The voltage has nothing to do with the gauge of wire needed to supply a given circuit. The size wire is determined by the amperage of the overcurrent protection device (circuit breaker, etc.) being used to supply power to the circuit.
The National Electrical Code calls for #4 copper or #2 aluminum.
#10 wire.
The gauge depends on how the maximum current supplied through the wire.
A. It's 240 volts & B. Wire size is a function of amperage. 12-gauge wire is used with 20 amperes or less. So, 12-gauge wire can be used with 120V/20A or 240V/20A. Keep in mind though that 240V in the U.S. has 2 live 120V lines so if you encounter a white wire, it's probably an unmarked live & should be repainted as black or better yet, red (to indicate the 2nd live wire).
In order to safely run 30 amps of electricity, a minimum of a #10 gauge wire is needed. For longer runs of wire, #8 gauge is better.
The National Electrical Code calls for #4 copper or #2 aluminum.
#10 wire.
The gauge depends on how the maximum current supplied through the wire.
3/0 gauge
16 mm to 18 mm
A. It's 240 volts & B. Wire size is a function of amperage. 12-gauge wire is used with 20 amperes or less. So, 12-gauge wire can be used with 120V/20A or 240V/20A. Keep in mind though that 240V in the U.S. has 2 live 120V lines so if you encounter a white wire, it's probably an unmarked live & should be repainted as black or better yet, red (to indicate the 2nd live wire).
Use 8 gauge wire.
#6 gauge copper
In order to safely run 30 amps of electricity, a minimum of a #10 gauge wire is needed. For longer runs of wire, #8 gauge is better.
Depends on the size of the heater but home water heaters normally require AWG#10 wire on a 30 amp breaker.
Yes
10 gauge will suffice.