Pefc

[steve.t.]

Hi
just doing some tests on a tt instillation, will be doin 2392 shortly. getting 1A on PEFC, can anyone explain this. the Ze is 174.
Any help would be great thanks

 

[IQ Electrical]

Hi
just doing some tests on a tt instillation, will be doin 2392 shortly. getting 1A on PEFC, can anyone explain this. the Ze is 174.
Any help would be great thanks

If you think about how you are deriving PEFC on a TT system, by Ohms law, the value will be quite small.

In your case with an Ra (not Ze) of 174 Ohms, a calculated PEFC would be 230/174 = 1.32 Amps so not too far away.

Of course PSSC will be much higher and will therefore become PFC.

 

[DurhamSparky]

Good Response IQ...

oh and with a rod reading of 174 i would be slightly concerned about proximity to the 200 mark...!

 

[steve.t.]

it was 280 so another rod was put in

 

[DurhamSparky]

i would consider going deeper rather than more rods..! get a 3/4 inch with couplers!

 

[IQ Electrical]

Yes, depth is king, I'd take a deeply driven rod (oooh matron!) with an Ra of 500 Ohms over a short rod at 100 Ohms, reason being the deeply driven rod will be virtually immune to soil drying/freezing so is highly unlikely to approach the true maximum of 1667 Ohms (assuming 30mA RCD protection)