Andy Wade wrote:
wrote:
Thanks for the reply.
Just a small point here. It has a 40A RCD and two mcbs. On the top of
the casing there are two terminal strips, one neutral and one earth. A
blue neutral wire is supplied that goes from the neutral terminal strip
to the "bottom" of the RCD switch. A small link is provided that
links the RCD with the two mcbs at the bottom of the RCD and mcbs.
The small link is for the live and is called a bus bar. It is three
lugs that slot into the live terminals of all three switches of RCD and
two mcbs.
I'm not familiar with that particular CU, but is sounds like a perfectly
standard layout.
The instructions are not that good. Looking at it, it seems the live
enters the RCD at the bottom as the neutral does too. Is that so?
Well, no. From the description given above the incoming supply must go
to the top RCD terminals because the bottom ones would appear to be the
outgoing feeds to the 'live' (strictly, phase) busbar and to the neutral
bar.
Yes, that appears logical. Live in top of RCD and lives out to mcbs via
a small bus bar. It is the neutral wire from the neutral terminal that
goes directly to the output terminal of the RCD, which has thrown me.
The neutral is not switched through the RCD, although a terminal is
there to switch it on the RCD. I assess that this is to make the RCD
work not being familiar of operation.
The two outgoing final circuits are taken from the top terminal of each
MCB and the neutral bar.
If an mcb has a switching mechanism for both live and neutral (two
terminals on the input and output) can these be used and not take the
neutrals from the common neutral terminal strip? It must be safer to
isolate both live and neutral when the mcbs are off.
The earth bar is common to everything: the
incoming earth (or local earth rod, if it's a separately earthed TT
installation), the outgoing circuit earths and any main bonding conductors.
HTH - but if not, please provide a photo somewhere.
Sorry, I can't get a picture of it just yet. They are on the shelves at
Wickes. ;-) Once again thanks.
--
Andy