There is a 85 amp, 2 pole breaker at gen output that feeds the wire to the xfer switch.
Is 1 gauge aluminum wire sufficient size for current conductors? 2 gauge for neutral and 3 gauge for ground? The NEC handbook has my head swimming.
Thanks,
Steve

Yes, it is sufficient. If you already have the wire, use it.

Thanks for the quick answer. Here's the back story.

My neighbor hired an electrician to do the wiring. The guy showed up today with 4/0. On Thursday he plans on stuffing it, along with 4 control wires, into 1 1/2" conduit, which he put in today.

I had convinced my neighbor I didn't know enough to do the install; now I have to convince him that I know enough to tell the electrician his wire is too big and his conduit is way too small!

This better teach me not to be a nosy neighbor!

Thanks again,
Steve

Is this generator for a sub panel or to power the main panel?

It's for the 200 amp main panel. The output of the xfer switch to the main will be 4/0. The major appliances are gas.