In message , John
Rumm writes


Hi John and others for your comments, all appreciated.



Your experience adequately illustrates why the "whole house" RCD
arrangement is deprecated - it was never a great idea, and the march of
time (and things with leaky input filters) has only made the
limitations more apparent.

Indeed, filtering is all well and good, but causes lots of other issues.




So is it a practical idea?

Practical - yes certainly. Its the "Rolls Royce" solution that gives
the best possible discrimination in the even of an earth fault.
Obviously its more expensive than other options.


Although cost is, obviously, a factor I feel it would be worth it to
only lose one circuit in the event of a fault. I can only see things
getting worse with more electronics making their way into homes and so
more filtering, unless of course they are manufactured in a well known
far East country where the various components are very obviously missing
from the PSUs by the empty holes in the PCBs, Maybe that is an
advantage of some of these dodgy imports??? There is no leakage from
the filtering because they omitted it to save 5p per unit. But that
is another discussion for another day...



Split load does not have to mean a 50/50 split. Some 17th edition CUs
may have say 4 RCDs and some unprotected (aka "high integrity") ways as
well (for feeding circuits that meet the requirements for not being RCD
protected). You can also arrange the split in various combinations of
ways as suits your application.

Yes, sorry, badly phrased on my part there. I should have just said
split.



Yes I am competent to do it, just nervous that I may have missed a
fundamental flaw in the idea.

If it matters the CU is a Crabtree Starbreaker with a single 80A
switch/30mA RCD and 14 MCBs and a DIN mount bell transformer.

Without checking I don't know if you can get single module wide RCBOs
for this enclosure (and if so if there is really enough space to wire
them). You may find you need to replace the enclosure as well.

If no one puts me off the ideas I'm having then checking physical sizes
is next on the agenda. Hopefully in the same enclosure, I'm not too
worried about doing that. But if it came to a new enclosure then the
panic will set in! Although there is plenty of space behind the CU, I
would not look forward too much to replacing it.


Apart from the cost, am I crazy?

No, although you probably ought to look at some pragmatic options. You
may find a combination of several RCDs covering a two or three circuits
each, plus a smaller number of RCBOs would make for a system that is
equally effective, but also leave more money to spend on improving
other aspects of the system.

To get a quick, ball park, idea of cost I checked on TLC's web site
earlier and although scary I managed to not quite fall off my chair. So
if it does come to it I'm hopeful to find a slightly cheaper route.

I'm quite happy with the rest of the electrics in the house, all bar one
slight anomaly which I can easily sort out, just waiting on a round tuit
appearing.


--
Bill