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InternationalTelecommunicationUnionITU-TK.21TELECOMMUNICATIONSTANDARDIZATIONSECTOROFITU(04/2008)SERIESK:PROTECTIONAGAINSTINTERFERENCEResistibilityoftelecommunicationequipmentinstalledincustomerpremisestoovervoltagesandovercurrentsRecommendationITU-TK.21Rec.ITU-TK.21(04/2008)iRecommendationITU-TK.21ResistibilityoftelecommunicationequipmentinstalledincustomerpremisestoovervoltagesandovercurrentsSummaryRecommendationITU-TK.21specifiesresistibilityrequirementsandtestproceduresfortelecommunicationequipmentthatisinstalledinoronacustomerpremisesbuilding.OvervoltagesorovercurrentscoveredbythisRecommendationincludesurgesduetolightningonornearthelineplant,short-terminductionfromadjacenta.c.powerlinesorrailwaysystems,earthpotentialriseduetopowerfaults,directcontactsbetweentelecommunicationlinesandpowerlinesandelectrostaticdischarges.Thesourcesforovervoltagesininternallinesaremainlyinductivecouplingcausedbylightningcurrentsbeingconductedinnearbylightningstrokesorlightningcurrentsbeingconductedinnearbyconductors.Majorchangescomparedwiththe2003versionofthisRecommendationinclude:•removingthepowerinductiontestrequirementforantennaportswheretheinstallationiswithinthescopeofRecommendationITU-TK.71;•clearerdefinitionofwhentheinternalandexternalportclassificationappliestoantennaports.SourceRecommendationITU-TK.21wasapprovedon13April2008byITU-TStudyGroup5(2005-2008)underRecommendationITU-TA.8procedure.iiRec.ITU-TK.21(04/2008)FOREWORDTheInternationalTelecommunicationUnion(ITU)istheUnitedNationsspecializedagencyinthefieldoftelecommunications,informationandcommunicationtechnologies(ICTs).TheITUTelecommunicationStandardizationSector(ITU-T)isapermanentorganofITU.ITU-Tisresponsibleforstudyingtechnical,operatingandtariffquestionsandissuingRecommendationsonthemwithaviewtostandardizingtelecommunicationsonaworldwidebasis.TheWorldTelecommunicationStandardizationAssembly(WTSA),whichmeetseveryfouryears,establishesthetopicsforstudybytheITU-Tstudygroupswhich,inturn,produceRecommendationsonthesetopics.TheapprovalofITU-TRecommendationsiscoveredbytheprocedurelaiddowninWTSAResolution1.InsomeareasofinformationtechnologywhichfallwithinITU-T'spurview,thenecessarystandardsarepreparedonacollaborativebasiswithISOandIEC.NOTEInthisRecommendation,theexpressionAdministrationisusedforconcisenesstoindicatebothatelecommunicationadministrationandarecognizedoperatingagency.CompliancewiththisRecommendationisvoluntary.However,theRecommendationmaycontaincertainmandatoryprovisions(toensuree.g.interoperabilityorapplicability)andcompliancewiththeRecommendationisachievedwhenallofthesemandatoryprovisionsaremet.Thewordsshallorsomeotherobligatorylanguagesuchasmustandthenegativeequivalentsareusedtoexpressrequirements.TheuseofsuchwordsdoesnotsuggestthatcompliancewiththeRecommendationisrequiredofanyparty.INTELLECTUALPROPERTYRIGHTSITUdrawsattentiontothepossibilitythatthepracticeorimplementationofthisRecommendationmayinvolvetheuseofaclaimedIntellectualPropertyRight.ITUtakesnopositionconcerningtheevidence,validityorapplicabilityofclaimedIntellectualPropertyRights,whetherassertedbyITUmembersorothersoutsideoftheRecommendationdevelopmentprocess.AsofthedateofapprovalofthisRecommendation,ITUhadnotreceivednoticeofintellectualproperty,protectedbypatents,whichmayberequiredtoimplementthisRecommendation.However,implementersarecautionedthatthismaynotrepresentthelatestinformationandarethereforestronglyurgedtoconsulttheTSBpatentdatabaseat©ITU2009Allrightsreserved.Nopartofthispublicationmaybereproduced,byanymeanswhatsoever,withoutthepriorwrittenpermissionofITU.Rec.ITU-TK.21(04/2008)iiiCONTENTSPage1Scope............................................................................................................................12References.....................................................................................................................13Definitionsandabbreviations.......................................................................................13.1Definitions......................................................................................................14Tests..............................................................................................................................1Bibliography.............................................................................................................................18Rec.ITU-TK.21(04/2008)1RecommendationITU-TK.21Resistibilityoftelecommunicationequipmentinstalledincustomerpremisestoovervoltagesandovercurrents1ScopeThisRecommendationspecifiesresistibilityrequirementsandtestproceduresfortelecommunicationequipmentwhichisattachedtoorinstalledwithinacustomerpremisesbuilding.TherequirementsofthisRecommendationassumethatearthingandbondingisinaccordancewith[ITU-TK.66].ThetypesofequipmentcoveredbythisRecommendationincludesalltypesoftelecommunicationequipment,e.g.,modems,telephones,routers,XDSL,etc.ThisRecommendationisnotmeanttoapplytoPCsandprinters,etc.ThisRecommendationappliestobothexternal