2 way switched light not working

[AMJ66]

I have a problem with my Stair light. It is controlled by 2 switches. If the light is switched off from one switch it does not turn off from the other. I have had an electrician look at it and he could not find the problem. The wiring to the switches has been checked and also to the junction box. Frustrated I decided to check the fitting itself, this is a new fitting. There are 3 wires to the fitting, red, black and earth. The red is connected to the live terminal and is always live regardless of the switches. whe the switches are off the black is not live. If I turn on one switch the black is then live, I used one of the screwdriver type testers where you touch the wire and put a finger on the end to make the circuit. If I then try to turn off the light using the other switch the black is then not live but, and this seems very odd to me, if I touch the black wire with the tester, have my finger on the end and then touch the metal cover of the first switch the tester lights up.
Anyone have any ideas what the problem could be?

 

[deadshort]

Hi, don't mention neon screw drivers around here !

If your electrician could not resolve the problem, he is not an electrician. Get another.


Regards,

DS

 

[AMJ66]

It has been checked by 2 electricians

 

[bernardgreen]

Then get a third person who really is an electrician ( who can fault find ) and not an "electrician" ( aka house basher ) who can install cables and fixtures but has no idea about fault finding and may not even have any basic electrical knowledge.

That said if you can safely take photos of the wires at the rear of the switches and post them here it may be possible to diagnose the wiring error or fault.

As said throw away that neon driver, they are dangerous as they can be touched on a LIVE wire and NOT light up. They can also light up when touching an earthed item if the person is very close to a cable going to a light switch.

 

[AndyPRK]

lots of pictures may help.

rear of switches
junction box internals
light fitting

 

[EddieM]

Hang on a 2 way switch and there is a red (permanent live) and black (switched live) and an earth Surely it's only a one way switch or am I missing something??

 

[JohnW2]

Hang on a 2 way switch and there is a red (permanent live) and black (switched live) and an earth Surely it's only a one way switch or am I missing something??

I think what you may be missing is that, AFAICS, we've been told nothing about the cables/conductors at the switches, only at the light fittings.

Kind Regards, John

 

[AMJ66]

Photo's as requested

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[JohnW2]

Photo's as requested

If the light is switched off from one switch it does not turn off from the other. I have had an electrician look at it and he could not find the problem.

As has been said, it looks as if you need a third electrician, and one who has some idea of what he is doing. I presume that the switches have never worked as you would like (at least, not since any changes were made to the wiring). As far as I can make out from the photos, that wiring could never have worked as you would like, since it is not wired as proper '2-way switching' (i.e. two switches controlling the same light{s}).

Kind Regards, John

 

[flameport]

Difficult to see clearly, but wiring appears to be correct.
Switch wires to L1 and L2.
Additional wires from COM, L1 and L2 in one switch connected to the same terminals in the other switch.

However:
That blue tape covered COM wire requires further investigation - why is it covered in tape, and what is underneath the tape? Is this a completely separate wire, or part of another cable?
The junction box and the cables joined in it has no earth connection at all.
The metal light switches are not connected to earth either - THIS IS DANGEROUS
The light appears to have an earth wire connected - but what is the other end connected to - presumably nothing?

 

[JohnW2]

Difficult to see clearly, but wiring appears to be correct. Switch wires to L1 and L2. Additional wires from COM, L1 and L2 in one switch connected to the same terminals in the other switch.

On reflection, I think you're right - I misinterpreted the second of the pics.

However: That blue tape covered COM wire requires further investigation - why is it covered in tape, and what is underneath the tape? Is this a completely separate wire, or part of another cable?

I'm sure it's in your mind, but you have not actually mentioned what is possibly the most likely (and 'orrible/dangerous) explanation - namely that T+E has been used to join the switches and that there is a bare conductor (what should be the CPC/earth) under that blue tape! However, if that's the case, it's rather amazing that two 'electricians' have apparently 'passed' it!

The junction box and the cables joined in it has no earth connection at all. The metal light switches are not connected to earth either - THIS IS DANGEROUS ... The light appears to have an earth wire connected - but what is the other end connected to - presumably nothing?

All agreed.

Kind Regards, John

 

[AMJ66]

The wire covered in tape is brown, the electrician put the tape on it. I have checked the continuity of the cables from the second switch to the first, with a multimeter, and they are all ok. The photo's do not show it but the switches are earthed. I don't know where the earth wire from the light fitting goes to.

The history of this is:
The light started to stay on continuously reason unknown. I changed the light fitting, making sure I swapped the wires from the old fitting to the same terminals on the new one. That is when the current problem started. I thought it might be the switches so they were both changed, again swapping the wires to the same terminals on the new switches.

 

[JohnW2]

The wire covered in tape is brown, the electrician put the tape on it.

Oh, that's interesting - and also slightly bizarre for someone to have put blue tape on it (since it clearly is being used as a live conductor). Can you tell whether that brown wire is just 'on its own' or whether it comes out of a cable which also has a blue wire (and a bare one) in it?

Kind Regards, John

 

[AMJ66]

It is part of the same cable as the red and black wires from the second switch

 

[JohnW2]

It is part of the same cable as the red and black wires from the second switch

I don't want to sound awkward, but are you sure? Red, Black and Brown in one cable would be extremely unusual.

Kind Regards, John