Terry Pinnell wrote:

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.

So, let's get this straight:

The MCB in position 1 on your CU (just that and nothing else) tripped.
In doing so it cut power not only to the immersion heater, but also to
your computer and some other appliances?

To restore normal operation you reset that single MCB for the immersion
heater, and did not need to touch the RCD itself?

If this is the case then you have a serious wiring error that needs
immediate attention.


--
Cheers,

John.

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