1、NFPA79Electrical Standard for Industrial MachineryHandbook 2015 79NFPA, 1 Batterymarch Park, Quincy, MA 02169-7471, USAAn International Codes and Standards OrganizationNFPA, 1 Batterymarch Park, Quincy, MA 02169-7471An International Codes and Standards OrganizationNFPA79Electrical Standard for Indus
2、trial MachineryHandbook 2015 Second EditionAnnotated by Mark CloutierCopyright 2015National Fire Protection AssociationOne Batterymarch Park Quincy, Massachusetts 02169-7471 All rights reserved. About this Handbook EditionThis PDF contains the complete 2015 edition of NFPA 79, Electrical Standard fo
3、r Industrial Ma-chinery, annotated to assist the readers understanding of the standards language and the intent behind it. The annotations are not part of the NFPA Standard but provide a valuable commen-tary reflecting the views, explanations, and insights of authors and contributors selected by the
4、 NFPA based on their knowledge of and experience with the standard.How to Navigate Between the Text of the Standard and the AnnotationsNavigate between code or standard text and annotations by using hyperlinked icons and code numbers. While in code or standard text, click on hyperlinked s icon* to t
5、he left of the standard sec-tion to navigate to corresponding annotations. Click on the hyperlinked annotative standard section number 1.1 to return to previous standard section.*Please note, only the sections featuring icons contain annotations.For longer blocks of annotations, it is recommended th
6、at you enable the back arrow functional-ity in Acrobats page navigation menu, which will also allow you to return to the previous stan-dard section.How to Ensure You Have the Most Up-to-date Version of the NFPA StandardThe NFPA Standard, in the edition contained herein, is current as of the effectiv
7、e date des-ignated at the time the standard was issued 2015. This Handbook Edition does not, however, include errata, tentative interim amendments (TIAs), or formal interpretations (FIs) that may have been issued after the effective date. For all errata, TIAs, or FIs that may have been issued since
8、the effective date, or for any new editions that may have superseded this edition, please visit the “Document Information pages” link for the relevant NFPA Standard located in the “Codes email: stds_adminnfpa.org.For more information about NFPA, visit the NFPA website at www.nfpa.org. IMPORTANT NOTI
9、CES AND DISCLAIMERS CONCERNING THE HANDBOOk EDITIONNotice and Disclaimer Concerning LiabilityPublication of this Handbook Edition is for the purpose of circulating information and opinion among those concerned for fire and electrical safety and related subjects. While every effort has been made to a
10、chieve a work of high quality, neither the NFPAnor the contributors to this Handbook Edition guarantee the accuracy or completeness of or assume any liability in connec-tion with the information and opinions contained in this Handbook Edition. The NFPA and the contributors shall in no event be liabl
11、e for any personal injury, property, or other damages of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, or reliance upon this Handbook Edition.This Handbook Edition is published with the understanding t
12、hat the NFPA and the contribu-tors to this Handbook Edition are supplying information and opinion but are not attempting to render engineering or other professional services. If such services are required, the assistance of an appropriate professional should be sought.NFPA codes, standards, recommen
13、ded practices, and guides (“NFPA Standards”), includ-ing the NFPA Standard that is the subject of this Handbook Edition, are made available for use subject to Important Notices and Disclaimers Concerning NFPA Standards, which are separately bookmarked and viewable in this Handbook Edition, and which
14、 can also be viewed at www.nfpa.org/disclaimers.Notice Concerning Interpretations Contained in the AnnotationsNFPA codes, standards, recommended practices, and guides (“NFPA Standards”), including the NFPA Standard that is the subject of this Handbook Edition are developed in accordance with the pub
15、lished procedures of the NFPA by technical committees comprised of volunteers drawn from a broad array of relevant interests. In this Handbook Edition the text of the NFPA Standard is accompanied with annotations providing explanation and commentary on the meaning and intent of the Standard. The ann
16、otations contained in this Handbook Edition are not a part of the NFPA Standard and do not constitute Formal Interpretations of the NFPA (which can be obtained only through requests processed by the responsible technical committees in accordance with the published procedures of the NFPA). The annota
17、tions, therefore, solely reflect the personal opinions of the author or other contributors and do not necessarily represent the official position of the NFPA or its technical committees.ISBN: 978-1455910274 Copyright 2014 National Fire Protection Association. All Rights Reserved.NFPA79Electrical Sta
18、ndard forIndustrial Machinery2015 EditionThis edition of NFPA 79, Electrical Standard for Industrial Machinery, was prepared by theTechnical Committee on Electrical Equipment of Industrial Machinery and released by theCorrelating Committee on National Electrical Code. It was issued by the Standards
19、Councilon April 29, 2014, with an effective date of May 19, 2014, and supersedes all previous editions.This edition of NFPA 79 was approved as an American National Standard on May 19, 2014.Origin and Development of NFPA 79This standard was first submitted at the 1961 NFPA Annual Meeting under the ti
20、tle Electri-cal Standard for Machine Tools and was tentatively adopted subject to comments. It was exten-sively revised and resubmitted at the 1962 Annual Meeting, where it was officially adopted. In1965 a revised edition was adopted, reconfirmed in 1969, and in 1970, 1971, 1973, 1974, 1977,1980, 19
21、85, 1987, 1991, 1994, 1997, 2002 and 2007, revised editions were adopted.In September 1941, the metalworking machine tool industry wrote its first electrical stan-dard to make machine tools safer to operate, more productive, and less costly to maintain,and to improve the quality and performance of t
22、heir electrical components. That particularstandard served as an American “War Standard.”To study the special electrical problems involved with machine tools, in 1941 the ElectricalSection of the National Fire Protection Association sanctioned a Special Subcommittee onWiring, Overcurrent Protection,
23、 and Control of Motor-Operated Machine Tools. This sub-committee, cooperating with machine tool builders, manufacturers of control equipment,and Underwriters Laboratories Inc., conducted tests and investigated the peculiar conditionsinvolved with machine tools that might warrant exception to certain
24、 specific National ElectricalCoderequirements. This investigation resulted, on August 4, 1942, in a Tentative InterimAmendment and first appeared in a 1943 supplement to the 1940 edition of the NationalElectrical Code as Article 670, “Machine Tools.” It remained essentially unchanged through the1959
25、 edition.Meanwhile, manufacturers of other types of industrial equipment erroneously began tofollow the specialized practices permitted by Article 670. Late in 1952, a Technical Subcom-mittee on Fundamentals of Electrically Operated Production Machinery and Material Han-dling and Processing Equipmen
26、t for Fixed Locations was organized to attempt to group thespecial requirements of this broad field into one article. The extremely broad scope intro-duced so many problems that, in December 1956, this technical subcommittee was reorga-nized into an NFPA committee whose scope was limited to machine
27、tools and whose objectivewas the preparation of this NFPA standard with corresponding revisions in Article 670 in theNational Electrical Code.Modern machine tool electrical equipment may vary from that of single-motor machines,such as drill presses, that perform simple, repetitive operations, to tha
28、t of very large, multimo-tored automatic machines that involve highly complex electrical control systems, includingelectronic and solid-state devices and equipment. Generally these machines are speciallydesigned, factory wired, and tested by the builder and then erected in the plant in which theywil
29、l be used. Because of their importance to plant production and their usually high cost, theyare customarily provided with many safeguards and other devices not often incorporated inthe usual motor and control application as contemplated by the National Electrical Code.Although these machines may be
30、completely automatic, they are constantly attended,when operating, by highly skilled operators. The machine usually incorporates many specialdevices to protect the operator, protect the machine and building against fires of electricalorigin, protect the machine and work in process against damage due
31、 to electrical failures, andprotect against loss of production due to failure of a machine component. To provide these791NFPA and National Fire Protection Association are registered trademarks of the National Fire Protection Association, Quincy, Massachusetts 02169.ssafeguards, it may be preferable
32、to deliberately sacrifice a motor or some other component, rather than to chanceinjury to the operator, the work, or the machine. It is because of such considerations that this standard varies from thebasic concepts of motor protection as contained in the National Electrical Code.As NFPA 79 evolved,
33、 it became apparent that certain classes of light industrial machinery (e.g., small drill presses,bench grinders, sanders, etc.) were not appropriately covered. The 1977 edition of the standard recognized thisproblem and purposely excluded tools powered by 2 hp or less.Subsequent to publication of t
34、he 1977 standard, a light industrial machinery standard development activity wasinitiated by the Power Tool Institute. The 1985 edition of NFPA 79 reflects this activity, and appropriate requirementsare now included in the standard.In 1975, the Society of the Plastics Industry requested that this st
35、andard be enlarged in scope to include plasticsmachinery. A formal request was received by NFPA in September 1978, and, through the combined efforts of theNFPA 79 committee and representatives of the Society of the Plastics Industry, the scope was broadened to include suchmachinery in the 1980 editi
36、on.In June 1981, the Joint Industrial Council (JIC) Board of Directors acknowledged the dated state of the electricaland electronic standards and requested that NFPA 79 incorporate into its standard the material and topics covered bythe JIC electrical (EMP-1-67, EGP-1-67) and electronic (EL-1-71) st
37、andards with the intention that the JIC standardseventually would be declared superseded. The NFPA Standards Council approved the request with the stipulation thatthe material and topics incorporated from the JIC standards be limited to areas related to electrical shock and firehazards. The 1985 edi
38、tion reflected the incorporation of the appropriate material from the JIC electrical (EMP-1-67,EGP-1-67) standards not previously covered. The 1991, 1994, and 1997 editions included additional references tointernational standards and reflected the committees efforts in harmonization.The 2002 edition
39、 was a major rewrite and represented a significant and historic effort in harmonizing an existingNFPA standard with an existing IEC standard. Major changes for this edition included renumbering section andchapter numbers to align with IEC 602041. A new chapter was added to address testing. An inform
40、ative Annex A wasadded to assist the user in understanding the mandatory text portion of the standard, and a new annex, Annex H, wasadded to assist the user with cross-references to previous edition section numbers.To better coordinate its work, this committee reports to the Association through the
41、Correlating Committee of theNational Electrical Code Committee. The primary reason is to correlate this standard and the National Electrical Code,especially with respect to Article 670.The 2007 edition continued to be aligned with IEC 602041. Because so much electrical equipment today containsboth e
42、lectrical and electronic equipment, Chapter 11, Electronic Equipment, was deleted, and any sections thatremained applicable were dispersed to the appropriate chapters. The deletion of Chapter 11 caused all chapters afterChapter 11 to be renumbered to one less than in previous editions. A new Chapter
43、 19, entitled “Servo Drives andMotors,” was added to the end of the standard. This new chapter addressed some of the user concerns that are arisingas servo drives and servo motors are integrated into industrial machinery. Other changes include further defining ofcables and cords, clarifying emergenc
44、y stop functions, permitting system isolation equipment, clarifying short-circuitcurrent markings, and refining requirements associated with software- and firmware-based control systems performingsafety-related functions.Changes to the 2012 edition continued to align the standard with IEC 602041. Du
45、e to the continued advancementand expansion of wireless and cableless technology, major changes for this edition included a revised definition for theterm cableless control and a new definition for the term cableless operator control station, along with revisions to Chapter 9,which aligned with IEC
46、60204-1. The title of Chapter 6 was changed, to recognize that there are other hazards (such asarc flash and stored energy) besides electrical shock. New sections were added to Chapters 6 and 16 to recognize thesehazards and correlate with NFPA 70E. Furthermore, the sections on the hazards from stor
47、ed energy in Chapter 7 weremoved to Chapter 6 for clarity and proper location of those rules in the document. To align with the NEC, therequirements in 7.2.10 were changed for selecting overcurrent devices for motors. Chapter 12 received a new sectionto address user concerns permitting the use of ap
48、pliance wiring material (AWM) as special cables, with clarifications ondetermining suitability for use under specific conditions. An important addition of a 90C (194F) temperaturecolumn to the conductor ampacity table in Chapter 12 was included to correlate with the NEC.Other changes included adding
49、 the definition for short-circuit current rating (SCCR), extracted from the NEC;revising the definition for equipment grounding conductor; and adding a new definition for safety-related functionspecific to industrial machines to harmonize with IEC and ISO standards. Further changes to Chapter 19 addressedsome of the user concerns arising from servo drives and servo motors being more commonly used in industrialmachinery. Adding ANSI indications to the appropriate UL referenced publications in several sections, Chapter 2, andAnnex J provided consistency. Finally, add
