NEC and IEC 60364

Comparison and Contrast

 

 

 

 

 


Prepared for

 

NFPA International Operations

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Ed Comeau

writer-tech.com

September 17, 1999


 


© 1999 NFPA   Used with permission


The following is a summary of the material contained within the document Electrical Installation Requirements, A Global Perspective (April 1999), prepared by Paul Duks, Underwriters Laboratory (UL).  This report was commissioned by the National Electrical Manufacturers Association (NEMA™) as an effort to compare the material contained within the National Electrical Code (NEC®) and the IEC 60364.  Funding for this study came from NEMA, the National Fire Protection Association (NFPA), UL and the National Institute of Standards and Technology (NIST).  IEC provided funding for David Latimer (IEC T64 chairman).

 

The study underwent peer review by the following individuals:

Mark Earley, NFPA

Ken Gettman, NEMA

David Latimer, IEC TC64 Chairman

Francois Martzloff, NIST

John Minick, NEMA

Bob McCullough, IAEI, Ocean County Construction Inspection Department

George Ockuly, Cooper Bussmann

Jim Pauley, Schneider Electric

Jack Wells, Pass & Seymour Legrand

John Young, Siemens

 

This summary was commissioned by Richard Candee, Assistant Vice President, NFPA International Operations, and was prepared by Ed Comeau, writer-tech.com.  The sources of information used in this document are comprised of a PowerPoint presentation prepared by Jim Pauley (provided to Comeau by NFPA), a report prepared by Paul Duks for Underwriters Laboratory, information from the NEMA web site and personal communications with NFPA staff.  Most of the information was gathered from the Duks report.  It is noted in the text when information was obtained from other sources.


A comparison of the NFPA National Electrical Code (NEC) and IEC 60364

 

Two documents serve as the basis for electrical wiring in 90% of the world, according to a report prepared by Underwriters Laboratory.

 

The NEC was developed based on a need in North America to standardize the installation of electrical systems as they were being developed.  The NEC therefore evolved, historically, as systems and technology progressed.  The NEC contains mandatory language that allows for use by designers, installers and AHJ’s to ensure that adequate safety levels are met.  It covers a wide range of requirements, including hazardous locations (explosive atmospheres), which IEC 60364 does not.

 

On the other hand, IEC 60364’s purpose is to only provide guidance.  Efforts were made to harmonize the electrical installation requirements in 1969, but these efforts were unsuccessful because of the large number of differences between the various systems prevalent throughout Europe.  The result, therefore, was a document (IEC 60364) that provided guidance to an authority on developing national wiring principles that would, in turn, serve as the basis to further develop practices, such as are outlined in the NEC.  As stated in a report prepared by Underwriters Laboratory, “Countries adopting IEC 60364…need to develop additional rules usable by electrical system designers, installers, and enforcing authorities.”[i]

 

The NEC is in use in all 50 states in the United States.  Countries that have formally adopted the NEC include Mexico, Costa Rica, Venezuela and Columbia.  Many countries in South America use the Code, and it has been translated into Spanish, Korean and Japanese. (Candee, Keith, Bunker)

 

The NEC has a regular, three-year cycle for updating its material.  There are 478 people on 20 NEC code-making panels involved in a rigorous review of the material contained within the NEC and ensuring that it reflects the current state of the art.  (Bunker)

 

Revision of IEC 60364 is not done on a regular timetable, as with the NEC.  It is a collection of 38 documents and 10 amendments, all of which have varying publications date.  There are some documents contained within IEC 60364 that have not been updated since being issued in 1977.

 

The NEC does not limit specific voltage requirements for an installation.  The IEC, on the other hand, does limit its scope to the installation of circuits up to 1,000 V.  Such limitations, the report states, “this could be a serious consideration for high-rise building installations.”

 

The report outlines some of the difficulties involved with using IEC 60364 because of the layout of the document.  Requirements are located throughout a number of chapters, some of which contain information that was issued in 1977, for example.  (An amendment was appended to this chapter, however, to delete the references to some of the outdated information.)  The report goes on to further state “rules which cover one safety feature are located in different parts of the documents.”

 

Furthermore, because IEC 60364’s rules stop at the socket outlet, it does not take into account the overcurrent protection that may be required for current-using equipment, as does the NEC.  This could result in “inappropriate or hazardous installations” when using IEC 60364.

 

Even though it would be necessary to make some adjustments in the NEC because of metric conversions and the use of 240 V systems versus 120 V systems, the report goes on to say that “from the standpoint of uniform application and enforcement, the NEC, with its comprehensive requirements, would be a more appropriate base document for development of national wiring rules.”  Few changes would be necessary to adopt the NEC because it is designed as a model code, suitable for adoption.

 

IEC 60364 is not designed as a model code document.  This document only provides the authority with guidance on developing national wiring rules-it is not the code itself, as with the NEC.  Another document, compatible with IEC 60364, must be developed to provide these rules. 

 

Duk’s report also states, in relation to adoption:

“The IEC 60364 standard on Electrical Installations of Buildings is intended to serve as a model for development of national requirements.  It has been characterized as not being suitable for direct adoption as an installation practice.  Due to its composition, layout, and inclusion or recommendatory and advisory provisions, effort is needed to create documents that include mandatory installation language which can be uniformly applied.  (emphasis added)

 

For example, this process is being undertaken in Britain where a European version of IEC 60364 exists (HD 60384).  The British Institution of Electrical Engineers (IEE) then had to develop BS7671, Requirements for Electrical Installations, based on the material contained within HD 60384.  Furthermore, IEE then developed an On-Site Guide to BS 7671, which is the actual document used by installers and verifiers.  However, this guide does not cover all installations.  For installations that are not contained within the Guide, the user must then refer to the original source document, BS 7671.

 

It is important to note that there are many common factors between the two documents and, according to Merton Bunker, NFPA’s Chief Electrical Engineer, the NEC is compatible with IEC 60364.  NEMA also states that the report “highlights more similarities than differences,”

 


In a Tentative Interim Amendment (TIA) to the NEC,

Reference: 90-1 (d) (New)

TIA 99-1

 

(d) Relation to International Standards.  The requirements in this Code address the fundamental principles of protection for safety contained in the International Standard “Electrical Installations of Buildings, IEC 60364-1, Section 131.

 

FPN:  IEC 60364-1, Section 131 contains fundamental principles of protection of safety that encompass: protection against electric shock, protection against thermal effects, protection against overcurrent, protection against fault currents, and protection against overvoltage.  All of the above potential hazards are addressed by the requirements in the Code.[ii]

 

Jim Pauley states, “The NEC has been amended to link its safety practices and procedures with those of the fundamental principles of the IEC document.”[iii] 

 

In comments made by David Latimer (IEC TC64 chairman) as part of the report, he says:

“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 of situations.  I believe that installations carried out to the NEC will comply with the requirements of IEC 60364.  Without doubt, they comply with Chapter 13.”

 

He goes on further to state:

“The point is made in the report that because of the limited experience of national committees and delegates to TC64 in 110 volt systems, the requirements of IEC 60364 do not fully reflect the needs of such systems.  This may be possibly so.  I would welcome any 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.”

 


 

NEC

IEC 60364

NEC evolved along the 100 year development of electrical systems in the US

IEC 60364 began as a process of harmonization of existing rules in European countries to facilitate trade

NEC is a set of specific rules intended to be used for design, installation and uniform enforcement of electrical system installations based on North American principles and practices

IEC 60364 is a collection of documents that define fundamental principles, practices and performance requirements that have their basis in the European concept of wiring and distribution systems

NEC and IEC 60364 both establish performance requirements that address fire and electric shock protection, i.e., protection of persons and property.

 

NEC and IEC 60364 both address installation, use and maintenance of premises wiring systems and equipment

 

NEC and IEC 60364 are both applicable to wiring systems of premises for residential, commercial and industrial use.  Hazardous locations

 

NEC covers hazardous locations (explosive atmospheres)

IEC 60364 does not cover explosive atmospheres (covered separately in IEC 60079).

Neither document covers installations for generation, transmission or distribution of electrical energy

 

Neither document covers installations under the exclusive control of electrical or communications utilities

 

NEC is a comprehensive set of electrical installation requirements that can be adopted and implemented without the development of additional wiring rules

IEC 60364 provides broad performance requirements and is NOT usable as an installation document by electrical systems designers, installers or enforcing authorities.  Rather, it can serves as a guide for the development of national wiring rules.

 

Countries adopting IEC 60364 in whole (or only Chapter 13, Fundamental Principles) need to develop additional rules usable by electrical system designers, installers and enforcing authorities.

NEC and IEC 60364 need effective coordination with appropriate product standards to be successful in implementing electrical safety.

 

[iv]


 

 

NEC

IEC 60364

Adoption

Model code intended for legal adoption or reference by countries, states, counties, cities, etc.

Intended to serve as the basis for the development of national requirements.

Revision Cycles

Regular, 3-year cycle

Continual, as determined by the technical committee

Language

Mandatory language

Mandatory language, but also contains much advisory material or recommendations

Requirements

Prescriptive

Performance-based

Product Standards

Lacks a solid (direct) tie to product standards.  This is handled through coordination by the SDO’s.

Has a direct tie to IEC product standards through direct reference.

Organization and Layout

 

 

 

Arranged by parts of the electrical installation (branch circuit, panelboard, overcurrent protection, etc.)

Arranged by element of protection (overvoltage, thermal effects, electric shock, etc.)

 

No voltage limitation specified

Limited to 1,000 volts AC

 

Covers all elements of the premises wiring system as well as some utilization equipment requirements

Coverage includes the premises wiring system, but stops at the outlet

 

Addresses hazardous locations (explosive atmospheres)

Hazardous locations requirements are not contained in 60364 (contained in IEC 60079)

Suitability for Adoption

Designed to be legally adopted as the requirements for electrical installations

Provides a framework for development of an installation code.  The fundamental principles are contained within Chapter 13.


 

Suitability for Enforcement

Suitable for mandatory enforcement by verification bodies

Intended to be the document upon which countries base their document.

 

Contains mandatory requirements-no recommendations

Contains mandatory language, but also contains recommendations

 

No design guidance

Compliance with some provisions can be agreed upon by the owner and the installer.

Existing Infrastructures

North America-120 V branch circuits (increased fault currents)

Europe-240 V branch circuits (higher touch voltages)

Systems

Both cover TN, TNC, TNCS, IT.  Prohibits TT systems.

Both cover TN, TNC, TNCS, IT.  Allows TT systems.

 

 

 

[v]

 



[i] Duks, Paul. Electrical Installations, A Global Perspective.  National Electrical Manufacturers Association, 1999.

[ii] NFPA 70, National Electric Code, 1999 edition

[iii] NEMA, http://www.nema.org/publications/ei/jun99/iec_nec2.html, June 1999

[iv] The source material for this table was taken from a PowerPoint presentation prepared by Jim Pauley and provided to writer-tech.com by NFPA.  Actual text from the presentation was used in this table.  NFPA is responsible for determination of further use of this content based on copyright requirements or issues (if any).

[v] ibid.