generator feeder sizing.

[Coppersmith]

I'm installing a 20kW whole house generator. The generator is feeding the entire panel. Since the house uses gas for appliances, it's expected no load shedding will be required. Should I size the feeders according to the services calculation or standard wire ampacity?

 

[Adamjamma]

Only learning but.. wouldn’t you base the wires on the maximum output of the generator, including its surge? Like a 4000/8000 inverter I would use wires for the 8000 Watts? Again, just learning the codes but seems like a common sense to me unless I was using a breaker to limit the amount the inverter could put out before entering the wires...