I have a 30KW 3 phase generator I purchased from government surplus. After repairing the generator it runs fine and I will only be using 2 of the phases. Now my question. I have a new Cutler-Hamer model DT224URK-NPS 200 amp transfer switch which I have mounted above where my service enters my home. The switch is after my meter and main cut off breaker. The service to my home is 4/0 aluminum with 2/0 neutral and 4AWG ground. I can disconnect and pull the wire back from my main breaker box and feed the transfer switch with not much problem. The feed is long enough. What I want to know is can I use 2/0 copper feed, 2/0 neutral and 4AWG ground from the switch back into my breaker box or do I have to use the 4/0 aluminum feed wire? This would make the job much more easy.

Thanks much