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                                                                     EXHIBIT 5

                   FRIED, FRANK, HARRIS, SHRIVER & JACOBSON
              A PARTNERSHIP INCLUDING PROFESSIONAL CORPORATIONS


                              ONE NEW YORK PLAZA
                        NEW YORK, NEW YORK 10004-1980
                                 212-859-8000
                               FAX 212-859-4000


           

September 3, 1998


SPX Corporation
700 Terrace Point Drive
Muskegon, Michigan 49443-3301

Gentlemen:

        We are acting as special counsel for SPX Corporation, a Delaware
corporation (the "Company"), in connection with the preparation of the
Registration Statement on Form S-4, Registration No. 333-60853 (the
"Registration Statement"), under the Securities Act of 1933, as amended (the
"Act"), relating to the issuance by the Company of shares of the Company's
common stock, par value $10.00 per share ("SPX Common Stock"), in connection
with the merger (the "Merger") of General Signal Corporation, a New York
corporation ("General Signal"), with and into SAC Corp., a Delaware corporation
and wholly owned subsidiary of the Company ("MergerSub"), pursuant to the
Agreement and Plan of Merger, dated as of July 19, 1998 (the "Merger
Agreement"), among the Company, MergerSub and General Signal.  In the Merger,
each General Signal stockholder will be entitled to receive, at his or her
election but subject to the limitations and proration procedures set forth in
the Merger Agreement, for each share of common stock, par value $1.00 per
share, of General Signal ("General Signal Common Stock") held by such
stockholder, either (i) 0.6977 of a share of SPX Common Stock; (ii) $45.00 in
cash, without interest; or (iii) 0.4186 of a share of SPX Common Stock and
$18.00 in cash, without interest, provided that only 40% of the outstanding
shares of General Signal Common Stock will be exchanged for cash and only 60% of
the outstanding shares of General Signal Common Stock will be exchanged for
shares of SPX Common Stock.  This opinion is delivered in accordance with the
requirements of Item 601(b)(5) of Regulation S-K promulgated under the Act.

        With your permission, all assumptions and statements of reliance herein
have been made without any independent investigation or verification on our
part except to the extent otherwise expressly stated, and we express no opinion
with respect to the subject matter or accuracy of such assumptions or items
relied upon.



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          In connection with this opinion, we have (i) investigated such
questions of law, (ii) examined originals or certified, conformed or
reproduction copies of such agreements, instruments, documents and records of
the Company and its subsidiaries, such certificates of public officials,
officers or other representatives of the Company and its subsidiaries, and other
persons, and such other documents, and (iii) reviewed such information from
officers and representatives of the Company and others as we have deemed
necessary or appropriate for the purposes of this opinion.

          In all such examinations, we have assumed the legal capacity of all
natural persons, the genuineness of all signatures on original or certified
copies, and the conformity to original or certified documents of all copies
submitted to us as conformed or reproduction copies. As to various questions of
fact relevant to the opinion expressed herein, we have relied upon, and assumed
the accuracy of or compliance with, representations and warranties contained in
the documents relevant hereto and certificates and oral or written  statements
and other information of or from public officials, officers or other
representatives of the Company, and other persons. To the extent it may be
relevant to the opinion expressed herein, we have assumed that the parties to
the documents other than the Company have the power and authority to enter into
and perform such documents and to consummate the transactions contemplated
thereby, that the documents have been duly authorized, executed and delivered
by, and constitute legal, valid and binding obligations of such parties
enforceable against such parties in accordance with their terms, and that such
parties will comply with all of their obligations under the documents and all
laws applicable thereto.

          Based upon the foregoing, assuming that the General Signal Common
Stock is validly issued, fully paid and nonassessable and subject to the
limitations, qualifications and assumptions set forth herein, it is our opinion
that, if SPX Common Stock is issued and delivered as described in the
Registration Statement and in accordance with the Merger Agreement upon
satisfaction of the conditions to closing set forth therein, at such time of
issuance such shares of SPX Common Stock will be validly issued, fully paid and
nonassessable.

          The opinion expressed herein is limited to the General Corporation
Law of the State of Delaware, as currently in effect. The opinion expressed
herein is given as of the date hereof, and we undertake no obligation to
supplement this letter if any applicable laws change after the date hereof or
if we become aware of any facts that might change the opinion expressed herein
after the date hereof, or for any other reason.




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         We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to this firm under the captions
"Certain Federal Income Tax Consequences of the Merger" and "Legal Matters" in 
the Joint Proxy Statement/Prospectus forming a part of the Registration 
Statement.  In giving this consent, we do not hereby admit that we are in the 
category of persons whose consent is required under Section 7 of the Act.



                                        FRIED, FRANK, HARRIS, SHRIVER & JACOBSON




                                        By: /s/ ROBERT C. SCHWENKEL             
                                            ------------------------------------
                                                Robert C. Schwenkel










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