0V.
The generation of 0V voltage is relative, you can just regard the 220V as a battery, the positive pole as the fire wire, the negative pole as the zero wire, the negative pole is in good contact with the earth, and the ground wire is also in good contact with the earth (the earth is a good conductor). In this way, the positive pole (fire wire) to the negative pole (zero wire) generates voltage, the positive pole (fire wire) to the ground, to the earth are generating voltage, and in turn, the negative pole (zero wire), the ground, the earth to the positive pole (fire wire) also generates voltage. And for the person standing on the earth only relative to the firewire produces voltage, to the zero line and ground are at the same potential, does not produce voltage.
Expanded:
Zero wire is charged:
1, there is current, which is caused by three-phase imbalance.
2, there is voltage, which is the zero line broken, which is very dangerous, very easy to cause damage to electrical equipment, must be overhauled
For three-phase four-wire (TN-C) system in the zero line charged, most of the three-phase load imbalance is caused by a fault condition, the zero line will be charged.
But in the three-phase five-wire system (TN-S), the zero line is generally with a very weak current, especially in the power supply of the computer system, this is because the computer system's operating voltage is a micro-voltage is generally between 0 ~ 5V, but also DC power supply, so according to the working principle of the DC system, the zero potential is the current through the DC zero potential within the computer is the DC/AC conversion of the incoming line to the DC/AC conversion of the incoming line to the DC/AC conversion of the incoming line to the DC/AC conversion of the incoming line to the DC/AC conversion of the incoming line to the DC/AC conversion of the incoming line. DC/AC conversion of the incoming power supply AC zero as DC zero potential point, so in the computer system in the power line in the zero line is normally a micro-current through, so in the computer power distribution design are not installed leakage protection devices.