2 way switching not working

[dust66]

Hi guys
Just moved in a new flat and I'm trying to figure out if the 2 lights in the corridor are wired as 2 way switching.
I attach the photos I took as part of initial investigation.

2x Lights in corridor, Light 1 and Light 2
2x 2-gang switches in corridor Switch 1(next to Light 1) and Switch 2(next to Light 2)

Switch 1A turns Light 1 on and off all good
Switch 1B turns Light 2 on and off all good
Switch 2A has no effect (I am guessing this was installed as a switch to turn Light 2 on and off when exiting flat)
Switch 2B turns outside light on and off all good

Light 2 has a 3-way connector block with:
1x White -> into lamp brown wire
3x Black -> into lamp blue wire
3x Red -> N/C


Can anyone see anything odd with the wiring, I'm still getting my head around the 2-way switching wiring.
Should I, as initial trouble shooting, turn off the light circuit in the CU and do some continuity tests to see what wire goes where?

Any initial tips much appreciated

 

[securespark]

It's all very jumbled and difficult to see, I'm afraid.

If those two switches control that light, I would have thought the strappers would have been the same colours at both ends.

I deduce it's a 1960s block of flats with screwed conduit buried in the ceilings and walls. They have likely used the conduit as the earth, which will be easy to test for with a multimeter. As long as someone hasn't replaced the consumer unit and butchered it, they should have maintained earth continuity.

Red, white and blue is an old combination of insulation colours for conductors, after which yellow took over from white.

Reds, whites and blues are usually used as line conductors, unless marked otherwise.

Blacks are usually neutrals, unless marked otherwise.

 

[SUNRAY]

It was very unusual to use black singles for live wiring.

With both lights on does switch 2A make a difference?

I assume you have played long and hard but have you tried all 8 combinations of positions, ignoring 2B - I don't actually expect anything different to your results

 

[AndyPRK]

Just my thoughts.
White wires goto ceiling lights. ?

Switch 1 has been replaced. A red link wire was added, that wasn’t there previously.

Remove red link wire from 1B (and get rid)
Move to white wire from below into the top Com terminal. (1b)

Move black wire from 1A to spare hole in 1B

Someone else should check and confirm.

 

[FrodoOne]

Do you own the "Flat"
and
are you permitted to do any electrical work on it?

 

[dust66]

Do you own the "Flat"
and
are you permitted to do any electrical work on it?

Yes I "own" the flat.
I am a competent person as I work with mains distribution units.
Any other "questions" ?

 

[dust66]

It's all very jumbled and difficult to see, I'm afraid.

If those two switches control that light, I would have thought the strappers would have been the same colours at both ends.

I deduce it's a 1960s block of flats with screwed conduit buried in the ceilings and walls. They have likely used the conduit as the earth, which will be easy to test for with a multimeter. As long as someone hasn't replaced the consumer unit and butchered it, they should have maintained earth continuity.

Red, white and blue is an old combination of insulation colours for conductors, after which yellow took over from white.

Reds, whites and blues are usually used as line conductors, unless marked otherwise.

Blacks are usually neutrals, unless marked otherwise.

Thank you. That's great and helpful information.
Yes spot on it's a 60s flat.
I'll do some continuity tests to see where the black wires from switch 2A go.
It is all very messy I'm afraid...the colours are all over the place. I'm guessing the 2 black wires on 2A can't possibly be neutrals can they?

 

[dust66]

It was very unusual to use black singles for live wiring.

With both lights on does switch 2A make a difference?

I assume you have played long and hard but have you tried all 8 combinations of positions, ignoring 2B - I don't actually expect anything different to your results

Yea the wiring seems very messy generally speaking.. I will do some more investigation in the next couple of days.

Cheers

 

[dust66]

Just my thoughts.
White wires goto ceiling lights. ?

Switch 1 has been replaced. A red link wire was added, that wasn’t there previously.

Remove red link wire from 1B (and get rid)
Move to white wire from below into the top Com terminal. (1b)

Move black wire from 1A to spare hole in 1B

Someone else should check and confirm.

Thanks for the reply.
Yes from a visual check the white goes up to the L of the ceiling lights. I haven't properly checked with continuity as I didn't have a long enough lead for my Megger. Will source one and see how everything is connected.

How can you see that the red wire link has been added later on? Are you suspicious that the 2 way switching has been wired incorrectly?

Cheers!

 

[AndyPRK]

The 2 black wires are the "strappers" between the 2 way light switches (or that is their intended function, as can be seen from the old switch by your front door.)

It's clear one of them is a new switch. The configuration of the old switch is upside down to the new switch. This may have caused a DIYer confusion when installing the replacement. This resulted in one light not working and the red link was added to get both lights working. It's an educated assumption. But when wired correctly as I have stated, its not required.

When you remove the red link, you will probably be able to tell its more modern. Copper coloured and not stranded

 

[dust66]

The 2 black wires are the "strappers" between the 2 way light switches (or that is their intended function, as can be seen from the old switch by your front door.)

It's clear one of them is a new switch. The configuration of the old switch is upside down to the new switch. This may have caused a DIYer confusion when installing the replacement. This resulted in one light not working and the red link was added to get both lights working. It's an educated assumption. But when wired correctly as I have stated, its not required.

When you remove the red link, you will probably be able to tell its more modern. Copper coloured and not stranded

Awesome, thanks mate. Will do a bit more investigation and obviously call a proper electrician if it needs more than just re-wiring a switch.

Out of curiosity, could it be that the switch 2A is just busted? Or these switches are bulletproof?

 

[AndyPRK]

No. It's clearly wired incorrectly. More by luck things work as well as they do.


It should be wired as per the top left diagram here.

Electrics:Two way lighting

www.diynot.com

Red wire coming in on the left, 2black strappers between the switches, white wire going out to lamp

 

[SUNRAY]

No. It's clearly wired incorrectly. More by luck things work as well as they do.


It should be wired as per the top left diagram here.

Electrics:Two way lighting

www.diynot.com

Red wire coming in on the left, 2black strappers between the switches, white wire going out to lamp

It took me a while to see where you're 'coming from' as I was aiming for 2 sets of 2 way (which is in no way there), I didn't pick up that any wire was different but I haven't looked at the pics again yet.

 

[AndyPRK]

The other switch with blue wire does the outside light. 1 Way

All connections at the old MK switch are correct

 

[SUNRAY]

Just my thoughts.
White wires goto ceiling lights. ?

Switch 1 has been replaced. A red link wire was added, that wasn’t there previously.

Remove red link wire from 1B (and get rid)
Move to white wire from below into the top Com terminal. (1b)

Move black wire from 1A to spare hole in 1B

Someone else should check and confirm.

That makes a lot of sense and yes the red link does look different.

As an aside to this if it would be desirable for both lights to be on together then add both white wires into the 'com' leaving the second switch with no wires.

The other switch with blue wire does the outside light. 1 Way

All connections at the old MK switch are correct

Yes I'd picked up on that but at silly oclock in the morning after struggling for several hours to see why my tax return was only showing a bill for £300 my head had started going down the 'look at where the wires go in the conduits' route, especially as it was unusual to use live loop-in at the light with conduit.