Mixed up cables when changing 2 gang 1 way light switch.

[Nesmy]

Hi Guys,

I've decided to change some light switches as the old ones were all tatty and yellow from uv exposure. I've changed three 1 gang 1 way switches and it took me like 5 minutes (with two cables there is not much to mess up). I proudly went to the kitchen to change the 2 gang one and in that overconfidence-fuelled haze I removed the switch, detached most of the wires and then had that moment of realisation what the hell have I just done. There are 5 red wires there plus the one that is bridged between COMs. I've tried to rearrange them as they were before but it didn't work - even though the switch did turn on lights in the kitchen, all the other ceiling lights in the house were dead. I've tried to rearrange them few more times but results only became more peculiar each time I've tried (eg kitchen light switch started operating my living room lights). I understand basics when it comes to electricity, enough not to kill myself, but the way all the lights are connected with each other is above my understsnding. I can make photos if that will help but as I said earlier - 5 red wires, one bridging and not much else. On a side note - I have a volt stick and multimeter in my toolbox. I've already used the volt stick to determine that 3 red cables are live and 2 neutral.

There are 6 cable terminals in the switch - two L1's, two L2's and 2 COM's.

I hope somebody more experienced will be able to help!

 

[winston1]

There are unlikely to be any neutrals at your switch. More likely switched lives.

Trial and error with electrics is dangerous. Best pay some money and call in a sparks.

 

[Nesmy]

I'd love to call an electrician and have that sorted but quite frankly, I'm broke. I do know a very good sparky whom I have hired in the past - but as I said, money's tight. I even think he would come and fix it free of charge because he's a really nice chap, but I hate taking advantage of people. And that's why I'm here. I can't see however how trial and error on that case could result in something dangerous.

 

[EFLImpudence]

Then -

https://www.diynot.com/wiki/Electrics:Lighting

 

[Taylortwocities]

I agree with Winston (shock horror). You may be faced with getting someone to sort you out.

You could post a pic of the wiring, just in case we can suggest something obvious.

 

[Taylortwocities]

I can't see however how trial and error on that case could result in something dangerous.

We don't do that around here. We've all had the "bang test" gene removed from our DNA.

 

[Nesmy]

I will post a photo when I'll be back home. I will ask the question differently - what would the electrician do in order to sort it out?

 

[rsgaz]

trial and error

It's not just the danger.

You have 5 conductors to go in 6 holes, so 6*5*4*3*2= 720 possible ways of doing it, with only one conductor per hole. BUT, you also have the link wire, one end of which has a 6 possible positions, the other end 5, so...

6*5*4*3*2*6*5= 21600 different ways to wire it. Still want to try trial and error?!

 

[EFLImpudence]

what would the electrician do in order to sort it out?

Determine which three wires come from the other switch that also operates the same light as one on this switch.

Put the three relevant wires in the same terminal as they are at that other switch.

The remaining two wires will be for the other gang switch

 

[SUNRAY]

Determine which three wires come from the other switch that also operates the same light as one on this switch.

Put the three relevant wires in the same terminal as they are at that other switch.

The remaining two wires will be for the other gang switch

Is there another switch?
The fact that all the rest of the house is off and

plus the one that is bridged between COMs.

I'd doubt it's wired the way EFL describes.
My initial GUESS is this is likely to be used as a 1W and 2W and MAY be wired like this:

However that does not explain why 3 wires appear to be live, but volt sticks can be easily confused.

 

[Taylortwocities]

Yes. Use your meter not the volt stick.

 

[Nesmy]

Hi Sunray!

Thanks for a first reply that is actually explaining something in depth instead of telling me off for being reckless

To give a bit more of an explanation:

There is a single two gang switch in the kitchen, one gang is for the downlights in whole kitchen and the other one is for a security light in the back garden that is not currently used (though i've checked in the past and it does work when triggered by PIR). There is no other way in the house to turn kitchen lights on, neither the back garden ones, therefore it has to be one way switch by definition? There are other light switches in the house (obviously) but the ones affected by mixing up the wires are all three bedrooms upstairs and the living room. All the other (hallway lights, lights above the stairs, bathroom lights) work just fine. Kitchen lights worked with most of the cable combinations, sometimes it changed on which side of the switch they operated. Also, when I was trying my trial and error approach, one combination allowed living room lights to work normally but the ones in all bedrooms didn't work.
As I said earlier on, I have a multimeter so if there is a way to solve this problem using one, I'm happy to try. My volt stick was really sensitive, sonetimes beeping half an inch away from the cable but I did my best to check all the cables properly.

I will be sending pics in few minutes. Meanwhile, thanks for giving me a chance!

 

[Nesmy]

Hi guys,

It's me again. I've checked all the cables again and there are 5 cables IN TOTAL. So 4 cables are coming from the wall and the 5th one is a piece of cable bridging COM's. I'm attaching photos. Let me know what you think.

 

[Taylortwocities]

Ok
Let’s hope that green/yellow wire is earth.

Use your test meter and test between the earth and each of the reds in turn. The one with 240v is your live in.
Now, one at a time, connect each of the remaining reds to the live one.
You are looking for the one that enables the other lights in the house to work. That’s the live out.
Those two reds go in the Com terminals with a link wire between them.
You then have two reds left. These are the switched lives out to kitchen and garden lights.
They each go into an L1 terminal on the switch.
That should do it.

 

[SUNRAY]

Ok
Let’s hope that green/yellow wire is earth.

Use your test meter and test between the earth and each of the reds in turn. The one with 240v is your live in.
Now, one at a time, connect each of the remaining reds to the live one.
You are looking for the one that enables the other lights in the house to work. That’s the live out.
Those two reds go in the Com terminals with a link wire between them.
You then have two reds left. These are the switched lives out to kitchen and garden lights.
They each go into an L1 terminal on the switch.
That should do it.

That is as correct as it can be.