Thanks for the quick reply. The supplier finally told me the built in breaker is 600amp . Where would I order a dual lug setup from? Kohler ? . The gen doesn't come in till January but the rough in has to be done next week . I have to pull the feeders next week as well . Right now I'm figuring parallel sets of 350 mcm copper . Good for I think roughly 620 Amps . That should cover the 100% of OC .