249OccupationalSafetyandHealthAdmin.,Labor§1926.352shallhaveasafecurrentcarryingca-pacityequaltoorexceedingthespeci-fiedmaximumoutputcapacityofthearcweldingorcuttingunitwhichitservices.Whenasinglegroundreturncableservicesmorethanoneunit,itssafecurrent-carryingcapacityshallequalorexceedthetotalspecifiedmaximumoutputcapacitiesofalltheunitswhichitservices.(2)Pipelinescontaininggasesorflammableliquids,orconduitscon-tainingelectricalcircuits,shallnotbeusedasagroundreturn.Forweldingonnaturalgaspipelines,thetechnicalportionsofregulationsissuedbytheDepartmentofTransportation,OfficeofPipelineSafety,49CFRpart192,MinimumFederalSafetyStandardsforGasPipelines,shallapply.(3)Whenastructureorpipelineisemployedasagroundreturncircuit,itshallbedeterminedthattherequiredelectricalcontactexistsatalljoints.Thegenerationofanarc,sparks,orheatatanypointshallcauserejectionofthestructuresasagroundcircuit.(4)Whenastructureorpipelineiscontinuouslyemployedasagroundre-turncircuit,alljointsshallbebonded,andperiodicinspectionsshallbecon-ductedtoensurethatnoconditionofelectrolysisorfirehazardexistsbyvir-tueofsuchuse.(5)Theframesofallarcweldingandcuttingmachinesshallbegroundedei-therthroughathirdwireinthecablecontainingthecircuitconductororthroughaseparatewirewhichisgroundedatthesourceofthecurrent.Groundingcircuits,otherthanbymeansofthestructure,shallbecheckedtoensurethatthecircuitbe-tweenthegroundandthegroundedpowerconductorhasresistancelowenoughtopermitsufficientcurrenttoflowtocausethefuseorcircuitbreak-ertointerruptthecurrent.(6)Allgroundconnectionsshallbeinspectedtoensurethattheyareme-chanicallystrongandelectricallyade-quatefortherequiredcurrent.(d)Operatinginstructions.Employersshallinstructemployeesinthesafemeansofarcweldingandcuttingasfollows:(1)Whenelectrodeholdersaretobeleftunattended,theelectrodesshallberemovedandtheholdersshallbesoplacedorprotectedthattheycannotmakeelectricalcontactwithemploy-eesorconductingobjects.(2)Hotelectrodeholdersshallnotbedippedinwater;todosomayexposethearcwelderorcuttertoelectricshock.(3)Whenthearcwelderorcutterhasoccasiontoleavehisworkortostopworkforanyappreciablelengthoftime,orwhenthearcweldingorcut-tingmachineistobemoved,thepowersupplyswitchtotheequipmentshallbeopened.(4)Anyfaultyordefectiveequipmentshallbereportedtothesupervisor.(5)See§1926.406(c)foradditionalre-quirements.(e)Shielding.Wheneverpracticable,allarcweldingandcuttingoperationsshallbeshieldedbynoncombustibleorflameproofscreenswhichwillprotectemployeesandotherpersonsworkinginthevicinityfromthedirectraysofthearc.[44FR8577,Feb.9,1979;44FR20940,Apr.6,1979,asamendedat51FR25318,July11,1986]§1926.352Fireprevention.(a)Whenpractical,objectstobewelded,cut,orheatedshallbemovedtoadesignatedsafelocationor,iftheobjectstobewelded,cut,orheatedcannotbereadilymoved,allmovablefirehazardsinthevicinityshallbetakentoasafeplace,orotherwisepro-tected.(b)Iftheobjecttobewelded,cut,orheatedcannotbemovedandifallthefirehazardscannotberemoved,posi-tivemeansshallbetakentoconfinetheheat,sparks,andslag,andtopro-tecttheimmovablefirehazardsfromthem.(c)Nowelding,cutting,orheatingshallbedonewheretheapplicationofflammablepaints,orthepresenceofotherflammablecompounds,orheavydustconcentrationscreatesahazard.(d)Suitablefireextinguishingequip-mentshallbeimmediatelyavailableintheworkareaandshallbemaintainedinastateofreadinessforinstantuse.(e)W...
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