The work is to modify the lighting arrangements in a friends living room.
At present there are four wall lights and the plan is to remove these and at
each location extend the wiring down the wall (recessed) to a new socket
(round pin) just above the skirting for some free standing lamps.

I thought this would be peice of cake, I've just rewired my own house -
until I took the fittings off and saw the wiring arrangements.

The house was built around 1984.
There is a conventional, if old, Wylex consumer unit.
Ring main and power radial circuit cables are conventional twin and earth
(grey outer-old style) A photo of the interior of the box with cables and
some diagrams may be seen he
http://www.bluestar.65704.btinternet.co.uk/

The lighting circuit is something I had not encountered before.
it is not the conventional loopin system -or ISTM, the radial alternative.
The cables are all single, grey outer. Line (phase) red core plus earth
conductor, Neutral being single core black,

The lighting circuit is on one fuse. There are two line cables and two
neutral cables heading off, presumably a pair for each floor.

The arrangement appears to be that the line conductor is looped to each
switch in turn. The neutral cables are looped to each light fitting in
turn. A single cable (red inner) links each switch to its light fitting.

So at each switch there are three single red wires and at each lamp fitting
there are two blacks and a red. see diagram.

Presumably this arrangement makes for economy of cable.
I believe there are no hidden joint boxes anywhere (but I could be wrong..)

Question is...how to go about this job? (hopefully with access from the
floor above)
Can this type of single core cable still be obtained? I somehow doubt it.
So should the whole existing lighting circuit be replaced with a loop in
arrangement using twin and earth?
As the modifications required are only on the ground floor could this be
replaced with loop in and the upper floor be left as it is?

Please advise.

Roger R

Presumably this arrangement makes for economy of cable.

Yes, although this arrangement is now deprecated as it interferes with
hearing aids and might even have implications under the disability
discrimination act.

Can this type of single core cable still be obtained?

No need. At the existing light locations, drop a 1mm T&E down to the socket
and wire it up as if it is was the existing light fitting. As you will need
to bury these joins under plaster, you should crimp the connections (and
probably solder the crimps for good measure!), heat shrink the connections,
then heat shrink the entire bundle. Then bury in plaster (after testing, of
course).

So should the whole existing lighting circuit be replaced with a loop in
arrangement using twin and earth?

That's an alternative, although a little overboard, especially if hearing
aids aren't used, or you have no 'loop' audio appliances.

Christian.

Roger R wrote:
Can this type of single core cable still be obtained? I somehow doubt it.

Yes, I have a reel of it bought a year or so ago at my local
electrical wholesaler. Most wholesalers will stock it or get it to
order I should think.

--
Chris Green

Roger R wrote:

The lighting circuit is on one fuse. There are two line cables and two
neutral cables heading off, presumably a pair for each floor.

Not the question you asked (which Christian has answered fully), but
should you/they ever be temped to separate this into two circuits
(upstairs and downstairs) be very careful you don't create a 'borrowed
neutral' situation where one or more lamps gets live from one circuit
and neutral from the other. With the wiring system in question it's
highly likely that 2-way switched sub-circuits for the stairs and
landing lights take their live feed from one half and return the neutral
to the other. If this is the case it means you can't do the split
without re-wring the hall/landing lights.

And what's that piece of flex doing connected to the lighting fuse?

--
Andy

"Andy Wade" wrote in message
...
Roger R wrote:

The lighting circuit is on one fuse. There are two line cables and two
neutral cables heading off, presumably a pair for each floor.

Not the question you asked (which Christian has answered fully), but
should you/they ever be temped to separate this into two circuits
(upstairs and downstairs) be very careful you don't create a 'borrowed
neutral' situation where one or more lamps gets live from one circuit and
neutral from the other. With the wiring system in question it's highly
likely that 2-way switched sub-circuits for the stairs and landing lights
take their live feed from one half and return the neutral to the other.
If this is the case it means you can't do the split without re-wring the
hall/landing lights.

And what's that piece of flex doing connected to the lighting fuse?

Thanks, and to Christian and tinnews too.
Well the news was better than I'd hoped.

You make a good point about the 2 way hall /landing neutral return.
I believe this is exactly what happens in this case, the landing light is
fed from downstairs but its neutral returns to the upstairs circuit.

It did cross my mind that I could split the lighting if I replaced the dated
wire fuse CU with a new unit, as the existing six circuits is a bit limited.

But I'm in two minds about replacing the CU as (perhaps surprisingly) I
havn't looked in the outside meter cupboard to see if there is any switch
there or if the meter tails can be easily disconnected without calling out
the board for a tempory disconnection. As an interim measure I have
obtained Wylex MCB replacements for the existing wire fuses.

Piece of flex. Feeds an old burgular alarm, fitted by alarm co. for
original owner. (That alarm now deactivated but I leave that there because
the bodge makes a matching set with the piece of bicycle inner tube
bypassing the gas meter ;-)

Roger R

Roger R wrote:

Piece of flex. [...] fitted by alarm co.

Enough said! - but seriously, best to remove it if it's no longer doing
anything.

--
Andy