Sizing wire considering voltage drop

[Jpmigas]

200 amp 240/120 residential service with 2 meter sockets. 100 amps for a house and taking 100amps from the other meter to a 100 amp disconnect to a pole barn 300 feet underground in PVC schedule 40 conduit. I figured I need # 1 copper thhn or #2/0 aluminum to accommodate voltage drop so as not to exceed 5% drop. Is that right?

 

[iwire]

How did you determine what current to use?

The full 200 amps? The calculated load?

 

[Dennis Alwon]

If you use 100 amps then yes #2 would give you about 5% drop. I doubt you will have 100 amps on the feeder tho. BTW 5% is not code issue but it is a good idea. I would prefer 3% for the feeder as the drop will increase with the branch circuits

 

[Dennis Alwon]

Of course #1 is better and 1/0 would give about 3%

 

[infinity]

For a 100 amp load using the 300' portion @5%, yes #1 Copper or #2/0 Al.

http://www.southwire.com/support/voltage-drop-calculator.htm