Hi, I'm looking for some help with a wiring problem I have encountered
in the house we've just bought. I should add that I'm a reasonably
competent electrician, yet this one has me puzzled!!

We have a lounge ceiling light with rose, with a standard 1 way switch
attached. When I turn on the switch, the light works! Inside the rose
the connections appear to standard. LNE in, LNE Loop through, the
switch cable which has been wired with Twin & E so that the switch box
is earthed, and obviously a LNE to the actual light fitting.

At the lIve terminal in the switch there is another L going off to god
only knows where, this live comes from a separate Twin and Earth cable
of which the N has just been cut short, and the E goes to the earthing
point.

NOW for the fun bit.

We have an outside light which is switched by a fused switch next to
the front door. This has a Twin and Earth coming in, with a Twin and
Earth going to the fixture- no loop through, this seems to just be a
spur off the dowstairs lighting ring.

When the LOUNGE SWITCH is ON, there is 0v going to the OUTDOOR LIGHT
SWITCH.
When the LOUNGE SWITCH is OFF and the OUTDOOR SWITCH is OFF there is
240v at the OUTDOOR LIGHT SWITCH.

When the LOUNGE SWITCH is OFF and the OUTDOOR SWITCH is ON, there is
120v at the OUTDOOR SWITCH, and 120v at the LOUNGE LIGHT & SWITCH!!!!!
i.e both bulbs are at half power, even though the lounge switch is
OFF

Please help. I've given up trying to draw parallel and serial circuits
because I can't work out how the 1 way switch in the lounge can in
effect turn off or on the power in the Outdoor switch?

Many thanks for any suggestions.


James