Service wire required is AWG # 3/0 copper.
3/0 wire 3/0 wire
As a service entrance wire you need AWG # 3/0 gauge copper.
A 3/0 copper conductor with an insulation factor of 75 or 90 degrees C is rated at 200 and 210 amps respectively.
Service wire for 100 amps requires AWG #3 copper.
AWG 10.
Depends upon the voltage. The formula for amperage or (wire size) is Watts / Voltage. If the voltage is 220 volts, then the amperage would be over 400 amps. This would require a large wire size to run it. If it were 440 volts, the amperage would be 1/2 or 200 amps. That would require a smaller wire size. As the voltage goes up, the amperage goes down. At a thousand volts, the amperage would only be 90 amps. A wire gauge or size of a #2 would carry 90 amps for small distances.
120mm
To calculate the wire size you would have to find the amperage. I = W/E, 70000/240 = 291.67 amps. The wire size according to code has to be up sized to 125%. 291.67 x 125% = 364.6. 500MCM copper wire with an insulation factor of 75 and 90 degrees C is rated at 380 and 395 amps respectively. If parallel conductors were used the wire size for 75 degree wire would be 3/0 rated at 200 amps. Parallel conductors for 90 degree wire would be 2/0 rated at 185 amps.
Number 10 thnn copper wire.
A #1 copper wire with an insulation rating of 90 degrees C is rated at 140 amps.
Look on the heater and see what amps it is pulling. That will determine the wire size and breaker size. It must be on a dedicated circuit. 15 amps = AWG # 14 wire with 15 amp breaker 20 amps = AWG # 12 wire with 20 amp breaker 30 amps = AWG # 10 wire with 30 amp breaker 40 amps = AWG # 8 wire with 40 amp breaker
15 amps.