16mm SWA

[Jeremy Harris]

If you chose to connect an earth electrode to a TN-C-S supply PEN conductor, then you're adding another intermediate earth to the network, and that earth conductor then has to deal not just with local earth fault currents, but also those from the distribution network itself.

 

The normal CPC sizing calculation uses the prospective earth fault current to determine the current carrying capacity of the CPC (in this case perhaps the steel armour of an SWA cable).  The chances are that the cross section of the SWA wouldn't be adequate for dealing with the PEFC from a network fault, which may well result in the PEN at the incomer rising to a voltage above the maximum allowable of 70 VAC above the local true earth reference (because of voltage drop along the under-sized new intermediate earth CPC).

[richi]

  On 25/04/2019 at 08:40, Onoff said:

Potentially yes.

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He's here all week. Try the veal.