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Unfused spur.

Zoomup
Hello All,


Could an unfused R.C.D. protected spur, from a complient ring final circuit, supplying a single outdoor socket via 1.5mm2 6242Y cable of max. length 300mm through a brick wall from an indoor socket outlet be considered compliant?


Z.
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  • 0
    AJJewsbury:
    Zoomup:

    If the Ra is about 200 Ohms an L to E fault current is restricted in magnitude. And the 30 mA  R.C.D. is still very swift in disconnecting the fault. 


    Z.


    If the earth fault current is limited then I agree there's far less of an issue. Ra alone doesn't guarantee that though - bonding to metallic water or gas supplies can re-introduce a low impedance path (via neighbouring TN installations), so potentially bring prospective earth fault currents back up to TN levels.


       - Andy.




    Yes I suppose that the water pipe, if metal, could affect things. I did not check to see if it was plastic or metal. But I know that there is no mains gas as the owner said that he used bottled gas. He could not have a big under-lawn gas tank installed as the high water table would make it float and it could not be installed.


    Z.


Reply
  • 0
    AJJewsbury:
    Zoomup:

    If the Ra is about 200 Ohms an L to E fault current is restricted in magnitude. And the 30 mA  R.C.D. is still very swift in disconnecting the fault. 


    Z.


    If the earth fault current is limited then I agree there's far less of an issue. Ra alone doesn't guarantee that though - bonding to metallic water or gas supplies can re-introduce a low impedance path (via neighbouring TN installations), so potentially bring prospective earth fault currents back up to TN levels.


       - Andy.




    Yes I suppose that the water pipe, if metal, could affect things. I did not check to see if it was plastic or metal. But I know that there is no mains gas as the owner said that he used bottled gas. He could not have a big under-lawn gas tank installed as the high water table would make it float and it could not be installed.


    Z.


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