250mcm

[puckman]

does anyone think sizing a 480 v 250 a 3 phase breaker with 250 mcm thwn thats a 300' plus run is a bad design ? it's 4wire 3 /# 250 with 1/#2 wire . its for a mcc with a 15kva trans for lighting and recept.

 

[benaround]

What is the calculated load ?

 

[whillis]

Assuming copper conductors, at 250A the voltage drop will be 1.4% for 300' of wire.