Answer to Question #118178 in Electrical Engineering for Tom

Question

What is the ground voltage with neutral? Why does it occur? How many Volts should it be? What can be done to prevent and eliminate it?

Answer 1

Q: What is the ground voltage with neutral? How many Volts should it be?

A: The ground voltage with neutral is the potential difference between PE and N wires. Ideally, it is zero. Usually, it is 1-3 V depending on the conditions of the system. 5 V is the maximum allowable limit.

Q: Why does it occur? What can be done to prevent and eliminate it?

A: It may occur for different reasons in three-phase networks: short-circuit that was not stopped when phase wire touches metal grounded parts of equipment, third harmonics generated by electronic equipment, high resistance of N or PE wires. Compensators and/or periodical maintenance will help to prevent and eliminate this voltage. The solution, of course, depends on the reason.