Drivers, drivers everywhere - isn't there a better way?

[Benpointer]

Just reviewed the first draft for our new-build from our lighting designer.  Ok, so I was expecting a lot of lights but there are 18 LED drivers which have to be found safe accessible homes for across the house.  

 

Given these units all cost a bit, fail from time to time and need to be replaced, are prone to creating interference, and are going to be a struggle to site appropriately within our (currently 25mm) service cavity...

 

... Given all that would it not be better to have one central driver in the plant room and a 24v DC circuit through the house to power all the lights?  

[ProDave]

or mains powered lights?

[joth]

Are these specifically for LED strip tape?

If so, yes I prefer using one central 24V PSU (or one per floor), PWM dimmers on the low voltage side of the PSU and then radials to the LED strips.

Size the cable appropriately (1mm2, or 1.5 if the runs are long or LED strips large) and never seen any problematic voltage drops. Put in a maintenance free junction box near the fitting to swap from thick T&E to finer flex cable to the strip itself.

 

56 minutes ago, ProDave said:

or mains powered lights?

This is going the other way: hide the driver inside the light fitting. (It still has one, just integrated into the GU10 bulb). Not really an option for LED tape.

But I'm increasingly favouring this in all but high end designs (preferring DALI there), not because it's technically elegant (dimming via mains phase cut is evil) but because the longevity of both the LED bulb, the fitting it is in, is bound to be higher than proprietary driver/emitter combos that may well be impossible to replace like for like in a few years.

 

 

[ToughButterCup]

3 hours ago, Benpointer said:

...

Given these units all cost a bit, fail from time to time and need to be replaced, are prone to creating interference, and are going to be a struggle to site appropriately

...

 

we decided to use 

 

3 hours ago, ProDave said:

mains powered lights

 

The lighting sector seems overfilled with ' designers ' , and people who have no qualification in design ( let alone lighting design ) and think that the more they charge, the more seriously they ought to take themselves.

 

At least Dick Turpin had the decency to wear a mask. 

[MikeSharp01]

Look at the Whitewing driver units for either LV LED or 240V LED, we have one, not yet commissioned, controls 16 channels of 240 LED lights DMX controlled and fully dimmable, all in a single DIN rail mounting unit  about 200mm x 120mm. Here is one we have: https://whitewing.co.uk/acdim.html I think others on here have these as well. 

[MikeSharp01]

3 hours ago, joth said:

(dimming via mains phase cut is evil)

Not if you use the right approach (Trailing edge / phase-cut) suitably choked surely!

[SteamyTea]

I thought this was going to be about Emmet's in their cars.

 

I have used cheap mains voltage LEDs from Poundland, they have proved to be remarkably good and reliable.

 

My bedside light is the only dimmable one, bought a Phillips build for that, cost 7 quid, so 7 times the price of the others. Not given and problems and I think it is 6 years old now.

[Benpointer]

Thanks all. So as I understand it the mains LEDs have a driver built into the bulb - it occurs to me that this is what we've used in the past when replacing incandescent with LED bulbs.  

 

Are these LEDs with inbuilt drivers dimmable?

[MikeSharp01]

6 minutes ago, Benpointer said:

 

Are these LEDs with inbuilt drivers dimmable?

Some of them yes. Look out for the logo on the box.

[SteamyTea]

14 minutes ago, MikeSharp01 said:

Look out for the logo on the box

Yes, it is the usual givaway they they be emmet.

 

[MikeSharp01]

here are the basic logo's !

 

Not dimmable:

 

 

Dimmable:

 

[Benpointer]

3 hours ago, MikeSharp01 said:

here are the basic logo's !

 

Not dimmable:

 

 

Dimmable:

 

Cheers - I think that may be sufficiently clear even for me 😉

[Mike]

14 hours ago, Benpointer said:

Given all that would it not be better to have one central driver in the plant room and a 24v DC circuit through the house to power all the lights?

Another option is to mount individual drivers in a central location, such as your plant room, switching them using regular mains wall switches.

 

But with 18 drivers involved I'd be considering DMX control as suggested by @MikeSharp01.

 

 

[jack]

19 hours ago, MikeSharp01 said:

Look at the Whitewing driver units for either LV LED or 240V LED, we have one, not yet commissioned, controls 16 channels of 240 LED lights DMX controlled and fully dimmable, all in a single DIN rail mounting unit  about 200mm x 120mm. Here is one we have: https://whitewing.co.uk/acdim.html I think others on here have these as well. 

 

I installed an 8-channel 240V DMX Whitewing unit a few years back, to replace some of the highly unreliable cheap dimmers we originally installed. Better dimming quality and they're been rock solid for several years.

 

I also have a similar multi-channel Theben KNX dimmer from a little while before that (KNX is built in to the v1 Loxone miniserver I run). It's also very good and rock solid, although more expensive than the Whitewing unit, and not quite as good at dimming at the low end. 

 

It's worth noting that the dimming characteristics of mains dimmers at the low end aren't great. You need a minimum brightness to get the lights to come on. Constant current dimmer drivers are a lot better, but they do limit your choice of fixtures somewhat, especially at the budget end.

[jack]

15 hours ago, Benpointer said:

Thanks all. So as I understand it the mains LEDs have a driver built into the bulb - it occurs to me that this is what we've used in the past when replacing incandescent with LED bulbs.  

 

Are these LEDs with inbuilt drivers dimmable?

 

Halogen replacement LED bulbs have a driver (optionally dimmable) built into their base.

 

However, in a new build you'll generally be using LED fixtures, which are all-in-one units without a replaceable bulb. You can buy fixtures that come without a driver, so you can choose how you drive them.

[ProDave]

4 hours ago, jack said:

However, in a new build you'll generally be using LED fixtures, which are all-in-one units without a replaceable bulb

IF you make that choice (I advise against it and avoided doing so in my own house) then make sure you buy a LOT of spares.  You can almost guarantee when one fails in say 5 years time, you won't be able to buy an identical replacement.  So to avoid having an odd one out, or having to change the lot, buy lots of spares at original purchase time.

[jack]

2 hours ago, ProDave said:

IF you make that choice (I advise against it and avoided doing so in my own house) then make sure you buy a LOT of spares.  You can almost guarantee when one fails in say 5 years time, you won't be able to buy an identical replacement.  So to avoid having an odd one out, or having to change the lot, buy lots of spares at original purchase time.

 

On replacements, agreed. We had one of our fixtures fail after about three years (and, tbf, none fail in the seven years since). Unfortunately, the company had ceased trading, so no chance of a replacement. Given the time that had elapsed, there was no guarantee that one would have been available even if the company had been around.

That said, if you're talking about using halogen-type fixtures with replaceable bulbs instead, I'm not sure whether our building control guy would have allowed them at the time we did the build. From (admittedly decade+ old) memory, building regs require a certain proportion of low-energy lighting, and he didn't consider halogen type fittings as meeting that requirement, even though we would have used LED bulbs. It may be different now given that you'd have to be mad to use actual halogen bulbs in such fixtures.

 

Another approach would be to stick to fixtures with a separate driver. Assuming temperatures are kept under control, the chances of LEDs themselves failing is much lower than the driver failing. 

[Alan Ambrose]

>>> ... Given all that would it not be better to have one central driver in the plant room and a 24v DC circuit through the house to power all the lights?  

 

Yeah, +1 from me.

[joth]

On 13/05/2025 at 13:35, MikeSharp01 said:

Not if you use the right approach (Trailing edge / phase-cut) suitably choked surely!

No, still evil, because

- the lamp can't turn on until some low-threshold is reached (not enough power available when the phase cut ratio too high)

- the power level and lux brightness it comes on at will vary from one manf to next, even from one bulb to next within make/model, so you get random spotting on of lights on a slow fade up

- it's very laggy

- it's inefficient

 

Fundamentally, communicating direct to the bulb's low voltage driver and telling it what PWM to drive at (e.g. via DALI, KNX, or yes even some godawful wireless protocol) is going to give an electrically and visually better result. We're just now in the unlucky state that phase cut is the lowest common denominator communication protocol and commoditised solution for controls to speak to lamps.