- I know I need 30 amp breaker and # 10 wire but do I need more than 2 wires with a bare wire ground wire. The directions with the unit (kenmore 40 gal) are confusing = they say something about using a 3 wire cable if you want to take advantage of lower off peak rates. Intermatic makes clock timers that I think work on 2 wires. I want to be able to set the timer to start the heating at midnight and go off at 7 in the morning the times my elec co ( NYS E & G ) gives a lower kwh rate.

You really need the timer before you know how to wire this. If the timer is 240v you will need two wire cable, if the timer is 120V you will need three wire from the panel to the timer and two from the timer to the heater. So you need the timer and need to know where you are going to put it.