How many wires are needed for a 120V subpanel. I thought three is fine.. (Hot, Neutral, Ground) just the same as 4(Leg A, Leg B, Neutal, Ground) is fine with a 240V subpanel. 120V subpanels are very uncommon.. but I don't want or need 220v in this case. A Colorado inspector just dinged me for a code violation on the panel. I'm not super strong on NEC.. but the foregoing sounded reasonable to me.