Light switches

[pulhamdown]

Having been in our new build house for nearly five years, I am getting round to addressing the very minor issues.  We have at least four rooms where the light switch is outside the room, and therefore very easy ( apparently! ) to forget to switch off the light when coming back out.  I have searched for replacement light switches with a warning light which lights up when the room lights are on, and goes off when the switch is turned off.  No joy.  Does anyone know of any?  If not, is it possible to wire in a separate "on" warning light, just as I would in my car.  I have no experience of 240v wiring, so would not be attempting this on my own!    I am about to use ( yet another ) electrician, and would like to know what is possible.

Thank you

 

Colin 

[Jeremy Harris]

The problem is that all the indicator switches that have this capability need a neutral, and unless your lighting circuit has been wired so the neutral is commoned in the back box (ours is, I think it makes the most sense) then there's no way to power a light with the switch on without running an extra neutral to the switch point.

 

In terms of what's available, then there's no technical reason why a normal indicating DP switch can't be used, but you are pretty restricted  in terms of design.

 

First thing to do is check whether there is a neutral in the box behind the switch.  Turn off the power, check that the circuit really is dead, then unscrew the light switch and pull it far enough away so that you can see the wiring.  Either sketch what you see or post a photo and one of us will be able to have a good go at guessing whether you have the neutrals commoned at the switch or up at the light fitting.  Doing it at the light fitting has been the "traditional" way for a long time, but isn't my favourite method, as there often isn't much room in the fitting, whereas there usually  is in the back box of the switch.  It's also easier to make multiple connections standing on the floor than it is up a set of steps!

[PeterW]

You can use a neon in parallel with the switching - MK do them and they fit behind the normal back plate.

 

https://www.tlc-direct.co.uk/Products/MKK3041.html?source=adwords&ad_position=1o1&ad_id=45425533757&placement=&kw=&network=g&matchtype=&ad_type=pla&product_id=MKK3041&product_partition_id=174047748547&test=finalurl_v2&gclid=Cj0KCQiAkNfSBRCSARIsAL-u3X9V3jpUs68NERvkJJ4tUK2sjyrH4McApTvLDF-OyPSd4DgOcQGPTi8aAiaoEALw_wcB

[Jeremy Harris]

8 minutes ago, PeterW said:

You can use a neon in parallel with the switching - MK do them and they fit behind the normal back plate.

 

https://www.tlc-direct.co.uk/Products/MKK3041.html?source=adwords&ad_position=1o1&ad_id=45425533757&placement=&kw=&network=g&matchtype=&ad_type=pla&product_id=MKK3041&product_partition_id=174047748547&test=finalurl_v2&gclid=Cj0KCQiAkNfSBRCSARIsAL-u3X9V3jpUs68NERvkJJ4tUK2sjyrH4McApTvLDF-OyPSd4DgOcQGPTi8aAiaoEALw_wcB

 

That works the "wrong" way around though, the indicator is on when the light is off and the indicator is off when the light has been left on.

 

Edited to add:

 

However, if the wiring is such that there is a neutral available in the back box, then I am pretty sure you could wire these across the neutral and switched line, rather than across the switch, to get the light to work the right way.

Edited January 10, 2018 by JSHarris

[PeterW]

7 minutes ago, JSHarris said:

 

That works the "wrong" way around though, the indicator is on when the light is off and the indicator is off when the light has been left on.

 

Yep just realised that ! Doh,.....!

 

Apparently they flicker if you use them with a CF lamp, not sure about when used with LED...??

[Jeremy Harris]

6 minutes ago, PeterW said:

 

Yep just realised that ! Doh,.....!

 

Apparently they flicker if you use them with a CF lamp, not sure about when used with LED...??

 

I was editing the post above as you were typing  - I think they should work OK if there is a neutral in the box.  We need to know which way the lighting circuit has been wired.  If it's wired as "switch loop" then this should be easy, if wired as "loop in" then it won't.

Edited January 10, 2018 by JSHarris

[pulhamdown]

I've just been and had a look.  There are neutral wires in the back box, but they are not connected to the switch.  Just sitting there.

 

Colin

[PeterW]

Just now, pulhamdown said:

I've just been and had a look.  There are neutral wires in the back box, but they are not connected to the switch.  Just sitting there.

 

Colin

 

OK

 

In that case you can use the neon back plates I posted...!

 

One wire goes to the switched live, the other to the neutral and it will glow when its on.

 

 

[Jeremy Harris]

Good news, and nice to hear that "switch loop" is getting to be used more, as I've always felt it made more sense. 

 

Like ring finals, I have a feeling that "loop in", where all the common neutrals are in the light fitting or a nearby junction box, was just a way of minimising the amount of cable, during the period when there was a shortage of copper wire, or it was expensive.

Edited January 10, 2018 by JSHarris

[pulhamdown]

It is indeed good news!  Thank you both for your quick replies.  Yet another example of what a brilliant resource this forum and it's members are.

 

Colin 

[dpmiller]

I fitted a switch backplate as a nightlight in the youngster's room. Not that MK one, can't remember the brand but it's a white LED rather than a neon and works just fine with either a CFL or LED in the circuit.