brother
Senior Member
I say #2 is all you need. Note 1 T. 250.66. Table 8 has 3/0 at 167800 cir mil. Multiply by 2 and you get 335600 cir mil. This is equi. to 350 KCM. Table 250.66 allows #2 for 350 KCM copper
I was comming up with something different, 167800 cir mil 3/0 Multipied by FOUR 4 instead 2 that would be 167800 * 4 = 671200 which means a 2/0 copper GEC according to table 250.66.
The reason I see 4 instead of 2 3/0 is he said he had 2 200 amp breakers (Homeline), Im assuming that there are 2 3/0 to EACH breaker (correct me if im wrong), which would give you a total of 4 3/0 wires.
The GEC is sized according to the total circular mills of the ungrounded conductors 2008 NEC 250.24(D), 250.30(A)(3), AND of course 250.66.
By the way is the a single phase service (residential)??