Wiring a 3 gang two way light switch

[dipstick]

The light switch has connections: A1, A2, B Com, C1, C2, on the top and A Com, B1, B2, and C Com on the bottom. a four core cable is connected: red to C1, Blue to C2, yellow to C Com, and a bare copper to the metal box earth point.

The four core operates a two way ceiling rose correctly.

There are three other cables which are taped up. They are all "red plus bare copper" pairs. They were "provisions for future connections left by the original sparks.

Outside, sticking out of the wall above the back door, there is one "red, plus bare copper" pair, and one single core black.

I have an outside lamp with PIR and I wish to connect it to the light switch. I suspect that one of the three pairs in the switch is the same as the one outside akthough I do not know which one. Also I do not know where the external black goes to.

In very simple terms, what do I do next (polite suggestions please).

 

[il78]

Me reckons the two red conductors in the switch (3gang) need to go into
A com & A1 (but you need to check with a tester, as you may have loop / borrow from the live already in the switch, the 2 reds might both be switch wires)

Is there another light apart from outside that is not connected?

Otherwise:

Connect the PIR fitting as instructed

Red - Live
Black - Neutral
Copper - Earth

You will have to leave the switch in the on posistion to keep the PIR working....

Oh yes.....turn the power off first...

 

[dipstick]

Many thanks IL78.

After SuperDon (a neighbour with previous) arrived, we discovered that none of the three red / copper pairs were live. So we traced the pair that fed the outside light, and strapped a live from the existing switch.

So....in the switch... the strap went from C1 to A Com, and the right Red went to A1, and the corresponding copper, with a sleeve, went to the box earth. In the outside light: red to brown, black to blue, copper to green/yellow as you'ld expect.

Everything worked a treat, and we celebrated with a few glasses.