Loop at switch - 2 gang switch

C

Cod58

-
Hi All, I am new to the site and have recently started doing more and more electrical work in my house, nothing too major, changing face plates, light fittings etc, however I have encountered an issue that I cannot sort out.
I have a 2 gang light switch where it is looped in the switch. Nothing too strange there. There are a total of 5 sets of cables entering the switch, as far as I can understand there should only be 4. The live in, live out, then the 2 cables that are running to the respective lights. Therefore I don't know what the 5th cable is for, also I think whoever wired in the previous switch did something else wrong. There was a connecting wire from one side of the switch to the other, which from what I understand should have been on the COM terminals, presume this is to carry on the power to the other side of the switch and then out to the rest of the ring. however they had put it on the L2 terminals, if they had also put the 'live' wires in the L2 terminals would that have the same effect as if they were all in the COM terminals? I have managed to get the fuse box to come back on but none of the lights are working. To make matter worse, one of the 'live' wires is a T&E in a grey sheath, but the other T&E in a grey sheath goes out to one of the lights, the other light has open red, black and earth cables going to the switch, but there are another 2 sets of cables like this in there as well. Am sure after reading this you may understand why I am confused. How can I find out what wire does what without stripping all of my plaster and ceiling? Thanks
 
Cod58 said:
Hi All, I am new to the site and have recently started doing more and more electrical work in my house, nothing too major, changing face plates, light fittings etc, however I have encountered an issue that I cannot sort out.
I have a 2 gang light switch where it is looped in the switch. Nothing too strange there. There are a total of 5 sets of cables entering the switch, as far as I can understand there should only be 4. The live in, live out, then the 2 cables that are running to the respective lights. Therefore I don't know what the 5th cable is for, also I think whoever wired in the previous switch did something else wrong. There was a connecting wire from one side of the switch to the other, which from what I understand should have been on the COM terminals, presume this is to carry on the power to the other side of the switch and then out to the rest of the ring. however they had put it on the L2 terminals, if they had also put the 'live' wires in the L2 terminals would that have the same effect as if they were all in the COM terminals? I have managed to get the fuse box to come back on but none of the lights are working. To make matter worse, one of the 'live' wires is a T&E in a grey sheath, but the other T&E in a grey sheath goes out to one of the lights, the other light has open red, black and earth cables going to the switch, but there are another 2 sets of cables like this in there as well. Am sure after reading this you may understand why I am confused. How can I find out what wire does what without stripping all of my plaster and ceiling? Thanks
Click to expand...
Can you provide a photograph?
 
it's possible that it was once a 2 way switch and the other switch has been made redundant.
 
Hi Cod and Welcome to the Forum :) .
If it's any consolation I still fondly remember sorting out a similar mess while up a ladder. Birds nest of wires stuffed into the ceiling space, oh the joy. Do you have any test kit?
 
telectrix said:
it's possible that it was once a 2 way switch and the other switch has been made redundant.
Click to expand...
Could the switch have been a 3 gang? and the mystery cable is a set of strappers going off the the next 2 way switch withthel and SL going to the light which has been fed by a LandN from elsewhere, Crikey I've confused myself now.
 
this is the best one I can find, the COM terminals are at the top, all the black cables are in a terminal together and the earth cables were just in a clump in the back but I have attached these to the terminal on the box.

light switch.jpg
 
telectrix said:
it's possible that it was once a 2 way switch and the other switch has been made redundant.
Click to expand...
that is a possibility knowing what my house is like, however I have no way of finding out which one that would be, guess it would be just trial and error, looks like I may have to purchase a tester but then I would still need to know what the readings actually mean!!
 
Cod58 said:
that is a possibility knowing what my house is like, however I have no way of finding out which one that would be, guess it would be just trial and error, looks like I may have to purchase a tester but then I would still need to know what the readings actually mean!!
Click to expand...

Say goodbye to about £350 then you won't know how to use it .....
 
Pete999 said:
Could the switch have been a 3 gang? and the mystery cable is a set of strappers going off the the next 2 way switch withthel and SL going to the light which has been fed by a LandN from elsewhere, Crikey I've confused myself now.
Click to expand...
again this could be a possibility, it has always been 2 gang since we have lived here, roughly 20 years, the three cables that I can't fully identify all disappear in the same direction, could it have been a second light coming off the same switch? so two lights working off one of the switches and one off the other?
 
I think I have identified my two live wires, I know that one of them is a grey T&E and the other T&E goes to a light in my cellar, so I attached one to COM and the other to L2 and then attached one of the other red cables to COM, the light in the cellar came on, so presume this means that the ring has completed as it didn't trip? So if I now do the same with the other red cables I should be able to identify the other light's cable and presumably the one that isn't doing anything? Does this sound about right?
 
scratch that, i have just switched the 2 T&Es round and same thing was happening so assume they are creating a circuit no matter which way round they go!!
 
that's coz all the sparks are waiting fora royal command.... the lights have gone off in windsor castle.
 
Not sure if they are your terminations in the picture or what was there previously, but they are very poor, bordering on dangerous. There should be no visable copper on the cables outside of the terminal. Also, if they are all kinked like that they are likely to snap when you squash it all back in to the box.

If that was how you found it, it may be an indication of the rest of the wiring ib the house and could be worth getting it properly tested and inspected.
 
There are times to attempt jobs in most disciplines,there are also times that are not the best course of action

I think I best divert my attention to a more romantic subject now playing
 
update, i have now identified 2 'live' cables that form the ring, I have also identified the cable that goes to the light in my cellar, so the 2 lives are in a COM terminal and the light in the FL2 terminal, whenI swap out the L2 terminal for either of the other 2 wires the circuit trips, if I just leave the 2 lives in the COM terminal all the other downstairs lights work apart from the cellar and the kitchen. One of the rogue wires is for the light in the kitchen so I am assuming that there may be something wrong with the light fitting or bulb but still not sure what the other wire is for!!
 
Cod58 said:
update, i have now identified 2 'live' cables that form the ring, I have also identified the cable that goes to the light in my cellar, so the 2 lives are in a COM terminal and the light in the FL2 terminal, whenI swap out the L2 terminal for either of the other 2 wires the circuit trips, if I just leave the 2 lives in the COM terminal all the other downstairs lights work apart from the cellar and the kitchen. One of the rogue wires is for the light in the kitchen so I am assuming that there may be something wrong with the light fitting or bulb but still not sure what the other wire is for!!
Click to expand...

I would advise cessation of this cause of action. Put your feet up, go watch the telly, and call an electrician in on Monday.
 
The chances on anyone being confident enough to tell you what is what from a distance is less than zero. You need professional help.
 
Cod58 said:
View attachment 42341
Click to expand...

From your photo & you saying about 5 sets of cables & your expecting 4 sets etc.

Have you tried drawing out the circuits to understand how its wired?

As we are not there to confirm via testing
Ive done a very rough & quick drawing of the possible setup.

Looks like they have used L2 ( also L2s are linked together) as feed in & outs & the two Coms go to each light rose, blacks are neutrals together in a connector block & earths together in a connector block. looks like that 5th set is being used to feed out to another light circuit.

Here's my very quick & rough drawing of what your circuit could be but without testing to confirm if it is or not.

20180519_125152.jpg
 
I don't think anyone has asked yet,
Did both switches function correctly before you started, i.e switch specific lights on and off?

If so then someone hadn't done something wrong, it was all working.
What is it you were trying achieve at the start, fitting a new switch or making both switches work if they didn't?
 
I think Loki's pic is nigh on correct. The wiring looks over 40 yrs old and the method is somewhat unusual.
 
The idea is to identify the cables first, with tape or a little dab from a marker pen on the cables first, then take a photo BEFORE disconnecting anything.
Change switch putting the cables back where they were, according to your original picture.

If all you are doing is swapping reds about, leaving all the blacks together, you wont trip the MCB. Either some, if not all the lights wont work at all, or will be on all the time.

Lights are not wired in a "ring"

You must have 3 lives there if each switch controls only one light each. Its very possible for ease of installation in the first place.

It looks like someone originally saw the switch, looked at "L1" and decided that's where the lives go.

Trial and error, you will get there, but a professional with a test kit would be able to fix in short space of time.
 
Cod58 said:
I think I have identified my two live wires, I know that one of them is a grey T&E and the other T&E goes to a light in my cellar, so I attached one to COM and the other to L2 and then attached one of the other red cables to COM, the light in the cellar came on, so presume this means that the ring has completed as it didn't trip? So if I now do the same with the other red cables I should be able to identify the other light's cable and presumably the one that isn't doing anything? Does this sound about right?
Click to expand...

That's an awful mess, all the exposed copper at the switch terminals etc.

You don't sound like you know about 2 way switching and you consider a lighting circuit to be a 'ring' so I'll say it, get an electrician in.
 
Thanks for your replies, I now have the downstairs lights working, I managed to work out which cables made up the loop in the back of the switch and then worked out which wire ran to the cellar lights and which one ran to the light in the kitchen, the other wire is still confusing me though. When connecting the kitchen light it trips the fuse for the lights, am assuming that this would mean there is an issue with either the light fitting itself or the wire leading to it. so, the problem is almost sorted, at least we have some light in the kitchen from under cupboard lights.
 
So you have a 2g switch which you are changing to new, one switch does the cellar light(s) the other the ceiling kitchen light. Then how are these under unit kitchen lights switched and what box is this switch mounted on?
 
under cabinet lights must be off a different circuit - plugged into sockets.
There must be a short between that red and neutral/earth somewhere.
Have you done any other work that may have caused it?
Screwed into a wall and damaged a cable?

A professional with a test kit will be able to find it.
 

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Cod58

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Loop at switch - 2 gang switch
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