UL502003EnclosuresforElectricalEquipment

UL50ISBN1-55989-909-3EnclosuresforElectricalEquipment(UL)333PfingstenRoadNorthbrook,IL60062-2096ULStandardforSafetyforEnclosuresforElectricalEquipment,UL50EleventhEdition,DatedOctober19,1995Revisions:ThisStandardcontainsrevisionsthroughandincludingSeptember12,2003.SummaryofTopicsThisrevisiontoANSI/UL50isbeingissuedtoupdatetheTitlePagetoindicateapprovalasanAmericanNationalStandard.ULStandardsforSafetyaredevelopedandmaintainedintheStandardGeneralizedMarkupLanguage(SGML).SGML--aninternationalstandard(ISO8879-1986)--isadescriptivemarkuplanguagethatdescribesadocument’sstructureandpurpose,ratherthanitsphysicalappearanceonapage.DuetoformattingdifferencesresultingfromtheuseofUL’snewelectronicpublishingsystem,pleasenotethatadditionalpages(onwhichnorequirementshavebeenchanged)maybeincludedinrevisionpagesduetorelocationofexistingtextandreformattingoftheStandard.Textthathasbeenchangedinanymannerismarkedwithaverticallineinthemargin.Changesinrequirementsaremarkedwithaverticallineinthemarginandarefollowedbyaneffectivedatenoteindicatingthedateofpublicationorthedateonwhichthechangedrequirementbecomeseffective.TherevisedrequirementsaresubstantiallyinaccordancewithUL’sBulletin(s)onthissubjectdatedFebruary13,2003andJuly8,2003.Thebulletin(s)isnowobsoleteandmaybediscarded.TherevisionsdatedSeptember12,2003includeareprintedtitlepage(page1)forthisStandard.Asindicatedonthetitlepage(page1),thisULStandardforSafetyisanAmericanNationalStandard.AttentionisdirectedtothenoteonthetitlepageofthisStandardoutliningtheprocedurestobefollowedtoretaintheapprovedtextofthisANSI/ULStandard.Asindicatedonthetitlepage(page1),thisULStandardforSafetyhasbeenadoptedbytheDepartmentofDefense.ThemasterforthisStandardatUL’sNorthbrookOfficeistheofficialdocumentinsofarasitrelatestoaULserviceandthecomplianceofaproductwithrespecttotherequirementsforthatproductandservice,oriftherearequestionsregardingtheaccuracyofthisStandard.UL’sStandardsforSafetyarecopyrightedbyUL.NeitheraprintedcopyofaStandard,northedistributiondisketteforaStandard-on-DisketteandthefilefortheStandardonthedistributiondisketteshouldbealteredinanyway.AllofUL’sStandardsandallcopyrights,ownerships,andrightsregardingthoseStandardsshallremainthesoleandexclusivepropertyofUL.Allrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystem,ortransmittedinanyformbyanymeans,electronic,mechanicalphotocopying,recording,orotherwisewithoutpriorpermissionofUL.RevisionsofULStandardsforSafetyareissuedfromtimetotime.AULStandardforSafetyiscurrentonlyifitincorporatesthemostrecentlyadoptedrevisions.SEPTEMBER12,2003−UL50tr1″asis″withoutwarrantyofanykind,eitherexpressedorimplied,includingbutnotlimitedto,theimpliedwarrantiesofmerchantabilityorfitnessforanypurpose.InnoeventwillULbeliableforanyspecial,incidental,consequential,indirectorsimilardamages,includinglossofprofits,lostsavings,lossofdata,oranyotherdamagesarisingoutoftheuseofortheinabilitytousethisStandard,evenifULoranauthorizedULrepresentativehasbeenadvisedofthepossibilityofsuchdamage.InnoeventshallUL’sliabilityforanydamageeverexceedthepricepaidforthisStandard,regardlessoftheformoftheclaim.ULwillattempttoanswersupportrequestsconcerningelectronicversionsofitsStandards.However,thissupportserviceisofferedonareasonableeffortsbasisonly,andULmaynotbeabletoresolveeverysupportrequest.ULsupportstheelectronicversionsofitsStandardsonlyiftheyareusedundertheconditionsandoperatingsystemsforwhichitisintended.UL’ssupportpoliciesmaychangefromtime-to-timewithoutnotification.ULreservestherighttochangetheformat,presentation,filetypesandformats,deliverymethodsandformats,andthelikeofbothitsprintedandelectronicStandardswithoutpriornotice.PurchasersoftheelectronicversionsofUL’sStandardsforSafetyagreetodefend,indemnify,andholdULharmlessfromandagainstanyloss,expense,liability,damage,claim,orjudgement(includingreasonableattorney’sfees)resultingfromanyerrorordeviationintroducedwhilepurchaserisstoringanelectronicStandardonthepurchaser’scomputersystem.Ifasingle-userversionelectronicStandardwaspurchased,onecopyofthisStandardmaybestoredontheharddiskofasinglepersonalcomputer,oronasingleLANfile-serverorthepermanentstoragedeviceofamultiple-usercomputerinsuchamannerthatthisStandardmayonlybeaccessedbyoneuseratatimeandforwhichthereisnopossibilityofmultipleconcurrentaccess.Ifamultiple-userversionelectronicStandardwaspurchased,onecopyoftheStandardmaybestoredonasingleLANfile-server,oronthepermanentstoragedeviceofamultiple-usercomputer,oronanIntranetserver.Thenumberofconcurrentusersshallnotexceedthenumberofusersauthorized.ElectronicStandardsareintendedforon-lineuse,suchasforviewingtherequirementsofaStandard,conductingawordsearch,andthelike.OnlyonecopyoftheStandardmaybeprintedfromeachsingle-userversionofanelectronicStandard.OnlyonecopyoftheStandardmaybeprintedforeachauthorizeduserofamultiple-userversionofanelectronicStandard.Becauseofdifferencesinthecomputer/software/printersetupusedbyULandthoseofelectronicStand