ECN Forum Forums General Topics of the Trade General Discussion Area Voltage drop & over sized conductors

Using the information from the Bussmann point-to-point short circuit calculations I come up with the following. I assumed a 1000 amps available at the breaker, 120 volt single phase circuit, and 100' of wire to the fault. The fault currents at 100' are:
#12 270amps, #10 370 amps, #8 425amps, #6 538amps, and #4 647amps.
Don(resqcapt19)

http://www.bussmann.com/tech/S_circuit.html

I had suggested 20' for the reason that the longer runs do act significantly to reduce the SCA.

I am not sure that this is the sole criterion.

I want to know in the case of a 20 A CB how many joules could be delivered before the breaker opens. My intuition tells me that the CB will open sooner with the higher fault current.

I mean let's suppose that the SCA was 30 A because the run was 2000'. I would not consider this safer.