"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