On Mon, 9 Aug 2004 21:28:10 +0000 (UTC), "Rick Hughes"
strung together this:

Wrong here I'm sorry I referred to lighting circuits not to light bulbs,
(but it could just be the sequence you are reading mail in) ... floreescents
are earthed and it is these that typically give the nuiscence tripping
reports, again an RCD would actiuvate not an MCB as there is an imbalance
but no overload.

Ah, with you now. Not heard that one too often, the lightbulb scenario
I presentede is a far more common aoccurence so I assumed that it was
that you were referring to.
TBH, all circuits are likely to trip at some time or other. I don't
think the technical basis of your plans is particularly sound. I think
with a bit more electrical knowledge and experience you would see this
whole ting as a 'fiasco', (as I do)!

The 3 classes of protection are deliberate .... unprotrected, fire
protection and life protection - all defined separte calssses of
protection - exactly what I want on this project.

Do you have a comment on my qusetion ? I would be interested in your answer.

Q was - To RCD protect a cooker and immersion or not .... the regs do not
require it, but that may not be best practise.

I've answered that, twice. Only you can decide how much additional
protection over and above the regs you require.
I think from what you've said you'd be better off with RCBO's for all
final circuits, then all circuits have their own RCD and MCB so any
earth fault or overload will affect that circuit only.
--

SJW
A.C.S. Ltd