Non-motoring > Replacement light switch wiring advice please Miscellaneous
Thread Author: smokie Replies: 18

 Replacement light switch wiring advice please - smokie
I am messing a bit with home automation and have put in Google Home and some LIFX bulbs.

I have some lights which I can't or don't want to replace the bulbs so I've been looking at replacement switches.

If I look at the wiring diagram in this page and compare it to the wiring I have behind a three way switch it seems to not be suitable as a direct swap.

tinyurl.com/ycypbwzk search for 3 gang wiring instruction for the pic.

Behind my switch I have three separate circuits, each with a live and neutral each side of the switch. The wiring on all of my switches (singles and doubles) are basically the same.

Can anyone confirm this please? Is there an easy resolution if it's not a direct swap?


(I have an alternative, which I am going to use in the bathrooms where I have no wall switch - which is to put one of these into the ceiling tinyurl.com/huda5d5 - cheapen than the switches anyway, but a bit more faff to install!))

TIA.
Last edited by: smokie on Thu 1 Mar 18 at 11:47
 Replacement light switch wiring advice please - RichardW
Don't understand what you are trying to do - are you talking about a 3 gang switch (i.e. one with 3 switches on it?) or a 3-way switch (i.e. one which is part of a switch system with 3 switches in it)? Can you post a photo of the wiring in the switch in question, plus info on how it integrates with other switches?

Normally a 2-way switch would have 3 wires - although depending on where the feed and load is wired it may have more. A 3 way intermediate switch needs 4 wires (the other 2 switches which are each end of the circuit only need 3 wires. Or more!
 Replacement light switch wiring advice please - smokie
I am looking at replacing up to 8 single switches, 2 double ones and 2 triples. The multiple ones would be 2 and 3 gangs, (except 1 of the three way which has hall/stairs/outside, and there is a further single switch for stairs upstairs which I assume I could just leave open (i.e. not replace)).

I'll try to find a way to host the pic of my switch but the triple gang simply has two wires for each light at the top and bottom of each switch, so it doesn't, to me, look like their example.

I just found the manufacturers page which has a little more info and more diagrams. tinyurl.com/y8sp4p6n . But I'm still a bit puzzled - though I think I could replicate the pic with the fan being powered off a plug.

Here's the photo of the back of an existing 3 gang photos.app.goo.gl/G8Y4YEva67zWEe4v1
 Replacement light switch wiring advice please - smokie
Decided it's not compatible after all, and I'm not sure the second option is either but I've ordered a couple of the in-line switches to play with.
 Replacement light switch wiring advice please - Zero
Apart from the boys toys excuse, whats the rationale behind automating turning on the light switches?
Last edited by: Zero on Thu 1 Mar 18 at 12:24
 Replacement light switch wiring advice please - smokie
None whatsoever. I hadn't realised that was a pre-requisite! :-)

Though having got some LIFX bulbs on the (very) cheap, I'm quite enjoying using voice control for my lighting.
 Replacement light switch wiring advice please - devonite
Most things in our house are voice controlled - "Please Dear, would you....." and She does! ;-)
 Replacement light switch wiring advice please - No FM2R
I'm a bit confused (nothing new).

When you're talking multiples (gangs or way) are you just referring to the number of switches in a single box, or do you mean the number of switches controlling a single bulb?

e.g.

1) on the stairs you may have two switches, bottom of stairs and top, controlling a single light.

2) In the hallway there maybe two switches, one for the porch and one for the hallway itself.

Though in both cases each individual switch is a simple and single on/off so you'd expect most things to be compatible, surely? It's only the wiring which is slightly different.

And typically only the live is switched, so I'd expect each switch to have two wires, one in and one out. But you think you've got two of each for each light?

What is the compatibility that you're concerned about?

Or am I even more confused than I think?


Last edited by: No FM2R on Thu 1 Mar 18 at 12:49
 Replacement light switch wiring advice please - RichardW
Looks like std wiring to me - the RH switch is wired 3 way - red on common and blue / yellow on straps. The other 2 are wired one way; the red ones should be perm live, then the black one will go live when the switch is in the on position. Really the black wires should have red tape on them to show they are switched live.
 Replacement light switch wiring advice please - No FM2R
Makes sense.

The 3-way will be two switches and one light I assume. The others one switch per light.
 Replacement light switch wiring advice please - smokie
I know I'm not making myself clear, sorry!

But forget the three gang. On an existing one gang I have two wires, one at the top and one at the bottom of the switch. One presumably comes from the circuit and the other goes to the light. The N from the light must go back to a spur from which the switch is fed.

The new switches say they require a live and neutral feed, into the L & N sockets, then the "return" from the light also goes into the N hole (along with the one from the mains) and the "red" to the light goes into L1 (Out).

So that's 4 wires I need coming into the box, and I only have 2.

Any better?

(I've tried adding the manufacturer's pic to the album but not sure it's worked - photos.app.goo.gl/G8Y4YEva67zWEe4v1 )
 Replacement light switch wiring advice please - No FM2R
>>The N from the light must go back to a spur from which the switch is fed.

Are you sure that the N is not hidden in the hole somewhere, albeit not connected to the switch?
 Replacement light switch wiring advice please - No FM2R
Normally wire is two or three core. It is simply easier to take it all to the switch, connect the live to the switch and then use another cable to the bulb with the live connected to switch out and the neutral connected to the incoming neutral (if you see what I mean). To start running single core makes no sense and is hard work.
 Replacement light switch wiring advice please - smokie
No, not sure of anything!!

Thanks for the info, I'll have a better look at one tomorrow.

The house is probably early 70s and hasn't been rewired.
 Replacement light switch wiring advice please - No FM2R
I would be very surprised if you did not find 4 wires - Live in/out and Neutral in/out. If you cannot see the neutral, dig about, it's probably there somewhere.

Do turn off the power, digging about is a fine way to short something or get a shock.

You may or may not (probably not) find earth wires.
 Replacement light switch wiring advice please - tyrednemotional
...it appears to me that you have fairly conventional wiring for your existing lights, and that means it *will* be incompatible with the switches you originally highlighted (unless you want to rip the wiring out ;-) ).

As has already been alluded to, there is no neutral at the switch, the black is a switched live, and should conventionally have a red sleeve.

Whilst the following diagram is rather simplistic (since it is an end of circuit, and shows only one light and switch dropped from it - in non-end-of-circuit circumstances, the lighting circuit would continue via another feed *taken at ceiling level* to the next "rose" and switch), by reference to it you can see how the wiring works.

lightwiring.co.uk/wp-content/uploads/2013/03/loop-in-junction-box-wiring-diagram-end-of-circuit.jpg

The majority of the wiring remains at ceiling level. Only the live to the lamp is passed downwards through the switch, and back up again to the lamp via the sleeved black.

At the switch you have only a live-in (and out, when so switched), and if you're lucky, an earth grounded to the box.

There is no neutral at the switch, which you need for your originally proposed replacement switches, which are designed for a different wiring mechanism.
 Replacement light switch wiring advice please - No FM2R
>>The majority of the wiring remains at ceiling level. Only the live to the lamp is passed downwards through the switch, and back up again to the lamp via the sleeved black.

I guess it must vary because on mine in the UK both are passed down. Both in it's very old [and now gone] wiring and its replacement brand new wiring.

If you pass only the live down that typically implies that the neutrals and/or lives are joined in the ceiling. I don't like hidden joins, I prefer joins in the switch or behind an accessible and removable panel however well and securely they are made. In the US it must be that way by law, I don't know about the UK.
 Replacement light switch wiring advice please - tyrednemotional
...whilst there certainly are other means of wiring lights, AIUI the "loop-in" method that the diagram shows is historically the most widely used in the UK. It's certainly the only method I've come across in all my years of "tinkering".

The connections could quite easily be made in a ceiling rose, in order to keep them accessible.
 Replacement light switch wiring advice please - No FM2R
I agree except that i find that both wires are passed down to the switch, not solely the live.
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