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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..
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  • Former Community Member
    0 Former Community Member

    John Peckham:

    No it is TN-S. So any bonding can be 1/2 the CSA of the earthing conductor subject to a minimum of 6mm and need not exceed 25mm.



    Have you had a change of heart then, John ?


    Regards


    OMS 
     

Reply
  • Former Community Member
    0 Former Community Member

    John Peckham:

    No it is TN-S. So any bonding can be 1/2 the CSA of the earthing conductor subject to a minimum of 6mm and need not exceed 25mm.



    Have you had a change of heart then, John ?


    Regards


    OMS 
     

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