Background: The wife is unimpressed by the SmartLife stuff I’ve set up so far, but she does see a need for being able to switch on a light in our entrance hall. A Tuya smart switch will do that job! In fact it solves another problem for me because the current switch is 2 gang, and the second gang powers two exterior lamps which are night sensing. But that arrangement is easily defeated by just turning the switch off. So if I can set up schedules on SmartLife then I don’t care if that switch gets turned off - it will just turn on again according to the schedule (this is not fool proof, but it is better, and besides I can set up multiple schedules to turn it on).
So I’ve been reading about the smart light switches. I’m hoping I won’t have to call in an electrician because well it’s a light switch, and I change one of those, can’t I?
A lot of these smart switches cater for wiring where there is no neutral. I assume they mean no neutral wire in the switch box.
OK. So what do I have? Well I don’t understand this. Well… maybe I do, but I how I use it with the smart switch is another story.
A picture is worth a 1000 words. So here is the current wiring in the box
Just two brown wires and an earth. I assume that live is routed via the switch box, and neutral and earth are just taken to the fitting from the DB direct through the ceiling.
So now what do I do?
Is this kosher? Can I use a smart switch with this setup?
I think I’m OK. Here’s a wiring diagram’s for a commonly available switch. I think I have the arrangement shown on the right. You have to fit a capacitor that they supply across the L & N of the light nearest to the switch. I think I can manage that. But what is that capacitor doing?
only lines/lives → neutral and line/live will not be connected to the two poles of the switch (will be a short circuit when closing the switch).
the conductors to/from the switch almost look like flexible cord (extension cable) that as far as I know is not allowed as part of a fixed installation.
seems like it, yes
it allows current to flow to keep the smart switch powered but at a level that the light will not illuminate
Yup. You are allowed, I think since a few years now, to use “cabtyre” in conduit, but not like this.
There is no neutral in that box. Just a live (brown), and then the blue and yellow/green is being used as live conductors to the lamps. Very naughty…
What concerns me even more, is the wiring at the lamp itself looks like “twin flex” or also sometimes called “speaker wire”. Since it is not the same blue from below, there is a junction somewhere… possibly in the roof space, twisted together with some insulation tape or something. I’m not feeling very confident about that install.
When you fix it, or get a sparky to do it, you/he should be able to pull a neutral back from the light to the switch box. That is much easier than (re)routing a neutral from the distribution board to the switch box.
The wiring in this house is the gift that keeps on giving. I think you’re right, I think it is speaker flex. It has a ridge on the one side as speaker flex usually does. Also cunning that there’s chocolate box in there and it’s not used.
You should have seen the other switch box. That had two neutrals. Well a black wire and a blue wire, which just seemed to come into the box and then go out again. I got a shock off of the blue one… On the outbound side there were three hot wires, two of which were blue…
The light fitting I posted a picture of is interesting because it’s clearly not being supplied by that piece of cabtyre that drops down into the switch box. There are a total of three fittings supplied by that box, and none of them seemed to be supplied by the cabtyre. Presumably this goes to some box in the roof.
Anyway, the smart switches are in now and working. A bit tricky because they are about a mm all around smaller than the usual CBI or crabtree switch.
You are allowed, in the black/red colour scheme still in use in SA, to use a blue wire for the switched side of a light fixture. So black is neutral, red is your (permanent) live, blue is the switched live. I’ve seen it a couple of times where you have two-way switching (two switches controlling the same lamp). Then you have two wires running between all the controlling switches, and those are often coloured blue so they can be easily identified. At least, that is what I have seen.
If you are using Euro colours, then of course blue is neutral.
Thanks. That explains some of what I found. There were a black and a blue, that came down from the roof, were joined to another wire of the same colour with those twist on cap wotchamacallems and went straight back up again. They were not used inside the box.
I’d had enough brains to find the isolator for that box in the DB and switch that off. The Lights weren’t working but still there was something live in there.
Anyway, I don’t open these things because I’m bored and the smart switch is working now. Because I got the shock I decided I couldn’t trust the colour of anything and so couldn’t route either wire to the switch to give a neutral. So I had to put the capacitor inside a light fitting.
