Matt wrote:

It's quite true that if everything is (and remains) in good condition
you can go for years and years with a single whole-house 30 mA RCD and
have no trips. The arrangement still doesn't comply with 314-01-01
though because "inconvenience in the event of a fault" hasn't been
minimised.


Inconvenience on the death of the occupant really ought to be a
greater consideration

It is. Falling down stairs and breaking your neck is considered to be a
far more likely inconvenience than melting your kettle cable.

If the installation is up to scratch then
even a 10mA RCD shouldn't cause any problems due to "nuisance"
tripping.

My computer setup on its own would probably trip that...

adjacent to other sound and properly earthed metalwork. A tripped RCD
and having to reset the timer on the video is I would expect
preferable in most peoples eyes (with the obvious exception of the
IET) to an identification visit to the mortuary.

To an extent this is a moot point. In most installations done today, it
is a fairly safe bet that most if not all the socket outlets will be RCD
protected. Rumour has it that the 17th edition of the regs will make
this standard practice. Remember also that the original question was not
about a socket outlet, but a fixed and hard wired appliance.

The only drawback of the RCD tripping rather than the MCB is that
discrimination by the way of direct indication of the circuit
concerned is not provided.

and/or you fall and break your neck...

The RCD is perfectly capable of handling
this type of duty. That the occupant of the premises noticed the radio
in the kitchen go off when they accidentally made contact between the
hob and the oven ought to be a reasonable indication to anyone
investigating further.

I still maintain, as do many others that on domestic premises with
PME, RCD protection at around 30mA for the whole installation,

If you mean the *same* 30mA (i.e. one RCD shared between all circuits),
then that is neither practical in most cases, or desirable in any. If
instead you mean that each circuit should have RCD protection at a trip
threshold no higher than 30mA (e.g. RCBOs or multiple CUs), then it is a
more plausible suggestion. (although not warranted by the accident
statistics it would seem)

together with maintained lighting is the safest for the user. If
maintained lighting is not/cannot be provided then lighting only on
the non RCD protected circuits is marginally acceptable. Everything
else,

Including fire alarms?

especially internal sockets located nowhere near the garden
(such as in the kitchen, children's bedrooms) AND supplies to
appliances with exposed metalwork should go on the RCD protected side
of a split load consumer unit.



--
Cheers,

John.

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