shall determine could reasonably be expected to have a
     Material Adverse Effect.

          (j) No Violation of Existing Agreements.  Neither the Borrower nor any
              -----------------------------------
     Subsidiary of the Borrower is in violation of any material agreement or
     instrument to which it is party or by which it or any of its properties
     (now owned or hereafter acquired) may be subject or bound;

          (k)  Refinancing.
               -----------

               (i)  The total commitments in respect of the Indebtedness to be
     Refinanced shall have been terminated, and all loans and notes with respect
     thereto shall have been repaid in full, together with interest thereon, all
     letters of credit issued thereunder shall have been terminated and all
     other amounts (including premiums) owing pursuant to the Indebtedness to be
     Refinanced shall have been repaid in full and all documents in respect of
     the Indebtedness to be Refinanced and all guarantees with respect thereto
     shall have been terminated (except as to indemnification provisions, which
     may survive to the extent provided therein) and be of no further force and
     effect.

               (ii) The creditors in respect of the Indebtedness to be
     Refinanced shall have terminated and released any and all security
     interests and Liens on the assets owned by Borrower and its Subsidiaries.
     The Administrative Agent shall have received such releases of security
     interests in and Liens on the assets owned by Borrower and its Subsidiaries
     as may have been requested by the Administrative Agent, which releases

                                       44
<PAGE>

     shall be in form and substance reasonably satisfactory to the
     Administrative Agent.  Without limiting the foregoing, there shall have
     been delivered (i) proper termination statements (Form UCC-3 or the
     appropriate equivalent) for filing under the UCC of each jurisdiction where
     a financing statement (Form UCC-1 or the appropriate equivalent) was filed
     with respect to Borrower or any of its Subsidiaries in connection with the
     security interests created with respect to the Indebtedness to be
     Refinanced and the documentation related thereto, (ii) termination or
     reassignment of any security interest in, or Lien on, any patents,
     trademarks, copyrights, or similar interests of Borrower or any of its
     Subsidiaries on which filings have been made, (iii) terminations of all
     mortgages, leasehold mortgages, deeds of trust and leasehold deeds of trust
     created with respect to Property of Borrower or any of its Subsidiaries, in
     each case to secure the obligations in respect of the Indebtedness to be
     Refinanced, all of which shall be in form and substance reasonably
     satisfactory to the Administrative Agent, and (iv) all collateral owned by
     Borrower and its Subsidiaries in the possession of any of the creditors in
     respect of the Indebtedness to be Refinanced or any collateral agent or
     trustee under any related security document shall have been returned to
     Borrower or its respective Subsidiary, as the case may be.

          (l) Ratings.  The Administrative Agent shall have received a
              -------
     certificate of a senior financial officer of the Borrower, dated the
     Effective Date, setting forth the then current ratings of the Index Debt.

          (m) Officers' Certificates.  The Administrative Agent shall have
              ----------------------
     received, with an executed counterpart for each Lender, certificates from
     such officers of the Borrower as to such matters as the Administrative
     Agent may request.

          (n) Fees, Expenses, etc.  All fees and other items required to be paid
              --------------------
     to the Agents and the Lenders on or before the Effective Date (including
     all fees referenced in fee letters and offer letters) shall have been paid
     or received.

          (o)  Section 4.02 Conditions.
               -----------------------

               (i) Each of the representations and warranties made by the
          Borrower herein and in each other Loan Document shall be true and
          correct in all material respects on and as of the Effective Date as if
          made on and as of such date, both before and after giving effect to
          the Loans requested to be made on such date.

               (ii) No Default or Event of Default shall have occurred and be
          continuing on the Effective Date.

          (p) Additional Matters.  The Administrative Agent shall have received,
              ------------------
     with copies or executed counterparts for each Lender, such other
     certificates, opinions, documents and instruments as the Administrative
     Agent may have requested.  All corporate and other proceedings, and all
     documents, instruments and other matters in connection with the
     transactions contemplated by this Agreement and the other Loan Documents
     shall be satisfactory in form and substance to the Administrative Agent.

                                       45
<PAGE>

          SECTION 4.02  Conditions to All Loans.
                        -----------------------

          The obligation of each Lender to make, convert or continue any Loan on
the occasion of any Borrowing is subject to satisfaction of the conditions
precedent set forth in Section 4.01 and satisfaction of the following further
conditions precedent:

          (a) Notice.  The Borrower shall have executed and delivered to the
              ------
     Administrative Agent a Borrowing Request or Interest Election Request for
     such Borrowing in accordance with Section 2.03 or 2.05, as the case may be.

          (b) Representations and Warranties.  Each of the representations and
              ------------------------------
     warranties made by the Borrower herein and in each other Loan Document
     shall be true and correct in all material respects on and as of such date
     as if made on and as of such date, both before and after giving effect to
     the making, conversion or continuation of Loans requested to be made,
     converted or continued on such date.

          (c) No Defaults.  No Default or Event of Default shall have occurred
              -----------
     and be continuing on such date or after giving effect to the making,
     conversion or continuation of Loans requested to be made, converted or
     continued on such date.

          (d) No Violations of Law, etc.  Neither the making, conversion or
              -------------------------
     continuation nor use of the Loans shall cause any Lender to violate or be
     in conflict with any Law.

          (e) No Material Adverse Change.  There shall not have occurred, or be
              --------------------------
     threatened, any other event, act or condition which would reasonably be
     expected to have a Material  Adverse Effect.

          Each request by the Borrower for any Loan or conversion or
continuation thereof shall constitute a representation and warranty by the
Borrower that the conditions set forth in this Section 4.02 have been satisfied
as of the date of such request.  Failure of the Administrative Agent to receive
notice from the Borrower to the contrary before such Loan is made shall
constitute a further representation and warranty by the Borrower that the
conditions referred to in this Section 4.02 have been satisfied as of the date
such Loan is made.

                                   ARTICLE V
                             AFFIRMATIVE COVENANTS

     The Borrower hereby covenants to the Administrative Agent and each Lender:

SECTION 5.01  Basic Reporting Requirements.
              ----------------------------

          (a) Annual Audit Reports.  As soon as practicable, and in any event
              --------------------
within 90 days after the close of each fiscal year of the Borrower, the Borrower
shall furnish to the Administrative Agent, with a copy for each Lender,
consolidated statements of income, retained earnings and cash flows of the
Borrower and its consolidated Subsidiaries for such fiscal year and a
consolidated balance sheet of the Borrower and its consolidated Subsidiaries as
of the close of such fiscal year, and notes to each, all in reasonable detail,
setting forth in comparative form the corresponding figures for the preceding
fiscal year.  Such financial statements shall be

                                       46
<PAGE>

accompanied by an opinion of independent certified public accountants of
recognized national standing selected by the Borrower, which opinion shall not
be subject to any qualification as to scope of audit or as to any other matter
which the Required Lenders determine is adverse. Such opinion in any event shall
contain a written statement of such accountants substantially to the effect that
(i) such accountants examined such financial statements in accordance with
generally accepted auditing standards and accordingly made such tests of
accounting records and such other auditing procedures as such accountants
considered necessary in the circumstances and (ii) in the opinion of such
accountants such financial statements present fairly the financial position of
the Borrower and its consolidated Subsidiaries as of the end of such fiscal year
and the results of their operations and their retained earnings and cash flows
for such fiscal year, in conformity with GAAP.

          (b) Quarterly Consolidated Reports.  As soon as practicable, and in
              ------------------------------
any event within 45 days after the close of each of the first three fiscal
quarters of each fiscal year of the Borrower, the Borrower shall furnish to the
Administrative Agent, with a copy for each Lender, unaudited consolidated
statements of income, retained earnings and cash flows of the Borrower and its
consolidated Subsidiaries for the period from the beginning of such fiscal year
to the end of such fiscal quarter and an unaudited consolidated balance sheet of
the Borrower and its consolidated Subsidiaries as of the close of such fiscal
quarter, and notes to each, all in reasonable detail, setting forth in
comparative form the corresponding figures for the same periods or as of the
same date during the preceding fiscal year (except for the consolidated balance
sheet, which shall set forth in comparative form the corresponding balance sheet
as of the prior fiscal year end).  Such financial statements shall be certified
by a Responsible Officer of the Borrower as presenting fairly the financial
position of the Borrower and its consolidated Subsidiaries as of the end of such
fiscal quarter and the results of their operations and their retained earnings
and changes in cash flows for such fiscal year, in conformity with GAAP, subject
to normal and recurring year-end audit adjustments.

          (c) Quarterly Compliance Certificates.  The Borrower shall deliver to
              ---------------------------------
the Administrative Agent, with a copy for each Lender, a Quarterly Compliance
Certificate in substantially the form set forth as Exhibit D, duly completed and
signed by a Responsible Officer of the Borrower concurrently with the delivery
of the financial statements referred to in subsections (a) and (b) of this
Section 5.01.

          (d) Certain Other Reports and Information.  Promptly upon their
              -------------------------------------
becoming available to the Borrower, the Borrower shall deliver to the
Administrative Agent, with a copy for each Lender, a copy of (i) all regular or
special reports, registration statements and amendments to the foregoing which
the Borrower or any Subsidiary of the Borrower shall file with the Securities
and Exchange Commission (or any successor thereto) or any securities exchange,
and (ii) all reports, proxy statements, financial statements and other
information distributed by the Borrower to its stockbrokers, bondholders or the
financial community generally.

          (e) Further Information.  The Borrower shall promptly furnish to the
              -------------------
Administrative Agent, with a copy for each Lender, such other information and in
such form as the Administrative Agent or any Lender may reasonably request from
time to time.

                                       47
<PAGE>

          (f)   Notice of Certain Events.  Promptly (and, in the case of clause
                ------------------------
(i) below, no later than two Business Days) upon becoming aware of any of the
following, the Borrower shall give the Administrative Agent notice thereof,
together with a written statement of a Responsible Officer of the Borrower
setting forth the details thereof and any action with respect thereto taken or
proposed to be taken by the Borrower:

          (i)   Any Default or Event of Default.

          (ii)  The occurrence or existence of any event or condition (including
     (A) the violation or alleged violation of any Environmental Law by the
     Borrower or any Subsidiary of the Borrower or the assertion of any
     Environmental Claim against the Borrower or any Subsidiary of the Borrower,
     (B) the commencement of any other action, suit, proceeding or investigation
     by or before any Governmental Authority against or affecting the Borrower
     or any Subsidiary of the Borrower, or (C) the violation, breach or default
     or alleged violation, breach or default by the Borrower or any Subsidiary
     of the Borrower or any other Person under any agreement or instrument
     material to the business, operations, condition (financial or otherwise) or
     prospects of the Borrower and its Subsidiaries taken as a whole) which
     event or condition, either individually or in the aggregate, has, or would
     reasonably be expected to have, a Material Adverse Effect.

          (iii) Any change in the Index Debt rating.

          (g)   Visitation; Verification.  The Borrower shall permit such
                ------------------------
Persons as the Administrative Agent or any Lender may designate from time to
time to visit and inspect any of the properties of the Borrower and of any
Subsidiary, to examine their respective books and records and take copies and
extracts therefrom and to discuss their respective affairs with their respective
officers, employees and independent accountants at such times and as often as
the Administrative Agent or any Lender may reasonably request; provided,
                                                               --------
however, that the Borrower reserves the right to restrict access to any of its
generating facilities in accordance with reasonably adopted practices relating
to safety and security.  The Borrower hereby authorizes such officers, employees
and independent accountants to discuss with the Administrative Agent or any
Lender the affairs of the Borrower and its Subsidiaries.

          (h)   ERISA.  Within 30 days after the Borrower knows that any of the
                -----
events or conditions specified below with respect to any Plan or Multiemployer
Plan has occurred or exists, a statement signed by a Responsible Officer of the
Borrower setting forth details respecting such event or condition and the
action, if any, that the Borrower or its ERISA Affiliate proposes to take with
respect thereto (and a copy of any report or notice required to be filed with or
given to PBGC by the Borrower or an ERISA Affiliate with respect to such event
or condition):

                (i)  any Reportable Event and any request for a waiver under
     Section 412(d) of the Code for any Plan;

                (ii) the distribution under Section 4041 of ERISA of a notice of
     intent to terminate any Plan or any action taken by the Borrower or an
     ERISA Affiliate to

                                       48
<PAGE>

     terminate any Plan, in each case with respect to which there are
     insufficient assets to pay benefits as they become due;

               (iii) the institution by PBGC of proceedings under Section 4042
     of ERISA for the termination of, or the appointment of a trustee to
     administer, any Plan, or the receipt by the Borrower or any ERISA Affiliate
     of a notice from a Multiemployer Plan that such action has been taken by
     PBGC with respect to such Multiemployer Plan;

               (iv)  the complete or partial withdrawal from a Multiemployer
     Plan by the Borrower or any ERISA Affiliate that results in liability under
     Section 4201 or 4204 of ERISA (including the obligation to satisfy
     secondary liability as a result of a purchaser default) or the receipt by
     the Borrower or any ERISA Affiliate of notice from a Multiemployer Plan
     that it is in reorganization or insolvency pursuant to Section 4241 or 4245
     of ERISA or that it intends to terminate or has terminated under Section
     4041A of ERISA; and

               (v)   the adoption of an amendment to any Plan that, pursuant to
     Section 401(a)(29) of the Code or Section 307 of ERISA, would result in the
     loss of tax-exempt status of the trust of which such Plan is a part if the
     Borrower or an ERISA Affiliate fails to timely provide security to the Plan
     in accordance with the provisions of said Sections.

          (i)  Satisfaction of Certain Reporting Requirements.   Notwithstanding
               ----------------------------------------------
any other provision of this Section 5.01, the Borrower shall be deemed to have
satisfied its obligations pursuant to Sections 5.01(a) and (b) if and to the
extent that it shall have provided to the Administrative Agent and each Lender,
pursuant to Section 5.01(d), copies of its periodic reports (on Form 10-K or 10-
Q, as the case may be) as required to be filed with the Securities and Exchange
Commission (or any successor thereto) pursuant to the Securities and Exchange
Act of 1934, as amended (or any successor statute of similar import), for the
annual and quarterly periods described in such Sections.

          (j)  Delivery to Lenders.  The Administrative Agent shall promptly
               -------------------
deliver to each Lender each of the reports, statements, certificates or other
documents delivered to the Administrative Agent by the Borrower pursuant to this
Section 5.01.

          SECTION 5.02  Insurance.
                        ---------

          The Borrower shall, and shall cause each of its Subsidiaries to,
maintain with financially sound and reputable insurers insurance with respect to
its properties and business and against such liabilities, casualties and
contingencies and of such types and in such amounts as is customary in the case
of corporations engaged in the same or similar businesses or having similar
properties similarly situated and as is satisfactory from time to time to the
Required Lenders in their reasonable discretion.

          SECTION 5.03  Payment of Taxes and Other Potential Charges and
                        ------------------------------------------------
Priority Claims.
---------------

          The Borrower shall, and shall cause each of its Subsidiaries to, pay
or discharge

                                       49
<PAGE>

          (a) on or prior to the date on which penalties or Liens attach
     thereto, all Taxes imposed upon it or any of its properties;

          (b) on or prior to the date when due, all lawful claims of
     materialmen, mechanics, carriers, warehousemen, landlords and other like
     Persons which, if unpaid, might result in the creation of a Lien upon any
     such Property; and

          (c) on or prior to the date when due, all other lawful claims which,
     if unpaid, might result in the creation of a Lien upon any such Property or
     which, if unpaid, might give rise to a claim entitled to priority over
     general creditors of the Borrower or such Subsidiary in a case under the
     Bankruptcy Code;

provided, that, unless and until foreclosure, distraint, levy, sale or similar
--------
proceedings shall have been commenced, the Borrower or such Subsidiary need not
pay or discharge any such Tax, assessment, charge or claim so long as (x) the
validity thereof is contested in good faith and by appropriate proceedings
diligently conducted, and (y) such reserves or other appropriate provisions as
may be required by GAAP shall have been made therefor.

          SECTION 5.04  Preservation of Corporate Status and Franchises.
                        -----------------------------------------------

          The Borrower shall, and shall cause each of its Subsidiaries to,
maintain its status as a corporation, trust or limited liability company duly
organized, validly existing and in good standing under the Laws of its
jurisdiction of organization, and to be duly qualified to do business as a
foreign corporation, trust or limited liability company and in good standing in
all jurisdictions in which the ownership of its properties or the nature of its
business or both make such qualification necessary or advisable; provided,
                                                                 --------
however, that nothing in this Section 5.04 shall prevent the withdrawal by the
-------
Borrower or any of its Subsidiaries of its qualification as a foreign
corporation in any jurisdiction where such withdrawal could not have a Material
Adverse Effect .  The Borrower shall, and shall cause each of its Subsidiaries
to, do or cause to be done, all things necessary to preserve and keep in full
force and effect its material rights, franchises, licenses and patents.

          SECTION 5.05  Governmental Approvals and Filings.
                        ----------------------------------

          The Borrower shall keep and maintain in full force and effect all
Governmental Actions necessary or advisable in connection with execution and
delivery of any Loan Document, consummation of the transactions herein or
therein contemplated, performance of or compliance with the terms and conditions
hereof or thereof or to ensure the legality, validity, binding effect or
enforceability hereof or thereof.

          SECTION 5.06  Maintenance of Properties.
                        -------------------------

          The Borrower shall, and shall cause each of its Subsidiaries to,
maintain or cause to be maintained in good repair, working order and condition
the properties now or hereafter owned, leased or otherwise possessed by it and
shall make or cause to be made all needful and proper repairs, renewals,
replacements and improvements thereto so that the business carried on in
connection therewith may be properly and advantageously conducted at all times.

                                       50
<PAGE>

          SECTION 5.07  Avoidance of Other Conflicts.
                        ----------------------------

          The Borrower shall not, and shall not permit any of its Subsidiaries
to, violate or conflict with, be in violation of or in conflict with, or be or
remain subject to any liability (contingent or otherwise) on account of any
violation or conflict with

          (a) any Law;

          (b) its articles of incorporation or by-laws; or

          (c) any agreement or instrument to which it is party or by which any
     of them or any of their respective Subsidiaries is a party or by which any
     of them or any of their respective properties (now owned or hereafter
     acquired) may be subject or bound,

except for matters which would not reasonably be expected, either individually
or in the aggregate, to have a Material Adverse Effect.

          SECTION 5.08  Financial Accounting Practices.
                        ------------------------------

          The Borrower shall, and shall cause each of its Subsidiaries to, make
and keep books, records and accounts which, in reasonable detail, accurately and
fairly reflect its transactions and dispositions of its assets and maintain a
system of internal accounting controls sufficient to provide reasonable
assurances that (a) transactions are executed in accordance with management's
general or specific authorization, (b) transactions are recorded as necessary
(i) to permit preparation of financial statements in conformity with GAAP and
(ii) to maintain accountability for assets, (c) access to assets is permitted
only in accordance with management's general or specific authorization and (d)
the recorded accountability for assets is compared with the existing assets at
reasonable intervals and appropriate action is taken with respect to any
differences.

          SECTION 5.09  Use of Proceeds.
                        ---------------

          The Borrower shall apply the proceeds of all Loans hereunder only (a)
to fund a cash payment in an aggregate amount of up to $460,000,000 to be made
in connection with the Mergers and (b) for working capital and general corporate
purposes of the Borrower, including commercial paper backup.  The Borrower shall
not use the proceeds of any Loans hereunder directly or indirectly for any
unlawful purpose, in any manner inconsistent with Section 3.11, or inconsistent
with any other provision of any Loan Document.

          SECTION 5.10  End of Fiscal Periods.
                        ---------------------

          The Borrower shall cause (a) each of its, and each of its
Subsidiary's, fiscal years to end on December 31 and (b) each of its, and each
of its Subsidiary's, fiscal quarters to end on March 31, June 30, September 30
and December 31.

                                       51
<PAGE>

                                  ARTICLE VI
                              NEGATIVE COVENANTS

          The Borrower hereby covenants to the Administrative Agent and each
Lender as follows:

          SECTION 6.01  Financial Covenants.
                        -------------------

          (a) Maximum Leverage.  The Borrower shall not permit the ratio of (a)
              ----------------
Total Indebtedness  to (b) the sum of Total Indebtedness and Shareholders'
Equity, determined as of the last day of each fiscal quarter, to exceed 0.65 to
1.

          (b) Minimum Tangible Net Worth.  The Borrower shall not permit
              --------------------------
Tangible Net Worth to be less than $1,250,000,000 at any time.

          (c) Fixed Charge Coverage Ratio.  The Borrower shall not permit the
              ---------------------------
Fixed Charge Coverage Ratio, determined as of the last day of each fiscal
quarter for the period consisting of the four consecutive fiscal quarters ended
on such last day, to be less than 1.5 to 1.

          SECTION 6.02  Liens.
                        -----

          The Borrower shall not, and shall not permit any of its Subsidiaries
to, at any time create, incur, assume or suffer to exist any Lien on any of its
Property (now owned or hereafter acquired), or agree, become or remain liable
(contingently or otherwise) to do any of the foregoing, except for the following
("Permitted Liens"):
  ---------------

          (a) Liens existing on the date hereof and securing obligations
     existing on the date hereof, other than Indebtedness to be Refinanced, as
     such Liens and obligations are listed on Schedule IV;

          (b) Liens securing obligations of NPC issued under and pursuant to the
     terms and conditions of the NPC First Mortgage Indenture;

          (c) Liens securing obligations of SPPC issued under and pursuant to
     the terms and conditions of the SPPC First Mortgage Indenture;

          (d) Liens on NPC First Mortgage Bonds issued as collateral for
     pollution control revenue bonds issued for the benefit of NPC or its
     Subsidiaries (and related rights and interests) to secure obligations of
     NPC or such Subsidiaries for the benefit of the holders of such bonds,
     provided that such bonds are not secured by any other assets or Properties
     of NPC or its Subsidiaries;

          (e) Liens on SPPC First Mortgage Bonds issued as collateral for
     pollution control or gas or water facility revenue bonds issued for the
     benefit of SPPC or its Subsidiaries (and related rights and interests) to
     secure obligations of SPPC or such Subsidiaries for the benefit of the
     holders of such bonds, provided that such bonds are not secured by any
     other assets or Properties of SPPC or its Subsidiaries;

                                       52
<PAGE>

          (f) Liens on SPPC First Mortgage Bonds issued as collateral for
     medium-term notes issued pursuant to the Collateral Trust Indenture, dated
     as of June 1, 1992, between SPPC and Bankers Trust Company, as Trustee;

          (g) Liens on "transition property" arising pursuant to Section 843 of
     the California Public Utility Code for the benefit of holders of rate
     reduction bonds issued pursuant to a valid financing order of the
     California Public Utilities Commission;

          (h) Liens arising from taxes, assessments, charges or claims described
     in Section 5.03 that are not yet due or that remain payable without penalty
     or to the extent permitted to remain unpaid under the proviso to such
     Section 5.03;

          (i) Deposits or pledges of cash or securities in the ordinary course
     of business to secure (i) worker's compensation, unemployment insurance or
     other social security obligations, (ii) performance of bids, tenders, trade
     contracts (other than for payment of money) or leases, (iii) stay, surety
     or appeal bonds, or (iv) other obligations of a like nature incurred in the
     ordinary course of business;

          (j) Zoning restrictions, easements, minor restrictions on the use of
     real Property, minor irregularities in title thereto and other minor Liens
     that do not secure the payment of money or the performance of an obligation
     and that do not in the aggregate materially detract from the value of an
     asset to, or materially impair its use in the business of, the Borrower or
     such Subsidiary; and

          (k) Liens on Property securing all or part of the purchase price
     thereof and Liens (whether or not assumed) existing in Property at the time
     of purchase thereof, provided that: (i) such Lien is created before or
     substantially simultaneously with the purchase of such Property by the
     Borrower or such Subsidiary, (ii) such Lien is confined solely to the
     Property so purchased, improvements thereto and proceeds thereof, (iii) the
     aggregate amount secured by such Liens on any particular Property at the
     time purchased by the Borrower or such Subsidiary, as the case may be,
     shall not exceed the lesser of the purchase price of such Property and the
     fair market value of such Property at the time of purchase thereof by the
     Borrower or such Subsidiary, and (iv) the aggregate amount secured by all
     Liens described in this Section 6.02(k) shall not at any time exceed
     $150,000,000.

"Permitted Liens" shall in no event include any Lien imposed by, or required to
be granted pursuant to, ERISA or any Environmental Law.

          SECTION 6.03  Mergers.
                        -------

          The Borrower shall not, and shall not permit any of its Subsidiaries
to, (a) merge with or into or consolidate with any other Person, (b) liquidate,
wind-up, dissolve or divide, or (c) agree, become or remain liable (contingently
or otherwise) to do any of the foregoing, except:

          (i) A Person may merge with or into or consolidate with any Subsidiary
     of the Borrower, provided that (x) the surviving Person shall be a
     Subsidiary of the Borrower, (y) no Default or Event of Default shall have
     occurred and be continuing or shall exist at such

                                       53
<PAGE>

     time or after giving effect to such transaction and (z) the Borrower shall
     deliver to the Administrative Agent (A) a certificate, in a form reasonably
     satisfactory to the Administrative Agent, certifying that no Default or
     Event of Default exists or will result from such merger and (B) pro forma
     financial statements in support of such certification; and

          (ii) A Person may merge with or into or consolidate with the Borrower,
     provided that (x) the Borrower shall be the surviving Person, (y) no
     Default or Event of Default shall have occurred and be continuing or shall
     exist at such time or after giving effect to such transaction and (z) the
     Borrower shall deliver to the Administrative Agent (A) a certificate, in a
     form reasonably satisfactory to the Administrative Agent, certifying that
     no Default or Event of Default exists or will result from such merger and
     (B) pro forma financial statements in support of such certification.

          SECTION 6.04  Dispositions of Properties.
                        --------------------------

          The Borrower shall not, and shall not permit any of its Subsidiaries
to, sell, convey, assign, lease, sale-leaseback, transfer, abandon or otherwise
dispose of, voluntarily or involuntarily (collectively, "Dispose"), any of its
                                                         -------
Properties, or agree, become or remain liable contingently or otherwise to do
any of the foregoing, except that, so long as no Default or Event of Default
shall have occurred and be continuing or shall exist at such time or after
giving effect to such transaction, the Borrower and its Subsidiaries may Dispose
of Property (a) in transactions in the ordinary course of business, (b) that is
obsolete, (c) comprising generating assets, provided that the aggregate book
                                            --------
value of all generating assets Disposed of pursuant to this Section 6.04(c) from
and after the date hereof shall not exceed $1,100,000,000, and (d) in
transactions other than as provided in Section 6.04 (a), (b) and (c), provided
                                                                      --------
that the aggregate book value of all Property Disposed of pursuant to this
Section 6.04(d) from and after the date hereof shall not exceed $120,000,000.

          SECTION 6.05  Investments and Acquisitions.
                        ----------------------------

          Prior to the making of any Investment or the consummation of any
Acquisition by the Borrower or any of its Subsidiaries, the amount or purchase
price of which, as the case may be, when aggregated with the amounts and
purchase prices of other Investments and Acquisitions made by the Borrower and
its Subsidiaries, would exceed $70,000,000 in the aggregate at any time, the
Borrower shall deliver to the Administrative Agent (i) a certificate, in a form
reasonably satisfactory to the Administrative Agent, certifying that no Default
or Event of Default exists or will result from such Acquisition and (ii) pro
forma financial statements in support of such certification.

          SECTION 6.06  Dividends and Stock Repurchases.
                        -------------------------------

          The Borrower shall not declare or pay any dividend on its capital
stock (except for dividends in the form of capital stock), or redeem or
repurchase any of its capital stock, if a Default or Event of Default shall have
occurred and be continuing or shall exist at such time or after giving effect to
such transaction.

                                       54
<PAGE>

          SECTION 6.07  Transactions with Affiliates.
                        ----------------------------

          The Borrower shall not enter into any transaction of any kind with any
Person that Controls the Borrower or is controlled by the Borrower or is under
common control with the Borrower other than (a) salary, bonus, employee stock
option and other compensation arrangements with directors or officers in the
ordinary course of business, (b) transactions that are fully disclosed to the
board of directors (or executive committee thereof) of the Borrower and
expressly authorized by a resolution of the board of directors (or executive
committee) of the Borrower which is approved by a majority of the directors (or
executive committee) not having an interest in the transaction, (c) transactions
between or among the Borrower and its Wholly-Owned Subsidiaries and (d)
transactions on overall terms at least as favorable to the Borrower as would be
the case in an arm's-length transaction between unrelated parties of equal
bargaining power.

          SECTION 6.08  Equal and Ratable Lien.
                        ----------------------

          If, notwithstanding the prohibition contained in Section 6.02, the
Borrower or any of its Subsidiaries shall create, assume or permit to exist any
Lien upon any of its Property, other than those permitted by the provisions of
Section 6.02, it will make or cause to be made effective provision whereby the
Borrowings will be secured equally and ratably with any and all other
obligations thereby secured, such security to be pursuant to agreements
reasonably satisfactory to the Administrative Agent and, in any such case, the
Borrowings shall have the benefit, to the fullest extent that, and with such
priority as, the Lenders may be entitled under applicable law, of an equitable
Lien on such Property.  Such violation of Section 6.02 will constitute an Event
of Default, whether or not provision is made for an equal and ratable Lien
pursuant to this Section.

          SECTION 6.09  Restrictive Agreements.
                        -----------------------

          Except as otherwise permitted under Article VI hereunder, Article VI
of the SPPC Credit Agreement and Article VI of the NPC Credit Agreement, the
Borrower will not, and will not permit any of its Subsidiaries to, directly or
indirectly, enter into, incur or permit to exist any agreement or other
arrangement that prohibits, restricts or imposes any condition upon (a) the
ability of the Borrower or any Subsidiary to create, incur or permit to exist
any Lien upon any of its Property or assets, or (b) the ability of any
Subsidiary to pay dividends or other distributions with respect to any shares of
its capital stock or to make or repay loans or advances to the Borrower or any
other Subsidiary or to guarantee Indebtedness of the Borrower or any other
Subsidiary.

          SECTION 6.10  Year 2000.
                        ---------

          At the request of any Lender, the Borrower will make available to such
Lender the Borrower's Year 2000 Plan, together with any updates or progress
reports with respect thereto.  The Borrower will promptly notify the
Administrative Agent in the event the Borrower discovers or determines that any
computer application, including those of its suppliers and vendors, that is
material to its business, operations or conditions (financial or otherwise) will
not be Year 2000 Compliant on a timely basis, except to the extent that such
failure could not reasonably be expected to have a Material Adverse Effect.

                                       55
<PAGE>

                                  ARTICLE VII
                                   DEFAULTS

          SECTION 7.01  Events of Default.
                        -----------------

          An "Event of Default" shall mean the occurrence or existence of one or
              ----------------
more of the following events or conditions (for any reason, whether voluntary,
involuntary or effected or required by Law):

          (a) The Borrower shall fail to pay when due principal of any Loan.

          (b) The Borrower shall fail to pay when due interest on any Loan, any
     fees, indemnity or expenses, or any other amount due hereunder or under any
     other Loan Document and such failure shall have continued for a period of
     three business days.

          (c) Any representation or warranty made or deemed made by the Borrower
     in or pursuant to or in connection with any Loan Document, or any statement
     made by the Borrower in any financial statement, certificate, report,
     exhibit or document furnished by the Borrower to the Administrative Agent
     or any Lender pursuant to or in connection with any Loan Document, shall
     prove to have been false or misleading in any material respect as of the
     time when made or deemed made (including by omission of material
     information necessary to make such representation, warranty or statement
     not misleading).

          (d) The Borrower shall default in the performance or observance of any
     covenant contained in Article VI or any of the covenants contained in
     Sections 5.01(f)(i) or 5.09 or 5.10.

          (e) The Borrower shall default in the performance or observance of any
     other covenant, agreement or duty under this Agreement or any other Loan
     Document and (i) in the case of a default under Section 5.01 (other than as
     referred to in subsection (f)(i) thereof) such default shall have continued
     for a period of ten Business Days and (ii) in the case of any other default
     such default shall have continued for a period of 30 days after notice from
     the Administrative Agent to the Borrower.

          (f) The Borrower or any Subsidiary of the Borrower shall (i) fail to
     make any payment (x) on account of any Indebtedness under the NPC Credit
     Agreement or the SPPC Credit Agreement, (y) on account of any Indebtedness
     aggregating $10,000,000 or more in principal amount or (z) aggregating
     $10,000,000 or more on any Indebtedness, or any interest or premium
     thereon, in each case, when due (whether by scheduled maturity, required
     prepayment, acceleration, demand or otherwise), and, in each case, such
     failure shall have continued beyond any applicable grace period specified
     in any agreement or instrument relating to such Indebtedness, or (ii) fail
     to perform or observe any other term, covenant or condition on its part to
     be performed or observed under any agreement or instrument relating to any
     Indebtedness when required to be performed or observed, and such failure
     shall have continued beyond any applicable grace period specified in any
     agreement or instrument relating to such Indebtedness, if the effect of
     such failure to perform or observe is to accelerate, or to permit the
     acceleration of, the maturity of such Indebtedness, the unpaid principal
     amount of which then aggregates $10,000,000.

                                       56
<PAGE>

          (g) One or more final judgments or orders for the payment of money
     shall have been entered against the Borrower or any Subsidiary of the
     Borrower, which judgments or orders exceed $10,000,000 in the aggregate,
     and such judgments or orders shall have remained undischarged and unstayed
     for a period of thirty consecutive days.

          (h) One or more writs or warrants of attachment, garnishment,
     execution, distraint or similar process exceeding in value the aggregate
     amount of $10,000,000 shall have been issued against the Borrower or any
     Subsidiary of the Borrower or any of their respective properties and shall
     have remained undischarged and unstayed for a period of thirty consecutive
     days.

          (i) Any Governmental Action now or hereafter made by or with any
     Governmental Authority in connection with any Loan Document is not obtained
     or shall have ceased to be in full force and effect or shall have been
     modified or amended or shall have been held to be illegal or invalid, and
     the Required Lenders shall have determined (which determination shall be
     conclusive provided it is reached in good faith) that the consequence of
     any of the foregoing events would reasonably be expected to have,
     individually or in the aggregate, a Material Adverse Effect.

          (j) Any Loan Document or any material term or provision thereof shall
     have ceased to be in full force and effect, or the Borrower or any
     Governmental Authority with jurisdiction over the Borrower shall, or shall
     purport to, terminate, repudiate, declare voidable or void or otherwise
     contest, any Loan Document or any material term or provision thereof or any
     obligation or liability of the Borrower thereunder.

          (k) An event or condition specified in Section 5.01(h) hereof shall
     occur or exist with respect to any Plan or Multiemployer Plan or any Lien
     arises pursuant to ERISA and, as a result of such event or condition or
     Liens, together with all other such events or conditions or Liens, the
     Borrower or any ERISA Affiliate shall incur or shall be reasonably likely
     to incur a liability to a Plan, a Multiemployer Plan or PBGC or suffer an
     encumbrance to exist in favor of any thereof (or any combination of the
     foregoing) which would constitute a Material Adverse Effect.

          (l) The Borrower or any Subsidiary of the Borrower shall have violated
     any Environmental Law or become subject to any Environmental Claim and, in
     either case, the Required Lenders shall have determined (which
     determination shall be conclusive provided it is reached in good faith)
     that such event would reasonably be expected, either individually or in the
     aggregate, to have a Material Adverse Effect.

          (m) A proceeding shall have been instituted in respect of the Borrower
     or any Subsidiary of the Borrower:

               (i) seeking to have an order for relief entered in respect of
          such Person, or seeking a declaration or entailing a finding that such
          Person is insolvent or a similar declaration or finding, or seeking
          dissolution, winding-up, charter revocation or forfeiture,
          liquidation, reorganization, arrangement, adjustment, composition or
          other similar relief with respect to such Person, its assets or its
          debts

                                       57
<PAGE>

          under any Law relating to bankruptcy, insolvency, relief of debtors or
          protection of creditors, termination of legal entities or any other
          similar Law now or hereafter in effect, or

              (ii) seeking appointment of a receiver, trustee, liquidator,
          assignee, sequestrator or other custodian for such Person or for all
          or any substantial part of its Property,

     and such proceeding shall result in the entry, making or grant of any such
     order for relief, declaration, finding, relief or appointment, or such
     proceeding shall remain undismissed and unstayed for a period of thirty
     consecutive days.

          (n) The Borrower or any Subsidiary of the Borrower shall become
     insolvent; shall fail to pay, become unable to pay, or state that it is or
     will be unable to pay, its debts as they become due; shall voluntarily
     suspend transaction of its business; shall make a general assignment for
     the benefit of creditors; shall institute (or fail to controvert in a
     timely and appropriate manner) a proceeding described in Section
     7.01(m)(i), or (whether or not any such proceeding has been instituted)
     shall consent to or acquiesce in any such order for relief, declaration,
     finding or relief described therein; shall institute (or fail to controvert
     in a timely and appropriate manner) a proceeding described in Section
     7.01(m)(ii), or (whether or not any such proceeding has been instituted)
     shall consent to or acquiesce in any such appointment or to the taking of
     possession by any such custodian of all or any substantial part of its
     Property; shall dissolve, wind-up, revoke or forfeit its charter (or other
     constituent documents) or liquidate itself or any substantial part of its
     Property; or shall take any action in furtherance of any of the foregoing.

          (o) A Change in Control shall occur.

          (p) NPC or SPPC shall cease to maintain a first mortgage bond rating
     of at least Baa3 by Moody's and BBB- by S&P.

          (q) The Borrower shall fail to maintain ongoing utility segment-
     identifiable assets (exclusive of cash and marketable securities) and
     operating income relating to the generation, transmission and/or
     distribution of electricity, gas or water in a proportion not less than 80%
     of total assets (exclusive of cash and marketable securities) and operating
     income.

          SECTION 7.02  Consequences of an Event of Default.
                        -----------------------------------

          (a) If an Event of Default specified in subsections (a) through (l),
(o), (p) or (q) of Section 7.01 shall occur and, be continuing or shall exist,
then, in addition to all other rights and remedies which the Administrative
Agent or any Lender may have hereunder or under any other Loan Document, at law,
in equity or otherwise, the Lenders shall be under no further obligation to make
Loans hereunder, and the Administrative Agent may, and, upon the written request
of the Required Lenders shall, by notice to the Borrower, from time to time do
any or all of the following:

                                       58
<PAGE>

          (i)  Declare the Commitments terminated, whereupon the Commitments
     will terminate and any fees hereunder shall be immediately due and payable
     without presentment, demand, protest or further notice of any kind, all of
     which are hereby waived, and an action therefor shall immediately accrue.

          (ii) Declare the unpaid principal amount of the Loans, interest
     accrued thereon and all other obligations to be immediately due and payable
     without presentment, demand, protest or further notice of any kind, all of
     which are hereby waived, and an action therefor shall immediately accrue.

          (b)  If an Event of Default specified in subsection (m) or (n) of
Section 7.01 shall occur or exist, then, in addition to all other rights and
remedies which the Administrative Agent or any Lender may have hereunder or
under any other Loan Document, at law, in equity or otherwise, the Commitments
shall automatically terminate and the Lenders shall be under no further
obligation to make Loans, and the unpaid principal amount of the Loans, interest
accrued thereon and all other obligations shall become immediately due and
payable without presentment, demand, protest or notice of any kind, all of which
are hereby waived, and an action therefor shall immediately accrue.

                                 ARTICLE VIII
                                  THE AGENTS

          SECTION 8.01  Appointment.
                        -----------

          Each Lender hereby irrevocably appoints Mellon Bank, N.A. to act as
Administrative Agent for such Lender under this Agreement and the other Loan
Documents.  Each Lender hereby irrevocably authorizes the Administrative Agent
to take such action on behalf of such Lender under the provisions of this
Agreement and the other Loan Documents, and to exercise such powers and to
perform such duties, as are expressly delegated to or required of the
Administrative Agent by the terms hereof or thereof, together with such powers
as are reasonably incidental thereto.  Mellon Bank, N.A. hereby agrees to act as
Administrative Agent on behalf of the Lenders on the terms and conditions set
forth in this Agreement and the other Loan Documents, subject to its right to
resign as provided in Section 8.10. Each Lender hereby irrevocably authorizes
the Administrative Agent to execute and deliver each of the Loan Documents
executed after the date hereof and to accept delivery of such of the other Loan
Documents delivered after the date hereof as may not require execution by the
Administrative Agent (with such consents of the Lenders as required pursuant to
Section 9.01).  Each Lender agrees that the rights and remedies granted to the
Administrative Agent under the Loan Documents shall be exercised exclusively by
the Administrative Agent, and that no Lender shall have any right individually
to exercise any such right or remedy, except to the extent expressly provided
herein or therein.

          SECTION 8.02  General Nature of Administrative Agent's Duties.
                        -----------------------------------------------

          Notwithstanding anything to the contrary elsewhere in this Agreement
or in any other Loan Document:

                                       59
<PAGE>

          (a) The Administrative Agent shall have no duties or responsibilities
     except those expressly set forth in this Agreement and the other Loan
     Documents, and no implied duties or responsibilities on the part of the
     Administrative Agent shall be read into this Agreement or any other Loan
     Document or shall otherwise exist.

          (b) The duties and responsibilities of the Administrative Agent under
     this Agreement and the other Loan Documents shall be mechanical and
     administrative in nature, and the Administrative Agent shall not have a
     fiduciary relationship in respect of any Lender.

          (c) The Administrative Agent is and shall be solely the agent of the
     Lenders.  The Administrative Agent does not assume, and shall not at any
     time be deemed to have, any relationship of agency or trust with or for, or
     any other duty or responsibility to, the Borrower or any other Person
     (except only for its relationship as agent for, and its express duties and
     responsibilities to, the Lenders as provided in this Agreement and the
     other Loan Documents).

          (d) The Administrative Agent shall be under no obligation to take any
     action hereunder or under any other Loan Document if the Administrative
     Agent believes in good faith that taking such action may conflict with any
     Law or any provision of this Agreement or any other Loan Document, or may
     require the Administrative Agent to qualify to do business in any
     jurisdiction where it is not then so qualified.

          SECTION 8.03  Exercise of Powers.
                        ------------------

          The Administrative Agent shall take any action of the type specified
in this Agreement or any other Loan Document as being within the Administrative
Agent's rights, powers or discretion in accordance with directions from the
Required Lenders (or, to the extent this Agreement or such Loan Document
expressly requires the direction or consent of some other Person or set of
Persons, then instead in accordance with the directions of such other Person or
set of Persons).  In the absence of such directions, the Administrative Agent
shall have the authority (but under no circumstances shall be obligated), in its
sole discretion, to take any such action, except to the extent that this
Agreement or such Loan Document expressly requires the direction or consent of
the Required Lenders (or some other Person or set of Persons), in which case the
Administrative Agent shall not take such action absent such direction or
consent.  Any action or inaction pursuant to such direction, discretion or
consent shall be binding on all the Lenders.  The Administrative Agent shall not
have any liability to any Person as a result of (a) the Administrative Agent
acting or refraining from acting in accordance with the directions of the
Required Lenders (or other applicable Person or set of Persons), (b) the
Administrative Agent refraining from acting in the absence of instructions to
act from the Required Lenders (or other applicable Person or set of Persons),
whether or not the Administrative Agent has discretionary power to take such
action, or (c) the Administrative Agent taking discretionary action it is
authorized to take under this Section (subject, in the case of clauses (b) and
(c), to the provisions of Section 8.04(a)).

                                       60
<PAGE>

          SECTION 8.04  General Exculpatory Provisions.
                        ------------------------------

          Notwithstanding anything to the contrary elsewhere in this Agreement
or any other Loan Document:

          (a) The Administrative Agent shall not be liable for any action taken
     or omitted to be taken by it under or in connection with this Agreement or
     any other Loan Document, unless caused by its own gross negligence or
     willful misconduct.

          (b) The Administrative Agent shall not be responsible for (i) the
     execution, delivery, effectiveness, enforceability, genuineness, validity
     or adequacy of this Agreement or any other Loan Document, (ii) any recital,
     representation, warranty, document, certificate, report or statement in,
     provided for in, or received under or in connection with, this Agreement or
     any other Loan Document, (iii) any failure of the Borrower or any Lender to
     perform any of their respective obligations under this Agreement or any
     other Loan Document, or (iv) the existence, validity, enforceability,
     perfection, recordation, priority, adequacy or value, now or hereafter, of
     any Lien or other direct or indirect security afforded or purported to be
     afforded by any of the Loan Documents or otherwise from time to time.

          (c) The Administrative Agent shall not be under any obligation to
     ascertain, inquire or give any notice relating to (i) the performance or
     observance of any of the terms or conditions of this Agreement or any other
     Loan Document on the part of the Borrower, (ii) the business, operations,
     condition (financial or otherwise) or prospects of the Borrower or any
     other Person, or (iii) except to the extent set forth in Section 8.05(f),
     the existence of any Default or Event of Default.

          (d) The Administrative Agent shall not be under any obligation, either
     initially or on a continuing basis, to provide any Lender with any notices,
     reports or information of any nature, whether in its possession presently
     or hereafter, except for such notices, reports and other information
     expressly required by this Agreement or any other Loan Document to be
     furnished by the Administrative Agent to such Lender.

          SECTION 8.05  Administration by the Administrative Agent.
                        ------------------------------------------

          (a) The Administrative Agent may rely upon any notice or other
communication of any nature (written or oral, including but not limited to
telephone conversations, whether or not such notice or other communication is
made in a manner permitted or required by this Agreement or any other Loan
Document) purportedly made by or on behalf of the proper party or parties, and
the Administrative Agent shall not have any duty to verify the identity or
authority of any Person giving such notice or other communication.

          (b) The Administrative Agent may consult with legal counsel
(including, without limitation, in-house counsel for the Administrative Agent or
in-house or other counsel for the Borrower), independent public accountants and
any other experts selected by it from time to time, and the Administrative Agent
shall not be liable for any action taken or omitted to be taken in good faith by
it in accordance with the advice of such counsel, accountants or experts.

                                       61
<PAGE>

          (c) The Administrative Agent may conclusively rely upon the truth of
the statements and the correctness of the opinions expressed in any certificates
or opinions furnished to the Administrative Agent in accordance with the
requirements of this Agreement or any other Loan Document.  Whenever the
Administrative Agent shall deem it necessary or desirable that a matter be
proved or established with respect to the Borrower or any Lender, such matter
may be established by a certificate of the Borrower or such Lender, as the case
may be, and the Administrative Agent may conclusively rely upon such certificate
(unless other evidence with respect to such matter is specifically prescribed in
this Agreement or another Loan Document).

          (d) The Administrative Agent may fail or refuse to take any action
unless it shall be indemnified to its satisfaction from time to time against any
and all amounts, liabilities, obligations, losses, damages, penalties, actions,
judgments, suits, costs, expenses or disbursements of any kind or nature which
may be imposed on, incurred by or asserted against the Administrative Agent by
reason of taking or continuing to take any such action.

          (e) The Administrative Agent may perform any of its duties under this
Agreement or any other Loan Document by or through agents or attorneys-in-fact.
The Administrative Agent shall not be responsible for the negligence or
misconduct of any agents or attorneys-in-fact selected by it with reasonable
care.

          (f) The Administrative Agent shall not be deemed to have any knowledge
or notice of the occurrence of any Default or Event of Default unless the
Administrative Agent has received notice from a Lender or the Borrower referring
to this Agreement, describing such Default or Event of Default, and stating that
such notice is a "notice of default".  If the Administrative Agent receives such
a notice, the Administrative Agent shall give prompt notice thereof to each
Lender.

          SECTION 8.06  Lenders Not Relying on Administrative Agent or Other
                        ----------------------------------------------------
Lenders.
-------

          Each Lender acknowledges as follows:

          (a) Neither the Administrative Agent nor any other Lender has made any
     representations or warranties to it, and no act taken hereafter by the
     Administrative Agent or any other Lender shall be deemed to constitute any
     representation or warranty by the Administrative Agent or such other Lender
     to it.

          (b) It has, independently and without reliance upon the Administrative
     Agent or any other Lender, and based upon such documents and information as
     it has deemed appropriate, made its own credit and legal analysis and
     decision to enter into this Agreement and the other Loan Documents.

          (c) It will, independently and without reliance upon the
     Administrative Agent or any other Lender, and based upon such documents and
     information as it shall deem appropriate at the time, make its own
     decisions to take or not take action under or in connection with this
     Agreement and the other Loan Documents.

                                       62
<PAGE>

          SECTION 8.07  Indemnification.
                        ---------------

          Each Lender agrees to reimburse and indemnify the Administrative Agent
and its directors, officers, employees and agents (to the extent not reimbursed
by the Borrower and without limitation of the obligations of the Borrower to do
so, in each case pursuant to the terms of this Agreement and the other Loan
Documents), based on its Applicable Percentage, from and against any and all
amounts, losses, liabilities, claims, damages, expenses, obligations, penalties,
actions, judgments, suits, costs or disbursements of any kind or nature
(including, without limitation, the fees and disbursements of counsel for the
Administrative Agent or such other Person in connection with any investigative,
administrative or judicial proceeding commenced or threatened, whether or not
the Administrative Agent or such other Person shall be designated a party
thereto) that may at any time be imposed on, incurred by or asserted against the
Administrative Agent or such other Person as a result of, or arising out of, or
in any way related to or by reason of, this Agreement, any other Loan Document,
any transaction from time to time contemplated hereby or thereby, or any
transaction financed in whole or in part or directly or indirectly with the
proceeds of any Loan, provided that no Lender shall be liable for any portion of
                      --------
such amounts, losses, liabilities, claims, damages, expenses, obligations,
penalties, actions, judgments, suits, costs or disbursements resulting solely
from the gross negligence or willful misconduct of the Administrative Agent or
such other Person, as finally determined by a court of competent jurisdiction.
Payments under this Section 8.07 shall be due and payable on demand, and to the
extent that any Lender fails to pay any such amount on demand, such amount shall
bear interest for each day from the date of demand until paid (before and after
judgment) at a rate per annum (calculated on the basis of a year of 360 days and
actual days elapsed) which for each day shall be equal to the Federal Funds
Effective Rate for such day.

          SECTION 8.08  Administrative Agent in its Individual Capacity.
                        -----------------------------------------------

          With respect to its Commitment and the Obligations owing to it, the
Administrative Agent shall have the same rights and powers under this Agreement
and each other Loan Document as any other Lender and may exercise the same as
though it were not the Administrative Agent, and the terms "Lenders," "holders
of Notes" and like terms shall include the Administrative Agent in its
individual capacity as such.  The Administrative Agent and its affiliates may,
without liability to account, make loans to, accept deposits from, acquire debt
or equity interests in, act as trustee under indentures of, and engage in any
other business with, the Borrower and any stockholder, subsidiary or affiliate
of the Borrower, as though the Administrative Agent were not the Administrative
Agent hereunder.

          SECTION 8.09  Holders of Notes.
                        ----------------

          The Administrative Agent may deem and treat the Lender which is payee
of a Note as the owner and holder of such Note for all purposes hereof unless
and until an Assignment and Acceptance with respect to the assignment or
transfer thereof shall have been filed with the Administrative Agent in
accordance with Section 9.12.  Any authority, direction or consent of any Person
who at the time of giving such authority, direction or consent is shown in the
Register as being a Lender shall be conclusive and binding on each present and
subsequent holder, transferee or assignee of any Note or Notes payable to such
Lender or of any Note or Notes issued in exchange therefor.

                                       63
<PAGE>

          SECTION 8.10  Successor Administrative Agent.
                        ------------------------------

          The Administrative Agent may resign at any time by giving 10 days'
prior written notice thereof to the Lenders and the Borrower.  The
Administrative Agent may be removed by the Required Lenders at any time with or
without cause by giving 10 days, prior written notice thereof to the
Administrative Agent, the other Lenders and the Borrower.  Upon any such
resignation or removal, the Required Lenders shall have the right to appoint a
successor Administrative Agent.  If no successor Administrative Agent shall have
been so appointed and consented to, and shall have accepted such appointment,
within 30 days after such notice of resignation or removal, then the retiring
Administrative Agent, on behalf of the Lenders, may appoint a successor
Administrative Agent.  Each successor Administrative Agent shall be a commercial
bank or trust company organized under the Laws of the United States of America
or any State thereof and having a combined capital and surplus of at least
$1,000,000,000.  The appointment of any successor Administrative Agent at any
time pursuant to this Section 8.10 shall be subject to the approval of the
Borrower, provided that at such time there shall not have occurred and be
continuing any Default or Event of Default, and provided further that the
Borrower's consent to any such appointment shall not be unreasonably withheld.
Upon the acceptance by a successor Administrative Agent of its appointment as
Administrative Agent hereunder, such successor Administrative Agent shall
thereupon succeed to and become vested with all the properties, rights, powers,
privileges and duties of the former Administrative Agent without further act,
deed or conveyance.  Upon the effective date of resignation or removal of a
retiring Administrative Agent, the Administrative Agent shall be discharged from
its duties under this Agreement and the other Loan Documents, but the provisions
of this Agreement shall inure to its benefit as to any actions taken or omitted
by it while it was Administrative Agent under this Agreement.  If and for so
long as no successor Administrative Agent shall have been appointed, then any
notice or other communication required or permitted to be given by the
Administrative Agent shall be sufficiently given if given by the Required
Lenders, all notices or other communications required or permitted to be given
to the Administrative Agent shall be given to each Lender, and all payments to
be made to the Administrative Agent shall be made directly to the Borrower or
Lender for whose account such payment is made.

          SECTION 8.11  Additional Administrative Agents.
                        --------------------------------

          If the Administrative Agent shall from time to time deem it necessary
or advisable, for its own protection in the performance of its duties hereunder
or in the interest of the Lenders, the Administrative Agent and the Borrower
shall execute and deliver a supplemental agreement and all other instruments and
agreements necessary or advisable in the opinion of the Administrative Agent to
constitute another commercial bank or trust company, or one or more other
Persons approved by the Administrative Agent, to act as co-Administrative Agent,
with such powers of the Administrative Agent as may be provided in such
supplemental agreement, and to vest in such bank, trust company or Person, as
such co-Administrative Agent, any properties, rights, powers, privileges and
duties of the Administrative Agent under this Agreement or any other Loan
Document.  The appointment of any co-Administrative Agent at any time pursuant
to this Section 8.11 shall be subject to the approval of the Borrower, provided
that at such time there shall not have occurred and be continuing any Default or
Event of Default, and provided further that the Borrower's consent to any such
appointment shall not be unreasonably withheld.

                                       64
<PAGE>

          SECTION 8.12  Calculations.
                        ------------

          The Administrative Agent shall not be liable for any calculation,
apportionment or distribution of payments made by it in good faith, in the
absence of its own gross negligence or willful misconduct.  If such calculation,
apportionment or distribution is subsequently determined to have been made in
error, the sole recourse of any Lender to whom payment was due but not made
(except as provided in the preceding sentence) shall be to recover from the
other Lenders any payment in excess of the amount to which they are determined
to be entitled or, if the amount due was not paid by the Borrower, to recover
such amount from the Borrower.

          SECTION 8.13  Syndication Agents.
                        ------------------

          As Syndication Agents, neither First Union National Bank nor Wells
Fargo Bank, N.A. shall have any right, power, obligation, liability,
responsibility or duty under this Agreement other than those applicable to all
Lenders as such.  Without limiting the foregoing, neither First Union National
Bank nor Wells Fargo Bank, N.A. shall have any or be deemed to have any
fiduciary relationship with any Lender.  Each Lender acknowledges that it has
not relied, and will not rely, on First Union National Bank or Wells Fargo Bank,
N.A. in deciding to enter into this Agreement or in not taking action hereunder
or under the Loan Documents.

                                  ARTICLE IX
                                 MISCELLANEOUS

          SECTION 9.01  Amendments and Waivers.
                        ----------------------

          Neither this Agreement nor any other Loan Document may be amended,
modified or supplemented except in accordance with the provisions of this
Section 9.01. The Administrative Agent and the Borrower may from time to time
amend, modify or supplement the provisions of this Agreement or any other Loan
Document for the purpose of amending, adding to or waiving any provision, or
changing in any manner the rights and duties of the Borrower, the Administrative
Agent or any Lender.  Any such amendment, modification or supplement made by the
Borrower and the Administrative Agent in accordance with the provisions of this
Section 9.01 shall be binding upon the Borrower, each Lender and the
Administrative Agent.  The Administrative Agent shall enter into such
amendments, modifications or supplements from time to time as directed by the
Required Lenders, and only as so directed, provided, that no such amendment,
                                           --------
modification or supplement may be made which will:

          (a) Increase the Commitments of any Lender  over the amount thereof
     then in effect, without the written consent of each Lender affected
     thereby;

          (b) Extend either Revolving Termination Date, without the written
     consent of all the Lenders;

          (c) Reduce the principal amount of or extend the time for any payment
     of principal of any Loan, or reduce the rate of interest or extend the time
     for payment of any interest borne by any Loan, or extend the time for
     payment of or reduce the amount of any fees, or reduce or postpone the date
     for payment of any other obligation, without the written consent of each
     Lender affected thereby;

                                       65
<PAGE>

          (d) Change the definition of "Required Lenders" or amend this Section
     9.01 or Section 9.12(a) or any other provision of this Agreement that
     requires the consent of all of the Lenders to the taking or failure to take
     action hereunder, without the written consent of all the Lenders; or

          (e) Amend or waive any of the provisions of Article VIII, or impose
     additional duties upon the Administrative Agent or otherwise adversely
     affect the rights, interests or obligations of the Administrative Agent,
     without the written consent of the Administrative Agent;

and provided, further, that Assignment and Acceptances may be entered into in
    --------
the manner provided in Section 9.12. Any such amendment, modification or
supplement must be in writing and shall be effective only to the extent set
forth in such writing.  Any Default or Event of Default waived or consented to
in any such amendment, modification or supplement shall be deemed to be cured
and not continuing to the extent and for the period set forth in such waiver or
consent, but no such waiver or consent shall extend to any other or subsequent
Default or Event of Default or impair any right consequent thereto.

          SECTION 9.02  No Implied Waiver; Cumulative Remedies.
                        --------------------------------------

          No course of dealing and no delay or failure of the Administrative
Agent or any Lender in exercising any right, power or privilege under this
Agreement or any other Loan Document shall affect any other or future exercise
thereof or the exercise of any other right, power or privilege; nor shall any
single or partial exercise of any such right, power or privilege or any
abandonment or discontinuance of steps to enforce such a right, power or
privilege preclude any further exercise thereof or of any other right, power or
privilege.  The rights and remedies of the Administrative Agent and the Lenders
under this Agreement and any other Loan Document are cumulative and not
exclusive of any rights or remedies which the Administrative Agent or any Lender
would otherwise have hereunder or thereunder, at law, in equity or otherwise.

          SECTION 9.03  Notices.
                        -------

          (a) Except to the extent otherwise expressly permitted hereunder or
thereunder, all notices, requests, demands, directions and other communications
(collectively "notices") under this Agreement or any other Loan Document shall
               -------
be in writing (including telecopied communication) and shall be sent by first-
class mail, or by nationally-recognized overnight courier, or by telecopier
(with confirmation in writing mailed first-class or sent by such an overnight
courier), or by personal delivery.  All notices shall be sent to the applicable
party at the address stated on the signature pages hereof or in accordance with
the last unrevoked written direction from such party to the other parties hereto
in all cases with postage or other charges prepaid.  Any such properly given
notice shall be effective on the earliest to occur of receipt, telephone
confirmation of receipt of telecopy communication, one Business Day after
delivery to a nationally-recognized overnight courier, or three Business Days
after deposit in the mail.

          (b) Any Lender giving any notice to the Borrower or any other party to
a Loan Document shall simultaneously send a copy thereof to the Administrative
Agent, and the

                                       66
<PAGE>

Administrative Agent shall promptly notify the other Lenders of the receipt by
it of any such notice.

          (c) The Administrative Agent and each Lender may rely on any notice
(whether or not such notice is made in a manner permitted or required by this
Agreement or any other Loan Document) purportedly made by or on behalf of the
Borrower, and neither the Administrative Agent nor any Lender shall have any
duty to verify the identity or authority of any Person giving such notice.

          SECTION 9.04  Expenses; Taxes; Indemnity.
                        --------------------------

          (a) The Borrower agrees to pay or cause to be paid and to save the
Administrative Agent and each of the Lenders harmless against liability for the
payment of all reasonable out-of-pocket costs and expenses (including but not
limited to reasonable fees and expenses of counsel) incurred by the
Administrative Agent or any Lender from time to time arising from or relating to
(i) in the case of the Administrative Agent, the negotiation, syndication,
preparation, execution, delivery, administration and performance of this
Agreement and the other Loan Documents, (ii) in the case of the Syndication
Agents, the syndication of this Agreement and the other Loan Documents, (iii) in
the case of the Administrative Agent, any amendments, modifications,
supplements, waivers or consents to this Agreement or any other Loan Document
(whether or not ultimately entered into or granted), and (iv) in the case of the
Administrative Agent or any Lender, the enforcement or preservation of rights
under this Agreement or any other Loan Document (including but not limited to
any such costs or expenses arising from or relating to (A) collection or
enforcement of an outstanding Loan or any other amount owing hereunder or
thereunder by the Administrative Agent or such Lender, and (B) any litigation,
proceeding, dispute, work-out, restructuring or rescheduling related in any way
to this Agreement or the Loan Documents).

          (b) The Borrower hereby agrees to pay all stamp, document, transfer,
recording, filing, registration, search, sales and excise fees and taxes and all
similar impositions now or hereafter determined by the Administrative Agent or
any Lender to be payable in connection with this Agreement or any other Loan
Documents or any other documents, instruments or transactions pursuant to or in
connection herewith or therewith (which determination shall be conclusive
provided it is reached in good faith), and the Borrower agrees to save the
Administrative Agent and each Lender harmless from and against any and all
present or future claims, liabilities or losses with respect to or resulting
from any omission to pay or delay in paying any such fees, taxes or impositions.

          (c) The Borrower hereby agrees to reimburse and indemnify each of the
Indemnified Parties from and against any and all losses, liabilities, claims,
damages, expenses, obligations, penalties, actions, judgments, suits, costs or
disbursements of any kind or nature whatsoever (including, without limitation,
the reasonable fees and disbursements of counsel for such Indemnified Party in
connection with any investigative, administrative or judicial proceeding
commenced or threatened, whether or not such Indemnified Party shall be
designated a party thereto) that may at any time be imposed on, asserted against
or incurred by such Indemnified Party as a result of, or arising out of, or in
any way related to or by reason of, this Agreement or any other Loan Document,
any transaction from time to time contemplated hereby or thereby, or

                                       67
<PAGE>

any transaction financed in whole or in part or directly or indirectly with the
proceeds of any Loan (and without in any way limiting the generality of the
foregoing, including any violation or breach of any Environmental Law or any
other Law by the Borrower or any Subsidiary of the Borrower; any Environmental
Claim arising out of the management, use, control, ownership or operation of
Property by any of such Persons, including all onsite and off-site activities
involving Hazardous Materials; or any exercise by the Administrative Agent or
any Lender of any of its rights or remedies under this Agreement or any other
Loan Document); but excluding any such losses, liabilities, claims, damages,
expenses, obligations, penalties, actions, judgments, suits, costs or
disbursements resulting solely from the gross negligence or willful misconduct
of such Indemnified Party, as finally determined by a court of competent
jurisdiction. If and to the extent that the foregoing obligations of the
Borrower under this subsection (c), or any other indemnification obligation of
the Borrower hereunder or under any other Loan Document, are unenforceable for
any reason, the Borrower hereby agrees to make the maximum contribution to the
payment and satisfaction of such obligations which is permissible under
applicable Law.

          SECTION 9.05  Severability.
                        ------------

          The provisions of this Agreement are intended to be severable.  If any
provision of this Agreement shall be held invalid or unenforceable in whole or
in part in any jurisdiction such provision shall, as to such jurisdiction, be
ineffective to the extent of such invalidity or unenforceability without in any
manner affecting the validity or enforceability thereof in any other
jurisdiction or the remaining provisions hereof in any jurisdiction.

          SECTION 9.06  Prior Understandings.
                        --------------------

          This Agreement, the other Loan Documents and that certain letter
agreement regarding fees dated March 30, 1999 among Mellon Bank, N.A., SPPC and
the Borrower, as such agreements shall be amended from time to time, supersede
all prior and contemporaneous understandings and agreements, whether written or
oral, among the parties hereto relating to the transactions provided for herein
and therein.

          SECTION 9.07  Duration; Survival.
                        ------------------

          All representations and warranties of the Borrower contained herein or
in any other Loan Document or made in connection herewith or therewith shall
survive the making, and shall not be waived by the execution and delivery, of
this Agreement or any other Loan Document, any investigation by or knowledge of
the Administrative Agent or any Lender, the making of any Loan, or any other
event or condition whatever.  All covenants and agreements of the Borrower
contained herein or in any other Loan Document shall continue in full force and
effect from and after the date hereof so long as the Borrower may borrow
hereunder and until payment in full of all Obligations.  Without limitation, all
obligations of the Borrower hereunder or under any other Loan Document to make
payments to or indemnify the Administrative Agent or any Lender shall survive
the payment in full of all other Obligations, termination of the Borrower's
right to borrow hereunder, and all other events and conditions whatever.  In
addition, all obligations of each Lender to make payments to or indemnify the
Administrative Agent shall survive the payment in full by the Borrower of all
Obligations, termination of the Borrower's right to borrow hereunder, and all
other events or conditions whatever.

                                       68
<PAGE>

          SECTION 9.08  Counterparts.
                        ------------

          This Agreement may be executed in any number of counterparts and by
the different parties hereto on separate counterparts each of which, when so
executed, shall be deemed an original, but all such counterparts shall
constitute but one and the same instrument.

          SECTION 9.09  Limitation on Payments.
                        ----------------------

          The parties hereto intend to conform to all applicable Laws in effect
from time to time limiting the maximum rate of interest that may be charged or
collected.  Accordingly, notwithstanding any other provision hereof or of any
other Loan Document, the Borrower shall not be required to make any payment to
or for the account of any Lender, and each Lender shall refund any payment made
by the Borrower, to the extent that such requirement or such failure to refund
would violate or conflict with nonwaivable provisions of applicable Laws
limiting the maximum amount of interest which may be charged or collected by
such Lender.

          SECTION 9.10  Set-Off.
                        -------

          The Borrower hereby agrees that, to the fullest extent permitted by
Law, if any Obligation of the Borrower shall be due and payable (by acceleration
or otherwise), each Lender shall have the right, without notice to the Borrower,
to set-off against and to appropriate and apply to such Obligation any
indebtedness, liability or obligation of any nature owing to the Borrower by
such Lender, including but not limited to all deposits (whether time or demand,
general or special, provisionally credited or finally credited, whether or not
evidenced by a certificate of deposit) now or hereafter maintained by the
Borrower with such Lender.  Such right shall be absolute and unconditional in
all circumstances and, without limitation shall exist whether or not such Lender
or any other Person shall have given notice or made a demand to the Borrower or
any other Person, whether such indebtedness, obligation or liability owed to the
Borrower is contingent, absolute, matured or unmatured (it being agreed that
such Lender may deem such indebtedness, obligation or liability to be then due
and payable at the time of such setoff), and regardless of the existence or
adequacy of any collateral, guaranty or any other security, right or remedy
available to any Lender or any other Person.  The Borrower hereby agrees that,
to the fullest extent permitted by Law, any Participant and any branch,
subsidiary or affiliate of any Lender or any Participant shall have the same
rights of set-off as a Lender as provided in this Section (regardless of whether
such Participant, branch, subsidiary or affiliate would otherwise be deemed in
privity with or a direct creditor of the Borrower).  The rights provided by this
Section are in addition to all other rights of set-off and banker's lien and all
other rights and remedies which any Lender (or any such Participant, branch,
subsidiary or affiliate) may otherwise have under this Agreement, any other Loan
Document, at law or in equity, or otherwise, and nothing in this Agreement or
any other Loan Document shall be deemed a waiver or prohibition of or
restriction on the rights of set-off or bankers' lien of any such Person.

          SECTION 9.11  Sharing of Collections.
                        ----------------------

          The Lenders hereby agree among themselves that if any Lender shall
receive (by voluntary payment, realization upon security, set-off or from any
other source) any amount on account of the Loans, interest thereon, or any other
Obligation contemplated by this Agreement or

                                       69
<PAGE>

the other Loan Documents to be made by the Borrower pro rata to all Lenders (or
pro rata to holders of Notes) in greater proportion than any such amount
received by any other applicable Lender, then the Lender receiving such
proportionately greater payment shall notify each other Lender and the
Administrative Agent of such receipt, and equitable adjustment will be made in
the manner stated in this Section 9.11 so that, in effect, all such excess
amounts will be shared ratably among all of the applicable Lenders. The Lender
receiving such excess amount shall purchase (which it shall be deemed to have
done simultaneously upon the receipt of such excess amount) for cash from the
other applicable Lenders a participation in the applicable Obligations owed to
such other Lenders in such amount as shall result in a ratable sharing by all
applicable Lenders of such excess amount (and to such extent the receiving
Lender shall be a Participant). If all or any portion of such excess amount is
thereafter recovered from the Lender making such purchase, such purchase shall
be rescinded and the purchase price restored to the extent of such recovery,
together with interest or other amounts, if any, required by Law to be paid by
the Lender making such purchase. The Borrower hereby consents to and confirms
the foregoing arrangements. Each Participant shall be bound by this Section as
fully as if it were a Lender hereunder.

          SECTION 9.12  Successors and Assigns; Participations; Assignments.
                        ---------------------------------------------------

          (a)   Successors and Assigns.  This Agreement shall be binding upon
                ----------------------
and inure to the benefit of the Borrower, the Lenders, all future holders of the
Notes, the Agents and their respective successors and assigns, except that the
Borrower may not assign or transfer any of its rights hereunder or interests
herein without the prior written consent of all the Lenders and the
Administrative Agent, and any purported assignment without such consent shall be
void.

          (b)   Participations.  Any Lender may, in the ordinary course of its
                --------------
commercial banking business and in accordance with applicable Law, at any time
sell participations to one or more commercial banks or other Persons (each a
"Participant") in all or a portion of its rights and obligations under this
------------
Agreement and the other Loan Documents (including, without limitation, all or a
portion of its Commitments and the Loans owing to it and any Note held by it);

provided, that
--------

          (i)   any such Lender's obligations under this Agreement and the other
     Loan Documents shall remain unchanged,

          (ii)  such Lender shall remain solely responsible to the other parties
     hereto for the performance of such obligations,

          (iii) the parties hereto shall continue to deal solely and directly
     with such Lender in connection with such Lender's rights and obligations
     under this Agreement and each of the other Loan Documents,

          (iv)  such Participant shall be bound by the provisions of Section
     9.11, and

          (v)   no Participant (unless such Participant is an Affiliate of such
     Lender, or is itself a Lender) shall be entitled to require such Lender to
     take or refrain from taking action under this Agreement or under any other
     Loan Document, except that such Lender may agree with such Participant that
     such Lender will not, without such Participant's consent, take any action,
     or consent to the taking of any action, of the type described in Section
     9.01(a), (b) or (c).

                                       70
<PAGE>

The Borrower agrees that any such Participant shall be entitled to the benefits
of Sections 2.13, 2.14, 2.15 and 9.04 with respect to its participation in the
Commitments and the Loans outstanding from time to time; provided, that no such
                                                         --------
Participant shall be entitled to receive any greater amount pursuant to such
Sections than the transferor Lender would have been entitled to receive in
respect of the amount of the participation transferred to such Participant had
no such transfer occurred.

          (c)   Assignments.  Any Lender may, in the ordinary course of its
                -----------
commercial banking business and in accordance with applicable Law, at any time
assign all or a portion of its rights and obligations under this Agreement and
the other Loan Documents (including, without limitation, all or any portion of
its Commitments and Loans owing to it and any Note held by it) to any Lender,
any Affiliate of a Lender or to one or more additional commercial banks or other
Persons (each a "Purchasing Lender"); provided, that
                 -----------------    --------

          (i)   any such assignment to a Purchasing Lender which is not a Lender
     or an affiliate of a Lender shall be made only with the consent (which in
     each case shall not be unreasonably withheld) of the Borrower (so long as
     no Default or Event of Default shall have occurred and be continuing) and
     the Administrative Agent;

          (ii)  if a Lender makes such an assignment of less than all of its
     then remaining rights and obligations under this Agreement and the other
     Loan Documents, such transferor Lender shall retain, after such assignment,
     a minimum principal amount of $10,000,000 of the Commitments and Loans then
     outstanding, and such assignment, unless made to an assignee who is a
     Lender hereunder prior to such assignment, shall be in a minimum principal
     amount of $10,000,000 of the Commitments and Loans then outstanding;

          (iii) each such assignment shall be of a constant, and not a varying,
     percentage of the 364-Day Commitment and 3-Year Commitment of the
     transferor Lender and of all of the transferor Lender's rights and
     obligations under this Agreement and the other Loan Documents; and

          (iv)  each such assignment shall be made pursuant to an Assignment and
     Acceptance.

In order to effect any such assignment, the transferor Lender and the Purchasing
Lender shall execute and deliver to the Administrative Agent a duly completed
Assignment and Acceptance (including the consents required by clause (i) of the
preceding sentence) with respect to such assignment, together with any Note or
Notes subject to such assignment and a processing and recording fee of $3,500;
and, upon receipt thereof, the Administrative Agent shall accept such Assignment
and Acceptance.  Upon receipt of notice from the transferor Lender that it has
received the consideration described in the Assignment and Acceptance, the
Administrative Agent shall record such acceptance in the Register.  Upon such
execution, delivery, acceptance and recording, from and after the close of
business at the Administrative Agent's Office on the settlement date specified
in such Assignment and Acceptance:

          (x)   the Purchasing Lender shall be a party hereto and, to the extent
     provided in such Assignment and Acceptance, shall have the rights and
     obligations of a Lender hereunder, and

                                       71
<PAGE>

          (y) the transferor Lender thereunder shall be released from its
     obligations under this Agreement to the extent so transferred (and, in the
     case of an Assignment and Acceptance covering all or the remaining portion
     of a transferor Lender's rights and obligations under this Agreement, such
     transferor Lender shall cease to be a party to this Agreement) from and
     after the settlement date.

On or prior to the settlement date specified in an Assignment and Acceptance,
the Borrower, at its expense, shall execute and deliver to the Administrative
Agent (for delivery to the Purchasing Lender) new Notes evidencing such
Purchasing Lender's assigned Commitments or Loans and (for delivery to the
transferor Lender) replacement Notes in the principal amount of the Loans or
Commitments retained by the transferor Lender (such Notes to be in exchange for,
but not in payment of, those Notes then held by such transferor Lender).  Each
such Note shall be dated the date and be substantially in the form of the
predecessor Note.  The Administrative Agent shall mark the predecessor Notes
"exchanged" and deliver them to the Borrower.  Accrued interest and accrued fees
shall be paid to the Purchasing Lender at the same time or times provided in the
predecessor Notes and this Agreement.

          (d) Register.  The Administrative Agent shall maintain at its office a
              --------
copy of each Assignment and Acceptance delivered to it and a register (the

"Register") for the recordation of the names and addresses of the Lenders and
---------
the Commitments of, and principal amount of the Loans owing to, each Lender from
time to time.  The entries in the Register shall be conclusive absent manifest
error and the Borrower, the Administrative Agent and the Lenders may treat each
Person whose name is recorded in the Register as a Lender hereunder for all
purposes of the Agreement.  The Register shall be available for inspection by
the Borrower or any Lender at any reasonable time and from time to time upon
reasonable prior notice.

          (e) Financial and Other Information.  The Borrower authorizes the
              -------------------------------
Administrative Agent and each Lender to disclose to any Participant or
Purchasing Lender (each, a "transferee") and any prospective transferee any and
                            ----------
all financial and other information in such Person's possession concerning the
Borrower and its Subsidiaries and Affiliates which has been or may be delivered
to such Person by or on behalf of the Borrower in connection with this Agreement
or any other Loan Document or such Person's credit evaluation of the Borrower
and its Subsidiaries and Affiliates.

          (f) Assignments to Federal Reserve Bank.  Any Lender may at any time
              -----------------------------------
assign all or any portion of its rights under this Agreement, including without
limitation any Loans owing to it, and any Note held by it, to a Federal Reserve
Bank.  No such assignment shall relieve the transferor Lender from its
obligations hereunder.

          (g) Special Purpose Funding Vehicles.  Notwithstanding anything to the
              --------------------------------
contrary contained herein, any Lender (a "Granting Lender") may grant to a
special purpose funding vehicle (an "SPC") the option to fund all or any part of
any Loan that such Granting Lender would otherwise be obligated to fund pursuant
to this Agreement; provided that (i) nothing herein shall constitute a
commitment by any SPC to fund any Loan, and (ii) if an SPC elects not to
exercise such option or otherwise fails to fund all or any part of such Loan,
the Granting Lender shall be obligated to fund such Loan pursuant to the terms
hereof.  The funding of a Loan by an SPC hereunder shall utilize the Revolving
Credit Commitment of the Granting

                                       72
<PAGE>

Lender to the same extent, and as if, such Loan were funded by such Granting
Lender. Each party hereto hereby agrees that no SPC shall be liable for any
indemnity or payment under this Agreement for which a Lender would otherwise be
liable for so long as, and to the extent, the Granting Lender provides such
indemnity or makes such payment. Notwithstanding anything to the contrary
contained in this Agreement, any SPC may disclose on a confidential basis any
non-public information relating to its funding of Loans to any rating agency,
commercial paper dealer or provider of any surety or guarantee to such SPC. This
Section may not be amended without the prior written consent of each Granting
Lender, all or any part of whose Loan is being funded by an SPC at the time of
such amendment.

          SECTION 9.13  Governing Law; Submission to Jurisdiction Waiver of Jury
                        --------------------------------------------------------
Trial; Limitation of Liability.
------------------------------

          (a)  Governing Law.  THIS AGREEMENT AND ALL OTHER LOAN DOCUMENTS
               -------------
(EXCEPT TO THE EXTENT, IF ANY, OTHERWISE EXPRESSLY STATED IN SUCH OTHER LOAN
DOCUMENTS) SHALL BE GOVERNED BY, AND CONSTRUED AND ENFORCED IN ACCORDANCE WITH,
THE LAWS OF THE STATE OF NEW YORK, WITHOUT REGARD TO CHOICE OF LAW PRINCIPLES.

          (b)  Certain Waivers.  EACH PARTY TO THIS AGREEMENT HEREBY IRREVOCABLY
               ---------------
AND UNCONDITIONALLY:

          (i)  AGREES THAT ANY ACTION, SUIT OR PROCEEDING BY ANY PERSON ARISING
     FROM OR RELATING TO THIS AGREEMENT OR ANY OTHER LOAN DOCUMENT OR ANY
     STATEMENT, COURSE OF CONDUCT, ACT, OMISSION, OR EVENT OCCURRING IN
     CONNECTION HEREWITH OR THEREWITH (COLLECTIVELY, "RELATED LITIGATION") MAY
                                                      ------------------
     BE BROUGHT IN ANY STATE OR FEDERAL COURT OF COMPETENT JURISDICTION SITTING
     IN NEW YORK, NEW YORK AND SUBMITS TO THE JURISDICTION OF SUCH COURTS (AND,
     TO THE FULLEST EXTENT PERMITTED BY LAW, THE BORROWER AGREES THAT IT WILL
     NOT BRING ANY RELATED LITIGATION IN ANY OTHER FORUM, BUT NOTHING HEREIN
     SHALL AFFECT THE RIGHT OF THE ADMINISTRATIVE AGENT OR ANY LENDER TO BRING
     ANY ACTION, SUIT OR PROCEEDING IN ANY OTHER FORUM IN WHICH THE BORROWER OR
     ANY OF ITS ASSETS MAY BE LOCATED OR IN WHICH THE BORROWER MAY BE DOING
     BUSINESS OR THE RIGHT OF THE BORROWER TO ASSERT ANY DEFENSE OR COUNTERCLAIM
     TO ANY ACTION BROUGHT BY THE ADMINISTRATIVE AGENT OR ANY LENDER IN ANY
     FORUM);

          (ii) WAIVES ANY OBJECTION WHICH IT MAY HAVE AT ANY TIME TO THE LAYING
     OF VENUE OF ANY RELATED LITIGATION BROUGHT IN ANY SUCH COURT, WAIVES ANY
     CLAIM THAT ANY SUCH RELATED LITIGATION HAS BEEN BROUGHT IN AN INCONVENIENT
     FORUM, AND WAIVES ANY RIGHT TO OBJECT, WITH RESPECT TO ANY RELATED
     LITIGATION BROUGHT IN ANY SUCH COURT, THAT SUCH COURT DOES NOT HAVE
     JURISDICTION OVER IT;

                                       73
<PAGE>

          (iii) CONSENTS AND AGREES TO SERVICE OF ANY SUMMONS, COMPLAINT OR
     OTHER LEGAL PROCESS IN ANY RELATED LITIGATION BY REGISTERED OR CERTIFIED
     U.S. MAIL, POSTAGE PREPAID, TO IT AT THE ADDRESS FOR NOTICES DESCRIBED IN
     SECTION 9.03, AND CONSENTS AND AGREES THAT SUCH SERVICE SHALL CONSTITUTE IN
     EVERY RESPECT VALID AND EFFECTIVE SERVICE (BUT NOTHING HEREIN SHALL AFFECT
     THE VALIDITY OR EFFECTIVENESS OF PROCESS SERVED IN ANY OTHER MANNER
     PERMITTED BY LAW); AND

          (iv)  WAIVES THE RIGHT TO TRIAL BY JURY IN ANY RELATED LITIGATION.

          (c)   Limitation of Liability.  TO THE FULLEST EXTENT PERMITTED BY
                -----------------------
LAW, NO CLAIM MAY BE MADE BY ANY PARTY TO THIS AGREEMENT AGAINST ANY OTHER PARTY
TO THIS AGREEMENT OR ANY AFFILIATE, DIRECTOR, OFFICER, EMPLOYEE, ATTORNEY OR
AGENT OF ANY OF THEM FOR ANY SPECIAL, INCIDENTAL, INDIRECT, CONSEQUENTIAL OR
PUNITIVE DAMAGES IN RESPECT OF ANY CLAIM ARISING FROM OR RELATING TO THIS
AGREEMENT OR ANY OTHER LOAN DOCUMENT OR ANY STATEMENT, COURSE OF CONDUCT, ACT,
OMISSION, OR EVENT OCCURRING IN CONNECTION HEREWITH OR THEREWITH (WHETHER FOR
BREACH OF CONTRACT, TORT OR ANY OTHER THEORY OF LIABILITY). EACH PARTY TO THIS
AGREEMENT HEREBY WAIVES, RELEASES AND AGREES NOT TO SUE UPON ANY CLAIM FOR ANY
SUCH DAMAGES, WHETHER SUCH CLAIM PRESENTLY EXISTS OR ARISES HEREAFTER AND
WHETHER OR NOT SUCH CLAIM IS KNOWN OR SUSPECTED TO EXIST IN ITS FAVOR.

                                       74
<PAGE>

          IN WITNESS WHEREOF, the parties hereto have caused this Agreement to
be duly executed and delivered as of the day and year first above written.


Address                                         SIERRA PACIFIC RESOURCES
-------

Sierra Pacific Resources
6100 Neil Road
P.O. Box 30150                                  By____________________________
Reno, Nevada 89520                              Name:
Attn: Mark Ruelle                               Title:

                                       75
<PAGE>

Address                                    MELLON BANK, N.A., as Administrative
-------                                     Agent, Arranger and as a Lender

Mellon Bank
One Mellon Bank Center
Pittsburgh, Pennsylvania 15258
Attn: Richard A. Matthews                  By_______________________________
                                           Name:  Richard A. Matthews
                                           Title: Vice President

                                       76
<PAGE>

Address                                    FIRST UNION NATIONAL BANK, as
-------                                     Syndication Agent and as a Lender

First Union National Bank
One First Union Center
301 South College Street
Charlotte, North Carolina 28288-0735       By_______________________________
Attn: Dana Maloney                         Name:
                                           Title:

                                       77
<PAGE>

Address                                     WELLS FARGO BANK, N.A., as
-------                                      Syndication Agent and as a Lender

Wells Fargo Bank
201 Third Street
8/th/ Floor
San Francisco, California 94103            By_______________________________
Attn: Maria Josefa Prosperi                Name:
                                           Title:

                                       78
<PAGE>

Address                                    BANK OF AMERICA NATIONAL TRUST
-------                                    AND SAVINGS ASSOCIATION

Bank of America
300 South Fourth Street
2/nd/ Floor
Las Vegas, Nevada 89101                    By_______________________________
Attn: Dolores A. Rippo                     Name:
                                           Title:

                                       79
<PAGE>

Address                                    THE BANK OF NEW YORK
-------

The Bank of New York
One Wall Street
New York, New York 10286                   By_______________________________
Attn: Kathy D'Elena                        Name:
                                           Title:


                                       80
<PAGE>

Address                                    THE FIRST NATIONAL BANK OF CHICAGO
-------

The First National Bank of Chicago
One First National Plaza
Suite 0573
Chicago, Illinois                          By_______________________________
Attn: Mari Albanese                        Name:
                                           Title:

                                       81
<PAGE>

Address                                    CREDIT SUISSE FIRST BOSTON
-------

Credit Suisse First Boston
5 World Trade Center
New York, New York 10048                   By_______________________________
Attn: Genaro Sarasola                      Name:
                                           Title:

                                       82
<PAGE>

Address                                         PARIBAS
-------

Paribas
787 7/th/ Avenue
New York, New York 10019                        By____________________________
Attn: Telca Hurley                              Name:
                                                Title:


                                                By____________________________
                                                Name:
                                                Title:

                                       83
<PAGE>

Address                                         UNION BANK OF CALIFORNIA, N.A.
-------

Union Bank of California
Energy Capital Services - LA Office
445 South Figueroa Street                       By_____________________________
15/th/ Floor                                    Name:
Los Angeles, CA 90071                           Title:
Attn Patricia A. Gonzales

                                       84
<PAGE>

Address                                        BANK OF MONTREAL
-------

Bank of Montreal
700 Louisiana Street
Suite 4400                                     By_______________________________
Houston, TX 77002                              Name:  Cahal B. Carmody
Attn: Cahal B. Carmody                         Title: Director

                                       85
<PAGE>

Address                                       BAYERISCHE LANDESBANK
-------                                       GIROZENTRALE

Bayerische Landesbank Girozentrale
560 Lexington Avenue
New York, New York 10022
Attn: Patricia Sanchez                        By______________________________
                                              Name:  Peter Obermann
                                              Title: Senior Vice President


                                              By_______________________________
                                              Name:  Sean O'Sullivan
                                              Title: Vice President

                                       86
<PAGE>

Address                                       FLEET NATIONAL BANK
-------

Fleet National Bank
One Federal Street
Boston, Massachusetts 02110                   By_______________________________
Attn: Francia Castillo, Loan Administrator    Name:
                                              Title:

                                       87
<PAGE>

Address                                 FIRST SECURITY BANK OF NEVADA
-------

First Security Bank of Nevada
P.O. Box 19250
Las Vegas, Nevada 89132                 By_______________________________
Attn: Cheryl Moss                       Name:  Cheryl Moss
                                        Title: Senior Vice President & Manager
                                               Corporate Banking Department

                                       88
<PAGE>

Address                                        KBC BANK, N.V.
-------

KBC Bank, N.V.
125 West 55/th/ Street
10/th/ Floor                                   By______________________________
New York, New York 10019                       Name:
Attn: Claire Kowalski/Charlene Cumberbatch     Title:


                                               By______________________________
                                               Name:
                                               Title:

                                       89
<PAGE>

Address                                       U.S. BANK NATIONAL ASSOCIATION
-------

U.S. Bank National Association
Commercial Loan Servicing Department
555 S.W. Oak Street, PL-7                     By______________________________
Portland, Oregon 97204                        Name:
Attn: Jan Knox, Participation Specialist      Title:

                                       90
<PAGE>

                                                                               I
                                                                               -

                                  Commitments
                                  -----------
               [See definitions of "Commitment" in Section 1.01]

                              364-Day Commitments
                              -------------------

LENDER                                  COMMITMENT AMOUNT
------                                  -----------------

Mellon Bank, N.A.                          $ 15,937,500
First Union National Bank                  $ 12,187,500
Wells Fargo Bank, N.A.                     $ 12,187,500
Bank of America National
 Trust and Savings Association             $ 11,250,000
The Bank of New York                       $ 11,250,000
The First National Bank of Chicago         $ 11,250,000
Credit Suisse First Boston                 $ 11,250,000
Paribas                                    $ 11,250,000
Union Bank of California, N.A.             $ 11,250,000
Bank of Montreal                           $  9,375,000
Bayerische Landesbank Girozentrale         $  9,375,000
Fleet National Bank                        $  9,375,000
First Security Bank of Nevada              $  4,687,500
KBC Bank, N.V.                             $  4,687,500
U.S. Bank National Association             $  4,687,500
  Total                                    $150,000,000
                                           ============

                                       91
<PAGE>

                                                                      SCHEDULE I
                                                                          Page 2

                              3-Year Commitments
                              ------------------

LENDER                                       COMMITMENT AMOUNT
------                                       -----------------

     Mellon Bank, N.A.                          $ 37,187,500
     First Union National Bank                  $ 28,437,500
     Wells Fargo Bank, N.A.                     $ 28,437,500
     Bank of America National
       Trust and Savings Association            $ 26,250,000
     The Bank of New York                       $ 26,250,000
     The First National Bank of Chicago         $ 26,250,000
     Credit Suisse First Boston                 $ 26,250,000
     Banque Paribas                             $ 26,250,000
     Union Bank of California, N.A.             $ 26,250,000
     Bank of Montreal                           $ 21,875,000
     Bayerische Landesbank Girozentrale         $ 21,875,000
     Fleet National Bank                        $ 21,875,000
     First Security Bank of Nevada              $ 10,937,500
     KBC Bank, N.V.                             $ 10,937,500
     U.S. Bank National Association             $ 10,937,500
          Total                                 $350,000,000
                                                ============

                                       92
<PAGE>

                               TABLE OF CONTENTS
                               -----------------
<TABLE>
<CAPTION>
                                                                                             Page
                                                                                             ----
<S>                                                                                          <C>
ARTICLE I
    DEFINITIONS; CONSTRUCTION...............................................................   1
    SECTION 1.01  Defined Terms.............................................................   1
    SECTION 1.02.  Classification of Loans and Borrowings...................................  17
    SECTION 1.03  Terms Generally...........................................................  17
    SECTION 1.04  Accounting Terms; GAAP....................................................  17

ARTICLE II
    THE CREDITS.............................................................................  17
    SECTION 2.01  The Commitments...........................................................  17
    SECTION 2.02  Loans and Borrowings......................................................  18
    SECTION 2.03  Requests for Revolving Borrowings.........................................  19
    SECTION 2.04  Funding of Borrowings.....................................................  20
    SECTION 2.05  Interest Elections........................................................  20
    SECTION 2.06  Termination, Reduction and Extension of Commitments.......................  22
    SECTION 2.07  Term Loan Conversion Option...............................................  25
    SECTION 2.08  Repayment of Loans; Evidence of Debt......................................  26
    SECTION 2.09  Prepayment of Loans.......................................................  27
    SECTION 2.10  Fees......................................................................  28
    SECTION 2.11  Interest..................................................................  28
    SECTION 2.12  Alternate Rate of Interest................................................  29
    SECTION 2.13  Increased Costs...........................................................  30
    SECTION 2.14  Break Funding Payments....................................................  30
    SECTION 2.15  Taxes.....................................................................  31
    SECTION 2.16  Payments Generally; Pro Rata Treatment; Sharing of Set-offs...............  32
    SECTION 2.17  Mitigation Obligations; Replacement of Lenders............................  34

ARTICLE III
    REPRESENTATIONS AND WARRANTIES..........................................................  35
    SECTION 3.01  Corporate Status..........................................................  35
    SECTION 3.02  Corporate Power and Authorization.........................................  35
    SECTION 3.03  Execution and Binding Effect..............................................  35
    SECTION 3.04  Governmental Approvals and Filings........................................  35
</TABLE>

                                       93
<PAGE>

<TABLE>
<CAPTION>
<S>                                                                                           <C>
    SECTION 3.05  Absence of Conflicts......................................................  36
    SECTION 3.06  Audited Financial Statements..............................................  36
    SECTION 3.07  Interim Financial Statements..............................................  36
    SECTION 3.08  Absence of Undisclosed Liabilities........................................  37
    SECTION 3.09  Absence of Material Adverse Effect........................................  37
    SECTION 3.10  Accurate and Complete Disclosure..........................................  37
    SECTION 3.11  Margin Regulations........................................................  37
    SECTION 3.12  Litigation................................................................  38
    SECTION 3.13  Absence of Events of Default..............................................  38
    SECTION 3.14  Absence of Other Conflicts................................................  38
    SECTION 3.15  Insurance.................................................................  38
    SECTION 3.16  Title to Property; No Liens...............................................  38
    SECTION 3.17  Taxes.....................................................................  39
    SECTION 3.18  Borrower Not An Investment Company or a Registered Public Utility Holding
                  Company...................................................................  39
    SECTION 3.19  Environmental Matters.....................................................  39
    SECTION 3.20  ERISA.....................................................................  40
    SECTION 3.21  Year 2000 Issues..........................................................  41
    SECTION 3.22  Pari Passu Status.........................................................  41
    SECTION 3.23  Indebtedness..............................................................  41

ARTICLE IV
    CONDITIONS..............................................................................  42
    SECTION 4.01  Effective Date............................................................  42
    SECTION 4.02  Conditions to All Loans...................................................  45

ARTICLE V
    AFFIRMATIVE COVENANTS...................................................................  46
    SECTION 5.01  Basic Reporting Requirements..............................................  46
    SECTION 5.02  Insurance.................................................................  49
    SECTION 5.03  Payment of Taxes and Other Potential Charges and Priority Claims..........  49
    SECTION 5.04  Preservation of Corporate Status and Franchises...........................  49
    SECTION 5.05  Governmental Approvals and Filings........................................  50
    SECTION 5.06  Maintenance of Properties.................................................  50
    SECTION 5.07  Avoidance of Other Conflicts..............................................  50
    SECTION 5.08  Financial Accounting Practices............................................  50
    SECTION 5.09  Use of Proceeds...........................................................  51
    SECTION 5.10  End of Fiscal Periods.....................................................  51

ARTICLE VI
    NEGATIVE COVENANTS......................................................................  51
</TABLE>

                                       94
<PAGE>

<TABLE>
<CAPTION>
<S>                                                                                           <C>
    SECTION 6.01  Financial Covenants.......................................................  51
    SECTION 6.02  Liens.....................................................................  51
    SECTION 6.03  Mergers...................................................................  53
    SECTION 6.04  Dispositions of Properties................................................  53
    SECTION 6.05  Investments and Acquisitions..............................................  54
    SECTION 6.06  Dividends and Stock Repurchases...........................................  54
    SECTION 6.07  Transactions with Affiliates..............................................  54
    SECTION 6.08  Equal and Ratable Lien....................................................  54
    SECTION 6.09  Restrictive Agreements....................................................  54
    SECTION 6.10  Year 2000.................................................................  55

ARTICLE VII
    DEFAULTS................................................................................  55
    SECTION 7.01  Events of Default.........................................................  55
    SECTION 7.02  Consequences of an Event of Default.......................................  58

ARTICLE VIII
    THE AGENTS..............................................................................  58
    SECTION 8.01  Appointment...............................................................  58
    SECTION 8.02  General Nature of Administrative Agent's Duties...........................  59
    SECTION 8.03  Exercise of Powers........................................................  59
    SECTION 8.04  General Exculpatory Provisions............................................  60
    SECTION 8.05  Administration by the Administrative Agent................................  61
    SECTION 8.06  Lenders Not Relying on Administrative Agent or Other Lenders..............  61
    SECTION 8.07  Indemnification...........................................................  62
    SECTION 8.08  Administrative Agent in its Individual Capacity...........................  62
    SECTION 8.09  Holders of Notes..........................................................  63
    SECTION 8.10  Successor Administrative Agent............................................  63
    SECTION 8.11  Additional Administrative Agents..........................................  64
    SECTION 8.12  Calculations..............................................................  64
    SECTION 8.13  Syndication Agents........................................................  64

ARTICLE IX
    MISCELLANEOUS...........................................................................  64
    SECTION 9.01  Amendments and Waivers....................................................  64
    SECTION 9.02  No Implied Waiver; Cumulative Remedies....................................  65
    SECTION 9.03  Notices...................................................................  66
    SECTION 9.04  Expenses; Taxes; Indemnity................................................  66
    SECTION 9.05  Severability..............................................................  67
</TABLE>

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<PAGE>

<TABLE>
<CAPTION>
<S>                                                                                           <C>
SECTION 9.06  Prior Understandings..........................................................  67
SECTION 9.07  Duration; Survival............................................................  68
SECTION 9.08  Counterparts..................................................................  68
SECTION 9.09  Limitation on Payments........................................................  68
SECTION 9.10  Set-Off.......................................................................  68
SECTION 9.11  Sharing of Collections........................................................  69
SECTION 9.12  Successors and Assigns; Participations; Assignments...........................  69
SECTION 9.13  Governing Law; Submission to Jurisdiction Waiver of Jury Trial; Limitation of
 Liability..................................................................................  72
</TABLE>

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