osha教材-electrical-电气安全

OSHAOfficeofTraining&Education1ElectricalSafety-ConstructionOSHAOfficeofTraining&Education2Electricity-TheDangers•About5workersareelectrocutedeveryweek•Causes12%ofyoungworkerworkplacedeaths•Takesverylittleelectricitytocauseharm•SignificantriskofcausingfiresOSHAOfficeofTraining&Education3Electricity–HowitWorks•Electricityistheflowofenergyfromoneplacetoanother•Requiresasourceofpower:usuallyageneratingstation•Aflowofelectrons(current)travelsthroughaconductor•TravelsinaclosedcircuitOSHAOfficeofTraining&Education4ElectricalTerms•Current--electricalmovement(measuredinamps)•Circuit--completepathofthecurrent.Includeselectricitysource,aconductor,andtheoutputdeviceorload(suchasalamp,tool,orheater)•Resistance--restrictiontoelectricalflow•Conductors–substances,likemetals,withlittleresistancetoelectricitythatallowelectricitytoflow•Grounding–aconductiveconnectiontotheearthwhichactsasaprotectivemeasure•Insulators--substanceswithhighresistancetoelectricitylikeglass,porcelain,plastic,anddrywoodthatpreventelectricityfromgettingtounwantedareasOSHAOfficeofTraining&Education5ElectricalInjuriesTherearefourmaintypesofelectricalinjuries:•Direct:ElectrocutionordeathduetoelectricalshockElectricalshockBurns•Indirect-FallsOSHAOfficeofTraining&Education6ElectricalShockAnelectricalshockisreceivedwhenelectricalcurrentpassesthroughthebody.Youwillgetanelectricalshockifapartofyourbodycompletesanelectricalcircuitby…•Touchingalivewireandanelectricalground,or•Touchingalivewireandanotherwireatadifferentvoltage.OSHAOfficeofTraining&Education7ShockSeverity•Severityoftheshockdependson:PathofcurrentthroughthebodyAmountofcurrentflowingthroughthebody(amps)Durationoftheshockingcurrentthroughthebody,•LOWVOLTAGEDOESNOTMEANLOWHAZARDOSHAOfficeofTraining&Education8DangersofElectricalShock•Currentsabove10mA*canparalyzeor“freeze”muscles.•Currentsmorethan75mAcancausearapid,ineffectiveheartbeat--deathwilloccurinafewminutesunlessadefibrillatorisused•75mAisnotmuchcurrent–asmallpowerdrilluses30timesasmuch*mA=milliampere=1/1,000ofanampereDefibrillatorinuseOSHAOfficeofTraining&Education9Burns•Mostcommonshock-relatedinjury•Occurswhenyoutouchelectricalwiringorequipmentthatisimproperlyusedormaintained•Typicallyoccursonhands•VeryseriousinjurythatneedsimmediateattentionOSHAOfficeofTraining&Education10Falls•Electricshockcanalsocauseindirectinjuries•Workersinelevatedlocationswhoexperienceashockmayfall,resultinginseriousinjuryordeathOSHAOfficeofTraining&Education11ElectricalHazardsandHowtoControlThemElectricalaccidentsarecausedbyacombinationofthreefactors:Unsafeequipmentand/orinstallation,Workplacesmadeunsafebytheenvironment,andUnsafeworkpractices.OSHAOfficeofTraining&Education12Hazard–ExposedElectricalPartsCoverremovedfromwiringorbreakerboxOSHAOfficeofTraining&Education13Control–IsolateElectricalParts•Useguardsorbarriers•ReplacecoversGuardlivepartsofelectricequipmentoperatingat50voltsormoreagainstaccidentalcontactOSHAOfficeofTraining&Education14Control–IsolateElectricalParts-Cabinets,Boxes&FittingsConductorsgoingintothemmustbeprotected,andunusedopeningsmustbeclosedOSHAOfficeofTraining&Education15Control–CloseOpenings•Junctionboxes,pullboxesandfittingsmusthaveapprovedcovers•Unusedopeningsincabinets,boxesandfittingsmustbeclosed(nomissingknockouts)PhotoshowsviolationsofthesetworequirementsOSHAOfficeofTraining&Education16Hazard-OverheadPowerLines•Usuallynotinsulated•Examplesofequipmentthatcancontactpowerlines:CraneLadderScaffoldBackhoeScissorsliftRaiseddumptruckbedAluminumpaintrollerOSHAOfficeofTraining&Education17Control-OverheadPowerLines•Stayatleast10feetaway•Postwarningsigns•Assumethatlinesareenergized•Usewoodorfiberglassladders,notmetal•Powerlineworkersneedspecialtraining&PPEOSHAOfficeofTraining&Education18Hazard-InadequateWiring•Hazard-wiretoosmallforthecurrent•Example-portabletoolwithanextensioncordthathasawiretoosmallforthetoolThetoolwilldrawmorecurrentthanthecordcanhandle,causingoverheatingandapossiblefirewithouttrippingthecircuitbreakerThecircuitbreakercouldbetherightsizeforthecircuitbutnotforthesmaller-wireextensioncordWireGaugeWIREWiregaugemeasureswiresranginginsizefromnumber36to0Americanwiregauge(AWG)OSHAOfficeofTraining&Education19Control–UsetheCorrectWire•Wireuseddependsonoperation,buildingmaterials,electricalload,andenvironmentalfactors•Usefixedcordsratherthanflexiblecords•UsethecorrectextensioncordMustbe3-wiretypeanddesignedforhardorextra-harduseOSHAOfficeofTraining&Education20Hazard–DefectiveCords&Wires•Plasticorrubbercoveringismissing•Damagedextensioncords&toolsOSHAOfficeofTraining&Education21Hazard–DamagedCords•Cordscanbedamagedby:AgingDoororwindowedgesStaplesorfasteningsAbrasionfromadjacentmaterialsActivityinthearea•Improperusecancauseshocks,burnsorfireOSHAOfficeofTraining&Education22Control–Cords&Wires•Insulatelivewires•Checkbeforeuse•Useonlycordsthatare3-wiretype•Useonlycordsmarkedforhardorextra-hardusage•Useonlycords,connectiondevices,andfittingsequippedwithstrainrelief•Removecordsbypullingontheplugs,notthecords•Cordsnotmarkedfor