All of the 3 wires connected to the compressor motor terminals will carry current while it is running. Depending on the method the mfr uses to cycle the compressor (breaking one or both power legs) some of the wires may remain `Hot` while it is off. A wiring diagram specific to the unit in question will answer that. By earth I assume you mean the ground or green wire, that wire is never intentionally powered.
The neutral wire does carry current in a closed AC circuit. Clamp a clamp on amp meter around the neutral wire directly after the circuit load and it will read the same current as is on the "hot" wire.
To carry the unbalanced load current.
The ground wire should carry no current at all, it is there in case of a short circuit to carry the (short circuit) current back to the breaker panel to trip the breaker. The neutral will carry the unbalanced load current between the 240 volt legs. e.g. L1 and N (neutral) 120 volts the load draws 8 amps. L2 and N (same neutral) 120 volts the load draws 12 amps. The difference between the two amperages is what the neutral will carry 12 - 8 = 4 amps.
No. Absolutely not. The ground conductor is not rated to carry constant current flow. It is only rate to carry fault current flow.
The current carried by the neutral of a three phase four wire system is the un balanced current. If the three phase system was completely balanced on all three phases there would be no need for a neutral, eg a three phase motor. This neutral current will be less that the phase current so a reduction in the neutral size is allowed.
A smaller neutral wire in a three phase system can be used because it does not carry the full line current. It carries the unbalanced current of all three leg loads. This is one reason that three phase loads on a distribution panel should be equalized as much as possible to reduce the current on the neutral.
Because neutral doesn't have to carry the load current .This is either used for unbalanced current (in Y-connection) or for earthing purpose which don't require high ampere rating....
In the UK Brown is the live, blue is the neutral and green/yellow is the earth. The live and neutral are the two wires that normally carry the current.
Yes, you can reduce the neutral in a three phase system. you must figure the unbalanced current the neutral will carry and also make allowances for any harmonics that may be present.
No, because the molecules are neutral so therefore there are no charged particles to carry a current.
Neutrons carry no charge - they are neutral.
If a load were only 240 volt on a single phase 240v system with a center tapped transformer the neutral conductor would carry no current.