2 way switches not working

Loky11 · Jan 4, 2019

Now guys,

Need some help please, i have a 2 way switch that not working correctly, got a 2 gang 2 way switch on landing of 1st floor, on second floor there's a 1 gang 2 way switch, now the problem is that if the light is turned on from 1st floor it can not be turned off from 2nd floor and vice versa, it will only turn off from the switch that turned it on. Is it possible that the wires in the switches arnt wires in the correct terminals ? All advise appreciated. Cheers.

westward10 · Jan 4, 2019

Think you are going to need an electrician, there is definitely a connection you are not seeing.

snowhead · Jan 4, 2019

Loky11 said:
Yea i got it wrong mate, on 2nd floor its 3 core and earth read my last post.

I remember reading that and I've drawn it in front of me,,

Loky11 · Jan 4, 2019

westward10 said:
Think you are going to need an electrician, there is definitely a connection you are not seeing.

Its baffled me tbh i know somethings missing, i will get a photo of 2 floor switch and ceiling rose tomorrow and upload them.

snowhead · Jan 4, 2019

Check what colour is in what terminal in the 2nd floor switch, that's your problem.

Obligatory warning; don't work on live wires and don't trust non contact testers.

Taylortwocities · Jan 5, 2019

Will wait until tomorrow, but if there is only a 3 core and earth at both ends, then there must be a junction box somewhere, probably an octopus in the loft somewhere.
We are unlikely to solve this on line if that's the case.

Loky11 · Jan 5, 2019

Taylortwocities said:
Will wait until tomorrow, but if there is only a 3 core and earth at both ends, then there must be a junction box somewhere, probably an octopus in the loft somewhere.
We are unlikely to solve this on line if that's the case.

Yea i understand that mate, will upload some pics tomorrow and see what you wonderful bunch can make of it.

Loky11 · Jan 5, 2019

Ok guys, managed to get some photos of 2nd floor switch and light.

[ElectriciansForums.net] 2 way switches not working

snowhead · Jan 5, 2019

There's a junction box / block somewhere with 2 x 3 cores /e R,Y,B, 1 from each switch and a Twin / Earth that goes to the light and either 1 or 2 more T&Es.
Picture needed or call a Spark in.

Taylortwocities · Jan 5, 2019

Agreed.

If you go up in the loft and follow the cable from your light, and the one from the switch, they will meet in a junction box of some sort. A Pic of the inside of that might help, but most of them look like a mad pasta chef has thrown a handful of multi-coloured spaghetti into a box and run away.

Lucien Nunes · Jan 5, 2019

We see two switches, both with one 3C+E. At the hidden junction box, there must be one of two configurations: Either A) PL and SL to the common of each switch and two strappers linked through, or B) all 3 conductors linked through and PL and SL paralleled with L1 & L2.

At the moment, the OP states that the only way to turn the light off is to turn off the switch at which it was last turned on, i.e. the switches are behaving as one-way in parallel. With config A), having the PL and SL at different switches makes this very unlikely as the switches are inherently in series. But with scheme B), the switches are inherently in parallel. If the common and either L1 or L2 are swapped at the switches, they will behave as described.

Without wanting to give inappropriate step-by-step instructions, I would personally start troubleshooting without seeing the hidden junction, by disconnecting both switches and identifying PL and SL using a meter. If they are at different switches, they should be connected to the commons regardless of colour, and if they are both present at both switches they should be connected to L1 & L2. The other connections then follow logically. I would not be surprised to find that yellow and red have been swapped.

Loky11 · Jan 5, 2019

snowhead said:
There's a junction box / block somewhere with 2 x 3 cores /e R,Y,B, 1 from each switch and a Twin / Earth that goes to the light and either 1 or 2 more T&Es.
Picture needed or call a Spark in.

I will have a look on monday for It

Taylortwocities said:
Agreed.

If you go up in the loft and follow the cable from your light, and the one from the switch, they will meet in a junction box of some sort. A Pic of the inside of that might help, but most of them look like a mad pasta chef has thrown a handful of multi-coloured spaghetti into a box and run away.

Haha i agree, but cant get into loft as theres no hatch. Must be under floor boards somewhere

Lucien Nunes · Jan 5, 2019

In fact, if the fault is miswiring of the switches, I'd wager I could correctly identify the wires and make it work within 2 minutes, without seeing the junction box or even using a meter, only a screwdriver, or the job would be FOC. Obviously if there's hidden damage that's a different matter. And I don't do domestic!

westward10 · Jan 5, 2019

No reason why the OP cannot swap the wires about and see what happens. Ensure power is isolated and mark the conductors so you know the original configuration if it fails, you never know.

Lucien Nunes · Jan 5, 2019

A simple test that could identify scheme A) or B) would be to connect all three leads in one switch, and disconnect them at the other, parking them in separate terminals of a terminal block. When made safe and re-energised, if the light lights it must be scheme B (parallel fed). Then, out of the three joined leads, the two that must be joined to make the light work must be L1 and L2. The same test can be made at the other switch, where the results should be identical. The remaining lead at each switch must be the common.

This all assumes there is no hidden fault such as one strapper being permanently live when it shouldn't, and that the neutral is not present. There was a crazy method that works but is pure evil, where the lamp is connected between the commons, L1 is L and L2 is N. It saves some cable especially if bridged between two circuits but there are any number of things wrong with it, I think we've heard of it being found a couple of times on here. In this case, my test would blow the fuse, so I'm generally reluctant to suggest any tests that require this sort of background experience, or rely on too many assumptions.

Loky11 · Jan 5, 2019

westward10 said:
No reason why the OP cannot swap the wires about and see what happens. Ensure power is isolated and mark the conductors so you know the original configuration if it fails, you never know.

I have swapped wires around, made no difference lol.

2 way switches not working

Loky11

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westward10

snowhead

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Loky11

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snowhead

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Taylortwocities

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Loky11

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Loky11

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snowhead

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Taylortwocities

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Lucien Nunes

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Loky11

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Lucien Nunes

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westward10

Lucien Nunes

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Loky11

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