DIY Doctor

Main navigation

Is my light switch ready for 3-wire?

Postby tiantianisfox » Sun Jul 18, 2021 7:05 pm

Hi, I want to swap my existing light switch to "smart" switch, which all seem to want to use 3-wire set up. (requiring neutral wire)

I have opened my old switch, and I can see some blue/black lines dangling around, are these the neutral?

The installation guide for the smart light: ... 200359.png
Rank: Labourer
Progress to next rank:
Posts: 1
Joined: Sun Jul 18, 2021 6:49 pm


Simply Build It

Postby chriscba » Mon Jul 19, 2021 10:02 am

It looks like a neutral, generally the neutral in a switch is not connected to anything, but it will need testing first.
The bottom red looks like the live feed.
It will need testing with a meter, as it could go bang if you short it out
Rank: Ganger
Progress to next rank:
Posts: 108
Joined: Thu Aug 27, 2009 10:00 pm

Postby Mr White » Mon Jul 19, 2021 8:45 pm

tiantianisfox, It is highly probable that the black and blue wires are neutral. It would be ideal if you could test them, but I would guess that you do not have the knowledge or equipment to test them. (I base this assumption on the fact that if you knew how to do it, you would not be asking on here.)

Without testing, all anyone can do is guess (Which is why I said it is highly probable the black and blue are neutral)

I would also offer the following advice.
Mark each wire with a permanent marker, then take a couple more pictures with the wires still connected, so you can see the marks, this way if it does not work, you can use the new pictures to see where to put the wires back.
Also measure the depth of the current back box and check what size back box your smart switch will require, often you have to change them.
Mr White
Rank: Site Agent
Progress to next rank:
Posts: 949
Joined: Tue Jun 20, 2017 9:54 pm

Display posts from previous
Sort by
Order by

  • DIY How to Project Guides
  • DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!

  • Related Topics