In article ,
Tim W writes:

I'm putting 4 rings in my house. 1.5 for the kitchen/diner (the other 0.5
serves utility and one bedroom), one for the rest of the ground floor and
one upstairs. It's not necessarily the case that the loads demand it, but
it's geographically convenient and povides sensible seggregation in the
event of one circuit tripping (ie I don't lose the whole house).

Last couple of kitchens I've done (16th Ed regs), I put two rings
into each, one RCD protected for the accessible socket outlets,
and one non-RCD protected for stationary/fixed appliances such as
fridge, freezer, oven, boiler, etc, which you don't want sharing
an RCD with anything else, and don't merit one themselves.

Thus far, I always used 30mA RCBO's per circuit (or 10mA in a
few cases), but never a single RCD covering multiple circuits.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]