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Rules regarding buried earth cables

Richard Cyphus

Nothing I can see in the regs differentiates between an earth cable and T&E when it comes to the rules regarding buried cables.

But what I can't work out is why it's OK to run a T&E in EARTHED conduit outside of safe zones, but NOT an earth cable, since from the perspective of a nail/screw penetrating into the wall and catching the cable or conduit - there is no difference.


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    Either I have misunderstood or this is an odd question.

    if you grab hold of the live nail trust me, you will feel the difference ;-)

    The idea of the earthed conduit is that the nail is already earthed to the conduit or cable armour, before it strikes the live core, so firstly the peak exposed voltage is reduced (being the voltage division of the resistances of  the live path to and the earth path from the point of fault and secondly, the exposed voltage is not there for long as the high current operates some sort of ADS on the supply side.

    The minimum sizes of lone earth wires are larger than those in cables like T and E to reduce the risk of being cut through by such abuse.

    Mike

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  • 0

    Either I have misunderstood or this is an odd question.

    if you grab hold of the live nail trust me, you will feel the difference ;-)

    The idea of the earthed conduit is that the nail is already earthed to the conduit or cable armour, before it strikes the live core, so firstly the peak exposed voltage is reduced (being the voltage division of the resistances of  the live path to and the earth path from the point of fault and secondly, the exposed voltage is not there for long as the high current operates some sort of ADS on the supply side.

    The minimum sizes of lone earth wires are larger than those in cables like T and E to reduce the risk of being cut through by such abuse.

    Mike

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