Roger Mills wrote:

In an earlier contribution to this discussion,
John Rumm wrote:


Cheapest (but not smallest) option may be:

http://www.tlc-direct.co.uk/Products...0slash80N.html
http://www.tlc-direct.co.uk/Products/CM7106B.html
http://www.tlc-direct.co.uk/Products/CM7120B.html



OK, after a lot of deliberation, this is the one I've gone with - and the
bits have just arrived.

A couple of questions - surprise, surprise!

The live busbar is supplied in one piece. I'm sure I've read somewhere -
though it ain't in the instructions supplied! - that I need to cut this into
two in a place appropriate to how many ways I want protected by the RCD. Is
this correct.

This is often the case. IIRC it was with the last contactum split load
CU I fitted... (thinking about it I remember it because I forgot to take
a hacksaw!)

There is already a live cross connection between the output of the main
switch and the input of the RCD. I assume that the part of the busbar
serving the non-RCD-protected ways needs to connect into the same output
from the main switch?

Yup, check the wiring carefully though, making sure it is correct and
tight! (I had a contactum CU where the wiring as supplied was seriously
wrong!)

[Next bit I am doing this from memory - so if it does not make sense
when you look at your one, ignore me!]

Assuming you are going with the main switch on the right, and the RCD in
the centre, then the phase and neutral from your SWA run into the top
terminals of the main switch (phase on left). The bottom right of the
main switch ought to have a neutral connection to the non RCD neutral
busbar - there may also be a connection to the top neutral on the RCD
(or that will more likely come from a wire on the end of the first
nutral bus bar). The phase (bottom left) of the main switch ought to
connect to the main phase busbar AND the flylead to the (top left) phase
input of the RCD. The phase output of the RCD (bottom left) should then
feed the other bit of phase busbar, while the bottom right of the RCD
should have a lead to the second neutral busbar.

Any of that seem plausable?

As supplied, neither the main switch nor the RCD will turn on. Is this
because they need a mains supply before they will operate, or are they duff?

It is normal for a RCD, but not a switch (assuming it is just a bog
standard two module wide switch). The Switch should snap from one side
to the other, with a bias toward "off".

Finally, bearing in mind that this is an insulated rather than metalclad CU,
what's the best way of terminating the incoming 6mm SWA cable? There's no
obvious place on the casing to fit an SWA gland. Do I need a junction box
next to the CU for this purpose?

Personally I would drill a suitable sized hole to take the SWA gland to
make it neat and tidy. Then use a ring terminal on the gland to pick up
the earth from the shield, and take that to the earth busbar (along with
the third core if you have one!).


--
Cheers,

John.

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