I can't imagine why you would run a 30 amp circuit. First, you need 10 gauge wire, which is really hard to use. Second, there are no 10 gauge appliance wires in any consumer grade products, including the heaviest extension cords you find at the hardware store. As noted, 12 gauge wire is not code on a 30 amp breaker. Also, where would you find 30 amp wall plugs? I could see multiple 15 amp circuits.
A Z4000 at full load pulls 400 watts (likely less). A 15 amp circuit has a max load of 1800 watts; 30 amp circuit has a max load of 3600 watts. Even with all of your power supplies, how can you run enough trains simultaneously to draw this much power? Further, why would you do it on one circuit?
