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What earthing arrangement is this?
Former Community Member
The supply is from a private transformer in a four core cable 3ph + n. The cable armour is earthed and connected to the MET. However there is also a green and yellow cable connected to the neutral terminal at the main isolator going back to a the transformer casing. The transformer is only 5 or 6 metres away. I think this must have been intended to make it a tncs supply but seems to me to just create parallel neutral conductors. Or is it tn-s-c-s? I have only been able to go off visual inspection because I could not disconnect the supply..
I feel sure that my brief explanation will be disagreed with but my reference sources are BS 7430 and IET Guidance Note 8. GN8 has very clear drawings of the different earthing systems.
If Kirsty asked me if I could only take one GN to my desert island which one would it be I would say GN8. My luxury would be Kirsty herself, just of course for the convivial conversation to while away the time!
Forget Kirsty and GN8. Take OMS instead. That way you have the expert opinion but, by all accounts, still keep the convivial company.
I feel sure that my brief explanation will be disagreed with but my reference sources are BS 7430 and IET Guidance Note 8. GN8 has very clear drawings of the different earthing systems.
If Kirsty asked me if I could only take one GN to my desert island which one would it be I would say GN8. My luxury would be Kirsty herself, just of course for the convivial conversation to while away the time!
Forget Kirsty and GN8. Take OMS instead. That way you have the expert opinion but, by all accounts, still keep the convivial company.
