Yet Another Cycling Forum

General Category => The Knowledge => OT Knowledge => Topic started by: velosam on 06 January, 2019, 08:15:33 pm

Title: Re wiring a 3wire light switch
Post by: velosam on 06 January, 2019, 08:15:33 pm

Can I wire a 3wire light switch into a two wire switch i.e don't wire the neutral?

My garage switch is broken and my spare switches are all 2 wire.

Thanks

Title: Re: Re wiring a 3wire light switch
Post by: Feanor on 06 January, 2019, 08:23:15 pm

3-wire light switches (if they are using all 3 terminals ) are wired for 2-way switching, and will need to be replaced like-for-like.
If only 2 of the terminals are used, and it's the only switch controlling this light, then yes, you can use a 2-wire switch.

There's not usually a Neutral at most light switches.
( There can be, but they will all be connected together in a chock-block at the back of the box, not to the switch itself. )

So usually, no.
Replace like-for-like unless you really know what you are doing.

Or post a clear photo of the existing wiring.

Title: Re: Re wiring a 3wire light switch
Post by: velosam on 06 January, 2019, 08:34:11 pm

Thanks .  Will have to buy the same one.  It a metal switch in the garage and the neutral wire is connected to the metal faceplate with two wires connected to the switch.

I have some plastic switches which I thought could be a quick replacement as I am trying to avoid a trip to Wickes before the weekend!

Title: Re: Re wiring a 3wire light switch
Post by: Ian H on 06 January, 2019, 08:52:28 pm

That doesn't sound like a 2-way switch, and only an earth wire should be connected to the body of a switch.

Title: Re: Re wiring a 3wire light switch
Post by: Feanor on 06 January, 2019, 08:55:37 pm

There will not be a Neutral wire connected to the faceplate.
That will be an Earth wire.
Usually, an un-insulated conductor running between the two insulated conductors in a Twin-and-Earth cable.
It should be sleeved in green-and-yellow sleeving in the back box.

It sounds like a 2 wire switch will be fine.

If your new switch don't have an earth connection, then terminate the earth wire at the terminal in the metal back box, or if there is none, then just terminate it in a single chock-block to keep it out of the way.

Title: Re: Re wiring a 3wire light switch
Post by: velosam on 06 January, 2019, 10:31:44 pm

Thanks -  it is sheathed in yellow and green so will just terminate it in the metal casing box which sits on the wall

Title: Re: Re wiring a 3wire light switch
Post by: hulver on 07 January, 2019, 10:28:34 am

velosam,

If you don't know what an earth wire is, you really shouldn't be touching your house electricals.

Seriously, that stuff is dangerous.