NEMA

ELECTRICAL INSTALLATIONREQUIREMENTS

A Global Perspective

N a t i o n a l E l e c t r i c a l M a n u f a c t u r e r s A s s o c i a t i o n

By Underwriters Laboratories Inc.Principal Investigator: Paul DuksApril 1999

Copyright 1999 by the National Electrical Manufacturers Association. All rights including translation into otherlanguages, reserved under the Universal Copyright Convention, the Berne Convention for the Protection of Literary andArtistic Works, and the International and Pan American Copyright Conventions.

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NOTICE

D i s c l a i m e r s a n d L i m i t a t i o n o n L i a b i l i t y

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In preparing this document, NEMA has endeavored to provide current content as of the date it wasprepared. NEMA does not represent or warrant that the content is current at the time the user reads thedocument or that it will remain current. Nor does NEMA represent or warrant that this document is free fromtypographical or other errors or that it contains all the information a reader needs to consider for its particularpurpose, since NEMA does not know to what use this document or its contents is contemplated. NEMAreserves the right to add to, change, or delete the contents of this document, or any part thereof, without notice.Any price or availability information with respect to this document is also subject to change without notice.

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TABLE OF CONTENTS

Foreword.............................................................................................................................................................v

Acronyms and Electrical Circuit Designations ............................................................................................vi

Executive Summary ...........................................................................................................................................1

Introduction........................................................................................................................................................2

Overall Assessment............................................................................................................................................3

Suitability for Adoption ....................................................................................................................................7

Effect of Normative References .....................................................................................................................8

Assessment of Style and Attributes ................................................................................................................9

Comparison of Significant Provisions, NEC to IEC 60364 .....................................................................14

Cross References, IEC 60364 to NEC.........................................................................................................48

Annex A-1, Layout and Arrangement of the NEC....................................................................................64

Annex A-2, Numbering System and Plan of IEC 60364 ..........................................................................65

Annex B-1, Normative References in IEC 60364 ......................................................................................68

Annex B-2, U.S. Product Requirements Corresponding to Normative References in IEC 60364 Documents...............................................................................75

Annex C, Excerpts from ISO/IEC Directives, Part 3 ..............................................................................79

Annex D, Example Circuits ...........................................................................................................................82

Annex E, Comparison of Conductor Ampacities ......................................................................................89

Annex F, Fuse and Circuit Breaker Characteristics....................................................................................91

Index ..................................................................................................................................................................95

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FOREWORD

This study was undertaken as part of the NEMA Global Strategy Initiative. Increased sales and use ofelectrical products in markets around the globe make it imperative that manufacturers, codes and standardsdevelopers, and conformance assessment organizations have a clear understanding of the electrical installationsystems in which electrical products are being used. The intent of this document is to foster a betterunderstanding of the similarities and differences between the National Fire Protection Association's NFPA 70,National Electrical Code, and the wiring rules promulgated by IEC 60364, Electrical Installations for Buildings.These two prominent documents collectively serve as the basis for electrical wiring used in over 90 percent ofthe world.

The extensive document comparison and analysis in this report was conducted by UnderwritersLaboratories under contract to NEMA. Funders include NEMA, NIST, NFPA, and UL. The IEC covered theexpenses of David Latimer, IEC TC64 Chairman. The effort was reviewed and critiqued periodically during theprocess by a Peer Review Committee convened expressly for this task. The professional standing of committeemembers made them particularly well suited for this assignment. Committee members included Paul Duks,Underwriters Laboratory; Mark Earley, NFPA; Ken Gettman, NEMA; David Latimer, IEC TC64 Chairman;Francois Martzloff, NIST; John Minick, NEMA; Bob McCullough, IAEI, Ocean County ConstructionInspection Department; George Ockuly, Cooper Bussmann; Jim Pauley, Schneider Electric; Jack Wells, Pass &Seymour Legrand; and John Young, Siemens.

This report reflects the contributions of committee members, all of whom believed in the importantimplications that the analysis will have for the electroindustry here and abroad. David Latimer offers thefollowing insights into the work of the committee:

I have been pleased to take part in the peer review group that assisted in the preparation of this report; mycontribution has been to further the understanding of IEC 60364.

The reference in the Assessment of Style Attributes section to IEC 60364 as not being intended as adocument for use by engineers and electricians is mine. Almost all countries that have adopted IEC 60364 as the basisfor national standards provide guidance either produced by themselves or another country, but not all.

The guidance can be divided into two classes, one of which is broad guidance, expanding upon the principle,and for the assistance of the senior designer engaged in large or difficult installations. The other is 'do it this way'guidance. The NEC is a 'do it this way' document. It has a broad scope and covers the widest possible range ofsituations. I believe that installations carried out to the NEC will comply with the requirements of IEC 60364.Without doubt, they comply with Chapter 13.

I do not believe that the NEC is suited to be, nor could it become, an international standard. What it issuited for and could be declared to be is a way of making an installation which complies with IEC 60364 when usingequipment listed in UL or U.S. standards.

The point is made in the report that because of the limited experience of national committees and delegates toTC 64 in 110 volt systems, the requirements of IEC 60364 do not fully reflect the needs of such systems. This maypossibly be so. I would welcome an indication of the way in which IEC 60364 might be amended to meet these needs,thus enabling IEC 60364 to be adopted by ANSI as a U.S. standard, with the NEC as a 'means to comply'document for those countries that wish to use it.

The work summarized in this report is the beginning of a more extensive effort by NEMA membercompanies. NEMA product technical sections are planning to use this report as a reference document and a roadmapto improve their understanding of the commercial applicability of their products in the installed electrical infrastructurein target countries or regions utilizing the wiring principles of IEC 60364. Some NEMA sections may choose tosimply take note of the differences between the two subject wiring approaches; others w