Wiring 3 gang switch - light is always on or always off

[sarahaddyman]

I have a three gang switch in my hall way. The switches are for the landing light, the hall light and the porch light. The landing light and hall light both work, but the porch light doesn't.

I turned of the electricity and opened the cover of the porch light, assuming the bulb had gone - to find the light wasn't wired up. (It's never worked in the time I've lived here.)

There are two red (live) wires, which are connected together. There are two black (neutral) wires which are separate. There is no earth wire, so I have replaced the light with a new one from B&Q that does not require an earth, just to be on the safe side.

If I separate the red wires, the landing light and hall light don't work. If I connect the black wires, the trip switch goes as soon as I put the electricity back on. So I know the two red need to stay connected and the two black ones need to stay separate.

If I wire the light up to both red wires in the live connection and one black wire in the neutral connection either the light doesn't work at all or it is permanently one, no matter what position the light switch is in.

DOES THIS MEAN THE SWITCH IS WIRED INCORRECTLY?

If it does, will buying a new three gang switch (for the instruction leaflet that comes with it!) to rewire it solve my problem? Or is it a more serious problem that requires an electrician?

(I've rewired a new security light and changed standard two gang switches for dimmer switches, so I'm competent with the basics.)

 

[Spark123]

Can you post a photo of what you have in the back of the switch?
Initial thoughts are it hasn't been connected in as there isn't a neutral at the switch, but I may be wrong.

 

[sparkyspike]

Mostly likely scenario:

Don't connect the two reds into your light. Leave them connected together in a terminal block, or wire them into the LOOP terminal of your new light if you have one. One of the black wires is the live, the other is neutral. To find out which is which, one may have a red tag or sleeve on it, or otherwise you will need a meter or test bulb to work out which one is neutral.

 

[sparkyspike]

In fact, as you have already determined which black wire makes the light permanently on, then this must be the neutral. The other black wire is a switched live. This isn't the correct or safe way to test, but as you have already done it, there you are.

I would still recommend you use a meter, or an electrician, to test the circuit properly. It is essential that you get the polarity correct - you need to confirm that the live only is switched, and that the correct terminal in the light is connected to live (very important with ES fittings).

 

[Taylortwocities]

In fact, as you have already determined which black wire makes the light permanently on, then this must be the neutral. The other black wire is a switched live.

So, Sarah. The bit missed out is how you connect it up.

You have two black wires: the neutral goes to the Neutral on your light the other black wire (switched live) goes to the live on your light. Put a bit of brown sleeving or tape on this one so the next person will know what is going on.

Connect the earth to the fitting if it is required. That's it/