Help with calcs

[mikenye]

I have a customer that installed his own underground from a 200 amp main in 3 inch pvc at a 300 foot to another 200 amp main on a modular, this is 2/0 copper THHN. I am confused about which table is correct for my install and the percent of load drop all that, I thought the 2/0 would be fine, 3/0 seems over kill.

Thank You

 

[bphgravity]

Re: Help with calcs

Your installation appears to be the main feeder to what I think is a mobile home. These conductors can be sized from 310.15(B)(6), therefore 2/0 copper is sufficent as far as the code is concerned. As far as voltage drop is concerned, the code recommends not more than 5% over the entire system with no part exceeding 3%.