On Saturday, 7 July 2018 06:11:39 UTC+1, ARW wrote:
On 07/07/2018 01:35, tabbypurr wrote:
On Friday, 6 July 2018 19:15:57 UTC+1, ARW wrote:
On 04/07/2018 19:45, tabbypurr wrote:
On Wednesday, 4 July 2018 18:42:18 UTC+1, ARW wrote:

I think I have a solution that would please you. Give a bit of time I
have just got in from work. It does away with the 100mA RCD main switch
and only used SP RCDs.

I await with interest. There's one way I can think of to do that, TN-C, but I don't think that's allowed now. Not on T&E anyway, which everything is wired with.

I do apologise for the delay. The World Cup and having to travel to
Durham everyday has left me little time. I also forgot that I had a
suggestion to make because of the number of World Cup matches I have to
watch in the pub.

we know how that works

Get rid of the 100mA main switch and just use a normal main switch with
SP switching RCBOs for all circuits.

I didn't realise one could omit RCD action for N-E faults. It would simplify things.

You still have NE protection

yes, the penny has dropped. The relevant SP RCBO would disconnect the load, thought not disconnect the N-E fault.


Feed the rooms meters off say a 32A or 20A RCBO (depending on what the
socket circuit is powered at) you then either use the fused connection
unit in the room for the lights that I suggested or back feed from the
meter to a 6A MCB in the CU for the lights.

I'll go with fuses otherwise the required CU becomes 25 ways.

The rooms will share a RCD but who cares?

hmm, I'd not thought of commoning the meter supplies.

I was still thinking of one RCD for each meter and each room, I meant
that the lights and sockets in that room would share a RCD

yes will do that, using your FCU strategy


If you want DP isolation for the rooms then fit a cooker switch before
the meter.

no need for that. N-E faults are almost always going to be in appliances.


If only SP RCD action is permitted this simplifies things. Cheers.

It is allowed as long as every circuit is RCD protected and there is no
100mA mainswitch.

That would make life a lot easier. John reckoned DP RCD cover was required for TT - I may have to go reading.

Cheers


NT