Arc flash incident energy reduction over distance

[mbaxter1]

This question was on the NETA level 2: "there is a guy standing 3ft and a guy 6 feet away from an exposed live part, how much incident energy is he exposed to compared to the 3 ft guy?" Options were something like 1/2, 1/16, 1/4. Does anyone know where I can find the curve for step potential?

[jts1976]

This question was on the NETA level 2: "there is a guy standing 3ft and a guy 6 feet away from an exposed live part, how much incident energy is he exposed to compared to the 3 ft guy?" Options were something like 1/2, 1/16, 1/4. Does anyone know where I can find the curve for step potential?

I don't believe you're looking for the step potential curve, but the formula for how arc flash incident energy reduces over distance from the source of the arc. I'll do some digging later on this.

[GregRooster]

This question was on the NETA level 2: "there is a guy standing 3ft and a guy 6 feet away from an exposed live part, how much incident energy is he exposed to compared to the 3 ft guy?" Options were something like 1/2, 1/16, 1/4. Does anyone know where I can find the curve for step potential?

Not always true, but the exponent is usually 2.

The distance doubled. 1/(doubled)^2. 1/4

Remember it by looking at the units. Cal/cm^2.


https://www.ecmag.com/section/safety/incident-energy-calculations

[jts1976]

I don't believe you're looking for the step potential curve, but the formula for how arc flash incident energy reduces over distance from the source of the arc. I'll do some digging later on this.

https://testguy.net/threads/2735-Keep-this-in-mind-when-working-around-energized-equipment?p=5225#post5225