The guage of wire for 20 amps is #12 copper.
The maximum current rating for a 20A wire gauge is 20 amperes.
12 AWG.
2
3/0 gauge
20a + 45 = 5(4a + 9)
-4(5a-3) = -20a + 12
4 gauge
It cannot be simplified any further, so it is: 5a³ + 15a² + 20a
For a 120V 20A motor, you would typically use a 12-gauge wire to ensure it can handle the current without overheating. This wire size is suitable for the amperage and voltage to provide proper insulation and safe operation for the motor.
12
At the service entrance you will need AWG 1/0 gauge.
Yes, HO track is needed to operate an HO train.