Wiring 3 gang, 2 way light switch

[Galliottman]

I have just got a house with a 3 gang, 2 way light switch which isn’t working properly. The wiring looks dodgy (particularly the connection from 2 COM to 3 COM) but I’m not totally sure where everything should be. Grateful for any ideas. Wiring diagram below:

 

[sparkwright]

The main sketch of the wiring at the 3 gang switch looks normal enough.

However, you haven't told us what isn't working correctly, so it's hard to say anything else at the moment!

 

[sparkwright]

Wait a minute, you specify switch 3 is 2 way - that is not wired up for 2 way operation.

 

[AndyPRK]

yes switch 3 L2 NU is the problem.

Open up the other 2 way switch and see what is there

 

[ban-all-sheds]

Wait a minute, you specify switch 3 is 2 way - that is not wired up for 2 way operation.

None of them are.

I wonder if the way he has written "1 & 2 operate single lights, 3 is a 2 way" indicates a different understanding of what "2-way" means.

 

[Echo the husky]

Hello, as the left hand cable has blue and red cores where is the yellow? This is where I'd put money that your fault is.

Is this switch in your hallway?

If this is standard I would expect the left switch (left on your diagram) to be connected with a 3core and earth to another switch (probably landing).

The centre switch would feed the hall light with the switched line being yellow, the last switch takes a neutral from the hall light via the 3core and earth (blue wire) for easy wiring of the outside light (the red and black 2core and earth)

Take care, this switch may be fed from more than one fuse/MCB.

Even with an additional core I can't make S3 work as a 2 way, only S1.

Do you have any photos of the switches? Or a diagram of the other switch in the 2 way?

 

[Galliottman]

Hi,

Thanks for the comments (I've been away for work and just got back, so catching up.)

I've spoken to the previous owner - he says everything was working OK but just before vacating he had a handyman replace the 3 gang as the previous one was cracked (though working). Workman wasn't a sparks and thought he had wired the new switch as the old. Now in the 3 gang the one that controls a single outdoor light doesn't and the one that controls a landing light on a 2 way with a switch upstairs isn't working as a 2 way should (if the upstairs switch is up, the downstairs switch (in the 3 gang) controls the light; if the upstairs switch is down, the one in the 3 gang does nothing.

The previous owner swears the upstairs switch wasn't touched, so whatever went wrong happened when the 3 gang was replaced. (The handyman isn't handy any more but I don't think he knows what needs doing anyway.)

As you look at the wiring diagram above, the left hand (as viewed from the rear) should control the landing light as a 2 way in conjunction with the switch upstairs. The centre controls the downstairs hall light and works OK. The right should just control the outdoor light - but doesn't.

The wiring is exactly as the diagram (the colours are the same e.g. yellow wire with short red sleeve).

very grateful for any more ideas.

 

[Iggifer]

Your diagram is less helpful than photos tbh. Does the outside light work if you switch the outside light on, and then turn the middle lightswitch on?

 

[Echo the husky]

I'm still putting money on your yellow wire being missing/ cut out from the cable going to your left hand landing switch. Can you see a stub of wire with the red and blue wires? Any photos?

The outside light fault:
Has the ceiling light been changed or messed about with in the hall?
Has the bulb blown in the outside light?
Has your handy man screwed a terminal screw into a wires insulation instead of into the copper?
Has the outside light been changed or messed about with?

Take care, this switch may be fed from more than one fuse/MCB.

 

[ban-all-sheds]

Galliotman - basically you have a choice between Plan A and Plan B.

PLAN A:

• Learn how lighting circuits are wired.
  • //www.diynot.com/wiki/Electrics:Lighting
    
  • http://www.google.co.uk/search?q=uk+lighting+wiring+(basics+OR+101)
    
  • //www.diynot.com/wiki/Electrics:books
    
  • //www.diynot.com/wiki/Electrics:index
• You'll probably need to get a multimeter and learn how to use it.
• Identify which conductors are which at the switches and the light positions.
• Check for circuit continuity, switches working etc.
• Connect everything up properly.

PLAN B:

• Get an electrician.

There are some irresponsible people here who will tell you that there is a Plan C, which is to start trying different things without really knowing what's going on, hoping to get it working by luck, or by blindly following instructions to put-this-wire-in-that-hole without any idea as to why. Please don't listen to them - you must know what, and truly understand what, you are doing.

Electrical-installation-by-guesswork is a foolish idea.

There is no Plan C for anybody sensible.