sandydog wrote:

John, I've had a look at the switch downstairs (which also has 3 cables
running into it.) This switch has a connector in it with 6 holes
(sorry about the terminology!) There are 2 commons. Both of these

OK - that is a two gang, two way switch - i.e. two separate two switches
built into one face plate. One no doubt for the light in the room, and
the other for the light upstairs.

have a red, but the bottom one has a loop of red (independant of
cables) going from the common to the 1 way switch hole in the centre,
which has a blue wire going into it. By the way, one of the cables has
a yellow wire - no blacks in sight.

One of the cables sounds like a three core and earth (that will be the
one with red, yellow, and blue wires). Normally you would just run this
to the other switch - but something different has been done here.

Have a look at the diagrams he

http://www.diydoctor.org.uk/projects...d_switches.htm

It might be worht looking at the connections at the light fitting
upstairs in the loft to see if that is where the three core and earth
has been taken.

Unfortunately I don't own a multimeter, but I don't mind working with

Might be worth picking up a cheap £5 jobbie from a local Maplin, they
often come in useful for lots of things.


--
Cheers,

John.

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