In message ,
(dmc) wrote:

In article ,
Gnube wrote:

Why would one not just get on with it and RCD the hell out of
everything at the source in one go? (he /perhaps/ naively asked!)

Fire downstairs melts eltrical insulation and causes an earth fault.
Family upstairs plunged into darkness as the lighting circuit is
tripped out...few extra seconds collecting the kids could make a lot
of difference.

Or, RCD on consumer unit trips on the day that you leave for 3 weeks
holiday - just as you shut the door. You return to a very defrosted
rather unpleasant freezer...

Opposite - it trips mid winter while you are away for a bit. Lack of
heating causes burst pipes and floods the place...

I'm sure other more experienced bods on here can come up with better
solutions.

From what's been said, they do a lot of good, and you can't put a
price on the safety they offer, why _not_ just go for it then?

Just a couple of ideas. I can't really talk - my whole house is currently
on one RCD at the CU and so suffers from both of the above problems.


One trusts you've not had a fire :-)

This is why whole-installation RCDs are no longer recommended.
"Discrimination" is the name of the game and the ultimate is to have as
many RCDs as you do outlets by using sockets with inbuilt RCDs.
Very expensive and probably completely unneccessary. Slightly
less expensive is to protect individual circuits by using combined
RCD/MCBs.

A common (and much cheaper) compromise is to use a "split" board and
leave the lights unprotected while RCD protecting sockets and the like.
If the RCD trips, all sockets will go off, but the lights won't. People
with earth rods may also have a slower-acting higher-trip-current RCD on
the whole installation such that lights are also protected.

If you are worried about the fridge and freezer then the obvious thing
to do is to put them on the unprotected side of a split CU, but if you
run them from simple wall sockets you are probably breaking the letter
of the regulation which states that all sockets "which may reasonably be
expected to supply portable equipment for use outdoors" should have RCDs
fitted; if the fridge socket is the closest to the back door, someone
*may* use that for the lawnmower. Answers in this instance involve the
use of fused connection units (i.e. hardwire the fridge in without a
plug), unusually-shaped plugs, and making sure the fridge socket has RCD
protection completely separate to that on other sockets.

Hwyl!

M.

--
Martin Angove (it's Cornish for "Smith") - ARM/Digital SA110 RPC
See the Aber Valley -- http://www.tridwr.demon.co.uk/abervalley.html
.... Thesaurus: ancient reptile with an excellent vocabulary.