Flash Protection Boundary

IEEE 1584 defines the Flash Protection Boundary as: “An approach limit at a distance from live parts that are uninsulated or exposed within which a person could receive a second degree burn." The accepted incident energy level is 1.2 Cal/Cm². NFPA 70E also defines the following related terms:

Limited Approach Boundary:

An approach limit at a distance from an exposed live part within which a shock hazard exists.

Restricted Approach Boundary:

An approach limit at a distance from an exposed live part within which there is an increased risk of shock, due to electrical arc over and inadvertent movement, for personnel working in close proximity to the live part.

Prohibited Approach Boundary:

An approach limit at a distance from an exposed live part within which work is considered the same as making contact with the live part. NFPA 70E Annex C, Limits of Approach describes the precautions that are required before crossing each of these boundaries, and for some conditions establishes default distance values.