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TNCS (PME) in food factories where there is an area deemed Atex (expolsive)

SW1
Is it acceptable to use TNCS (PME) for supplies to food factories where there are isolated areas deemed Atex (explosive)?

With PME the neutral & earth are linked together before the main ACB and then it is taken in a single cable back to the main star point of the transformer, and then to grounded.


Apparently petrol stations can not be PME.  ?


Any thoughts please?
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    gkenyon:

    As mrf says, the neutral and earth must not be combined in the hazardous area.


    Also "TN-C-S" isn't always PME.


    The risk considered for petrol filling stations is that of diverted Neutral currents from the portions of the system where the neutral and protective conductors are combined, through protective conductors. This is far more likely with a public PME supply than the sort of TN-C-S (transformer to main switcboard link) arrangement you are describing, provided that the distance is short.

    So provided the designer of your system is happy that won't happen, as mrf implies, it may well be acceptable.




    Excellent makes sense -  Cheers Graham

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    gkenyon:

    As mrf says, the neutral and earth must not be combined in the hazardous area.


    Also "TN-C-S" isn't always PME.


    The risk considered for petrol filling stations is that of diverted Neutral currents from the portions of the system where the neutral and protective conductors are combined, through protective conductors. This is far more likely with a public PME supply than the sort of TN-C-S (transformer to main switcboard link) arrangement you are describing, provided that the distance is short.

    So provided the designer of your system is happy that won't happen, as mrf implies, it may well be acceptable.




    Excellent makes sense -  Cheers Graham

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