If you're hiring an electrician, let him spec the wire. Assuming a 200 amp feed, which I agree is overkill, 3/0 copper or 250MCM Alu wire will be needed, so size your conduit accordinly. I pulled some 250MCM wire (3 250MCM cables, (1) 4ga ground) into a 2.5" conduit, and it went fairly easy...