I want to run an additional 200 amp out of a Milbank u3849-0-2/200 pedestal with breakers .At the present time I’m running 200 into the house. Now I want to tap the additional 200 breaker and run it 320' out to a barn. I was originally thinking of using 350/350/4/0 for the run, but I’m concerned about 4% line dropage and I want to maintain a full 200 amp at the new panel 320' from the feed at the pedestal .I would think about overseeing the wire to maintain it. Any suggestions on what size I should go to for maintaining the full load. Thanks.

Do you honestly need a full 200A at the barn? What kind of continuous loads are you looking at?

It will be for arena lighting and also to run future out building off it.

This really does not tell me anything about what the load will be. Arena lighting could mean 2000 watts, or 20,000 watts.

And future outbuilding could mean a 60 watt light bulb or a full on machine shop.


So will you really need the full 200A?

Yes

Assuming a mostly balanced load:
400mcm AL, or 250mcm CU.