Hi Folks. I have a slight problem with my 3 way light switch. Outside light not worked since I fitted it. Got fed up with it so gave up. Now dark nights have arrived need to get it working. See picture below. Any help would be gratefully received. 
3 Way Light Switch
- Thread starter neale63
- Start date
are there any wires joined in the back box?
Where have you taken the neutral from ? on the black wire to the light ?
What did you do? change the outside light or install it from scratch and fit a 3 gang switch?
Where have you taken the neutral from ? on the black wire to the light ?
What did you do? change the outside light or install it from scratch and fit a 3 gang switch?
Hi Andy thanks for you quick reply. I replaced the existing outside light with a new one and at the same time replaced the old brass switch inside to a new plastic one. I did take note of the wiring but thinking about it now only the colour not the exact position of the red except for the com wires. Behind the switch there are 2 black wires in a connector, all neutral wires are connected to a connector and the metal back box. Both these wiring were not touched when I fitted the new light and the plastic switch.
Just noticed that I have another red wire at back not connected to anything. Copper cable is flush with plastic sleeve but may have snapped, not sure !!!
Yep typo, earth comes in and out of back of back box.
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I am doing a count four red and one black. Now cables are either two reds or red and black so something wrong with count.
Standard method with switch is permanent line to switch and switched line return i.e. no neutrals however with outside light common for neutral to go into the switch and use a double pole switch so once switched off there are no issues with earth - neutral faults and tripping RCD once switched off.
I would guess somewhere it's down to a missing neutral. It's not uncommon to find outside lights wired in series with some inside light where some one has used a switched line as a neutral by mistake.
So step one is better drawing where there are rings around the wires forming each cable so we can see how they are related.
There are some obvious errors.
1) You show centre switch as being two way but bottom switch has the three wires required for two way wiring.
2) You show line linking all L terminals together normally the two way switch will have line to L1 or L2 not L.
Although school boy wiring of two way is like this
this is rare in practice and would require some connector block in the switch. So what is normally done is this
you will note how I have drawn circles around the wires found in each cable.
However as you can see this needs three wires between the two switches. Before the days of loop hearing aids, wifi and cordless phones it was common to borrow the live from another switch. This can produce mains hum so is no longer done but still found in old houses. Since you show links I would guess this has happened with yours.
Standard method with switch is permanent line to switch and switched line return i.e. no neutrals however with outside light common for neutral to go into the switch and use a double pole switch so once switched off there are no issues with earth - neutral faults and tripping RCD once switched off.
I would guess somewhere it's down to a missing neutral. It's not uncommon to find outside lights wired in series with some inside light where some one has used a switched line as a neutral by mistake.
So step one is better drawing where there are rings around the wires forming each cable so we can see how they are related.
There are some obvious errors.
1) You show centre switch as being two way but bottom switch has the three wires required for two way wiring.
2) You show line linking all L terminals together normally the two way switch will have line to L1 or L2 not L.
Although school boy wiring of two way is like this
However as you can see this needs three wires between the two switches. Before the days of loop hearing aids, wifi and cordless phones it was common to borrow the live from another switch. This can produce mains hum so is no longer done but still found in old houses. Since you show links I would guess this has happened with yours.
Hi All Thanks to all who replied. Stripped everything down and checked outside lights wiring and bulb, as this was the one not working. Rewired all wiring back in from original drawing I made when changed the light socket. Now everything works. 
. Can only assume there was a loose wire somewhere. I did find one of the 2 black wire's in the separate connector in the back box was broken but I looked like it was still connected, but again unsure if it was a good connection. I had checked them before but not by stripping them down. House we are in was built in early 50's and in the 14 years since we bought the house we have always found issues when doing DIY. Wife thinks it was the house that Jack built. Eric wiring drawing was upside down so it was a bad drawing. As for the red wire's they were as drawn with 1 spare not connected. By my count that makes a total of 5 red and 3 black. I can't work that one out either . But hey it now works. Again thanks to all who replied 
. Can only assume there was a loose wire somewhere. I did find one of the 2 black wire's in the separate connector in the back box was broken but I looked like it was still connected, but again unsure if it was a good connection. I had checked them before but not by stripping them down. House we are in was built in early 50's and in the 14 years since we bought the house we have always found issues when doing DIY. Wife thinks it was the house that Jack built. Eric wiring drawing was upside down so it was a bad drawing. As for the red wire's they were as drawn with 1 spare not connected. By my count that makes a total of 5 red and 3 black. I can't work that one out either . But hey it now works. Again thanks to all who replied 
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