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ARW

On 04/05/2019 13:35, wrote:
Incidentally I can buy RCBOs that have a short flying white wire which is a functional earth.

As I understand it, if there was ever a loss of earth, the RCBO then trips.

So can such an RCBO be used in a TT install as the electrode resistance will be much higher than a electricity board supplied earth via what I know as PME in old money

The fly lead is there so that the RCD part of the RCBO will still
function if the neutral is lost.

They are fine to use on TT supplies.

And that reminds me of an NICEIC inspections I had. The inspector chose
a house where we had added circuits to the CU using RCBOs and there were
already existing RCBOs. We did not over sleeve the white fly lead with
green/yellow sleeving but the RCBOs that were already installed were
oversleeved.

The inspector asked "Why did you not over sleeve the fly lead?" and I
replied "Because it not an earth it's a functional earth and it's colour
should be white". That was the correct answer.

--
Adam