arc flash approach boundaries - itu arc flash...

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)