one light switch stopped working - baffled by wiring!

[MasterMark]

Hello all, I'm an electrics novice but pretty confused. I have a 3 gang, dimmable light switch.

Left switch - 2 external dimmable led lights.
Middle switch - 10 led kitchen ceiling dimmable downlights.
Right switch - 7 led undercabinet kitchen dimmable downlights (the different-looking module)

All working great since full refurb in 2017. Then the right switch stopped working properly - felt like the button wouldn't "click" in (very occasionally it did and lights would work fine).

Opened it up, fiddled a bit, and it now clicks nicely again. But lights won't switch on, there's a wire that has come unconnected which you can see in the photo. And much more complicated wiring than I was expecting - the switches are 1-way, not 2-way, yet L2 is getting used.

If someone could explain what's going on / how to fix this, would be much appreciated!

(If needed I have a replacement dimmer module I could use to replace the one on the right, that's the other photo).

 

[ericmark]

Right switch 60 - 400 VA, so 7 LED's must be at least 8.6 watts, since likely wanting to run at 50% then really double that, so around 18 watt each, which is unlikely.

The other two are 5 to 75 watt so well within spec.

As to wire, seems most likely this

terminal on centre switch, but can only guess.

The replacement seems OK.

 

[SUNRAY]

I look like the middle switch has 3 wires into 'L', in which case I'd assume the odd wire goes into '~'

Did you disconnect the wires to the right switch while you had it apart?

 

[SUNRAY]

Are the undercupboard lights in 2 sets, ie each side of the kitchen?

 

[MasterMark]

Thanks all! So to answer some of the questions:

1. The right switch lights (undercabinet) - can't remember wattage, but unlikely to be more than 5w each.
2. I did indeed disconnect the wires on the right switch, but then put them back as they were.
3. Great point re under-cupboard lights - yes, they are 2 different sides (5 on one side, 2 on the other).
4. I have put the loose wire into the middle switch ~ as suggested.
5. I will try and replace the right module with the new one, seems if that does anything.

I will report back after that's done!

 

[MasterMark]

Ok, so replaced with the new module on the right. But the lights still don't turn on.

 

[SUNRAY]

Ok, so replaced with the new module on the right. But the lights still don't turn on.

are these extra low voltage LEDs with 2 different powersuppllies? can we have pictures
Do you have any sort of test equipment?


As a test to rule out the dimmer, I'd connect all 3 wires in that dimmer into one single terminal.

or a choc block. of course any re-wiring is done with the power off for safety.

 

[MasterMark]

So the undercabinet round lights are 3W Leyton round cabinet downlights. There are 7 in total - 5 down one side of the kitchen, 2 on the opposite side (if that's what you mean by "2 different power supplies"?

Re putting all 3 wires into one terminal - I will try that tomorrow morning in daylight. But I replaced the old module with the new one in the first picture, so I guess that should be working fine (unless I'm VERY unlucky!)

Test equipment - I only have a fairly cheap and cheerful multimeter, not sure if that would be of any use!

 

[terryplumb]

Your switch plate should be earthed ,and it isn't !!

 

[SUNRAY]

Your switch plate should be earthed ,and it isn't !!

I'll thank you, I thought I'd mentioned it

 

[terryplumb]

8 out of 10....must try harder SUNRAY

 

[SUNRAY]

So the undercabinet round lights are 3W Leyton round cabinet downlights. There are 7 in total - 5 down one side of the kitchen, 2 on the opposite side (if that's what you mean by "2 different power supplies"?

Re putting all 3 wires into one terminal - I will try that tomorrow morning in daylight. But I replaced the old module with the new one in the first picture, so I guess that should be working fine (unless I'm VERY unlucky!)

Test equipment - I only have a fairly cheap and cheerful multimeter, not sure if that would be of any use!

I'm making a guess the two brown wires at the dimmmer go one to each group.
The Leyton undercupboard lights I know are

12 volt units and require a transformer/powersupply/driver which are often screwed to the bottom of the cupboard or laying on top.

 

[SUNRAY]

8 out of 10....must try harder SUNRAY

Just found I'd started a reply on my phone while coming home.

 

[MasterMark]

Many apologies, I didn't get notification of the more recent replies - but thank you to you all!

So as someone suggested, I put all the wires into one single terminal on the "right" dimmer switch. They all turn on, but the undercabinet lights did could not be turned off. As you say, SUNRAY, they are 12V units.

But the plot thickens - I was having issues with a bedroom ceiling lamp. I thought it was the bulb, but the bulb is fine. With all 3 wires in one terminal, that bedroom light turns out. When I start changing the wire positions, it stops working. This is obviously a crazy situation, so I'll have to get an electrician in to look at this properly, far beyond my abilities. It's just bizarre everything seems to have been working perfectly for 7 years.

 

[SUNRAY]

Many apologies, I didn't get notification of the more recent replies - but thank you to you all!

So as someone suggested, I put all the wires into one single terminal on the "right" dimmer switch. They all turn on, but the undercabinet lights did could not be turned off. As you say, SUNRAY, they are 12V units.

So with those 3 wires in the same hole all the undercupboard lights are on. That demonstrates the lights, 12V power adapters and wiring is good. And the problem is the dimmer switch.

But the plot thickens - I was having issues with a bedroom ceiling lamp. I thought it was the bulb, but the bulb is fine. With all 3 wires in one terminal, that bedroom light turns out. When I start changing the wire positions, it stops working. This is obviously a crazy situation, so I'll have to get an electrician in to look at this properly, far beyond my abilities. It's just bizarre everything seems to have been working perfectly for 7 years.

Is the bedroom also on a dimmer?