Arc Flash Approach BoundariesLimited Approach Boundary• AnyonewithinthisareaissubjecttoinjuryshouldanArcFlashoccur.• Thequalifiedworkermustinsurenooneisallowedinthisareawhencoversare
removed.• Heatenergywithinthisareacouldcausegreaterthanseconddegreeburns.• ProperPPEmustbewornbyallpeopleinthisarea• Unqualifiedpeoplemaybethisclosewhensupervisedbyaqualifiedelectrician.
Restricted Approach Boundary• AnyonewithinthisareaissubjecttoinjuryshouldanArcFlashoccur.• Thequalifiedworkermustinsurenooneisallowedinthisareawhencoversare
removed.• Heatenergywithinthisareacouldcausegreaterthanseconddegreeburns.• ProperPPEmustbewornbyallpeoplewithinthisdistance.• Unqualifiedarenotallowedwithinthisdistance.• Voltageprotectionsuchasvoltageratedtoolsandglovesmustbeappliedwithinthis
distance.
Prohibited Approach Boundary• AnyonewithinthisareaissubjecttoinjuryshouldanArcFlashoccur.• Thequalifiedworkermustinsurenooneisallowedinthisareawhencoversare
removed.• Heatenergywithinthisareacouldcausegreaterthanseconddegreeburns.• ProperPPEmustbewornbyallpeoplewithinthisdistance.• Unqualifiedarenotallowedwithinthisdistance.• Voltageprotectionsuchasvoltageratedtoolsandglovesmustbeappliedwithinthis
distance.
Arc Flash Boundary• Thequalifiedworkermustinsurethatnooneisallowedinthisareawhencoversare
removed.• AnyonewithinthisareaissubjecttoinjuryordeathshouldanArcFlashoccur.• Heatenergywithinthisareacouldcausegreaterthanseconddegreeburns.• Theintenseheatwillvaporizemetalproducinggases,vapors,andmoltenshrapnel.• Thesegasesexpandrapidlyupto67,000timestheoriginalspaceoccupiedbythe
metal.ThisexplosionisroughlyequivalenttothedetenationpropertiesofTNT.• Thesoundwavecanexceed160db.
Barricadesshallbeusedinconjunctionwithsafetysignswhereitisnecessarytopreventorlimitemployeeaccesstoworkareascontainingenergizedconductorsorcircuitsparts.Conductivebarricadesshallnotbeusedwhereitmightcauseanelectricalhazard.Barricadesshallbeplacednocloserthanthelimitedapproachboundarygiveninthetable:NFPA70E2012EditionTable130.4(C)(a)andTable130.4(C)(b)