2 way switches not working

[Loky11]

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.

 

[Taylortwocities]

I think you mean blue and red.

Yes, sorry. Blue and red.
Brain thinking of other things (Xmas decs demolishment).

 

[Lucien Nunes]

Here's my entry for the scrappiest sketch competition RB eat your heart out.
I think you have the situation marked (4).

First, we can confirm the scheme:

And then if it is parallel fed as expected, which lead is which:

 

[DC-backfrom the past]

could we just have a faulty switch here ?

 

[DPG]

could we just have a faulty switch here ?

That would be funny. It sometimes is the obvious that is taken for granted though.

 

[Lucien Nunes]

I did consider this but it's unlikely. As both switches have an effect, there must be switch operation between common and one of the other terminals. The third would have to be S/C to Com, which seems very unlikely. If it were welded in one position, that switch would likely have no effect at all. A S/C across L1 and L2 would keep the light on all the time.

OTOH the OP has swapped wires around in the past, so a miswire seems very much more likely. Hence also, my suggestion to test the wire functions without the switches.

 

[Loky11]

That would be funny. It sometimes is the obvious that is taken for granted though.

Will get a new one and try, one of the terminal screws decided to unwind itself completely and skydived to floor and hid.

 

[Dave OCD]

I reckon at the underfloor JB the two three cores will be there as well as a supply and the switched live/neutral cable to the light.
Quite likely then that the live supply will feed one 'common' and the switched live to light will be to the other 'common'. Then both 'L1's and 'L2s' will connect together 1 to 1 and 2 to 2.[Aka strappers] If this were the case you could establish which cores should be L1 and L2 at each end by a simple continuity test which would tell you which colour should then be common at each switch, obviously test with the circuit isolated and lamp out at the problem light. And I wouldn't rule out different colours for common at either end, seen it before.

 

[Devonchris]

Sorry I'm getting left behind here. Are you saying the yellow goes where the red is, and red is changed with other red? Or have I logged on to a diy dancing forum?

 

[Devonchris]

And our special step by step guide this evening is the Loky Cokey.

You put the red wire in
You put the red wire out
In out in out etc etc.

 

[Loky11]

update. So i traced wire from 2nd floor switch back to a junction box, but as i was tracing wire back i came across this bugger (see photo) seemed the bas**rd plumbers decided to whack a screw straight through the cable and im guessing this in effect has made the switch live become permanent live. Any way all sorted now.

Cheers for you help boys

 

[Taylortwocities]

We love Mr Wet Pants, don't we?

How did you repair the cable?

 

[DPG]

We love Mr Wet Pants, don't we?

How did you repair the cable?

Removed the screw

 

[Loky11]

We love Mr Wet Pants, don't we?

How did you repair the cable?

Just replaced that length of cable luckily the switch is pretty much directly above the junction box, and is a stud wall.

 

[DPG]

When was the work carried out that caused this?

 

[Loky11]

When was the work carried out that caused this?

In the last 2/3 months, now thinking back it all adds, replaced the switch in top floor about 7 month ago and all worked then plumbers cam in, did their bit and was only on friday id gone to screw the switch fully back (left slighly off for deccys) and some one went to turn the light off at the switch on 1st floor and light stayed on, the only person to have to floor boards up at anytime was plumber.