When a friend of mine mentioned today, that when he touched the metal surfaces of his electrical equipment and felt a mild electric shock, I asked him to check if his house and the equipment had a ground connection. Both yes. Next, when I asked him to check the N-G voltage, it was 85 volts!

What are the causes of N-G voltage going up in a single phase wired house?

What should be checked for this issue?

Does having multiple groundings have a bad effect? His house had been wired in three separate sections, with three separate main switches and grounding.

Whats the best method of checking and rectifying this issue?

Thank you.

Such a large measured voltage N-E suggests that E isn't actually earthed.

 

Suggest setting up a known earth (big screwdriver in the lawn, water it well) and connecting that to the installation ground and re-measuring.

 

Also, check his metal-cased equipment is actually connected to the "ground", many extension leads which look like they are 3 wire are, in fact, only two.

 

Thank you very much Crossy. Shall check and revert back ASAP.

An issue I have had in the past is ground/earth getting energized by an outlet box full of gecko eggs.  The circuit for water pump so not on RCD and the fault not enough to trip a breaker but put a nasty zap on class-1 equipment.

On a single phase electrical circuit (domestic), is it advisable to have 3 separate ground connections? Or should all 3 be connected together?

What would be the result of having 3 separate grounds on a single phase circuit?

 

Edit

Still concerning the OP. Apparently the electrical circuit has 3 separate grounds. After an electrician came and did some work, now the N-E voltages had dropped to 9V, 19V and 21 Volts. Are 3 separate grounds advisable?

 

Oz regs would absolutely forbid it, UK regs would permit under certain circumstances (that don't apply here).

 

All your "earths" should be linked together to minimise the risk of shock between two "earths", it would also improve the overall earth resistance too and lower the N-E voltage.