2 way switch fault - advice needed!

[scoobasteve]

Hi,

Hoping someone can offer some advice on a problem I've found in a flat I'm decorating, as part of the job I'm changing all of the socket and switch fronts which I had hoped would be nice and straight forward!

The lounge has 2-way switching to the ceiling light from a 3 gang and a 2 gang switch, the other gangs in both switches control wall lights and the 3rd in the 3 gang is for the hallway.

After replacing the 2G and wiring up exactly as before (took a picture before removing) the light is now operable from both switches individually but when switched on at the 3G switch the 2G has no effect on the light i.e. it stays on whether the switch is up or down. If switched on from the 2G switch I am able to switch off from the 3G.

I don't know if this fault existed but can only assume it did as I have reconnected the new 2G exactly as before and have not been into the 3G yet - the owner doesn't know either as she has just bought the flat - nevertheless I want to rectify now that I've found it!

I'm assuming the 2G is the secondary switch as it only has 3 cores wired one into each of L1, L2 & Comm (Plus earth) - See attached picture (the 3 reds on the left are for wall lights in the other gang) it's not easy to see but the issue is with the other gang where there is a red into comm, black with red sleeve into L2 and a separate single black core into L1.

Am I correct in thinking these should all route back to the 3G switch point and so I should then be able to work out what is going on or is this wishful thinking?

Is there anything obviously wrong that someone can point out?
View media item 39426

 

[EFLImpudence]

the light is now operable from both switches individually

but when switched on at the 3G switch the 2G has no effect on the light i.e. it stays on whether the switch is up or down.

If switched on from the 2G switch I am able to switch off from the 3G.

The only way I can make that sequence happen is if the two black wires were in the same terminal. As it's not that switch it must be the other one.

Can we have a picture of the other switch?

 

[scoobasteve]

Thanks mate - I will get one tomorrow when I venture into the other switch! Didn't want to take it off til I was ready to change it as I know there will be a load of wires behind there, it's old multi-strand cable as well which is a nightmare to get in the back of the switch to start with!

I have however been informed by the old girls daughter that it was doing this beforehand so it's nothing I've introduced - would still like to sort it if I can but worst case I'll change the fronts and tell her she needs to get a spark to check it all over.

 

[scoobasteve]

My mistake yesterday, when the light is switched on at either switch the other becomes ineffective and the light stays on regardless.

 

[EFLImpudence]

OK

Well, it could just be wired like but then you have unnecessary wire at the pictured switch.

Can we have picture of the other switch?

 

[scoobasteve]

Ok here's the picture of the other switch, I think I've sourced the problem but the solution is beyond my electrical knowledge!

View media item 39455
In the picture the switch in question is the centre one, the one on the right is for the hallway which is working fine and the left switch is for the wall lights which i've disconnected for now. As you can see the red which is from the other lounge switch is in the common for the hallway - when I remove it from here the ceiling light in the lounge does not function at all!

With the switch at secondary position OFF and light off L1 is live, L2 dead whichever way this switch is positioned. When the light is on and the other switch is ON all 3 (L2, L1, Comm) at this switch are all live whichever way the switch is positioned!

Is there a simple fix to this? I've told the owner she needs to get a spark to rectify but if there is a simple fix I can sort it out tomorrow when I replace the switch.

Cheers all.

 

[ColJack]

we need better pictures of where the wires come out of the box, or better descriptions..
these black wires, are they singles or part of a 2 core red / black pair?


you need to drop the ceiling light also and post pics of what's going on in or behind there..

 

[sparkwright]

Out of interest, are you fitting new metal or plastic switches?

And are there any earth wires there?

 

[scoobasteve]

Fitting plastic replacements and the earths are all present inside the mounting boxes.

Regarding the wires the black in L2 is a single core which goes to the L2 in the other switch (I think anyway but it looks like the same double insulated cable.

The black in L1 is part of a 2-Core + E and it's the red out of this that is in the Common for the hallway light which when removed causes the lounge lght to not function at all.

The black in the Common is another single core - from my limited understanding is it possible this is actually from a 2-core and the source of the missing red?

Anyway, thanks all - I've finished the job now and wired back up as it was and informed the owner she should get a spark out to sort out the lounge light. Would have liked to have rectified it myself but it was beyond me!

Cheers Steve