I've just installed a fancy new 4-gang all-singing all dancing dimmer
The wiring diagram for this is at http://tinyurl.com/qdeo7e4
20Instructions%20819.pdf) and it shows the switch wired 'L' to the terminal
marked 'live' and 'N' to the one marked 'load'; and shows the light bulb on
the 'N' side.
Now - I'm a bit confused here... the neutrals in my switch cables are
sheathed at both end with brown sleeving, specifically to denote that both
wires are actually live, surely? Does it actually matter which goes where?
I'm putting the bedroom floor back down this afternoon (which is where the
wiring box is for the lights!) so would appreciate knowing whether I need
to rejig things...
It shows the permanent live coming into the dimmer switch (could be from
the rose or from a junction box), the load (switched live) going out to
one side of the bulb and the neutral going to the other side of the bulb.
The topology of the actual wires may vary.
not neutrals, just because they're blue
the brown sleeving is to indicate they're lives.
I suppose it's normal for the actual brown to be the permanent live to
the switch and the blue sleeved in brown to be the switched live (load),
but it's probably allowed to be the other way round at the risk of
confusing someone in future.
Indeed I was... I very quickly sorted the wiring - ie, swapped over a
couple of wires - which would have been a total bitch to have had to do
once floorboards/carpet/double bed were back in place!! Many thanks.
Your confusion seems to be on account you've not realised that the
circle with a cross is the symbol for the lamp itself. The brown
sleeved blue wire connects the live side of the lamp to the switch
whilst the other lamp connection goes to the 3 way neutral terminal in
the ceiling rose.
If the terminal marked "S-Link" remains unconnected to anything, you
might be able to get away with reversing the Live and Load terminals
but I'd recommend against trying this 'experiment'.
The normal practice with lighting wiring is to daisy chain the
lighting circuit cabling from the CU to each ceiling lamp rose fitting
in turn with a switch drop cable for each fitting being wired from the
ceiling rose to that room's light switch.
If more than one ceiling rose is installed per room and intended to
be switched from the one switch, the additional ceiling roses only
need to have the lamp connections wired in parallel back to the one
connected to the switch drop cable. Controlling a lamp or lamps from
more than one switch is an extra complication that I'll refrain from
going into right now.
A purpose made switch drop cable would, ideally have its own colour
coded wires (perhaps a blue with brown tracer colour, banded or
stripe(s) to indicate the switched live and brown for the permanent
live from the ceiling rose terminals along with a safety earth
conductor to facilitate earth bonding of any metal finish switch
plates). However, it is normal practice to simply use the normal FT&E
cable for such switch drops and fit a brown sleeve over both ends of
the blue insulated conductor to indicate that it is a switched live as
opposed to being a permanently connected neutral.
Alternative wiring arrangements may be used involving additional
junction boxes. This is typically done with more complex lamp wiring
arrangements usually involving multiple ceiling roses or even
additional wall lights but the circuit remains topologically the same
even if it seems physically more convoluted.
In short, connect the brown(red) to the LIVE terminal and the brown
sleeved blue(red sleeved black) to the LOAD terminal. The green/yellow
sleeved bare copper earth wire is usually connected to an earth
terminal (even if it's just a brass terminal post in a plastic back
Most likely there will be a total of four switch drop cables going
into the switch plate backbox so you will need to wire each dimmer
switch to its appropriate switch drop cable.
This doesn't preclude the possibility of there being a smaller number
of cables in use eg flat triple & earth and flat twin & earth cables,
a total of five wires, using only one of the wires as common live this
leaves the remaining 4 wires to act as switched lives routed to the
appropriate light fittings via additional joint boxes in the ceiling
As long as you connect the brown wire to the LIVE switch terminal and
the brown sleeved blue wire to the LOAD switch terminal, everything
should be fine.
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