The utility feed to my duplex with two 100A meters on it, is an underground cable in conduit. The main panel is 200A, but the utility feed is only 2 AWG Aluminum. The cable marking is: ALCAN 2 AWG ALUM 600 VOLT XLPE 1978. I think XLPE is Cross Linked Polyethylene, which I think has a higher temperature rating.
This document shows that a single conductor is good for 180A for direct burial. Is it appropriate to use that value in a conduit?
When I looked at the 90C rating for #2 Aluminum, I see 100A. Can someone explain why the other document shows it as 180A?
I'm assuming 180A is fine for two 100A breakers in a duplex, assuming some level of diversity. The cable going into the panel is a 2/0 Copper, but it is only 4 ft or so from the box you see into the panel