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1、UL50ISBN1-55989-909-3--```````,`,````,,,,,``````,``-`-`,,`,,`,`,,`---EnclosuresforElectricalEquipmentCopyrightUnderwritersLaboratoriesInc.DocumentprovidedbyIHSLicensee=HongKongPolytechnicUniv/9976803100,ProvidedbyIHSunderlicensewithUL09/23/200400:23:21MDTQuestionsorcommentsaboutthis
2、message:pleasecalltheDocumentPolicyGroupat303-397-2295.--```````,`,````,,,,,``````,``-`-`,,`,,`,`,,`---CopyrightUnderwritersLaboratoriesInc.DocumentprovidedbyIHSLicensee=HongKongPolytechnicUniv/9976803100,ProvidedbyIHSunderlicensewithUL09/23/200400:23:21MDTQuestionsorcommentsaboutth
3、ismessage:pleasecalltheDocumentPolicyGroupat303-397-2295.SEPTEMBER12,2003−UL50tr1UnderwritersLaboratoriesInc.(UL)333PfingstenRoadNorthbrook,IL60062-2096ULStandardforSafetyforEnclosuresforElectricalEquipment,UL50EleventhEdition,DatedOctober19,1995Revisions:ThisStandardcontainsrevision
4、sthroughandincludingSeptember12,2003.SummaryofTopicsThisrevisiontoANSI/UL50isbeingissuedtoupdatetheTitlePagetoindicateapprovalasanAmericanNationalStandard.ULStandardsforSafetyaredevelopedandmaintainedintheStandardGeneralizedMarkupLanguage(SGML).SGML--aninternationalstandard(ISO8879-
5、1986)--isadescriptivemarkuplanguagethatdescribesadocument’sstructureandpurpose,ratherthanitsphysicalappearanceonapage.DuetoformattingdifferencesresultingfromtheuseofUL’snewelectronicpublishingsystem,pleasenotethatadditionalpages(onwhichnorequirementshavebeenchanged)maybeincludedinre
6、visionpagesduetorelocationofexistingtextandreformattingoftheStandard.Textthathasbeenchangedinanymannerismarkedwithaverticallineinthemargin.Changesinrequirementsaremarkedwithaverticallineinthemarginandarefollowedbyaneffectivedatenoteindicatingthedateofpublicationorthedateonwhichthech
7、angedrequirementbecomeseffective.TherevisedrequirementsaresubstantiallyinaccordancewithUL’sBulletin(s)onthissubjectdatedFebruary13,2003andJuly8,2003.Thebulletin(s)isnowobsoleteandmaybediscarded.TherevisionsdatedSeptember12,2003includeareprintedtitlepage(page1)forthisStandard.Asindic
8、atedonthetitlepa