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Enclosure Standards
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  Industry standards for electrical enclosures exist to promote safety, encouragedesign efficiency and define minimum levels of product performance. In theEuropean and North American electrical industries, several standards areenforced for these reasons. Across the global marketplace, these or other standards may be followed or there may be no standards at all, which canlead to wide variations in product performance and price. In many cases, theend customer is not aware of the standards or does not clearly understand them and, therefore, does not insist that suppliers provide products that meet the standards. Focusing solely on low price without fully understanding or requiring industry standards can yield a low initial product cost, but could ultimately lead to high maintenance expenses, component failure and in theworst case, worker safety issues.   The pupose of this pape is to: 1. Clearly define the industry standards that exist for electrical enclosures2. Compare the most commonly used standards so enclosure users can understandthe key differences3. Equip decision makers with the knowledge needed to select an electricalenclosure that has the appropriate rating and price to value relationship for itsintended application 1.0 Stanas Oveview Globally, IEC, NEMA and UL are the three most commonly recognized standards organizations. Intenational Electotechnical Commission (IEC) Stana 60529 The IEC is the world’s leading organization that prepares and publishes International Standards for all electrical, electronic and related technologies — collectively known as electrotechnology. IEC 60529 includes a list of codes, called Characteristic Numerals, that are used to identifyingress protection levels. Commonly referred to as the IP rating, these codes reflect anelectrical enclosure’s ability to protect against access to electrified parts by people, tools,moisture, dust or dirt. National Electical Manufactue’s Association (NEMA) Stana 250 NEMA promotes the competitiveness of the US electrical product industry through thedevelopment of standards, advocacy in federal and state legislatures and executive agencies, and the collection and analysis of economic data. Similar to IEC 60529, NEMA 250 covers enclosures for electrical equipment. Like IEC 60529,NEMA 250 addresses ingress protection, but it differs in that it also addresses specificationsdetailing minimum construction, performance and test criteria, corrosion resistance andmore. Although its beginnings are based in the United States, NEMA is a global organizationthat is working to promote electrical standards worldwide. GLOBAL ENCLOSURE STANDARDSWITHIN THE ELECTRICAL INDUSTRY For more information onthis standard, visit IEC’sWeb site at: www.iec.chThe three most globallyrecognized standardsfor enclosures are:IEC 60529;UL 50, 50ENEMA 250For more information onthis standard, visit NEMA’sWeb site at: www.nema.org  Unewite Laboatoies® (UL) 50, 50E Underwriters Laboratories® is an independent product safety certification organization that hasbeen testing products and writing safety standards for more than a century. UL evaluates morethan 19,000 types of products, components, materials and systems annually, with 21 billion ULMarks appearing on 72,000 manufacturers’ products each year. UL 50, 50E is based on NEMA 250 standards. While they address many of the same points,NEMA simply indicates the design intent but does not mandate compliance via third partytesting and on-site compliance visits. A product can be built to NEMA standards but actualperformance compliance is at the discretion of the manufacturer. UL certification, however,is formal confirmation that required construction and performance are met after analysesand testing is completed. In summary, both NEMA and UL define standards, but only ULenforces compliance to their standards with third-party testing and inspection. Main Points Aesse by the Stanas  To standardize enclosure performance, organizations including IEC, NEMA and UL offer ratingsystems to identify an enclosure’s capacity to withstand environmental influences—fromdripping liquid to dust infiltration to complete submersion. The goal of all three organizations’ratings is to assist end-users in making an appropriate, informed enclosure selection that meetstheir application-specific requirements.Electrical enclosures are rated by Type (NEMA and UL) and/or IP rating (IEC) according to thedegree of protection provided. Both Type and IP ratings cover: ã Thedegreeofhumanprotectionfromhazardouscomponentsinsidetheenclosureã Thedegreeofprotectionforequipmentinsidetheenclosurefromingressofsolid foreign objects, including dust ã Thedegreeofprotectionforequipmentinsidetheenclosurefromingressofwater  These three primary standards have similarities and differences in their performance criteria,influence on an enclosure’s design elements, testing requirements and enforcementmethods. The table below indicates the main points addressed by each of the standards. Allthree address ingress protection, however NEMA 250 and UL 50, 50E also define minimumenclosure design requirements. These requirements are detailed in section 3.0.  Table 1:   Main Points Addressed by IEC 60529, NEMA 250 and UL 50, 50E standards StandardMain Points AddressedIEC 60529 ãLevelofingressprotection NEMA 250 ãLevelofingressprotectionãMinimumenclosuredesignrequirements UL 50, 50E ãLevelofingressprotectionãMinimumenclosuredesignrequirements GLOBAL ENCLOSURE STANDARDSWITHIN THE ELECTRICAL INDUSTRY For more information on thisstandard, visit UL’s Web site at:www.ul.com/global/eng/pages2  2.0 Ingess Potection While all three standards address ingress protection, they do not define it in the same way. Table 2 below lists the enclosure ratings for the various Types, as defined by UL 50, 50E andNEMA 250. Table 3 lists the enclosure IP ratings, as defined by IEC 60529.  Table 2:   Enclosure Type ratings as defined by UL 50, 50E and NEMA 250 GLOBAL ENCLOSURE STANDARDSWITHIN THE ELECTRICAL INDUSTRY Enclosue Types NEMA Enclosure UL SolidsLiquidsRatingSolidsLiquids     I    N    d    O    O    r Provides a degree of protectionagainst access to hazardous partsand ingress of solid foreign objects(falling dirt)No protection Type 1 Provides a degree of protection against incidentalcontact and falling dirtNo protectionProvides a degree of protectionagainst access to hazardous partsand ingress of solid foreign objects(falling dirt)Provides a degree of protectionagainst ingress of water (drippingand light splashing) Type 2 Provides a degree of protection against incidentalcontact and falling dirtProvides a degree of protectionagainst dripping and light splashing of non-corrosive liquidsProvides a degree of protectionagainst access to hazardous partsand ingress of solid foreign objects(falling dirt and settling airbornedust, lint, fibers and flyings)Provides a degree of protectionagainst ingress of water (drippingand light splashing) Type 5 Provides a degree of protection against incidentalcontact and falling dirt,settling airborne dust, lint,fibers and flyingsProvides a degree of protectionagainst dripping and light splashing of non-corrosive liquidsProvides a degree of protectionagainst access to hazardous partsand ingress of solid foreign objects(falling dirt and circulating dust,lint, fibers and flyings)Provides a degree of protectionagainst ingress of water (drippingand light splashing) and lightsplashing and seepage of oil andnon-corrosive coolants Type 12 Provides a degree of protection against incidentalcontact and falling dirt,circulating dust, lint, fibersand flyingsProvides a degree of protectionagainst dripping and light splashing of non-corrosive liquids; and against lightsplashing and consequent seepage of oil and non-corrosive coolantsProvides a degree of protectionagainst access to hazardous partsand ingress of solid foreign objects(falling dirt and circulating dust,lint, fibers and flyings)Provides a degree of protectionagainst ingress of water (drippingand light splashing) and spraying,splashing, and seepage of oil andnon-corrosive coolants Type 13 Provides a degree of protection against incidentalcontact and falling dirt,circulating dust, lint, fibersand flyingsProvides a degree of protection againstspraying, splashing, and seepage of water, oil, and non-corrosive coolants     I    N    d    O    O    r    &    O    U    T    d    O    O    r Provides a degree of protectionagainst access to hazardous partsand ingress of solid foreign objects(falling dirt and windblown dust)Provides a degree of protectionagainst ingress of water(windblown rain, sleet, snow) Type 3 Provides a degree of protection against incidentalcontact, falling dirt andwindblown dustProvides a degree of protectionagainst rain, sleet and snowProvides a degree of protectionagainst access to hazardous partsand ingress of solid foreign objects(falling dirt)Provides a degree of protectionagainst ingress of water (fallingrain, sleet, snow) Type 3R Provides a degree of protection against incidentalcontact and falling dirtProvides a degree of protectionagainst rain, sleet and snowProvides a degree of protectionagainst access to hazardous partsand ingress of solid foreign objects(falling dirt and windblown dust)Provides a degree of protectionagainst ingress of water (rain, sleet,snow, splashing water andhose-directed water) Type 4 Provides a degree of protection against incidentalcontact, falling dirt andwindblown dustProvides a degree of protectionagainst rain, sleet, snow, splashingwater and hose-directed waterProvides a degree of protectionagainst access to hazardous partsand ingress of solid foreign objects(falling dirt and windblown dust)Provides a degree of protectionagainst ingress of water (rain, sleet,snow, splashing water andhose-directed water) and providesan increased level of protectionagainst corrosion Type 4X Provides a degree of protection against incidentalcontact, falling dirt andwindblown dustProvides a degree of protectionagainst rain, sleet, snow, splashingwater, hose-directed water andcorrosionProvides a degree of protectionagainst access to hazardous partsand ingress of solid foreign objects(falling dirt)Provides a degree of protectionagainst ingress of water (hosedirected and occasional temporarysubmersion at a limited depth) Type 6 Provides a degree of protection against incidentalcontact and falling dirtProvides a degree of protectionagainst rain, sleet, snow, hose-directedwater and occasional temporarysubmersion at a limited depthProvides a degree of protectionagainst access to hazardous partsand ingress of solid foreign objects(falling dirt)Provides a degree of protectionagainst ingress of water (hosedirected and prolongedsubmersion at a limited depth) Type 6P Provides a degree of protection against incidentalcontact and falling dirtProvides a degree of protectionagainst rain, sleet, snow, hose-directedwater and prolonged submersion at alimited depth 3    Table 3:   Enclosure IP ratings as defined by IEC 60529 While UL Type ratings are based on and, therefore, very similar to NEMA Type ratings, theyare quite different from the IEC IP ratings and thus, cannot be compared or equated. Thedifference between the UL and IEC standards is primarily the type of testing required andthe pass/fail criteria for each. For example, in some markets UL Type 12 is often equated toIP55. However, the UL and NEMA Type 12 rating is more stringent in that no dust or liquidis allowed during testing, while the IP55 rating allows some dust and liquid to enter theenclosure, as long as deposits are not harmful. Table 4 defines the testing requirements andpass/fail criteria for UL and NEMA ratings. Tables 5 and 6 define the testing requirements andpass/fail criteria for IP ratings. GLOBAL ENCLOSURE STANDARDSWITHIN THE ELECTRICAL INDUSTRY Enclosue IP ratings Fist NumealSecon Numeal IPTestIPTest0 No protection 0 No protection 1 Protected against solid objects up to50 mm, e.g. accidental touch byhands 1 Protected against vertically fallingdrops of water, e.g. condensation 2 Protected against solid objects up to12 mm, e.g. fingers 2 Protected against direct sprays of water up to 15˚ from vertical 3 Protected against solid objects over2.5 mm, e.g. tools and wires 3 Protected against sprays to 60˚ fromvertical 4 Protected against solid objectsover 1 mm 4 Protected against water sprayed fromall directions (limited ingresspermitted) 5 Protected against dust (limitedingress, no harmful deposit) 5 Protected against low pressure jets of water from all directions (limitedingress permitted) 6  Totally protected against dust 6 Protected against strong jets of water 7 Protected against the effects of immersion between 15 cm and 1 m UL/NEMA Type ratings andIEC IP ratings are quitedifferent in their definitions,testing methods andpass/fail criteria.UL 50, 50E Listed hinged-door enclosures aresuitable for use as UL 508AIndustrial Control PanelEnclosures.UL 50, 50E Listed screw orclamp cover enclosures aresuitable for use as UL 508AIndustrial Control PanelEnclosures, if the devicesinside the enclosure do notrequire resetting or regularmaintenance. (Ref. Table SA1.1 Section 18, UL 508A) 4
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