1. how do the nec and iec 60364 help provide electrical safety.pdf

7/22/2019 1. How do the NEC and IEC 60364 help provide electrical safety.pdf

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HOW DO THE NEC AND IEC 60364 HELP PROVIDE ELECTRICAL SAFETY?

George D. GregorySenior Member IEEESquare D CompanyPO Box 3069Cedar Rapids, IA 52406USA

Melvin K. SandersMember IEEETECo., Inc.206 SE Eastlawn DriveAnkeny Iowa 50021USA

Copyright Material IEEEPaper No. PCIC-2000-34

Joseph H. KuscaMember IEEEKillark Electric Mfg. Co.3940 M L King Dr.Saint Louis, MO 631 13USA

Craig M. WellmanSenior Member IEEEDuPont Co.P.O. Box 80840Wilmington, DE 19880USA

Giuseppe PariseMember IEEEUnivers ity of RomeLa Sapienza00184 RomeItaly

Abstract - Electrical safety requires a combination of Our goals are to promote harmonized product standards sostandards and enforcement processes that must be carefully everyone can use the same standard product lines and tointegrated so they work together. Two main standards are promote correlation of the NEC, a national how to do itused to provide electrical safety in facilities: the lnternationale code, and IEC 60364, the international electrical installationElectrical Technical Commission (IEC) system in Europe and standard,so the process of harmonizing product standards isthe National Electrical Code (NEC). not impeded.These two systems provide electrical safety when usedseparately, but using a mix of the two raises many technicalissues that are complex and not obvious to most users. Thispaper examines some of them, showing some similarities anddifferences while looking at related product issues.

lndex Terms -- Codes, electrical safety, electricalstandards, international standards, global standardization,IEC 60364, NEC.

1. INTRODUCTION

II.THE ELECTRICAL SAFETY SYSTEMElectrical equipment and installations must satisfy bothfunctional and safety requirements. Products and instal lationscan be considered essentially free from hazards [NEC90.1(b)] This statement is essential to define the responsibili tyof every national or international nstallation code correctly. Itcomplies with the new approach of the European Resolutionof May 7, 1985 that states as voluntary and with presumptionof compliance the use of IEC-EN 60364. Figure 1provides avisualization as to how the components work together. [9]

Large organizations today are international, havingmultinational customers, clients or constituencies andfacilities in a variety of countries. Suppliers may be frommany countries, with products and services regulated byspecific codes, standards, duties and trade agreements incountries in which they are used and produced.This paper will look briefly at the elements of an electrical Safe P roducts andsafety system and how they impact decisions regarding Safe Installations

Certification

electrical installations, reviewing and comparing the NEC withIEC 60364. [I ,2] The base for the review and comparison ofthe two documents is a report for the National ElectricalManufacturers Association (NEMA) titled ElectricalInstallation Requirements - A Global Perspective. [3] Thisreport is available on NEMAS web site. It states One or theother of these documents serves as a basis for national wiringrules in various countries throughout the world.

0-7803-6338-5/00/$10.000 2000 IEEE

Fig. 1 Electrical Safety System

The installation code states requirements for safe systemsand is closely linked to product standards and conformityassessment certification processes. Performancerequirements for products must support the detai ls of theinstallation code and visa-versa. The inspection andenforcement function helps to assure that the installationcode has been followed. These functions are essential in

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providing for safe installations and must be linked andmutually supportive. Each function is in each system thoughthey may exist in different forms.The linkage of these components is important, sinceindividual components alone cannot be changed. Theeffectiveness of code requirements is also dependent onapplication of supporting products as well as enforcement.

111. COMPARETHENEC& IEC 60364One or the other of these documents serves as a basis fornational wiring rules in various countries. Electricalproduction based on the U.S. Central Intelligence Agencys1997 World Fact Book shows:

Billion kWh3,700

This indicates Europe, based on IEC 60364, plus NorthAmerica, where the NEC originates, account for more thanhalf of the worlds production of electricity. Both are widelyused throughout the world. The NEMA document provides asurvey of similarities and differences that should beaddressed.A. What Is The National Electrical Code?First published in 1897, it is presently revised every threeyears by the National Fire Protection Association. Itspurpose, stated in Section 90-1, is the practical safeguardingof persons and property from hazards arising from the use ofelectricity. [ I ] The NEMA report states it is a specific set ofrules intended to be used for design, installation and uniformenforcement of electrical system installations based on NorthAmerican principles and practices. [3]B. What Is IEC 60364?IEC 60364 was started by Technical Committee 64 of theIEC. Clause 12.1 of Part 1 states, This standard contains therules for the design and erection of electrical installations soas to provide safety and proper functioning for the useintended. [2) t is a single standard published in a number ofinterrelated parts and contains fundamental principles,practices and performance requirements based on Europeannational standards but are generally applicable to all systems.Individual user countries and localities draw from thisstandard for specific wiring rules.

The original drafts discussed were the few CENELCOM 100European documents available and the intent was to enableharmonization of electrical installation rules in order tofacilitate trade among them. European practices continue tobe adopted in IEC 60364 because the European countriesare predominant n TC 64 and the working groups.C. Relation Of One To The OtherIEC 60364 provides the fundamental principles for wiringrules used in the European Union (EU). Other countries eitherdevelop their own legally mandated and applied wiring rulesbased on IEC 60364 or use the application document ofanother country.The NEC provides wiring rules for the USA, and suitableversions are adopted in Mexico, Columbia, Venezuela,Panama, Puerto Rico, the Philippines and other nations.Until recently IEC 60364 and the NEC have had no formalrelationship to each other. The U.S. has been a member ofthe IEC since its inception, but participation has been nominaluntil very recently. While American National StandardsInstitute (ANSI) standards have been widely accepted andhave been the preferred standards in many countries, theNEC and IEC served different areas of the world.Globalization and international standardization has changedthis.We do find commonality. A 1999 Temporary InterimAmendment (TIA) to the NEC added Section 90-l(d) stating:The requirements of this Code address the fundamentalprinciples of protection for safety contained in InternationalStandard Electrical Installations of Buildings, IEC 60364,Section 131. They are in harmony, and fundamentalprinciples for electrical safety are the same throughout theworld. This change to the NEC was a significant step towardrecognizing IEC 60364 in ANSI electrical standards.This confirms a harmony for basic electrical safety -- there aremore similarities than differences between the two. Someinstallation and wiring rule differences do exist because of thedifferent electrical systems, building codes, practices,environments and infrastructure.D. Ho w Are They Similar?The following points come from the NEMA report. [3]

Both establish performance requirements that addressfire and electric shock protection.Both address installation of premises wiring systems andequipment.Both are applicable to electrical systems of premises forresidential, commercial and industrial use.

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Neither covers installations for generation, transmissionor distribution of electric energy, nor those underexclusive control of electric or communications utilities.Both need effective coordination with appropriate productstandards to be successful in implementing electricalsafety.The scope of both covers from the service point (point ofsupply) to outlets.Electrical safety in both is for avoidance of fire andelectrical shock hazards.

The NEMA report explores the various sections of bothdocuments point for point and in general finds that each pointin one is covered by a corresponding point in the other andeach provides an adequate range of coverage in terms of theother.E. How Are They Differen t?

1) Approach: The IEC 60364 approach is consideredopen as a way or a guide for a way. The IEC system isbased on an analytical approach of requirements,generalizing criteria, resolving additional situations andopened to non-specific items. The IEC system highlights therole of the technical operator, designer or inspector, etc toaccept the responsibility to choose, design and organize tothe specific installationcode. The installation hen has thepresumption of compliance.Inherent in this is the information & training requirementabout safety as an essential imperative for all workers(Council Directive 89/391/EEC of 12 June 1989) and as aduty for the technical operator. IEC 60364 is published in anumber of interrelated parts and contains normativereferences to other standards. Training in its use is difficultand is relatively expensive, as it does not have a formalrevision schedule.The NEC approach is considered closed, it is the way, ordo it this way. The NEC system is based on a synthetic(assumed set of conditions) approach (with feedback); it is acomprehensive set of electrical installat ion requirements forsafety and the Installat ion Code. It is revised every threeyears and highlights he variations.2) Approval: The approval of the IEC documents and of

the NEC is an effort respectively by manufacturers, testinglaboratories, inspectors, labor, utilities, facility owners.

3) Use: IEC 60364 provides broad performancerequirements and is not usable as an installation documentby electrical system designers, installers, or enforcingauthorities, but rather it can serve as a guide for developmentof national wiring rules. The NEC is a comprehensive set of

electrical installation requirements that can be adopted andimplemented without development of additional wiring rules.[3] It contains the detailed mandatory material needed tomake it comprehensive and enforceable.

4) Adoption By Authorit ies: IEC 60364-1, Chapter 13states: Fundamental Principles, Note: Where countries notyet having national regulations for electr ical installationsdeem it necessary to establish legal requirements for thispurpose, it is recommended that such requirements be limitedto fundamental principles which are not subject to frequentmodificat ion on account of technical development. Thecontents of Chapter 13 may be used as a basis for suchlegislation.The NEC states on the inside of the back cover: Adoption byReference: Public authorities and others are urged toreference this document in laws, ordinances, regulations,administrative orders or similar instruments. ... Adoption byTranscript: Public authorities with lawmaking or rulemakingpowers ... will be granted a royalty-free license to print andrepublish this document in whole or in part, with changes andadditions, if any, noted separately, in laws, ordinances,regulations, administrative orders, or similar instrumentshaving the force of law.... Adopting the NEC does requirethat a legislative body or agency adopt a change in the lawevery three years if they want to stay up-to-date.IEC 60364 is not an inspectors or planners document. Ratherit provides guidelines for writ ing such a document. The NECis a document intended for use by planners and inspectors, tobe adopted by authorities performing the inspection. Itcontains both performance and prescriptive requirements.

5) Scope: IEC 60364 covers a system from the point ofsupply for a building to the socket (receptacle) outlets. Itdoes not include rules for appliances or other electricalequipment. Product requirements are in separate IECstandards, which are developed by other committees withliaison to TC 64 for installation issues. The NEC covers asystem beginning at the service point of a premises up to andincluding the outlet(s) and it also includes some rules forappliances and other utilization equipment, which the codemaking panels elect to include in the installat ion code.IEC 60364 does not include rules for installations in areaswith explosive atmospheres. Those rules are provided in IEC60079. The NEC includes rules for hazardous (classified)locations (explosive atmospheres). NEC rules include bothtraditional North American systems and rules that harmonizewith those of IEC 60079.The scope of IEC 60364 is limited to voltages up to 1000 V,with no similar voltage limitation in the NEC. TC 99 is

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developing a standard for installations or over 1000 volts withthe European Standard, CENELEC HD 637 SI: 1998-12Power ins tallations exceeding 1 kV a.c. The draft presents aconflict between the values of admissible touch voltages onthe LV side stated by IEC 60364 and those suggested for theMV supply side of premises wiring [12].6) Examination Of Equipment For Safety: The NEMAreport concludes that for IEC 60364, compliance with the

safety requirements of the relevant equipment standards is tobe made by visual inspection on permanently wired electricalequipment. NEC provisions in 90-7 relieve the inspectionauthority from delving into internal wiring of appliances andequipment, and rely for safe operation on equipment that hasbeen certified by a qualified electrical testing laboratory asmeeting appropriate standards. [3 pg 121 The concept ofexamination of the run of goods at factories, called follow-upinspection and testing, is an integral requirement of ULproduct certification to satisfy the NEC.IEC 60364 allows examination of labels or documentation toverify that an item complies. Equipment made by amanufacturer with QA certification is readily identified asmeeting standards. However, European national lawsguarantee that production is independently monitored andregulated.

7) Referenced Documents: IEC 60364 makes extensivereferenceto normative documents.. The NEC does not makeany normative or mandatory references to other documents,which allows it to easily be adopted by legal jurisdictions.However, as the NEMA report says, some equipment isspecifically required to be listed (certified), which by definitionin the NEC means that the equipment ...meets appropriatedesignated standards.. .. It requires third party certification bylisting or labeling.

IV . APPLICATION EXAMPLESThe differences described above provide a macro idea ofdifferences. However, differences that impact systemdesigners and users will be found in their relation to specificinstallations. We will look at several examples.A. Conductors And O vercurren t ProtectionThe NEMA report points out that the ampacities of conductorsare similar for similar cross sections by comparing values of75% conductors in NEC Table 310-16 with dose of 70%conductors in IEC 60364-5-523, Table 52-C9. Thecomparison always shows the NEC value to be slightly moreconservative. Correction factors for ambient temperaturesand for number of conductors run together are similar.

In the NEC, 240-3 reads, Conductors ... shall be protectedagainst overcurrent in accordance with their ampacities .. .Protection against overcurrent implies protection against bothoverload and short circuit conditions. Similarly, IEC 60364-4433.1 reads, Protective devices shall be provided to breakany overload current before such a current could cause atemperature rise detrimental o insulation, joints, terminationsor surroundings of the conductors. Also, 434.1 reads,Protective devices shall be provided to break any short-circuit current flowing in the circuit conductors before such acurrent could cause danger due to thermal and mechanicaleffects produced in conductors and connections. Again, onfundamental principles, the two documents are in harmony.In IEC 60364 the cables ampacity IZshall not be less thanthe design circuit current IB (continuous and non-continuousload), and if the protective device is a circuit breaker, it shallalso be IZ= IS. For feeders, the NEC 215-2(a) and 215-3mandates that the overcurrent device (and then Iz) shall notbe less than the non-continuous load plus 125 percent of thecontinuous load [13].The starting-point of NEC in determining the overloadcapacity of cables is the conductor emergency loadingtemperature 8 E which can be tolerated by a cable for a givenmaximum time per overload. IEC 60364 deals with overloadprotection of cables essentially in terms of current values; theadmissibility of overload currents for moderate periods isasserted as a consequence of the prescribed coordinationcriteria between conductors and protective devices. Anemergency loading current (1.451~) is admissible in aconventional time (between one- and two-hours for CB) withinwhich the protective device shall ensure its operation. Briefly,in the IEC system for each admissible overload theconductors with a low cross sectional area are stressed morethan those with a high cross sectional area. In the NECsystem, all conductors are considered o be stressed equally~ 4 1 .The overcurrent protection requirements in the IEC systemare independent of the system. The manner of earthing willaffect the earth fault loop impedance and that will affect theway in which earth fault protection is provided. The overloadprotection and short-circuit protection are consideredseparately and may be provided by separate devices or asingle device. A single set of fuses or a single circuit breakeris the most common form of protection except in cases inwhich equipment protection requires dedicated brotectionsuch as in motor circuits. The short-circuit protective devicemust clear a fault in a time that will meet the k2S2requirements of IEC 60364-4 434.3, (adiabatic equationinvolving conductor cross sectional area, time tc 5% andenergy let through [15]. For a current limiting device the

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manufacturer declares this and for a non-current limitingdevice it is determined from fault 1%Under the NEC system, a single overcurrent protectivedevice, circuit breaker or set of fuses, is required forprotection of conductors in Section 240-20(a). Only wherespecific equipment is intended o be protected, such as motorcircuits in Article 430, are separate devices permitted foroverload and short-circuit protection. In these cases, theseparate overload device is primarily for protection of theequipment.Product standards for fuses and circuit breakers havedifferences that make the products not interchangeable.Fuse characteristics for time versus current and for short-circuit let-through values are different; however, circuitbreaker time versus current characteristics are quite similar.For short-circuit protection, North American circuit breakerstandards require tests with conductors rated for specifictemperatures. Circuit breakers are labeled with the range ofconductor sizes tested and with a maximum conductortemperature rating, because the conductor size and initialtemperature impacts the results: the conductor serves as aheat sink allowing more current to flow before the breakertrips. In some tests, the conductor also limits the test currentallowing a higher interrupting rating. The test with conductorsalso demonstrates protection. Alternatively, manymanufacturers of IEC rated circuit breakers publish values oflet-through 2t o compare with k2S2 alues of conductors.Terminal temperature rises during temperature tests at ratedcurrent are permitted to be a maximum of 70C under IEC60947-1 covering switches and circuit breakers as well ascontrol equipment. [6] Temperature rises in UL 98 forswitches are permitted to be a maximum of 30C measuredwith dummy fuses in place of real fuses, although this meansthe temperature rise with real fuses is not tested. [8]Temperatures rises in UL 489 for circuit breakers arepermitted o be a maximum of 50C. (71 Some suggestions forharmonizing circuit breaker standards appear below.As we review the design and installation of the system, wefind differences in products and practices that go far beyonddifferences in voltages and frequencies. Product standardsare closely linked to a particular installation standard, i.e.selection of conductors size, insulation temperature ratingand overcurrent devices is defined in the installationstandard, but product standards determine actualperformanceof this equipment using the family of underlyingproduct standards -- UL or IEC. In the NEC, the underlyingproduct standards are not listed as normative references andare not shown at all in most cases, although there is closecorrelation between those product standards and the NEC.

B. Circuit Breaker StandardsTo harmonize low-voltage circuit breakers, we would need tolook separately at the residential unit called a miniature circuitbreaker (MCB) in IEC terms and the industrial molded-casecircuit breaker (MCCB). Both products are covered in a singlestandard in North America, for example UL 489 in the USA.[7] In the IEC system, the MCBs are covered in IEC 898 andthe MCCBs in IEC 947-2. [lo, 111Concerning the MCCBs, it would be desirable to see theNorth American requirements included in the IEC Standard tofacilitate more universal designs. Items that might beconsidered are in at least three key areas.One area is individual pole short circuit tests in which multipleground faults are simulated at line-to-line voltage. AlthoughAnnex C of IEC 947-2 presently contains a test that goes along way toward satisfying this condition, the test currentvalues are 25% of ultimate interrupting rating and could beconsiderably lower than that required by North Americanstandards.A second is the wiring terminal temperature rise of 80Cpermitted in IEC 947-2 (after operational tests of breakingcapacity) compared with 50C (for a new unused breaker) inNorth American Standards. The elevated temperatures of theIEC rated products could cause hot spots in conductors of thetype used in North America that could lead to insulationfailure. Perhaps the lower temperature rise could be added inan annex since the higher temperatures are clearlyacceptable with wires used with IEC rated products in Europe.A third difference is the larger spacing for creepage andclearance in North American standards. The spacings asstated in UL 489 are linked to National Electrical Code Table384-36. They are larger than needed strictly for dielectricintegrity and include considerations for workmanship andunexpected occurrences. It is essential that productstandards remain correlated with the wiring rules to maintainthe integrity of the system, but why must the spacing remainin the NEC?If we turn to the MCB, the primary issue is that IEC 898 todaydoes not recognize North American voltages of 120, 120/240o r 240 Vac. We understand that Working Group 1 of IECTechnical Committee 23E is evaluating this addition.Such changes would go a long way toward bringing thestandards together for these circuit breaker products.

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V. HARMONIZATION EXAMPLE- NCREASED SAFETYSTANDARDS

An example of what can be accomplished can be seen in achange to the 1996 NEC - adoption of the international zonesystem of area classification.The Instrument Society of America (ISA), an organization ofusers and product manufacturers has played a leading role inthe drive to improve electrical safety in classified areas. It hasa committee (SP12) that focuses on standards and practicesfor classified areas. The SP12 Committee is made up ofmany subcommittees with specific scopes. For example,there are SP12 subcommittees for each of the protectiontechniques for classified areas both for the traditional NorthAmerican Division System and the IEC Zone System.An interesting example of working towards GlobalHarmonization can be found in the efforts of the ISA SP12.16Subcommittee that worked to develpp an American NationalStandard Institute (ANSI) standard and harmonize it with theIEC standard for the type of protection, Increased Safety.One factor that made the effort of developing a harmonizedstandard for increased safety different was that this protectiontechnique was developed in Europe and clearly the expertisefor the protection technique is still with Europeanorganizations and companies.One of the first meetings of the SP12.16 Subcommittee wasinstructional. A second meeting was held in Germany so itcould include lab tours to view demonstrations of the testtechniques for various types of increased safety products.Later, working group meetings to address motors and lightingwere held in Germany.After ANSI recognition of the ISA Increased Safety Standard,ISA arranged for that standard to be submitted to the IEC bythe U.S. National Committee so it could be considered or thenext revision to the IEC standard, with the US to act as theconvenor of the working group. This action resulted in theIEC establishing Working Group 13 to develop a revision. TheWG has submihed a revision proposal to TC 31.

VI. CONCLUSIONSA. What Should Users Be Doing Now?Simple mixing or combining of safe products and a soundinstallation code does not assure safety. Even specifying themost stringent code, standard or industry practice will notsuffice.Applying either installat ion standard with its related productstandards will assure a safe installation, but when mixingproduct and installation standards from the different systems,the designer must accept full responsibility for avoidingapplication or protection ailures. This is very difficult becausemany standards are involved and they are expensive and notreadily available.However, if characteristics and energy let-through figures areavailable, an installation can be designed to comply with IEC60364 using UL listed or labeled circuit breakers or fuses.Unfortunately, the NEC is presented in a way that preventsdoing this unless manufacturers obtain listings for theirproducts based on ANSI or American testing laboratorystandards or users get permission from the authority havingjurisdiction.Full resolution cannot be achieved until product standards areharmonized. In the meantime, users should maintain the NECand IEC separation of installation standards and relatedproducts wherever possible.5. Role Of The NEC Relative To T he IEC 60364David Latimer, chair of the TC64 Committee reported:Almost all countries which have adopted IEC 60364 as thebasis for their National Standards provide guidance eitherproduced by themselves or taken over from another country;but not all national standards which take up the IEC60364technical content are in the IEC 60364 format or layout.VDE100, NF C15-100, and BS7671 are ways of complyingwith 60364 using equipment to IECICENELEC standards andindeed to VDE, NF, and BS standards. All of these standardsare used widely.

This example demonstrates how an organization and theusers in one country not only worked to harmonize therequirements of an international standard for use in their owncountry, but how they worked to have some of their deviationsconsidered for adoption in the international standard to bringthe requirements of the national and international standardsinto harmony.

The installation guidance can be divided into two classes,one of which is broad guidance expanding upon the principle,for the assistance of the senior designer engaged in largeand/or difficult installations. The other is do it this wayguidance.The NEC is a do it this way document, which with its broadscope covers the widest possible range of situations. I believethat instal lations carried out to the NEC will in general comply

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with the requirements of IEC60364.comply with Chapter 13.

Without doubt they

"I do not believe that the NEC is suited to be nor could itbecome an international standard. What it is suited to be andcould be declared to be is a way of making an installationwhich complies with IEC60364 when using equipment listedby UL or to US Standards and Iwould welcome that."C. Where Do We Need ToGo?We need to harmonize dialectically IEC 60364 and the NECand the related product standards so a global market withworldwide access to best available products for all isachieved, and to do that in a way that maintains or improveselectrical safety.We need to move toward a standards system that maximizesthe commonality of product standards.Conflicts and voids between the two installation documentsand the product standards should be identified, analyzed incomparison, highlighting the different ranges of application,and resolved as needed to correlate them with the intent ofimproving safety requirements in each document andincreasing the flexibility to use alternate methods.Prescriptive requirements should be replaced with functionalrequirements so the market and product safety standardsorganizations can respond quickly to changing markets andtechnologies and can move toward reconciliation of NAproduct standards with EU product standards.The NEC contains no normative references to otherstandards, only references for information in "Fine PrintNotes." But, in the NEC process, approval of productrequirements is not completely left to manufacturers andtesting laboratories as it is in Europe. Inspectors, labor,utilities, facility owners, and other users also get a voice byparticipating n the development process for the next editionof the NEC. The NEC Code Making Panels acceptprescriptive product requirements in the NEC because that isthe only way they can assure those requirements will bemandatory. Unfortunately, this same process makesinnovation a slow and difficult process.As an alternative, a more rigorous process could be taken tohave qualified personnel investigate accidents and thenincorporate the learnings n product standards. [16]Usually standards issues are reconciled by moving to ahigher more general level and that has happened n the caseof IEC 60364. But providing safe installations in a practicalway means getting the details into an easily understood and

enforceable document, so design, construction, andinspect ion people can work effectively. Countries involved inthe IEC process do that with some level of a "how to do itdocument."Recognizing what should be reconciled and what should notbe reconciled s an important step. Examples and a direct ionfor each are listed below:123

45

6

7

8910

Hazardous classification systems -- NEC adopted Zonesystem in 1996!Units of measurement -- SI system is being proposed forNEC for 2002 edition!System voltages -- No change in practice is feasible dueto installed base, can add detailed requirements for 120volt system to IEC 60364.Plugs and receptacles -- No change feasible or justifiedin most countries due to installed base.Equipment compatibility with different voltages andfrequencies -- Electronic products already converted!Protected equipment zone up to receptacle as in 60364or including equipment as in NEC -- Can add as option in60364 if desired.Top voltage of 1000 volts in 60364 vs. no limit in NEC.IEC TC 99 Committee has started developing standardfor over 1000volts.Metal vs . plastic materials for product enclosures --Should reconcile rules for fire resistance.Grounding -- Appears to be quite different, but not asignificant conflict.Cable overcurrent protection -- Understand basis foreach standard's method as a first step.

Standards harmonization must be a two way street. If we aregoing to move toward common standards, both NorthAmerican and European committee members will have to beopen to accepting ideas, standards and products proposed bythe other side. We can then move toward commonstandards offering what the market demands: better safetyand reliability at the lowest possible price for each class ofapplication. As an example of successful product standardsevolution, for years Germany and the U.K had different fusecharacteristic standards. As part of harmonization, both gaveway a little and they agreed on a set of characteristics.Although the US has never declared IEC 60364 to be anANSI standard, the recently adopted TIA is a significant steptoward acceptance of the principles of IEC 60364. Thisdeclaration will help the harmonization process enormously.In the beginning, U.K., Germany, France, Italy etc. all hadtheir own very different rules or regulations or standards andgave them up reluctantly with much complaint from theirhome audiences. Strangely enough, some of the things that

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the UK objected to most strenuously turned out either not tobe a problem or to be beneficial.At the present time, several organizations are attempting toreconci le specific recommended practices used in the US tothose used in the IEC world. They are trying to accommodatethe need for industrial and manufacturing ndustries. But thereis no overall coordination, so there is duplicate effort whichcontributes o frustration and safety issues in machine design,operation, and maintenance. Although the work is difficult, theeffort must continue.

V I . SUMMARYThe North American and European countries have gone inseparate directions on electrical standards with large cost andsafety consequences for their home markets and internationalmarkets.In a survey of installat ion requirements in IEC 60364 and theNEC, we find more similarities than differences. Greatestsimilar ities exist in the fundamental principles. There are alsostrong similarities in the application of laws of physics.Differences arise in application of the codes to specificinstallations. Product standards and the enforcementsystems linked to each document are different and drivedifferent practices or installations. These differences arise inpart from differences in building codes, infrastructure, politicalstructure and environment as well as the different voltagesand electrical systems that have become standard. Therecent TIA revision of the NEC, which recognized theharmony in safety principles, is a first step in recognizingcommonality.At present, mixing of elements of the two approaches indesign and in the field can only be done with great care. Butcontinued cooperat ion between bodies working on areas ofharmonization will be supportive of organizations doingbusiness internationally. Though there will be a need for thetwo systems to exist independently for the indefinite future,we may reach a point in which a single system design cansatisfy the collective requirements of both systems withminimal conflict.Clearly there are potentially great benefits if there could be auniversal installation code, with harmonized productstandards that would lead to one product and certification orall markets. It is not practical to think that we can haveinternational codes and standards without provisions fornational or even local deviations, however, the objective mustbe to work towards global harmonization wherever practical.

VIII. REFERENCES

[ I ] ANSVNFPA 70, National Electr ical Code 1999, NationalFire Protection Association, Quincy, MA, USA 1998

[2] IEC Standard 60364, "Electrical installations ofBuildings," lnternationale Electrotechnical CommissionGeneva, Switzerland[3] "Electr ical Installation Requirements, A GlobalPerspective" A report by Underwriters Laboratories Inc.,Paul Duks, for the National Electrical ManufacturersAssociation, Rosslyn, VA, USA 1999

[4] Giuseppe Parise, "A Summary on the ProtectionAgainst Electric Shock," IEEE Transactions on IndustryApplications, September- October 1998 vol. 34 pagesGeorge Gregory, "North American or IEC Standards forCircuit Breakers - What is the Choice for NorthAmerica?", Conference Record of the 1999 IEEEIndustry Applications Society Annual Meeting.IEC 60947-1 (1999-02) "Low-VoltageSwitcher andController, Part 1 General rules," InternationalElectrotechnicale Commission, Geneva, Switzer landANSI/UL 489, Molded-Case Circuit Breakers, MoldedCase Switches and Circuit Breaker Enclosures,Underwriters Laboratories Inc., Northbrook, IL 1996.

[ 8 ] UL Standard No. 98 "Enclosed and Dead FrontSwitches," Underwriters Laboratories Inc., Northbrook,IL 1994James Pauley and George Gregory, "North AmericanCodes and Standards: A Global Challenge," ConferenceRecord of the 1998 IEEE Industry Applications SocietyAnnual Meeting, pp. 2372-2378.

[lo] IEC 60947-2 (1995-12), 'Low-Voltage Switchgear andControlgear, Part 2: Circuit Breakers, ' lnternationalElectrotechnicale Commission, Geneva, Switzerland.

[I 11 IEC 60898 (1995-02), "Electrical Accessories - Circuitbreakers for overcurrent protection for household andsimilar installations," International ElectrotechnicaleCommission, Geneva, Switzerland.

[ I21 G. Parise, "Electrical Installations Of Buildings: TheIECKENELEC Protection Against Indirect Contact ByGrounding And Automatic Disconnect ion Of The SupplyUp To And Exceeding 1 kV AC", IEEE Safety WorkshopApril 2000 India

[I 31 G. Parise, L.Martirano: "Circuits Operation Control AndOverloads Protection" IEEE Transactions on IndustryApplications, January / February 2000 vo1.36 n.1).

1141 G. Parise, G. Rubino: "A comparison between theANSVIEEE and the CENELECAEC approach tooverload protection of insulated power cables", IEEETransactions on Industry Applications, September -October 1997. 1362-1366)

.911-922[5]

[6]

[7]

[9]

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[15] Parise, U. Grasselli, R. Zan, M.K. Sanders: "ElectricalPower Systems: the NEC and the IEC Approach" 1996IEEE-IAS I&CPS Technical Conference New OrleansMay 5-7.

[I61 G. Parise, S. Annibaldi, L. Martirano Safe O peration ofElectrical Installations In EU, I&CPS ConferenceCleatwater, Florida 2000

IX. VITAGeorge D. Gregory has been an IEEE member since 1970.He earned the BSEE and MSEE degrees from the Ill inoisInstitute of Technology, Chicago. He is presently Manager,Industry Standards with Square D Company, Cedar Rapids,Iowa, USA with primary responsibilities in low-voltageovercurrent protective devices. Mr. Gregory is active in theIndustry Applications and Power System EngineeringSocieties of IEEE. He is Chair of the IAS Power SystemsProtection Committee, Chair of the Blue Book WorkingGroup, and a contributor o the Battery Systems ProtectionWorking Group. He is Chair of the NEMA Circuit BreakerSection, USA Deputy Technical Advisor to the IEC 176Subcommittee and a member of NEC Code Panel 10(representing NEMA). He is a registered ProfessionalEngineer in Illinois, Iowa and Puerto Rico.Joseph H. Kuczka graduated rom Washington UniversitySt.Louis in 1975 with a BSEE degree. He is Technical andIndustry Standards Manager for Ki llark of St. Louis, where hehas been employed since 1964. He is a member ofnumerous national and internationalstandards writingorganizations including IEEE, ISA, UL, NEMA, NFPA, CSAand IEC. He has co-authoredsix PClC papers.Giuseppe Parise has been an IEEE member since 1982. In1972 he received his degree in Electrical Engineering fromthe University of Rome. He has been at the university eversince and is currently an Associate Professor of Electr icalPower Systems. His research and consulting activities coverpower systems design, planning, safety, security, and energymanagement. Since 1983, he has been a member of SuperiorCouncil of Ministry of Public Works as expert of powersystems. He is member of the Italian Electr ical Commission(CEI) CT/SC 11A "Generation, transmission and distributionsystems of electric power" and of the IEEE\IAS PowerSystems Grounding Subcommittee.Melvin K. Sanders is President of TECo., Inc., a Codes andStandards Electrical Consulting and Education Corporationand licensed contractor Des Moines, Iowa. Retired after 24-1/2 years at John Deere Des Moines, he presents electricaleducation programs and is a contract Electrical nspector forPolk County, Iowa, graduate of Des Moines Area CommunityCollege with an Applied Sciences Associate Degree, and

NCCER instructor certified or Electr ical Apprenticeshiptraining. He is also a member of IAEI, NFPA, SAE and is anICBO Certified Electr ical nspector. He serves as an alternatemember of NEC CMP 3 for IEEE, a member of NFPA 708and NFPA 79, a member of four IEEE color book committees,and a member of the SAE HS 1738 Committee.Craig M.Wellman graduated from the University of Delawarein 1966 with a BEE degree. He has been a project engineerand consultant for the DuPont Company in WilmingtonDelaware since 1973. He is a senior member of IEEE, thesecretary of the Codes and Regulations Subcommittee of thePClC Standards committee, an author of three previous PClCpapers, and a presenter of two tutorials. He is a member ofthe NEC Technical Correlating Committee and a member ofthe CMA ElectricalCodes and Standards Task Group. He i s aregistered professionalengineer in the state of Delaware.

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