Hi,

Thanks for your reply.

Which DNO do you do your work with? Wonder if their requirements differ from
mine?

BigWallop coughed up some electrons that declared:

snip

Putting anything else in line will cause problems. The head fuse will
take
care of any phase short.

That would be the common sense and technically sound theory.

It's when EDF/SEEBOARD tell you that they want something withing 3m of the
origin, but fail to clarify what "somethign" is... I've heard of people who
fit DP isolators and people who fit switch-fuse units.

As there is a disparity of opinion on this specific point, I've just emailed
EDF Technical requesting their specific requirements (if any). They usually
reply within a day. No disrespect intended ;- But there's been a lot of
different opinion on this specific point.

When you consider that a short on the SWA will
not have adverse effect on anything passed the new CU, then it's fine the
way it
is. The RCD will protect the rest, if anything does happen between your
consumer unit and the supply. If anything else were needed on that end,
would it not be there already? If you are so worried, then install
another
cutout fuse after the meter and before the RCD. Now it's getting into
silly
zone again. :-)

One thing I'm lost on, is why have an RCD (RCCB?) if we are satisfied that
the circuit will disconnect in less than 5 seconds (by my calculations, it
will disconnect in 3 seconds at worst) and if we are no longer concerned
about touch voltages.


I've got that bit sorted - using a Hager JK series industrial metal board
with enough space to terminate the SWA into directly. Also takes RCBOs
without being cramped


This is the bit. I would advise you to make provision for a separate box
to
terminate the SWA and allow connection of tails to the CU from there. An
ABS box with three CEFCO terminal blocks inside, allows you to extend to
another set of tails in future. That way you have flexibility to extend
the final circuit to other installations, without touching the consumer at
all.

Example: You want to install a separate CU for external lighting at a
later
date. A box will allow you to take other tails off without disrupting
everything. But that's my opinion.


It's a good idea, though I'm personally not keen on multiple adjacent CUs.
My leaning is to leave enough spare ways that it will never be aproblem

Cheers

Tim