24v lighting circuit - good or bad idea?

[SBMS]

Looking at loxone home automation. Seems that life would be much easier and cheaper with regard to downlighter dimming if I went for 24v lighting circuits for downlights. Has anyone else done this? It seems very difficult to find 24v fittings but I assume I can use 230v fittings that don’t have lamps, add my own gu10 24v lamps and then can dim from the 24v loxone dimming relay (4 channels for £70 odd). 
 

Any downsides to the above?

[-rick-]

I've never heard of 24v GU10 lamps. I'm not sure I'd want to try and make my own especially as the best lights are ones with sophistcated lenses not just a bunch of leds on a board. If you did want to do that I would go for MR16 as a connector.

 

What you'd like to do does seem fairly optimal as a way of doing things. I'd like to do something similar. But I've not really found anyone selling much suitable. Especially as I want CCT controllable lights (at least in some places) so that I can alter the colour temp by time of day/activity. You either get 'smart' lights with their own wireless interface or dumb lights in MR16 (12v) or GU10 (mains voltage) or completely custom fittings. I think loxone do their own multi-colour light to connect to their controllers but its really pricey and didn't seem that good.

 

Oh for an industry standard option in this space. Most people just want something they can retrofit to existing system.

Edited August 24 by -rick-

[-rick-]

BTW Soraa do some high quality externally controlled lighting so it's one place to start looking. But it's expensive and still doesnt really fit the bill. They also look like they have been bought out/merged since I last looked so not sure their products are the same/same quality as when I last looked.

 

https://www.ecosenselighting.com/products/soraa/

[Nickfromwales]

23 minutes ago, SBMS said:

Looking at loxone home automation. Seems that life would be much easier and cheaper with regard to downlighter dimming if I went for 24v lighting circuits for downlights. Has anyone else done this? It seems very difficult to find 24v fittings but I assume I can use 230v fittings that don’t have lamps, add my own gu10 24v lamps and then can dim from the 24v loxone dimming relay (4 channels for £70 odd). 
 

Any downsides to the above?

230v fittings have current ratings to suit, and when you drop the voltage the current shoots up, simple V/I/R calcs will show you the impact there.

 

Also, you'd need to run bigger cables too, to combat voltage drop. Not a huge issue in a smaller house with a centralised 'cabinet', but if one end of a larger dwelling you will find it prohibitive / impractical I think.

[-rick-]

Looking at Nicks reply makes me wonder if I've answered a different question.

 

The 24v dimmers are generally for LED strips not fittings. If you want to use them to dim bulb type fittings, one idea is to run two MR16 bulbs in series from one dimmer channel. That should just work with standard dumb MR16 bulbs. Of course if one bulb failed it would take out both fittings but that might be a good trade off.

 

MR16 is designed to cope with 50W halogen so should have no problem with anything you can throw at it LED wise.

 

Do keep the cables to the controller pretty short though. Running long leads with PWM dimming signals is a recipe for issues (thats ignoring the voltage drop due to cable length).

[SBMS]

1 hour ago, -rick- said:

Looking at Nicks reply makes me wonder if I've answered a different question.

 

The 24v dimmers are generally for LED strips not fittings. If you want to use them to dim bulb type fittings, one idea is to run two MR16 bulbs in series from one dimmer channel. That should just work with standard dumb MR16 bulbs. Of course if one bulb failed it would take out both fittings but that might be a good trade off.

 

MR16 is designed to cope with 50W halogen so should have no problem with anything you can throw at it LED wise.

 

Do keep the cables to the controller pretty short though. Running long leads with PWM dimming signals is a recipe for issues (thats ignoring the voltage drop due to cable length).

Is MR16 not 24v? I assume the 24v dimmers wouldn’t work?

[-rick-]

MR16 is 12V, I believe historically AC, though I think DC is common too.

 

A 24V dimmer designed for LED strips should I think be able to drive two basic 12V MR16 LEDs in series assuming you are driving simple LEDs. I wouldn't expect it to work with LEDs that have any smart features. Even 'dimmable' ones might be difficult. To be clear, when I say work I mean work with the dimming function of the loxone driver. All will likely work if the set point is 100%.

 

A 24V dimmer designed for LED strips will likely be able to supply enough current to drive multiple sets of 2 in parallel but if you wired a single MR16 up to it (or multiple in parallel) the 24V will almost certainly pop them given they are designed for 12V (even if you set the dimmer to 50% - it doesn't work like that).

Edited August 24 by -rick-

[-rick-]

I checked, my old MR16 drivers are AC. First hit for MR16 driver now came up with a DC driver.

[SBMS]

Thanks all. Im a bit worried wiring  two 12v mr16s to 24v and was already concerned about putting non standard lighting circuits in.. I think it sounds like I am probably best off with mains downlights and trailing edge dimmers. The loxone 4 channel mains dimmer is ridiculously expensive so I’ll probably go for the whitewing dmx. I think I’m better off going for gu10 fittings and then getting something like a Philips master DimTone?

[-rick-]

That sounds like the best approach to keep things standard and understandable. GU10 seems to have won the war for replaceable bulb fittings even though its the worst format for dimmable LEDs.

[Alan Ambrose]

Actually I think your 24V idea is a good one. It’s a bit nonsense converting 230V to low voltage all over the place. These days, the only things actually needing 230V are the higher power items, appliances etc.

 

Regarding current and cable size at low voltage - the whole point of LEDs is that they are much lower power than the old fashioned lights they replace. Say you’ve got 100 off 5W leds in your place - that’s 500W or 20A and that’s with all your lights on (and they won’t all be on the same circuit).

Edited August 25 by Alan Ambrose

[G and J]

Standardisation and volume production are key to cost effective reliability.  Yes, maybe if we were designing our domestic systems from scratch we’d go low voltage dc.  But we aren’t.  And the range and variety and price of ac control options are impressive. 
 

Be a bit careful with dc ratings.  Some switches have a very low dc current rating compared to their ac rating (I think that’s due to arcing). 
 

And whilst it’s a seductive argument to replace all those ac-dc converters in each light bulb in reality a system would probably have just as many dc-dc converters which are pretty similar. 
 

A while ago I investigated dc domestic lighting, spurred on by the thought that I could easily battery back 12v lighting circuits and improve efficiency. But the argument disappears when one considers the efficiency of modern ac coupled battery units.  
 

So instead I settled on a split CU and an ac coupled battery unit with backup capability.  Simples. 

[Alan Ambrose]

Yeah, each to their own and you have to choose carefully where you want to innovate (if anywhere) and where quick and off the shelf is the order of the day. It’s Indicative though that Loxone lights are 24V and I think that style of technology (not necessarily that company and pricing) is where we’re heading eventually.

[-rick-]

1 hour ago, Alan Ambrose said:

Yeah, each to their own and you have to choose carefully where you want to innovate (if anywhere) and where quick and off the shelf is the order of the day. It’s Indicative though that Loxone lights are 24V and I think that style of technology (not necessarily that company and pricing) is where we’re heading eventually.

 

Yeh if a loxone bulb cost £20 rather than £80 they might have something but the prices compared to standard off the shelf are crazy. I'm guessing the price on the website can be got down a fair bit through a bulk order but still. Having looked again at their website thanks to their thread at least they now seem to have fittings with decent lenses, etc.

 

I doubt we will get there as standard in domestic properties in any time scale relevant to this forum.

[jimseng]

I am doing exactly this. My whole lighting circuit is going to be 24v DC and I have found some MR16 8w 24v lamps that work extremely well with PWM dimming, even at 4Khz. So I am going for a really cheap option of RGBW LED amplifiers (less than £4.00 for 4 channels), the MR16 bulbs work out at about £4.80 per bulb and will fit any MR16 fitting. I have also ordered some ES 24v bulbs to fit normal lighting fixtures. I hate mains dimming LEDs, they buzz and flicker at the cheap end of the market. 
I will probably try and run the whole lighting system from a 24v LiFePo4 battery eventually.

[Alan Ambrose]

@jimseng - possible to say a bit more about your set-up? Are these all radials sitting on some central relays or controllers somewhere or directly switched by standard switches? How’re you supplying your 24V - individual din rail transformers? What kind of cables are you using? Did you feel you had to run these separated from any mains cable?

[SteamyTea]

On 25/08/2025 at 07:35, Alan Ambrose said:

 

Regarding current and cable size at low voltage - the whole point of LEDs is that they are much lower power than the old fashioned lights they replace

But possibly a different resistance.

So may be the square of the current.

[jimseng]

My setup is nothing at the moment as my house is being built. But I have a plan! I don't know how much detail to go into before it gets boring for you all.
I have 85 8w MR16 bulbs coming on a slow boat from China at the moment from Benory lighting. They are about £4.50 per bulb and I have a mix of 4000 and 3000 colour temperatures. I have been looking over the last two years for low voltage LEDs that actually dim well at high PWM frequencies and these ones are specifically designed for it. They dim very well down to very (very) low levels at 3Khz PWM frequency and are very stable with no flicker or buzz. I have also purchased 24 x RGBW (4 channel) LED amplifiers from Alibaba at about £3.50 each. I have used these before and they seem very good and reliable, especially given how cheap they are. But then they are just mosfets in a box I guess.
So I will have 96 channels available to me in my house. Each room will have between 8 and 16 channels so every single LED will be on its own channel. I have designed a control system that sits behind a standard dual gang pattress which will look like a conventional 3 gang dimmer wall switch. But inside is a micro controller (RP2040) hooked up to an RS485 network. The micro controller is responsible for  generating the PWM signals and responding to the dimmer knobs and communicating with the house computer. I have the ability to run slave controls on the other side of the room , plus infrared (and my phone / laptop if I really want to). The idea is for it to be invisibly sophisticated so the light switches look and behave like normal dimmers switches but each individual LED in each room can be assigned to any knob on the room dimmer switch at any relative level (with a gamma curve). And I will be able to  change the dimmer knob assignments on a whim or a schedule.  (I might want different pre-sets and levels for different occasions. Who knows, maybe I'll set it up once and that will be it). I have also included temperature and door sensors. 
My plan is to have a 24v  dc "backbone" on each floor. I have yet to do the voltage drop calculations but it might be some fairly chunky DC cable (6mm? 4mm?) that then branches off, via a busbar to each room. The LEDS will have a common positive and then each negative will be taken back to the RGBW amplifiers on .5mm cable (8w at 24v is only about .33 amps so .5mm should be plenty) I will put up to 4 RGBW amplifiers (up to 16 channels) behind some sort of elegant service hatch in the service void in the wall in each room.
As for the power supply. I will probably start with a 500w 24v unit running off a 13amp plug as eventually I will have a 24v LiFePo4 battery tapped off my solar array. 80 x 8w MR16 bulbs is  640w, and that is with every single LED on at once so I don't think I need a massive supply. It works out at about 12 amps per floor, worst case. Over a 15 metre run that requires quite beefy cable if I want to obey the 3% voltage drop rule, but I will do some more calculations and start chunky and reduce it as I go further from the power supply. I think I will run 2.5mm for the common positive and then the negatives will be .5mm. I have yet to have a conversation with the electrician as he/she/they don't know what I am planning. I might run singles in a ring for the positive, I will have to see what regs apply.  
I have yet to set this all up so it will be interesting to see if it is a success but compared to Loxone kit I think it is likely about a 50th of the cost and will work the way I want it to with my own firmware that I can customize to my own diabolical ends.
Feel free to ask more questions, or tell me I'm mad. I don't care. It's my house and no-one can tell me what to do! (I don't have a wife).

[G and J]

I looked real hard at dc lighting, and I concluded it was do-able. But I also concluded that the volume of bits available to buy for good old fashioned BF&I 240Vac was several orders of magnitude greater than for dc lighting. 
 

I also concluded that there was nothing I could think of that I could do with dc lighting that I couldn’t do with mains, for less effort and cost. 
 

The killer though for dc is that I want it third party maintainable - when I am in my bathchair in the care home conveniently located just past the bottom of our garden I want J to be able to get an electrician to fix stuff easily.  In fairness I want that for me too in my advanced years, as eventually surely I’ll get over trying to do everything myself. 
 

But as you say, it’s only you and it’s your pad.  

[jimseng]

I think one of the things is that I have become slightly obsessed about efficiency. It might be a bit ideological but to me it doesn't make sense to have a DC current being produced by the solar, converting it into AC via an inverter, with the losses that introduces, in order to pump it round a lighting circuit only to have it converted back into DC to power LEDs. I know that is rather pedantic and I know the LEDs have a current converter inside. And it is true that since much of the rest of the house requires 240v ac why get so uppity about it but it does bug me. When I had the consumer unit replaced in my old house a few years ago the electrician couldn't sign it off because the lighting wiring had no earth in it. So I suggested fitting a cheap 12v transformer and switching over to low voltage LEDs. It was what I was used to on my boat and meant I could get an electrical certificate. And I found it was so easy and worked well enough that I decided it was the way to go for lighting now. I wish I had gone for 24 volt at the time but I had already purchased all the LEDs so I stayed with 12v.
But I take your point @G and J that future occupants might have a hard time dealing with it so I am certainly going to document it all as best I can. But my aim is that it won't need apps of any fancy panels or screens. Just knobs you turn and the lights get brighter or dimmer (properly, perceptively linear and no flickering, I hate the flickering). But beyond that there is more sophistication to the lighting system "under the hood". For me it was easy and really cheap to design a system where each LED has its own channel.

And, going back to the OP and the original question, I think 24v can be a good idea but the Loxone route looks very pricey. My LED downlighters are less than £8.00 per unit including the ceiling fitting. And the control side for 80+ channels will probably be around £300-£500. The cabling will definitely be significantly more but all in all, much less than an off the shelf system. We'll see, I might fall flat on my face!

 

[G and J]

2 minutes ago, jimseng said:

We'll see, I might fall flat on my face!

Don’t do that, or, if you do, put plasters on the wounds, giggle about it as you tell your mates, fix whatever is then wrong and tell us all on here.  
 

You might be wasting your time and tilting at windmills, but you might be a small part of the industry moving to low voltage dc over the next few decades.  Pioneers either die silently in the wilderness or they bring back new treasures (like tobacco, hmmmm).

 

I initially was spurred in by the notion that dc to ac conversion was inefficient. That was based on my experience of small, relatively cheap inverters for our campervan. When I checked I discovered that big inverters are much, much more efficient than I expected. 
 

Moving amps around costs copper. And as the biggest danger from electricity nowadays is not shock it’s fire, and more amps mean more heat, I deduce that low voltage dc is not necessarily safer.  
 

[JohnMo]

1 hour ago, jimseng said:

obsessed about efficiency

So how efficient is it running several miles of cable to the 80+ fitting? The 80+ light fittings isn't efficient either!

12 hours ago, jimseng said:

negatives will be .5mm

That may look on paper, but isn't suitable for a property that has to last several life times - not mechanically strong enough.

 

80+ fitting your house must be huge to need that many, that's more than twice what we have (200m²)! Or are you going for an 80s show house vibe, with way too many down lights?

 

Think you may need your head testing, too long thinking without real feedback - the problem of living alone.

 

We had a house many years ago with dimmable lights, twiddled with once or twice, than thought what a load of sh!te. Never bothered again, nor will I in the future, nothing much to go wrong with a couple of light switches - one does side lights the other main lights - flick on once and off once per day. Our whole house wiring cost less than you will end up spending on just lights, so you twiddle a few settings then get bored.

[jimseng]

Quote

80+ fitting your house must be huge to need that many, that's more than twice what we have (200m²)! Or are you going for an 80s show house vibe, with way too many down lights?

Yes.It is too many, but I can use as many as I want. Here in my stepfather's kitchen, when we are sat at the table we really only need the lights over the table on full, but we have to have all three switches on and the whole kitchen lit up due to how the 3 circuits are configured. And similar in the sitting room where I watch TV. I have to have most of the down lighters on when if fact I don't want the ones at the TV end of the room on for movie night. Or perhaps I do if it is parlour games night. (What if I want to woo a beautiful lady and the lights over the sofa are too bright?). You are right, I have been over thinking it but once the wiring is in and the ceiling up usually it can't be changed, no matter how the Feng Shui of the room transpires.  For me it is about having the choice, perhaps due to my theater lighting background. I will find out if it is pointless!

[G and J]

55 minutes ago, JohnMo said:

Think you may need your head testing, too long thinking without real feedback - the problem of living alone.

Me too.  
 

I don’t live alone but I still think in spirals till I’m certain that my daft ideas are brilliant.  Then I interact with others, (J, guys helping us on the build, buildhub, etc.), and that helps me get hone my ideas.  Happy days. 
 

I’m taking the approach that I’ll do a standard wiring with deep back boxes (thank you @JohnnyB for the noggin idea) and judiciously add wireless relay type bits where needed later. 
 

I'll still have some normal dimmers too though. 

[JohnMo]

29 minutes ago, jimseng said:

What if I want to woo a beautiful lady

That's what side lights are for, ours just switch on from a normal light switch - nothing like saying hold on a sec, while I get my phone out, need to reprogram the lights, it's a bit bright - moment lost - you will stay single for ever.

 

33 minutes ago, jimseng said:

And similar in the sitting room where I watch TV. I have to have most of the down lighters on when if fact I don't want the ones at the TV end of the room on for movie night

No down lights in living room you don't need them, we have 8 up/down wall lights than never get used, and a couple of side lights that are used daily and that's in a room with 6m high high vaulted ceiling and about 38m². The only down lights we installed are about 120 to 150mm dia (depending on room), kitchen/diner has a whopping six of them. Nice even light across the whole room no shadows. 50mm downlights cast a narrow beam of light, so worth considering and the main reasons we did the polar opposite.