Lurch wrote:

On Mon, 09 Jul 2007 08:32:40 +0100, Terry Pinnell
mused:


As all these circuits were off it is likely that the RCD operated.
This would have removed the supply from all the circuits on the RCD
side of the unit, but not those on the non-RCD side.

The only switch I reset in the Crabtree unit was the RCD one
controlling the immersion heater.

The RCD controls electricity to all the MCBs on the RCD side of the
unit. It does not just control the immersion heater.

When you have read up the differences between MCBs and RCDs and how
they are arranged you may be able to give us more precise
information.

OK, thanks, I'll do some more studying and come back. Meanwhile I've
taken a photo and labeled it as per my previous post.
http://www.terrypin.dial.pipex.com/Images/CU-1.jpg

(BTW, MCB #5 on the RCD side is disconnected.)

Also, I realise that "the RCD controls electricity to all the MCBs on
the RCD side of the unit. It does not just control the immersion
heater." (That of course is why everything I mentioned lost power.)
But think I was correct in my recollection that "The only switch I
reset in the Crabtree unit was the RCD one."

Still thing there's some confusion here but if you only reset the
'RCD' controlling the immersion heater then something is wrong
internally to the CU.

Can you amplify on that please? Why would it imply that?

If you meant the main RCD had tripped

No, just the immersion switch on the RCD side, the one I labeled #1 in
the photo I posted.

then it
could have been anything that tripped it. Was the immersion heater MCB
definitely on immediately prior to the tripping of the RCD
and everything losing power?

Yes

Were you doing anything at the time?

Authoring a DVD on my PC ;-(

--
Terry, West Sussex, UK