240
The key parameter in sizing wire is the current requirement. Once you know that you can look up value in a wire gauge table. The length of the run is important for longer runs because of the resistance of the wire itself. Aluminum wire requires a larger diameter than copper for the same current. Once you calculate the wire size you can then size the conduit.
You size wire by the current. Various insulations are rated for voltage, temperature and the medium where the wire will be run.
Depends on the size of the circuit which you did not list.
Presuming that you would like the least expensive installation, the following is calculated on overhead aluminum wire. The wire size needed to hold the voltage drop to 3% would be 3/0 MCM. If the installation could be run on 240 volts then the wire size can be reduced to #2.
you must run the proper size wire based on the ampacity needed, wire must have four conductors including the gound
A #10 copper conductor will limit the voltage drop to 3% or less when supplying 21 amps for 150 feet on a 240 volt system.
240
The key parameter in sizing wire is the current requirement. Once you know that you can look up value in a wire gauge table. The length of the run is important for longer runs because of the resistance of the wire itself. Aluminum wire requires a larger diameter than copper for the same current. Once you calculate the wire size you can then size the conduit.
You can't. The 120 volt GFCI is probably just a 2-wire (hot, neutral and ground) You would have to run a new 3-wire (2 hots, neutral and ground). The two hots are how you get the 240 volts (120+120=240). Also you must make sure the wire is gauged properly. #10 wire for 30 amps, #12 wire for 20 amps, etc.
It won't run.
You size wire by the current. Various insulations are rated for voltage, temperature and the medium where the wire will be run.
Depends on the size of the circuit which you did not list.
For a 75 amp circuit with a 100 ft run, you would need a #4 AWG copper wire to ensure minimal voltage drop and to meet electrical code requirements. Using the correct wire size helps maintain the efficiency and safety of the circuit.
Presuming that you would like the least expensive installation, the following is calculated on overhead aluminum wire. The wire size needed to hold the voltage drop to 3% would be 3/0 MCM. If the installation could be run on 240 volts then the wire size can be reduced to #2.
No, a 240 volt device runs on 240, and a 120 volt device runs on 120. Attempting to run a device on incompatible voltage results in damage.
At that distance you will have a voltage drop of 81.25 volts if you use the recommended #6 wire on a 240 volt, 100 amp single phase circuit. Therefore I recommend you contact you electric utility and let them figure the voltage drop and the size wire required to safely run this distance. Using too small a wire can damage the electronics at the end of the run.