200 amp feed through

M

menoknow

Member
Location
Washington State
Occupation
Electrician
I have a question on wire sizing for a feed through panel. I have a customer with a 240v single phase 320 amp service split into 2 separate 200 amp panels. 1 panel currently feeds their house while their second panel feeds their shed with a couple small loads. They just built a garage and want to bring the full 200 amps from the panel feeding the shed to the garage and maintain the small loads in the shed. the garage is about 250 feet away from the service and the shed is about 50 feet from it. The idea is to get a feedthrough panel. The incoming conductors to the panel are 4/0 4/0 2/0 alum.
So this is where my question comes in. Do the feeders heading to the garage need to be sized like a regular 200 amp feeder circuit? So minimum size being 250kcmil for both hots and neutrals and #4 alum ground. Or can I keep my feeders same size as the conductors coming from the utility? Personally I'm going to recommend we upsize the conductors anyways just for the distance, but do we need to have the neutral the same size as the hots? This is the first time I've run into this situation in a residential setting.
 
Is the service disconnect at the pedestal with the meter or are service conductors run to the shed with the service disconnect there per 2:30.40 exception number three? I guess either way the answer would be the same. Feeders running to the garage could be 4/0 AL using the next size up rule. Going up to 250 due to the length sounds reasonable. Like Larry said, the neutral is sized to the load, but for residential I just do two sized reduced 99% of the time, and that's what a cable assembly like Sweet briar or Pratt will have ( well you need four conductor so you would probably use mobile home feeder but I think that also has a two size reduced neutral typically).

Another option, which would be my preference, is to come directly out of the 320 meter socket with service conductors all the way to the garage (230.40 exception #3)
 
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