SafetyQuestion 425 of 521
The arc flash boundary is best defined as the distance at which:
a.The electrician can no longer physically reach the equipment
b.The incident energy equals 1.2 cal/cm², the onset of a second-degree burn to bare skin
c.The voltage on the conductors drops to zero
d.The restricted approach boundary begins
Explanation
The arc flash boundary is the distance from a potential arc source where incident energy is 1.2 cal/cm²—the level that would cause a second-degree burn to unprotected skin. It is a thermal (burn) boundary, not a reach limit or a shock (approach) boundary, and it has nothing to do with voltage reaching zero.
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