Switch Wiring

[alexh75]

I should point out first of all that I have looked through the Wiki for this forum, but just can't seem to find the answer.
Whilst decorating, have taken a light switch off the wall. Unfortunately, a couple of the wires have dislodged, and I can't work out how to wire everything up again.

On the switch I have 6 terminals
COM (x2)
L1 (x2)
L2 (x2)
The 2 COM terminals are linked by a jumper wire.

I have 2 red cables, and a black cable
And an Earth cable (hasn't moved)

The way it worked before -
Left switch operated light
Right switch operated extractor fan (but only if light switch was on).

Can anyone assist please?

Thanks
Alex

 

[ericmark]

L2 (x2) Not Used.
COM (x2) light.
L1 (x2) one will be line other will be extractor fan.
As to colours can't help to find which is which will need ringing out.

 

[alexh75]

thanks
ringing out?

 

[PrenticeBoyofDerry]

Do you have any testing equipment that can safely test for voltage and continuity?
The link between the coms would normally be connected to permanent live, but if you desire the same set up as before with fan only switching when light is on this would likely go to L1.
From here without testing it would be pure guess work, but there can only be a small number of combination, testing the circuit would help prevent any assumptions and guess work.
Does a pair and earth of the cables, enter the switch box in the same grey sheath? this could help.

 

[alexh75]

I don't have any testing equipment at all I'm afraid.
Attached are some pics of how it looked (I think the red wire is in the original correct position, and the jumper wire shown has definitely not moved).
Sorry for the quality of the pics.
Thanks
Alex

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[PrenticeBoyofDerry]

I'll a stab at the connected red is possibly the switch live to the fan and the twin and earth (Black and Red) are perm live and switch live to the light.
So if you still want the fan to only switch when light is on, try this.
To the opposite gang of the connected red cable, put the red in to L1 and the black to com (with the link/jumper in place]. See how that functions.
I assume/hope you have isolated this circuit!

 

[sparkwright]

On these old MK switches, you use COM and L2 for one way operation.

 

[PrenticeBoyofDerry]

On these old MK switches, you use COM and L2 for one way operation.

would it make a functional difference?

 

[sparkwright]

It would work upside down, that is all.

 

[alexh75]

Thanks Prenticeboy, like in the attached picture?

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• alexh75
• 4 Dec 2013
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[PrenticeBoyofDerry]

Yes it can be done that way, but logically I would put the black in the com of other gang.
We may not get it first time around as I am taking assumption, so we may need to swap them around, but it will at least give us an idea of what is doing what.
If the light stays on all the time then swap the two (black/red) loose cables over from com to L1 and visa-versa.

If as sparkwright has pointed out the operation works but the switch is upside down, then swapping the conductor from L1 to L2, should resolve that.
It should also be possible to have the fan operational, without the light being on, depends on your preferences. But we will deal with the issue at hand for the moment.