What Is a Short Circuit, and What Causes One? - The Spruce

A short circuit is an abnormal condition in an electrical circuit where the electrical current flows through an unintended, shorter pathway ... DorlingKindersley/GettyImages Electricitypowersnearlyeverythinginourhomes,andit'sabeneficialforcewhenhandledproperly.Butwhenelectricitygoeswayward,it'sadamaging,dangerous,andfrighteningeventcalledashortcircuit.Shortcircuitscanbepreventedandmanagedwithplanningandahealthyrespectforelectricity. WhatIsanElectricalShortCircuit? Ashortcircuitisanabnormalconditioninanelectricalcircuitwheretheelectricalcurrentflowsthroughanunintended,shorterpathwayinsteadoffollowingthecircuit. Anelectricalcircuitisacircularflowofenergyfromahome'selectricalservicepanelandbackagain.Thisflowiscontinuousandunbroken.Itemsalongthecircuitsuchasoutletsandlightsonlyborrowfromthecircuit;theydonotbreakthecircuit. Electricitylikestoflowalongthepathofleastresistance.Copperisusedforelectricalwiresbecauseitconductssowell,whilematerialslikewoodorfiberwouldbehighlyinefficientmaterialsforwiringbecausetheyresistelectricity.Evensteelandironarepoormaterialsforwiring,thoughbetterthanwoodorfiber. Thelongpathfortheenergytoflowbacktogroundisonthecircuit.Butwhenashorterpathisprovided,electricitynaturallyseeksthisroute—thepathofleastresistance.Theelectricityimmediatelychangesitscoursetoheadtogroundbythisshorter,easierpath. WhatCausesShortCircuits Shortcircuitscanbecausedby: verminorpestschewingthroughwires waterorotherfluidscomingintocontactwithelectricalwiring looseconnectionsinanelectricalbox oldordamagedoutlets,switches,lights,appliances,orotherelectricaldevices nailsorscrewspiercingthroughwallsandcomingintocontactwithwires deteriorationofelectricalcablesheathing build-uporsurgesofelectricity TypesofShortCircuits NormalShortCircuit Inanormalshortcircuit,apoweredorhotwiretouchesaneutralwire.Immediately,resistancedropsandcurrentbeginstomoveinanotherpath. GroundFaultShortCircuit Inagroundfaultshortcircuit,apoweredorhotwiretouchesagroundedsectionofabox,device,appliance,outlet,baregroundwire,oranythingelsesuppliedbytheelectricalcircuit. SignsofaShortCircuit PreviousShortCircuits Shortcircuitsoftendonotannouncethemselvesuntilthemomenttheyhappen.Insomecases,though,theremaybeawarningsignofapreviousshortcircuit. Thismaybeintheformofacharredwireorlightswitch.Iftheshortcircuitwasrecent,youmaysenseametallicsmell.Oryoumaysmellburnedplasticorrubber. OngoingShortCircuits Whenashortcircuithappens,thecircuitbreakerusuallyshutsoff.Sometimes,therearesparksandabrightlight.Aloudzappingsoundoraboomcanaccompanyashortcircuit. Thedevicepoweredbytheelectricalcurrentstopsworking.GFCIoutletswilltripoff. Ifyouaretouchingthedeviceorifyourbodyhappenstobetheshortwithinthisshortcircuit,youmayreceiveanelectricalshockandoftenaburnfromtheintenseheat. The7BestHomeToolKitsof2021 WhyShortCircuitsAreDangerous Whenthehumanbodyisintroducedasthepathofleastresistance,thecurrenttravelsthroughthebody.Shortcircuitscancauseinjuryordeaththroughelectricalshock,electrocution,orfires. Morepowerisdemandedduringashortcircuit,causingelectricalarcsandextremelyhightemperaturesthatcanmeltplasticsorsetfiretoflammablematerialssuchaswoodorfabrics. HowtoFixShortCircuits Warning Electricservicepanels,orcircuitbreakerboxes,canbedangerous.Leavethedead-frontcoverinplace,sinceitcoverstheenergizedmetallugs.Thelugsremainliveevenafterthemainbreakerhasbeenturnedoff. IsolateCircuit Identifythecircuit.Makesurethatyou'redealingwithonlythecircuitinquestion. MakeCircuitSafetoWorkon Turnoffandremovethecircuitbreaker.Removethebreakerbyrockingitbacktowardthesideoftheelectricservicepanel.Thebreakershouldliftoff. ListDevices Identifyalldevicesonthecircuit,includingoutlets,switches,appliances,lights,A/Cs,andmore—evenjunctionboxes. ExamineDevices Checktheoutsideofeachdeviceonthecircuit.Lookforblownfusesonindividualdevices.Lookforsignsofashortcircuit:sharpsmells,meltedplastic,orburnmarks. LookInsideDevices Wherepractical,checkwiresineachdevice.Openupelectricalboxesandcheckconnections.Lookatjunctionboxesthataren'tattachedtodevices.Removelightfixturesandlookinsidethefixturesandinsidetheirelectricalboxes. CheckCablesinWallsandAttics Whereyoucan,examinewiresbetweendevices.Sincewiresaregenerallyclosedupinwalls,thismaybedifficult.Butoften,wiresrunalongthejoistsinatticsandcanbeexaminedwithaflashlight. CallanElectrician Formanyhomeowners,shortcircuitscanbedifficulttofindandfix.Callalicensed,qualifiedelectricianforhelp. 2:10 WatchNow:TheDifferenceBetweenaGFCIReceptacle&GFCICircuitBreaker FeaturedVideo ArticleSources TheSpruceusesonlyhigh-qualitysources,includingpeer-reviewedstudies,tosupportthefactswithinourarticles.Readoureditorialprocesstolearnmoreabouthowwefact-checkandkeepourcontentaccurate,reliable,andtrustworthy. "ElectricalSafetyTrainingfortheManufacturingIndustry."OccupationalSafetyandHealthAdministration,U.S.DepartmentofLabor. ReadMore HowtoResetaTrippedBreaker GroundFaultvsShortCircuit:What'stheDifference? 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