Earthing questions

[Timlouth]

I work in a place where most of our equipment is supplied by generators. As a result earthing is achieved by connection back to the generator and it's earth/neutral link.
For some reason all the generators and equipment supplied have also got earthing electrodes (rod types) fitted. I work in the desert and, though I haven't tested these earthing arrangements, I can't imagine they are too efficient. Why have they been used when the earthing back to the generator should be sufficient? Any ideas anyone?

One of my bits of equipment is mains fed and there is over 3 volts between the neutral and the earth. On the generator fed systems this is never the case as the earth and neutral are at the same potential. Is this accepteble or should I tell my electricity supplier that he may need to investigate it further?

Any advice gratefully achieved.

Many thanks.

Tim

 

[NotHimAgain]

The generators will often need an earth reference just like the supply transformers in a UK sub-station. This is to provide for the detection and disconnection of any fault to earth (i.e. a bare conductor coming into contact with the ground or similar).

If you are operating in a desert it is unlikely that these electrodes will be effective. However, it is equally unlikely that a fault to the "ground" would cause any problems.

On the voltage question - this can depend on many factors - without much more detail I could not give an opinion.

 

[pompeygit]

Also the fact that both the generators and the equipment have electrodes suggests that the installation is struggling to get a good earth. Also the 3v potential between earth and neutral could be caused by a number of factors. Earth leaky equipment like air conditioning, water heaters, fridges, IT equipment, or maybe even the impedance of a PEN conductor

 

[pompeygit]

I would hope that all circuits are RCD protected under such arduous conditions