Service entrance conductors

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curtiscwilson

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Question? (Res)
200 amp meter/disconnect panel, service entrance conductors would be 4/0-4/0-2/0 alu or 2/0 cu wire. What size conductors would i need to feed a 200 amp subpanel after the 200 meter main? Can I use the same size wire as the service entrance or do i have to use another wire chart?

Thanks
Curtis
 
Re: Service entrance conductors

one question

is this a residential service? if so 310.15(B)(6)will suffice,if not, you will not be allowed to use either 4/0 AL or 2/0 CU, per 310.16, the 75*C column, (the column you have to use for sizing all wires, as bus ratings are rated at 75*C)
 
Re: Service entrance conductors

Thanks for the reply, I could not remember if after the main disconnect you had to use another table. So what about subfeeders, can you still use table 310.15
 
Re: Service entrance conductors

I want to make sure I know what you are asking before answering you. When you say "sub'feeders", if you are going from the main disco to a panel, those feeder conductors may be be sized from 310.15 (B)(6). If you go from a panel (other than service equipment) to another panel, you can NOT use 310.15(B)(6), you will have to use 310.16.

Does this answer your question?
 
Re: Service entrance conductors

Thanks for the reply, thats what I thought. One more question. I can install a meter main that only has a meter socket and main disconnect and use table 310.15 to feed another panel, what if I install a all in one meter main that has buss bars for other small branch circuits, and want to feed a subpanel after that, than do I use table 310.16?
Is that right?

Thanks Curtis
 
Re: Service entrance conductors

Curtis, you worry me, are you a qualified electrician? :confused:

310.15 is what you use for ampacities for conductors rated 0?2000 Volts. It includes notes for the tables and refers you to the tables. You keep referring to 310.15 and, I think, you mean Table 310.15(B)(6) which is referred to in 310.15(B)(6) (all tables in the NEC are referred to from the text). The text in 310.15(B)(6) tells you that you can use Table 310.15(B)(6) for the 120/240-Volt, 3-Wire, single-phase dwelling services and feeders that serve as the main power feeder to a dwelling unit and are installed in raceway or cable.

It does not seem to me like you are doing that if you are serving loads and then installing a feeder.
 
Re: Service entrance conductors

Table 310.15(b)(6) is only used for the main power feeder in a dwelling unit, typically from the meter to the main service panel. If your not sure, ask your AHJ when you pull the permit for the customer.
 
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