How do I calculate arc flash rating?

Question

How do calculate arc flash rating?
I 208/120 volt panel with a short curit current of about 13,000 amps. How many calories per cm^2 of energy does this create. And how do I calculate this?

This panel is fed with a 400 amp Molded case breaker

Answer 1

First you need to get your hands on an Arc-Flash Incident Energy Calculator. It is a chart. One place I know that has one is the Bussmann, Handbook for Electrical Safety, Editiion 2. Appendix G.

Just looking at the chart it looks like the incident energy value is between 0.96 to 1.11 cal/cm^2 for a 1 to 100 amp molded case circuit breaker. The Flash Protection Boundary is 15 to 17 inches.

You really need to look at the chart. I don't see an adjustment for voltage, just fault current, and the fault interuption device, various fuses and molded case circuit breakers.