Volts are the "electromotive force" that is needed to "drive" the electricity through the wiring.
Two wires are needed for 220 volts.
Zero. Watts is the product of Amps x Volts. As you can see an amperage value is needed. Voltage = Watts/Amps. Volts = 200/? 20 volts
12 volts will get it started. Once running, the alternater runs at about 14 volts.
I believe is 12 to 14 volts.
The equation that you are looking for is I = W/E. Amps = Watts / Volts.
Commercial lighting. In a facility where 3 phase 480 volts is needed for machinery, 277 is also readily available because each leg of 480 to ground is 277 volts. This way numerous supply transformers are not needed in a commercial building.
General Aviation typically uses 24 volts. Even the Boeing 777 uses 24 volts while the newer 787 is 32 volts.
3 things Volts, ohms, and amps
ohms = volts/amperes 6 ohms = 120 volts / 20 amperes
If the heater is rated as a 3 phase 480 volt heater then a neutral is not needed. If the voltage stated is 277 volts three phase then a neutral is needed.
#8 copper
The electric furnace operates on 240 volts so a two pole breaker is needed.