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What earthing arrangement is this?

Former Community Member
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..
Parents
  • No. The OP says the installation is TN-S as per the diagram in BS 7671.  I am assuming the neutral and earth are bonded at the transformer. I am still concerned why a green/yellow is connected to neutral at the incomer?
Reply
  • No. The OP says the installation is TN-S as per the diagram in BS 7671.  I am assuming the neutral and earth are bonded at the transformer. I am still concerned why a green/yellow is connected to neutral at the incomer?
Children
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