lakee911
Senior Member
- Location
- Columbus, OH
Utility is supplying a Wye-Wye transformer. I originally specified the following from the transformer secondary to the main disconnect: 3-(350MCM/phase,#1/0G,3?C). That's three sets of 350MCM per phase and 1/0 ground in a 3" conduit.
Contractor thinks a nuetral (grounded) conductor is required. Yes, it is required. My mistake.
I check my work .... I do not have any 277V loads and I'm only taking three wires from the switchgear so my unbalanced nuetral load is 0A.
So, I size the neutral (grounding conductor) per Table 250.66: 350 kcmil copper shows 1/0 copper ground. Ok.
I size the neutral (grounded conductor) per 220.61(A): the unbalanced load = 0A. For that, 250.24(C)(2) allows me to use a minimum size of 1/0 copper.
Am I correct?
3-(350MCM/phase,1/0,1/0G,3?C) or three sets of 350MCM per phase, plus 1/0 grounded conductor and 1/0G grounding conector. (I know it might be tough to pull, but it's a short distance).
Thanks!
Contractor thinks a nuetral (grounded) conductor is required. Yes, it is required. My mistake.
I check my work .... I do not have any 277V loads and I'm only taking three wires from the switchgear so my unbalanced nuetral load is 0A.
So, I size the neutral (grounding conductor) per Table 250.66: 350 kcmil copper shows 1/0 copper ground. Ok.
I size the neutral (grounded conductor) per 220.61(A): the unbalanced load = 0A. For that, 250.24(C)(2) allows me to use a minimum size of 1/0 copper.
Am I correct?
3-(350MCM/phase,1/0,1/0G,3?C) or three sets of 350MCM per phase, plus 1/0 grounded conductor and 1/0G grounding conector. (I know it might be tough to pull, but it's a short distance).
Thanks!