<PAGE>

                                                                   EXHIBIT 10.33


                FIRST AMENDMENT TO CREDIT AND SECURITY AGREEMENT
                             AND WAIVER OF DEFAULTS


         This Amendment, dated as of March 26, 2003, is made by and between
METRETEK, INCORPORATED, a Florida corporation (the "Borrower"), and WELLS FARGO
BUSINESS CREDIT, INC., a Minnesota corporation (the "Lender").

                                    RECITALS

         The Borrower and the Lender are parties to a Credit and Security
Agreement dated as of September 6, 2002 (the "Credit Agreement"). Capitalized
terms used in these recitals have the meanings given to them in the Credit
Agreement unless otherwise specified.

         The Borrower has requested that certain amendments be made to the
Credit Agreement, which the Lender is willing to make pursuant to the terms and
conditions set forth herein.

         NOW, THEREFORE, in consideration of the premises and of the mutual
covenants and agreements herein contained, it is agreed as follows:

         1.      Defined Terms. Capitalized terms used in this Amendment which
are defined in the Credit Agreement shall have the same meanings as defined
therein, unless otherwise defined herein.

         2.      Section 6.2(a). Section 6.2(a) of the Credit Agreement is
amended and restated in its entirety to read as follows:

                  "(a) MINIMUM TANGIBLE NET WORTH. The Borrower will maintain,
         during each period described below, its Tangible Net Worth, less (i)
         software development and (ii) intercompany indebtedness owing from all
         Corporate Guarantors to Borrower, determined as at the end of each
         month, at an amount not less than the amount set forth opposite such
         period (numbers appearing between "< >" are negative):

<TABLE>
<CAPTION>
                                Period                    Minimum Tangible Net Worth
                                ------                    --------------------------
<S>                                                             <C>
                            March 31, 2003                        $1,080,000
                            April 30, 2003                        $1,190,000
                             May 31, 2003                         $1,300,000
                            June 30, 2003                         $1,590,000
                            July 31, 2003                         $1,590,000
                           August 31, 2003                        $1,590,000
                          September 30, 2003                      $1,590,000
                           October 31, 2003                       $1,590,000
                          November 30, 2003                       $1,590,000
                   December 31, 2003 and thereafter               $1,590,000 "
</TABLE>
                                       1
<PAGE>
         3.       Section 6.2(b). Section 6.2(b) of the Credit Agreement is
amended and restated in its entirety to read as follows:

                  "(b) MINIMUM NET INCOME. The Borrower will achieve during each
         period described below, its Net Income, of not less than the amount set
         forth opposite such period (numbers appearing between "< >" are
         negative):

<TABLE>
<CAPTION>
                                Period                                   Minimum Net Income
                                ------                                   ------------------
<S>                                                           <C>
                            March 31, 2003                                   $625,000
                            April 30, 2003                                   $525,000
                             May 31, 2003                                    $425,000
                            June 30, 2003                                    $140,000
                            July 31, 2003                                    $215,000
                           August 31, 2003                                   $220,000
                          September 30, 2003                                 $235,000
                           October 31, 2003                                  $315,000
                          November 30, 2003                                  $400,000
                          December 31, 2003                                  $415,000 "
</TABLE>

         4.       Section 6.2(c). Section 6.2(c) of the Credit Agreement is
amended and restated in its entirety to read as follows:

                  "(c)     CAPITAL EXPENDITURES.  The Borrower will not incur or
         contract to incur unfinanced Capital Expenditures of more than $200,000
         in the aggregate during the fiscal year ending December 31, 2003."

         5.       Section 6.27. Section 6.27 of the Credit Agreement is amended
and restated in its entirety to read as follows:

                  "Section 6.27 Advances to Corporate Guarantors. Before making
         an advance to any Corporate Guarantor, and after making such advance to
         any Corporate Guarantor, Availability shall not be less than $100,000.
         Advances to Corporate Guarantors shall not exceed $500,000 in the
         aggregate during the fiscal year ending December 31, 2003."

         6.       Exhibit B. Exhibit B of the Credit Agreement is amended and
restated in its entirety and replaced with Exhibit B attached hereto.

         7.       No Other Changes. Except as explicitly amended by this
Amendment, all of the terms and conditions of the Credit Agreement shall remain
in full force and effect and shall apply to any advance or letter of credit
thereunder.

                                       2
<PAGE>

         8.       Waiver of Defaults. The Borrower is in default under Section
6.2(b) Minimum Net Income and Section 6.2(c) Capital Expenditures of the Credit
Agreement as of December 31, 2002 (collectively, the "Existing Defaults"). Upon
the terms and subject to the conditions set forth in this Amendment, the Lender
hereby waives the Existing Defaults. This waiver shall be effective only in this
specific instance and for the specific purpose for which it is given, and this
waiver shall not entitle the Borrower to any other or further waiver in any
similar or other circumstances.

         9.       Amendment Fee. The Borrower shall pay the Lender as of the
date hereof a fully earned, non-refundable fee in the amount of $3,000 in
consideration of the Lender's execution and delivery of this Amendment.

         10.      Conditions Precedent. This Amendment, and the waiver set
forth in Paragraph 8 hereof, shall be effective when the Lender shall have
received an executed original hereof, together with each of the following, each
in substance and form acceptable to the Lender in its sole discretion:

                  (a) The Acknowledgment and Agreement of Guarantors and the
Acknowledgment and Agreement of Subordinated Creditor set forth at the end of
this Amendment, duly executed by each Guarantor and Subordinated Creditor.

                  (b) Payment of the fee described in Paragraph 9.

                  (c) Such other matters as the Lender may require.

         11.      Representations and Warranties. The Borrower hereby represents
and warrants to the Lender as follows:

                  (a) The Borrower has all requisite power and authority to
execute this Amendment and to perform all of its obligations hereunder, and this
Amendment has been duly executed and delivered by the Borrower and constitutes
the legal, valid and binding obligation of the Borrower, enforceable in
accordance with its terms.

                  (b) The execution, delivery and performance by the Borrower of
this Amendment have been duly authorized by all necessary corporate action and
do not (i) require any authorization, consent or approval by any governmental
department, commission, board, bureau, agency or instrumentality, domestic or
foreign, (ii) violate any provision of any law, rule or regulation or of any
order, writ, injunction or decree presently in effect, having applicability to
the Borrower, or the articles of incorporation or by-laws of the Borrower, or
(iii) result in a breach of or constitute a default under any indenture or loan
or credit agreement or any other agreement, lease or instrument to which the
Borrower is a party or by which it or its properties may be bound or affected.

                  (c) All of the representations and warranties contained in
Article V of the Credit Agreement are correct on and as of the date hereof as
though made on and as of such date, except to the extent that such
representations and warranties relate solely to an earlier date.

         12.      References. All references in the Credit Agreement to "this
Agreement" shall be deemed to refer to the Credit Agreement as amended hereby;
and any and all references in the

                                       3
<PAGE>


Security Documents to the Credit Agreement shall be deemed to refer to the
Credit Agreement as amended hereby.

         13.      No Other Waiver. Except as set forth in Paragraph 8 hereof,
the execution of this Amendment and acceptance of any documents related hereto
shall not be deemed to be a waiver of any Default or Event of Default under the
Credit Agreement or breach, default or event of default under any Security
Document or other document held by the Lender, whether or not known to the
Lender and whether or not existing on the date of this Amendment.

         14.      Release. The Borrower, and each Guarantor by signing the
Acknowledgment and Agreement of Guarantors set forth below, and the Subordinated
Creditor by signing the Acknowledgment and Agreement of Subordinated Creditor
set forth below, each hereby absolutely and unconditionally releases and forever
discharges the Lender, and any and all participants, parent corporations,
subsidiary corporations, affiliated corporations, insurers, indemnitors,
successors and assigns thereof, together with all of the present and former
directors, officers, agents and employees of any of the foregoing, from any and
all claims, demands or causes of action of any kind, nature or description,
whether arising in law or equity or upon contract or tort or under any state or
federal law or otherwise, which the Borrower or such Guarantor or such
Subordinated Creditor has had, now has or has made claim to have against any
such person for or by reason of any act, omission, matter, cause or thing
whatsoever arising from the beginning of time to and including the date of this
Amendment, whether such claims, demands and causes of action are matured or
unmatured or known or unknown.

         15.      Costs and Expenses. The Borrower hereby reaffirms its
agreement under the Credit Agreement to pay or reimburse the Lender on demand
for all costs and expenses incurred by the Lender in connection with the Loan
Documents, including without limitation all reasonable fees and disbursements of
legal counsel. Without limiting the generality of the foregoing, the Borrower
specifically agrees to pay all fees and disbursements of counsel to the Lender
for the services performed by such counsel in connection with the preparation of
this Amendment and the documents and instruments incidental hereto. The Borrower
hereby agrees that the Lender may, at any time or from time to time in its sole
discretion and without further authorization by the Borrower, make a loan to the
Borrower under the Credit Agreement, or apply the proceeds of any loan, for the
purpose of paying any such fees, disbursements, costs and expenses and the fee
required under Paragraph 9 hereof.

         16.      Miscellaneous. This Amendment and the Acknowledgment and
Agreement of Guarantors and the Acknowledgment and Agreement of Subordinated
Creditor may be executed in any number of counterparts, each of which when so
executed and delivered shall be deemed an original and all of which
counterparts, taken together, shall constitute one and the same instrument.

                                       4

<PAGE>


         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed as of the date first written above.

WELLS FARGO BUSINESS CREDIT, INC.            METRETEK, INCORPORATED



By:      /s/ Patti Scudder                   By:      /s/ A. Bradley Gabbard
         -------------------------------              --------------------------
Name:    Patti Scudder                       Name:    A. Bradley Gabbard
         -------------------------------              --------------------------
Its:                                         Its:     Exec. VP
         -------------------------------              --------------------------



                                       5

<PAGE>


                   ACKNOWLEDGMENT AND AGREEMENT OF GUARANTORS


         The undersigned, each a guarantor of the indebtedness of Metretek,
Incorporated (the "Borrower") to Wells Fargo Business Credit, Inc. (the
"Lender") pursuant to a separate Guaranty each dated as of September 6, 2002,
(each a "Guaranty"), hereby (i) acknowledges receipt of the foregoing Amendment;
(ii) consents to the terms (including without limitation the release set forth
in Paragraph 14 of the Amendment) and execution thereof; (iii) reaffirms its
obligations to the Lender pursuant to the terms of its Guaranty; and (iv)
acknowledges that the Lender may amend, restate, extend, renew or otherwise
modify the Credit Agreement and any indebtedness or agreement of the Borrower,
or enter into any agreement or extend additional or other credit accommodations,
without notifying or obtaining the consent of the undersigned and without
impairing the liability of the undersigned under its Guaranty for all of the
Borrower's present and future indebtedness to the Lender.

METRETEK CONTRACT MANUFACTURING COMPANY, INC.     METRETEK TECHNOLOGIES, INC.



By:      /s/ A. Bradley Gabbard
Name:    A. Bradley Gabbard                       By:    /s/ A. Bradley Gabbard
         ------------------------------                  ----------------------
Its:     Exec. VP                                 Name:  A. Bradley Gabbard
         ------------------------------                  -----------------------
                                                  Its:   Exec. VP
                                                           ---------------------
POWERSECURE, INC.                                 SOUTHERN FLOW COMPANIES, INC.



By:      /s/ A. Bradley Gabbard                   By:    /s/ A. Bradley Gabbard
         ------------------------------                  ----------------------
Name:    A. Bradley Gabbard                       Name:  A. Bradley Gabbard
         ------------------------------                  -----------------------
Its:     Exec. VP                                 Its:   Exec. VP
         ------------------------------                  -----------------------


                                       1

<PAGE>


              ACKNOWLEDGMENT AND AGREEMENT OF SUBORDINATED CREDITOR


         The undersigned, a subordinated creditor of Metretek, Incorporated (the
"Borrower") to Wells Fargo Business Credit, Inc. (the "Lender") pursuant to a
Subordination Agreement dated as of September 6, 2002 (the "Subordination
Agreement"), hereby (i) acknowledges receipt of the foregoing Amendment; (ii)
consents to the terms (including without limitation the release set forth in
Paragraph 14 of the Amendment) and execution thereof; (iii) reaffirms its
obligations to the Lender pursuant to the terms of its Subordination Agreement;
and (iv) acknowledges that the Lender may amend, restate, extend, renew or
otherwise modify the Loan Documents and any indebtedness or agreement of the
Borrower, or enter into any agreement or extend additional or other credit
accommodations, without notifying or obtaining the consent of the undersigned
and without impairing the obligations of the undersigned under its Subordination
Agreement.

                                     METRETEK TECHNOLOGIES, INC.


                                     By:      /s/ A. Bradley Gabbard
                                              ----------------------------------
                                     Name:    A. Bradley Gabbard
                                              ----------------------------------
                                     Its:     Exec. VP
                                              ----------------------------------
                                       1

<PAGE>
                                      Exhibit B to Credit and Security Agreement


                             COMPLIANCE CERTIFICATE

To:      Wells Fargo Business Credit, Inc.
Date:    __________________, 200__
Subject: Financial Statements

         In accordance with our Credit and Security Agreement dated as of
September 6, 2002, as amended by a First Amendment to Credit and Security
Agreement and Waiver of Defaults dated as of March 26, 2003 (as so amended, the
"Credit Agreement"), attached are the financial statements of Metretek,
Incorporated (the "Borrower") as of and for ________________, 200__ (the
"Reporting Date") and the year-to-date period then ended (the "Current
Financials"). All terms used in this certificate have the meanings given in the
Credit Agreement.

         I certify that the Current Financials have been prepared in accordance
with GAAP, subject to year-end audit adjustments, and fairly present the
Borrower's financial condition as of the date thereof.

         EVENTS OF DEFAULT.  (Check one):

         [  ]     The undersigned does not have knowledge of the occurrence of a
                  Default or Event of Default under the Credit Agreement except
                  as previously reported in writing to the Lender.

         [  ]     The undersigned has knowledge of the occurrence of a Default
                  or Event of Default under the Credit Agreement not previously
                  reported in writing to the Lender and attached hereto is a
                  statement of the facts with respect to thereto. The Borrower
                  acknowledges that pursuant to Section 2.8(c) of the Credit
                  Agreement, the Lender may impose the Default Rate at any time
                  during the resulting Default Period.

         Financial Covenants.  I further hereby certify as follows:

         1. MINIMUM TANGIBLE NET WORTH. Pursuant to Section 6.2(a) of the Credit
Agreement, as of the Reporting Date the Borrower's Tangible Net Worth, less (a)
software development and (b) intercompany indebtedness owing from all Corporate
Guarantors to Borrower, was $____________ which [  ] satisfies [  ] does not
satisfy the requirement that such amount be not less than $_____________ on the
Reporting Date as set forth in the table below (numbers appearing between "< >"
are negative):

                      Period                    Minimum Tangible Net Worth
                      ------                    --------------------------
                  March 31, 2003                       $1,080,000
                  April 30, 2003                       $1,190,000


                                       1
<PAGE>
<TABLE>
<CAPTION>
                                Period                    Minimum Tangible Net Worth
                                ------                    --------------------------
<S>                                                           <C>
                             May 31, 2003                        $1,300,000
                            June 30, 2003                        $1,590,000
                            July 31, 2003                        $1,590,000
                           August 31, 2003                       $1,590,000
                          September 30, 2003                     $1,590,000
                           October 31, 2003                      $1,590,000
                          November 30, 2003                      $1,590,000
                   December 31, 2003 and thereafter              $1,590,000 "
</TABLE>


         2. MINIMUM NET INCOME. Pursuant to Section 6.2(b) of the Credit
Agreement, the Borrower's Net Income for the ________ period ending on the
Reporting Date, was $____________, which satisfies does not satisfy the
requirement that such amount be not less than $_____________ during such period
as set forth in the table below (numbers appearing between "< >" are negative):

<TABLE>
<CAPTION>
                                Period                                   Minimum Net Income
                                ------                                   ------------------
<S>                                                                      <C>
                            March 31, 2003                                    $625,000
                            April 30, 2003                                    $525,000
                             May 31, 2003                                     $425,000
                            June 30, 2003                                     $140,000
                            July 31, 2003                                     $215,000
                           August 31, 2003                                    $220,000
                          September 30, 2003                                  $235,000
                           October 31, 2003                                   $315,000
                          November 30, 2003                                   $400,000
                          December 31, 2003                                   $415,000 "
</TABLE>


         3. CAPITAL EXPENDITURES. Pursuant to Section 6.2(c) of the Credit
Agreement, for the year-to-date period ending on the Reporting Date, the
Borrower has expended or contracted to expend during the fiscal year ended
December 31, 2003, for unfinanced Capital Expenditures, $__________________ in
the aggregate, which [  ] satisfies [  ] does not satisfy the requirement that
such expenditures not exceed $200,000 in the aggregate during such year.

         4. SALARIES.  As of the Reporting Date, the Borrower [  ] is [  ] is
not in compliance with Section 6.8 of the Credit Agreement concerning salaries.

         5. ADVANCES TO CORPORATE GUARANTORS. Pursuant to Section 6.27 of the
Credit Agreement, for the year-to-date period ending on the Reporting Date, the
Borrower has advanced to Corporate Guarantors, during the fiscal year ended
December 31, 2003, $_________________ in the aggregate, which [  ] satisfies
[  ] does not satisfy the requirement that such advances not exceed $500,000
in the aggregate during such year.

                                       2
<PAGE>

         Attached hereto are all relevant facts in reasonable detail to
evidence, and the computations of the financial covenants referred to above.
These computations were made in accordance with GAAP.

                                       By:___________________________________
                                       Its Chief Financial Officer


                                       3