Single Gang Two Way Kitchen Light Problem

15 Apr 2004
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United Kingdom
DIY SOS ! Briefly, here is my problem. I had two 5 AMP single gang two way switches in my kitchen. I have bought two new 10 AMP single gang two way switches (brushed steel effect) from B&Q. Okay now for the confusing bit. When I removed both the old switches, I found that I had two insulated cores. One contains a black & a red wire (the black had a piece of red tape wrapped around it) and the other just had a red wire in it and an earth. Note that the earth wire is coming from both insulated cores (it is joined to both insulated cores). The red and the black (with the red tape on) went into L1 and L2 and the other red went into the Common. Similarily this was the case with the second switch (albeit the red and the black were in opposite L1 and L2 terminals) again with the other red in the Common. The light is more or less positioned between the two switches. The switch near the back door seems to have the main LIVE red in the common. I have tried fitting my new switches like the old ones but no joy ? I have tried all sorts of variations. I feel the 'single' reds should be in both respective Common terminals and the other red and black (with red tape on) should both be in the same respective L1 & L2 terminals. I can't fathom why they don't seem to work. Help !!! The diagrams I've found look different having yellow / blue wires..etc but I have a red and a black in one insulated core and another red in another insulated core in BOTH switches ? The old switches worked fine ? :confused:
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if you have copied the existing wiring exactly they should work maybe you disturbed the joint at the rose when messing with the cuircuit (pulling on cables)

i guess from your descrition of earths from both cable that the single red you refer to is red and earth cable (picture is from a harmonisation guide hence the brown version)

i would guess the system was originally
live from mains(inside rose)-----switch switch--------live on light

open up the rose if i am correct you should see the two single lives one conencted to the cuitcuit live one connected to the live in the lamp flex

if one of the single reds is loose in the rose there you have your problem and can fix it easilly

if one of the single reds is bissing from the rose then you have pulled it right out of the rose and will need to gain access from above to find it
There are two methods for wiring two way switchs.
The old method uses only two wires for the strapper to link the two switches L1 to L1 and L2 to L2.
The 'live' input goes to 'com' on one switch and the 'switched live' output goes to 'com' on the other switch.This one fits your situation.
com on one switch will always be live com on other switch will change according to switch position. If you can test them and prove both are live your problem is elsewhere.
The modern method is the one that uses yellow,blue and red to link the switches.The other difference is that both live and switched live both go to the same switch going to L1 and L2.These are in line with the diagrams you have been looking at.
5 mins with pencil and paper, draw diagram of both systems.
The red tape or sleeve on a wire is a requirement to indicate it can become live.
:rolleyes: :rolleyes: :rolleyes:
Mandate - thanks for your help - keep it coming ! I suspected my house had been wired the old way. Slightly worrying given my house is approx 16 years old ! Typical. Following on then, I've established that the single red in the common in the switch near the back door (presumably the 1st switch) is definitely the main Live feed. Subsequently then the 'other' single red (from the other single red and earth core) in the common of the second switch is the switched live ? I have matched L1 for L1 & L2 for L2 respectively (alternating between the red and the black with the red tape on) these I'm guessing are the strappers or travellers or whatever they are called ? This is doing my head in because I understand the principals behind it all yet I'm still stumped ! There must be something I have not done ? :(
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....(continued) by the way then if L1 should match L1 and L2 should match L2 then I'm puzzled as to why the 1st switch (the one with the main Live feed near the back door) had the red and the black with the red tape on in say L1 & L2 but the other switch had them the other way around ? Again, the switches worked perfectly before ? I wish I hadn't bothered now. I only wanted to tart my kitchen up ! :rolleyes:
1st prove wire going into com at switch 1 is live with mains tester
2nd apply mains tester to L1 on switch 1 and operate switch.
3rd apply mains tester to L2 on switch 1 and operate switch.
Now move to switch 2 when L1 on switch 1 is live L1 on switch 2 should also be live.
Also when L2 on switch 1 is live L2 on switch 2 should also be live.
Now prove com on switch 2 is live by operating any of the switches.
If com at switch 2 does not become live, there must be break or poor connection in the strapper wires. break in these wires can be checked with continuity tester

Just thought of something, double check the wiring connections, if you push wire too far into terminals the screw makes contact on the insulation and not on the wire (easily done)
When the outgoing wire becomes live on the operation of any of the switches, you will know the problem is elsewhere if it has not been resolved.

Are any of these two way switches in a 2 gang plate by any chance, the reason I ask is that Com L1 L2 form a triangle and when there two switches the adjacent switch has the triangular terminals inverted.
:rolleyes: :rolleyes: :rolleyes:
It does not make any difference if L1 and L2 are crossed over.
If you draw it out and follow the electrical paths you can see how the switches are open at both ends preventing any flow or allowing flow my closing any of the switches.
:rolleyes: :rolleyes: :rolleyes:
Okay we have progress. Basically the first switch is fine. Infact both switches are fine in terms of how they are wired. I got my mains tester out and it proved everything is o.k.
The first switch has been screwed to the wall. No problem there at all. The trouble lies at the second switch. When the second switch is ' dangling ' from the wall (that is when the faceplate has not been fixed to the wall) the LIGHT WORKS !! The switches work and everything. BUT the minute I touch the second switches faceplate and attempt to fixed it back on to the wall, there is a slight buzz and the light goes off when it should be on ? The minute I sort of pull the second switches faceplate immediately back away from the wall out towards me (there by straightening the wires behind the faceplate) the light comes back on !!! So I'm officially stumped. My mains tester indicates that both the switched live common and the L1 or the L2 (pending upon switch position) do both receive current when the movement of the faceplate is moved and makes the light go on and off ? How can they still both receive current when the faceplate is pushed in a certain direction making the light goes off ? I'd almost understand if they (that's L1 + switched live or L2 + switched live) didn't receive current possibly indicating a break somewhere along a copper wire but they do. HELP !!!!! I'm struggling to remain sane here. :evil:
sounds like a fault inside one of the wires

if you have the length availible strip back and re-terminate all the wires

if not i would raise an upstairs floorboard above the broken switch cut both the twin and earth and the red and earth up there terminate them in a junction box and lead a new 3 and earth from there to the light
Yes I agree it looks like there may be a break in one of the wires quite close to the second switch. The bending of the wire when you try to secure it being enough to open up the break.( thats causing the arcing and the buzzing sound) If the break is in the outgoing switched live you will not get a light at all, but if the break is in one of the strapper wires then you will get a light when the wire with break is not part of the electrical path.
I agree with pugwash you may have to replace the wires if there is insufficient wire to do a repair.
:rolleyes: :rolleyes: :rolleyes:
Success !!!!!! I identified a break in the copper wire within the switched live wire (the one that feeds the light out of the 2nd switch common) so using a connector block successfully resolved my problem. Luckily the break was just within reach so I didn't have to go to too much trouble. I really cannot thank you enough for all your support. Cheers and I hope I can help you sometime. Thanks again. :D :D :D
remember terminsl block should only be used inside fittings

from you desription it sounds like it's inside the box but you must make sure it does not stick out of the box at all

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