Mike Harrison wrote:

..and of course think about what happens to the earth rod impedance when we get a long hot spell &
the ground dries out...

Well it only needs to muster a feeble 8K ohms to be able to trip a 30mA
RCD.

The thing to bear in mind is that with a PME system and an exported
earth, there is the possibility that you will pass no leakage current in
the case of a disconnected CNE conductor to the property. That can leave
phase voltage on your exposed metalwork indefinately. Hence why
maintaining the equipotential zone in the outbuilding is important if
you are exporting the earth.

--
Cheers,

John.

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