I always have a little debate with myself on what size riser to use for a "400 amp" service or multi gang meter socket service. Of course they are theoretically sized to the load, but I never get asked for load calcs and dont usually do them for many of these, so its kinda like whatever I feel like (as in my professional judgment). On one hand I feel sort of obligated to provide a full 400 because that is what we are calling it, but of course its very overkill most of the time. The 320 and multi gang sockets I use only have provisions for one riser, so its kinda a pain to get a full 400 amps in with AL conductors considering the derating (would need 300MCM AL, odd size so likely it would be 350MCM). Right now I have two going on, and I have some nice 350 THHN simpul colors conductors left over from another job, so both will be getting the full 400 and them some. I would probably go two parallel 250 AL (368A) if I didnt have the 350.
