Parallel Conductor Sizing

[fcfjr]

I'm planning on installing a Meter Pack, Ring Style Meter Socket Covers, 1-Phase, 2 Meter Sockets, 120/240V AC, 200 AMP Socket Rating, 400 AMP Bus Rating service entrance panel. One 200 amp rated socket will be for a residential dwelling and the other 200 amp rated socket will be for AG use. Using 310.15(B)(7) I reduced the ampacity for the residential meter to 83% (166 amps) and added that to the AG load (200 amps) for 366 amps. According to table 310.15(B)(16) I can use 700 kcmil at 375 amps or after derating 80% for 4-6 current carrying conductors I can use parallel 250kcmil. 230 amps at 80% = 184 and 366 amps divided by 2 = 183. Am I missing anything? Thank you.

 

[infinity]

What is the calculated load?

 

[augie47]

My be missing a few $$ A load calculation might allow you to downsize a little but what you plan will work.
You don't want to wrestle the 750, go parallel.

 

[fcfjr]

Thank you for your replies. The residential calculated out to 125 amps. The AG load is about 55 amps. I know the 400 amp service is oversized but it is what the client is asking for.

 

[winnie]

Using 310.15(B)(7) as you describe is not strictly correct. It doesn't reduce the calculated demand of a residential service, but rather says that a given calculated individual load may be served by conductors with 83% ampacity.

It doesn't say that you can combine this reduced ampacity with other loads to get a reduced total ampacity.

I don't think you have a code problem here, since you are installing more than sufficient capacity for the calculated loads. But per customer request you are installing an oversized service so need to be able say that your 366A conductors are perfectly acceptable for a 200A residential service combined with a 200A other service.

Jon