[mikehinton]

I guess I should have added that the main supply lines to the various buildings are either 6 gauge or 8 gauge individual wires running in PVC conduit. I'm fairly certain that that is the case also for the wires going from the main service entrance panel on the house to the sub panel. I didn't actually witness that installation, but it was done by a well-known electrical contractor here in the Napa Valley.

I don't think there is actually any Romex underground, but if there is, it's the gray stuff that's rated for damp locations.

The junction box I'm referring to takes the feed from the main wires, and distributes it to the outlets and light fixtures in the barn.