Strange earthing arrangement.

Bobble23 · Mar 16, 2017

Hello all.

Had a job today putting in a new kitchen circuit. Plan was to put in a new CU just for the kitchen sockets and lights. When I looked at the cut out, found a Seeboard PME label and the neutral came out of the cut-out into a Henley block then onwards to the meter. So far so good but the Henley block was also the MET and was connected to the incoming main by a ribbon cable TNS-wise. Never seen anything like this before and not sure how to treat it. Anyone ever seen this before? Photo attached.

Thanks.
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westward10 · Mar 16, 2017

It isn't uncommon to see this arrangement at least you have a notice stating the system type. Could do with just one earthing conductor from the service terminal block.

Deleted member 26818 · Mar 16, 2017

That's TN-S converted to TN-C-S.

Had8Lives · Mar 17, 2017

spinlondon said:
That's TN-S converted to TN-C-S.

I agree. I'm guessing the incoming cable sheath has corroded somewhere underground so the neutral has been used as a PEN conductor and the consumer end sheath has been left connected for safety if someone accidentally digs through the cable.