Wiring for a 2 gang light switch

[flameport]

The only way to get that resolved and still have 2 switches for the kitchen light is to install new wiring. That will probably involve damage to walls/ceilings.

If you want the outside light working and only 1 switch for the kitchen light, then it can be done with the existing wires.
You could even use the same 2 gang switch, it would just mean that one of them won't do anything (much like it does now, except the working one would be for the outside light)

 

[flameport]

At the 3 gang switch:
Disconnect the wire A, and put it with the other wires at B. (3 wires in the same terminal).

At the other 2 gang switch:
Disconnect wire C, and put it into the terminal D with the other wire already there (2 wires in the same terminal)
Disconnect the wire at E and put it into terminal F
Wire G for the outside light goes into terminal H
Neutral I into the terminal block J
Earth K into the terminal block L, it should have a piece of green/yellow sleeving on it.

The left switch will do nothing.
The right switch is for the outside light.

If you want to change to a single gang switch later, then the two wires in D will need to be connected together with a piece of terminal strip, and the wires to F and H connect to the new single gang switch.

 

[SUNRAY]

Retains 2way system

 

[sparkwright]

Retains 2way system
View attachment 191837

This is interesting.

You have the neutrals connected to the switches I see.

 

[James Crinage]

I followed the post above to get one switch working constantly for the back light. I've seen the diagram above by Sunray but slightly confused by the diagram and how that relates to the wiring I have. I.e which wire is which

 

[sparkwright]

That diagram from Sunray is very interesting, I'm still tracing it out to see if it works properly with every switch movement...

 

[sparkwright]

With Sunray diagram it appears as you operate the kitchen two way switches, the live and neutral at the kitchen light become reversed. I THINK.

So if the lights are capable of having their polarity reversed and still work properly, and nothing else has been tagged on to them, this would work. I THINK.

That genius Sunray is a clever bugger - not sure if you should attempt it mind, also don't know what the builder's electrician would have to say!

 

[sparkwright]

At the 3 gang switch:
Disconnect the wire A, and put it with the other wires at B. (3 wires in the same terminal).

View attachment 191770


At the other 2 gang switch:
Disconnect wire C, and put it into the terminal D with the other wire already there (2 wires in the same terminal)
Disconnect the wire at E and put it into terminal F
Wire G for the outside light goes into terminal H
Neutral I into the terminal block J
Earth K into the terminal block L, it should have a piece of green/yellow sleeving on it.

The left switch will do nothing.
The right switch is for the outside light.

View attachment 191778

If you want to change to a single gang switch later, then the two wires in D will need to be connected together with a piece of terminal strip, and the wires to F and H connect to the new single gang switch.

Saved me writing it all out!

 

[winston1]

With Sunray diagram it appears as you operate the kitchen two way switches, the live and neutral at the kitchen light become reversed. I THINK.

It does. Which of course is dangerous and should not be done.

 

[bernardgreen]

The two way switching in Sunray's diagram does in theory work, in days of old it was often used with Live and Neutral looped to all the switches in the house.

BUT in those days change over switches had about an inch of separation between the Live and Neutral connections ( L1 and L2 ). The arc formed when the switch was operated could not reach from Live to Neutral. Modern switches have about 3 mm of separation and the arc can bridge the gap and continue to exist long enough to damage the switch,

 

[sparkwright]

Re Winston's post: Certainly a problem with ES lampholders, and some LED lights.

And confusing to say the least for the next electrician, particularly for anyone working on the kitchen light!


You've got to applaud Sunray's effort, he must have been hours on that!

 

[SUNRAY]

Re Winston's post: Certainly a problem with ES lampholders, and some LED lights.

And confusing to say the least for the next electrician, particularly for anyone working on the kitchen light!


You've got to applaud Sunray's effort, he must have been hours on that!

No not at all, the only time spent was making the drawing.
This is a system which used to be VERY common and is still very much the popular way of reversing polarity of the field wiring on a motor to reverse the rotation, sometimes with 2 switches to make it easy to allow the motor to stop before reversing and other times using a double pole 2 way switch [2PCO] the back emf from a motor is far more likely cause a big arc than domestic lighting.

It was only a year or 2 back the inspection of a substantial office block on behalf of their insurance company had coded C1's. The method was used exclusively for all of their 2 way switching of which there where possibly hundreds in use [including intermediates], I was involved when MK and Contactum technical staff attended site when that C1 code was challenged by the on site maintenance staff. Both manufacturers deemed it to be OK and to satisfy the inspectors took sample switches away for inspection.

The wiring was mostly done with MI cable so the building owners were very reluctant to make significant alterations.

The other manufacturers items on site were changed to MK as they didn't get involved in the discussions and would not say if their product was suitable for the system. I think I may even still have some of those in a box of junk.

 

[flameport]

It was only a year or 2 back the inspection of a substantial office block on behalf of their insurance company had coded C1's.

C2 would have been more appropriate.

Switching in the neutral hasn't been permitted since at least 1939.

 

[EFLImpudence]

Would the arrangement technically be classed as switching the neutral?

 

[flameport]

Would the arrangement technically be classed as switching the neutral?

Yes, because in some of the configurations the lampholder remains live even when off.
In the worst switch arrangement, the light is on, then the neutral is disconnected and then connected to line instead.

Doesn't comply with identification of conductors either, as what is line / neutral changes depending on the position of the switches.