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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
  • i see your point, but everyone calls it TNC-S that I have come across. which probably means PNB is a better term for it. 


    Usually, the multiple earth rods and tape is used to explain why its TNC-S 


    its not combined though, Ill have to check but I think its got a link between N and the transformer frame in the spreader box too
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  • i see your point, but everyone calls it TNC-S that I have come across. which probably means PNB is a better term for it. 


    Usually, the multiple earth rods and tape is used to explain why its TNC-S 


    its not combined though, Ill have to check but I think its got a link between N and the transformer frame in the spreader box too
Children
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