Hello— I'm installing a 100 amp sub panel in my detached garage. The panel that I have does not have a disconnect breaker on it, and I'd prefer to locate it away from the point of entry in the garage for convenience. So I have a 100amp outdoor disconnect (basically a 100amp breaker in a box, listed as "service equipment") My intent is to run conduit from the house to the garage, terminate it in the disconnect, (I think a disconnecting means is required where it enters the garage) then run to the panel elsewhere in the garage.
My question is, can I use PVC conduit in-wall with THHN to go from the disconnect to the panel? Is there another way that I should do it? Using SE cable in wall and attic seems like a minefield, so I figured conduit might be best, but I'm not sure. If the conduit is surrounded by insulation, do I need to derate the wire inside it? If I use conduit, do I need to use Sch 80?
Any thoughts or caveats greatly appreciated!