Can I wire in 12V transformer for LED strip at end of downlight chain?

[PipeDownSoldier]

Hi all,

Is it possible to wire in a 12V transformer at the end of a LED downlight chain (downlights are all mains downlights- LAP CosmosEco from Screwfix). This is so I can wire in a LED strip for some lights to put above a bathroom mirror.

My preference is to have the light switch turn all lights on at the same time, rather than have two separate switches.

I’ve attached a diagram of what I intend to do. Or does the transformer need to be wired in at the junction box?

Thanks

 

[ericmark]

Since 1966 all fixed 230 volt lamps (not pedants) must have an earth to the lamp, even if the lamps are class II, so you should have line, neutral and earth at each lamp, in which case no problem adding a hard wired transformer, however you say bathroom, so would need to be hard wired, plug and socket is not permitted, and in Wales bathrooms are special locations so needs notifying to LABC before the work is done if DIY or use a scheme member electrician which is likely cheaper.

 

[PipeDownSoldier]

Since 1966 all fixed 230 volt lamps (not pedants) must have an earth to the lamp, even if the lamps are class II, so you should have line, neutral and earth at each lamp, in which case no problem adding a hard wired transformer, however you say bathroom, so would need to be hard wired, plug and socket is not permitted, and in Wales bathrooms are special locations so needs notifying to LABC before the work is done if DIY or use a scheme member electrician which is likely cheaper.

Thanks very much. I can confirm that each downlight is earthed.

 

[EFLImpudence]

"Ring" is not another word for circuit.

 

[ericmark]

I did notice that, and it is unlikely lighting wired as a ring or a ring final. However could not see the point in correcting.

I would prefer to have lights split so I can decide how many lights I need, living room I have uplighters, display cabinet lights, main chandelier and spot lights for reading, and hey google turn on living room lights turns them all on, but I can also select to just use some.

 

[PipeDownSoldier]

Apologies - you are right - I was being lazy with my terminology when I drew that.

So is the proposal in my diagram okay? My concern is mainly that the LED downlight chain is a switched live and so the 12V transformer does not have a neutral unless fed from the junction box.

 

[ericmark]

Switching supply to a power supply is not a problem, and one can switch output from a true transformer, but often not from a switched mode power supply, some you can and some you can't, so better not to have switches after any electronic transformer. So yes seems OK.

 

[DetlefSchmitz]

My concern is mainly that the LED downlight chain is a switched live and so the 12V transformer does not have a neutral unless fed from the junction box.

This seems to be somewhat confused. Are you thinking that there is no neutral going to the downlights? I think what you do depends a lot on what is already there.

 

[flameport]

So is the proposal in my diagram okay?

Yes.

My concern is mainly that the LED downlight chain is a switched live and so the 12V transformer does not have a neutral unless fed from the junction box

The downlights have a switched line and a neutral.
Without a neutral they would not work.

 

[EFLImpudence]

I did notice that, and it is unlikely lighting wired as a ring or a ring final. However could not see the point in correcting.

Because it is wrong ???

It is apparent that lots of people think ring is just another word for circuit; like you calling many things Part P when they have nothing to do with it which is also frequently corrected.

 

[PipeDownSoldier]

Yes.


The downlights have a switched line and a neutral.
Without a neutral they would not work.

You're right - thank you for correcting me. I’ve drawn out an updated diagram….

 

[ericmark]

There is also a huge difference between a ring and ring final. We had the HV as a ring, so we could isolate part of the ring to work on it, but the ring final if part is isolated then it can be over loaded, but since homes are not wired as a ring, and are always wired as a ring final there seems no point in correcting.