EXHIBIT 2.5.2.1

                                      11.5%
                                 PROMISSORY NOTE

Amount: $30,000,000 September 1, 1998

         For value received, Able Telcom Holding Corp. ("Able") hereby agrees to
pay to the order of WorldCom Network Services, Inc., its successors or assigns
("WorldCom"), in lawful money of the United States of America and immediately
available funds, at its offices in Tulsa, Oklahoma (or at such other place or
places as WorldCom may designate) the principal amount of Thirty Million and
No/100 Dollars ($30,000,000) on December 15, 2000 ("Maturity Date").

         INTEREST. Interest on the unpaid principal amount hereof from time to
time shall accrue at an annual rate of 11.5% from the date hereof. Accrued
interest shall be payable on February 28, 1999 and on May 31, August 31,
November 30 and February 28 thereafter and on the Maturity Date.

         VOLUNTARY PREPAYMENTS. All or any portion of the unpaid principal
balance of this Note, together with all accrued interest thereon, may be prepaid
by Able at any time without penalty. Partial repayments of principal shall be
made in tranches of $3,000,000.

         MANDATORY PREPAYMENTS.

         The principal amount of the Note shall be prepaid as follows:

         a.       Subject to the consent of NationsBank, N.A., by applying as a
                  credit thereto an amount equal to 8% of the amount otherwise
                  payable by WorldCom, or any affiliate thereof, to Able, or any
                  affiliate thereof, under any "Management Services Agreement"
                  ("MSA"), including, without limitation, the MSA dated July 2,
                  1998; such credit to be made as of the date any payment is due
                  by WorldCom to Able under an MSA;

         b.       By Able paying WorldCom on the first business day after Able
                  receives the proceeds of any of the following:

                  i.       $7,000,000 upon the sale of NYSTA conduit;

                  ii.      $1,500,000 upon payment by The Williams Companies of
                           a fee for the installation of conduit; and

                  iii.     The greater of 50% of the net profits or 25% of the
                           proceeds received from time to time under any
                           maintenance agreement associated with the sale of
                           NYSTA conduit.

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          Whenever a payment on this Note is stated to be due on a day which is
not a business day, such payment shall be made on the next succeeding business
day with interest accruing to the date of payment. Interest hereunder shall be
computed on the basis of the actual number of days elapsed over a year of 360
days.

         If any amount owed by Able hereunder is not paid when due, Able shall
pay interest on all such past due amounts at a rate equal to 13.5% per annum
(the "Default Rate"), payable on demand of WorldCom. Nothing herein contained
shall be construed or so operate as to require Able to pay any interest, fees,
costs or charges at a rate or in an amount greater than is permitted by
applicable law.

         Upon the occurrence of a default in payment of principal, interest or
other amounts owing hereunder when due, the unpaid principal amount of this
Note, together with all accrued but unpaid interest thereon, may become, or may
be declared to be, (or in the case of bankruptcy or insolvency of Able, shall,
without action on the part of WorldCom, become), immediately due and payable,
without presentation, demand, protest or notice of any kind, all of which are
hereby waived by Able. Failure of the holder of this Note to assert any right
herein shall not be a waiver thereof.

         Able agrees to pay on demand all direct out-of-pocket losses, and
reasonable out-of-pocket costs and expenses, if any (including reasonable fees
and expenses of outside counsel), of WorldCom in connection with the enforcement
(whether by legal proceedings, negotiation or otherwise) of this Note and other
documents delivered hereunder.

         Upon the occurrence and during the continuance of any default, WorldCom
is hereby authorized at any time and from time to time, to the fullest extent
permitted by law, to set off and apply any and all amounts or other indebtedness
at any time owing by WorldCom to or for the credit or the account of Able
against any and all of the obligations of Able now or hereafter existing under
this Note, irrespective of whether or not WorldCom shall have made any demand
under this Note and of whether or not such obligations may be matured. WorldCom
agrees promptly to notify Able after any such set-off and application made by
WorldCom, but the failure to give such notice shall not affect the validity of
such set-off and application. The rights of WorldCom under this paragraph
are in addition to other rights and remedies (including, without limitation,
other rights of set-off) which WorldCom may have.

         In the event that this Note is transferred, assigned or pledged, Able
hereby waives, as against such transferee, assignee or pledgee, any defenses and
counterclaims that Able may have against the holder hereof.

         This Note shall be governed by and construed in accordance with the
laws of the state of New York without regard to conflicts of law provisions
thereof.

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         If any provision or obligation of the Note shall be determined to be
invalid, ineffective or unenforceable, the validity, effectiveness and
enforceability of the remaining provisions or obligations shall not in any way
be affected or impaired thereby.

         IN WITNESS WHEREOF, Able has caused this Note to be executed under seal
and delivered by their respective duly authorized officers as of the date first
above written.

                                     ABLE TELCOM HOLDING CORP.

                                     By: /s/ BILLY V. RAY
                                         --------------------------------------

                                     Title: CEO and PRESIDENT
                                            -----------------------------------


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