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T-N-S or TN-C-S ???? Help pls.

MrFox

I have been asked to replace a consumer unit. All seems fine, and the incoming earth seems to be on the sheath of the incomer, so, TN-S. But, it says TN-C-S on the previous EICR. Did that spark make a mistake or is there something here I'm missing? Also, do we presume the Line and Neutral are in that cable going to the meter??? I hope so… Thx in advance.

b13f6e8ca4a8740403be79c8a45433ce-huge-tns_or_tncs.png
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    The cable to the meter is  concentric anti-tamper cable. Think like jumbo version of TV antenna coax, but with better terminations. Common in places with history of electricity theft, and some meter installers just like to use it in all cases they do.

    It does present as TN-S. 

    It may be (who is the DNO) that the DNO advise to treat TN-S as TNC-s as they have a street main replacement policy that means sooner or later it will be. 

    UKPN for example advise this.

    If you are unsure, tick TNS, but in terms of bond size etc, treat as if it has to be TNC-s ready, then you get the best of all worlds.

    Mike.

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    The cable to the meter is  concentric anti-tamper cable. Think like jumbo version of TV antenna coax, but with better terminations. Common in places with history of electricity theft, and some meter installers just like to use it in all cases they do.

    It does present as TN-S. 

    It may be (who is the DNO) that the DNO advise to treat TN-S as TNC-s as they have a street main replacement policy that means sooner or later it will be. 

    UKPN for example advise this.

    If you are unsure, tick TNS, but in terms of bond size etc, treat as if it has to be TNC-s ready, then you get the best of all worlds.

    Mike.

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