Terry Pinnell wrote:
Hasty correction!

---------
OK, but this is where I'm still obviously being dense. Given a normal,
properly working setup, can you please summarise what *should* happen
and which switches in the main CU should open for each of the
following events:

1. A device on the LH side (non RCD) develops a short.

My assumption: it opens that MCB, but power remains for all other LH
and RH (RCD) circuits; and it probably blows a plug fuse too.

(The 'main LH switch' is MANUAL only, as you pointed out.)

--
Terry, West Sussex, UK