![]() Related shock-hazard approach boundaries include the limited and restricted approach boundaries, which refer to closer, more-hazardous distances from electrical equipment that require greater safety precautions in order to operate within. Arc Flash Boundary (AFB) The AFB is a safe approach distance from energized equipment or parts. Other standards require all equipment that necessitates an arc-flash boundary to be clearly labeled with information stating what that boundary is, thus enabling a quick understanding of the safe working distance by anyone near the equipment. Arc-flash boundary is defined as the boundary inside which a worker may be exposed to incident energy of more than 5 Joules/cm 2 (1.2 cal/cm 2). Both solutions also provide specific obligations for the PPE that must be used by individuals working closer to the equipment than the arc-flash boundary. NFPA 70E sets out a number of boundaries from the live electrical conductors, arc flash boundary and shock protection. In lieu of calculating the point at which incident energy will equal 1.2 cal/cm 2, the standard also provides a table-based solution for determining an arc-flash boundary based on the properties of the electrical equipment under consideration. 1- temps as high as 20000c (severe burns and fire) 2- flying objects, shrapnel and hot molten metal. The NFPA prescribes specific calculations for determining the arc-flash boundary under Annex D of this standard. what are the 6 effect that workers may experience when exposed to an arc flash. It is an OSHA-recognized consensus standard therefore, the arc-flash boundary has legal weight as a boundary that must be observed in workplaces in order for employers to meet their general duty obligations for workplace safety. The arc-flash boundary concept is defined by the National Fire Protection Association’s 70E standard. Flash Protection Boundary (outer boundary): The flash boundary is the farthest established boundary from the energy source.
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