service conductors for duplexes!

[Charlie Bob]

I've installed a new service for a duplex. Housing Authority. Dual Meter base 200 Amp disconnect per unit.
Now when i double check with POCO insp. He told me he wanted 350 kcmil for ungrounded cond. from service point to meter base. That's cool .
I;m the kind of guy that likes to know why i do things a certain way, so i went to my code book but when i added 200 +200 and got 400.amp. Then i went to my ampacity table but for about 4oo amp i would have to use just about 500 kcmil. well thats a lot. so i asked him and he say there's a reduction exeption for residential, I didn't find it. Can any one tell me where it is, if any? And how would you all figure this service conductors out? With the book i mean.
Thank you all !

 

[al hildenbrand]

2008 NEC Table 310.15(B)(6) . . . You might want to double check what the PoCo guy said with your electrical inspector for that location.

 

[Charlie Bob]

i meant the inpector was the one that told me that. I asked him if it was in the book he said yeah. He's not the kind that would stop and show you. He expect you to take his word for it.

 

[LarryFine]

CB, what do your load calcs show? The service conductors can be lower than 200 + 200 because of load diversity, the same way a service main need not equal the branch-circuit breaker total.

 

[Charlie Bob]

You're right.This are specs duplexes that i've been rewiring for a while. I don't remember my first load calc. on them but it's less than 200 amp. but the inspector is not going by that cause there's not even blueprints on this project. He's just going by "common practice" so to speak.

 

[480sparky]

i meant the inpector was the one that told me that. I asked him if it was in the book he said yeah. He's not the kind that would stop and show you. He expect you to take his word for it.

By law, he should be required to give you the Code reference.