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Calculate the incident energy and arc flash boundary based upon the IEEE simplified equations for a 480-V power circuit breaker (low voltage power circuit breaker [LVPCB]) of 800 A rating provided with electronic trip programmer, LS ( long time and short time). Also, calculate similarly for a 400-A molded case circuit breaker (MCCB) with thermal magnetic trip. The bolted fault current is 36.8 kA.

800-A LVPCB

The incident energy is given by the equation:

Substituting, incident energy is = 195.04 J/cm² = 46.80 cal/cm²

The arc flash boundary is given by the equation:

Substituting

Arc flash boundary = 173 in.

400-A MCCB

The incident energy equation is:

Which gives 1.80 cal/cm²

The arc flash boundary is:

Substituting, this gives: 20.9 in.