This is just an anecdote, but I’ve had multiple “10 year” LED bulbs fail after just a year or two. I suspect much of the claims for these bulbs are theoretical as they just don’t hold up, probably for reasons the grandparent poster is pointing out.
With Edison-style bulbs, anyway, the orientation they're mounted in makes a huge amount of difference. They're last a lot longer if they're oriented upright (base down) than in any other orientation because it reduces the heat buildup in the power supply.
If there was a "DC" light socket in the house we could have LEDs outlasting owners, and for cheap. Nearly all the expense of LED bulbs is the power supply. Everything else is dirt cheap. A single home DC power supply with ~200W of output could light an entire house, flicker free.
What's even more frustrating is I think we could fix it. A national regulation for DC light sockets would fix it. Mandate a voltage, shape, and max amperage and BAM, you'll get 1000 different manufactures making standard compliant bulbs and home power supplies that will last an eternity.
It seems like there would be a market for cheap as possible 10 mbit switches with 802.3bt/802.3af support though.
https://www.amazon.com/Gigabit-802-3af-100Mbps-250Meter-Unma... is pretty cheap as is, I'm sure you could buy something in bulk for cheaper.
That means it's totally fixable. You can install such a system in existing buildings right now, and it's not crazy expensive unless you want to run the wires inside the walls.
If we could shift cultural expectations around this, adding a LV system in new construction would not significantly increase the construction costs. It will start to be done if buyers start demanding it.
Having multiple transformers is perfectly doable and commercially viable -- though I would appreciate more product availability for something easy to stash in the hollow space of a ceiling, like recessed lighting is installed.
Everyone here is complaining about ultra-cheap LEDs that don't last very long because they're poorly engineered, but that's exactly what you're all trying to do here by using a separate, shared power supply. You could get away with that in the 1980s using incandescent bulbs, but you can't do it now unless you want the same crappy lifespan and reliability you're all complaining about.
The solution is very simple: buy fixtures that are engineered well. Switch-mode power supply electronics are not expensive at all, but when mfgs cheap out or do a crappy job designing them, you get bad results, usually short lifetime of either the power supply or the LED. What you're trying to do here is buy a really expensive power supply, which has to be engineered to a far greater degree and for a far wider range of operating conditions (since they don't know what you're going to connect to it), just because you had a bad experience buying some $2 light bulb that had a crappy power supply built-in. This really makes no sense.
The constant current thing is true, but that's not a terribly difficult problem.
Depending on who you ask, the limit for low voltage DC might be 42 or 50 or maybe 60 or 120 or 1500.
USB-C PD is at a useful voltage & wattage level, and so is Ethernet POE. I wouldn't be surprised to see them start to be used for general power distribution in niche applications, like RV's and off-grid cabins.
I don't think we're going to ever get a bulb standard, though.
I could definitely see this becoming more common. Powering the ~100 watts of fixed lighting spread across my whole house on ten different 15A 120v circuits, each with their own arcfault breaker and 12 gauge copper electrical lines running back to the panel is fabulously expensive for what could be done with a bunch of CAT5 in each floor running to some conveniently located “POE injector” type devices.
You would want to be able to take a standard fixture and just push DC through it and use special bulbs with a standard A19 base, but that’s problematic when the next owner tries to screw in a standard bulb - what happens when it sees 48V DC?
I would guess if for safety reasons it has to be a non-A19 connector, then your light fixture choices get cut down to almost nothing and no one will make the switch?
It’s really interesting to think about, most everything I’m plugging into AC outlets in my house, the first step is converting it to DC. A lot of my outlets I’ve switched to include USB ports so I don’t need the wall warts. If you have solar and battery backup even more-so you start to question why we are wasting so much money moving everything back and forth between DC/AC/DC within a house.
Either it lights up or not? I don't see a problem here.
But I'm not sure moving part of power supply elsewhere will help that much, it needs current driver electronics anyway.
If by "standard" you mean a incandescent tungsten filament bulb, nothing at all.
For a true LED driver power supply, it would be constant current, so the tungsten filament would see 25mA (or whatever the constant current is set for) of DC, and nothing bad would happen (the filament also would not likely illuminate either).
Screwing in an LED bulb with integrated power supply, the external supply will still feed the constant current value, so what happens depends upon the design of the LED bulb's integrated power supply. If 25mA is enough to drive everything, the LED bulb might light up. If 25mA is not enough to drive everything, most likely nothing lights up.
For constant current, you'd need to drive at least 9 watts so it would be more like 250mA if not higher.
A 1600 lumen LED module might take as much or more current than a 60w incandescent. If your constant current supply can output between 0 volts and input volts, and it's set for a bulb with such a module, it would be able to power an incandescent bulb.
(Of course, they’re quite hot and radiative cooling increases like T^4, so this isn’t necessarily a show stopper. But it’s probably not helpful.)
LEDs are like 15% efficient and power supplies are >95%. They just need to be separated slightly so the LEDs aren't heating the power supply. Most recessed LED lighting now has a separate junction box with the power supply.
I think the biggest problem is that many cheap power supplies cycle at lower frequencies that cause flickering which is perceptible subconsciously. A modern switchmode power supply might operate in the 50-500khz range which will not cause perceivable flickers.
I'd say it's a very bad choice for a bedroom or living room light, but I have nothing against it for the outdoor lights, signage and a bunch of other applications where cost is king.
Just don’t use these devices, please.
But then, a wise entrepreneur would recognize paying extra to have non-flickering signage would attract some customers.
Flickering lights can induce migraines in susceptible people, so literally, saving a penny here actively drives away business.
The lights are all basically cut 12v light strips inside of old light fixtures with a custom controller that also terminates PoE. The 48 volts that most PoE standards specify is more than enough to push power down the line for < 100 meter runs.
The advantage of PoE here is that anything under 50 volts is considered low voltage and does not need to follow the same rules as normal house wiring. I did not like that everything is hinging upon a beefy PoE switch so I actually made it passive PoE instead by design.
You can fudge it with resisters like in an LED strip, but you lose efficiency and dimming quality.
That being said, I expect that power supplies with 48VDC input or so would be cheaper.
Probably with some sort of current sensing system to make it compatible with dimmers.
Pair that with DC A19 LED bulbs that have no internal power systems.
Probably expensive to put together and to install, but if the goal was to have LEDs that last longer, that would do it.
The problem is that in 99.99% of homes outlets are on the same circuits as light fixtures, you would need to do some major rewiring.
Those bulbs would then have no internal switching systems to burn out and rely entirely on the module hidden behind the wall to handle their power needs.
I think the way to change it is to replace sockets with hardwired LED fixtures. This is easy for something like a standalone ceiling light. It may be harder for other devices like ceiling fans that integrate a light bulb socket, but converting those devices to take DC power as in your proposal isn't easy either (most would just get discarded and replaced).
Doing it well is more expensive in the short-term than screw-in bulbs. A quick look on Amazon suggests integrated ceiling lights are about 10x the price of LED bulbs, though I suspect the longer service life pays for itself.
Absolutely, the incandescent light bulbs have that shape for a reason: the screw is small because there is nothing to put in it and it doesn't heat, the bulb is large to dissipate all the light and heat it generates. And the LED light bulbs have exactly opposite problems: almost all of the heat is generated near the screw while the bulb itself generates almost none and the light-emitter doesn't even need the bulb that large around of it. Oh, and the casing around the screw is plastic so the thermal conductivity is horrible. Honestly, it's a profoundly terrible form-factor which we're now stuck with.
That's also the pitch of the smart bulbs: a sane way would be to make a smart light switch but what if you can't do that (e.g., you rent the apartment)? So we'll shove the controller chip into a disposable light bulb, that's still perfectly fine for the environment.
By the way, I don't know how things turned out in your part of the world but over here, after the ban went into the force the manufacturers of incandescent lightbulb started selling 95W light bulbs 8D
<https://www.designboom.com/technology/self-cooling-100-watt-...>
<https://i.pinimg.com/originals/b5/c2/c5/b5c2c5d69fb240a571ba...>
It's also helpful to recognise that existing lighting fixtures and lamps were designed around the constraints of incandescent bulbs. The first generation of LED bulbs and lamps largely conform to these. As LEDs mature, both fixtures and lamps which address the limitations and requirements of the technology (transformers, perhaps dedicated 12v circuits, heat dissipation for the transformer rather than lighting elements themselves, and better light-temperature and intensity regulation) should emerge.
We're presently in the somewhat-messy half-emerged state. Think horseless carriages, wireless, and the days of dual gas/electric lighting and lamping systems (yes, these existed, and yes, the failure modes were ... much as you might imagine).
24V is okay. 48V would be nicer for indoor use.
Also low voltage wiring can legally be done by anyone in NZ (a bonus when doing your own work, and a pitfall when buying a house?)
Other circuits must be 20A, e.g., kitchen outlets serving appliances.
A summary of standards here: <https://www.thespruce.com/common-electrical-codes-by-room-11...>
A 15A lighting circuit can serve up to 14 100W bulbs. Or 150 LEDs drawing 10W each....
And besides, idk if you have ever pulled 12ga wire, but it's a pita. Idk any electrician that would agree with you saying it would be a pain to cut back on heavy wire and pull half that with light 22 awg.
Not extremely thick. Wire losses remain similar at 12V as they were at 110V (Replace 100W bulb with a 10W bulb at 12V, current remains ~1A so wire losses stay the same as the were). Wire losses might be say 1W for 1mm2 cabling. 240V example: https://ausinet.com.au/voltage-drop/
Agree that it is worth upping voltage to chase a few more percent savings, but still need to consider other constraints.
Heck, with such a standard you could have 120VAC -> 48VDC converters and you'd be in the same position we are today with Leds, only better because you'd just have to replace the converter and not the whole bulb.
https://www.sansiled.com/blogs/learn/what-are-the-benefits-o...
Simple metal fins are more than sufficient along with a high efficiency power supply.
I live in Japan, and instead of just a pair of wires coming out of the ceiling, there is a standardized "ceiling socket" [0] which can also support the weight of a lamp. This means that swapping out light fixtures is plug and play, so the standard LED lamp is something like this [1] where you have a nice big flat metal plate backing the hardware is mounted to for heat-sinking.
I don't own any LED bulbs at all - all our lamps are of this type so I wouldn't have anywhere to put one.
It was the same when I lived in Sweden - a standard ceiling light outlet (IIRC there is a EU standard for this now called DCL) so that replacing light fixtures was easy. Moving into an apartment, often they wouldn't even come with light fixtures, you'd bring your own.
[0] https://www.e-connect.jp/images/to_quickB.jpg
[1] https://www.irisplaza.co.jp/IMAGE/HK/PRODUCT/H246902.jpg
But choosing a DC system for part of the house can make a lot of sense.
For one residential new construction room, it can be practical to have one shared power supply rather than one per LED. Say you have a 12 V, 5 A DC power supply. Using a star wiring topology, this can serve 10 lights (at 500 mA) fine with 16 AWG.
Not practical
And switch mode power supplies are relatively inexpensive and quite efficient.
I say this, because I was guilty of this exact shortcut thinking (in another comment). But I paused and thought to myself "I should run the numbers before just repeating the usual voltage drop criticism".
So I compared scenarios and it depends a lot on the topology, lengths, costs, and situation (new vs renovation).
Sure, a whole house system doesn't typically make sense, but I don't think that's what people are really talking about. I think people are interested in hybrid systems; e.g. DC power supply for each room.
I don't know if you meant it, but the sentence about "any sophomore level electrical engineering student can solve this" can easily come across as dismissive. I also think it gives too much credit to sophomore students. :)
I would have more confidence in an electrician apprentice on this one. I think they'd have more practical experience when it comes to figuring out what are the right questions to ask.
I did EE in college and do a fair bit of hands on residential electrical work.
P.S. How many sophomore level engineering students learn to do a sensitivity analysis?
I completely disagree. Where exactly are you going to put a power supply in a room? Make a special electrical box for it? Won't it be unsightly in many rooms, or need some huge special panel that looks like a breaker panel? The comments I see seem to be advocating a whole-house solution, where a power supply is mounted in the breaker panel to supply LVDC to the whole unit. But this makes no sense for several reasons, especially the voltage drop.
>I don't know if you meant it, but the sentence about "any sophomore level electrical engineering student can solve this" can easily come across as dismissive. I also think it gives too much credit to sophomore students. :)
It's supposed to be dismissive, because this whole discussion is a bunch of software people trying to make up solutions for a perceived problem when they obviously don't know one of the most basic things about electrical theory, which makes all of their solutions unworkable. It's like a bunch of people trying to make a new kind of personal vehicle to replace cars when they don't even understand Newton's Laws. It's really annoying, because I see this kind of discussion pop up every so often, over many many years.
I have another comment here I don't feel like copy-and-pasting, but basically this whole discussion is silly because people are trying to make a solution using a very expensive power supply to fix a problem they see because they're buying cheap $2 light bulbs that burn out quickly, instead of just buying light fixtures that were properly engineered in the first place. With modern SMPSs, you're not going to get any kind of benefit by centralizing the power supply to drive individual LEDs, you're only going to get problems. LEDs need a driver circuit to provide constant current, and that means the power supply needs to be matched to the emitters and kept very close to it.
This sounds like a non-issue, specially considering the pervasive use of "unsightly" installations like air ducts, heating vents, radiators, electrical sockets, telecommunication service panels, routers, and even light fixtures.
If you intentionally dismiss obvious solutions, of course you only end up with problems without obvious solutions.
> It's supposed to be dismissive, because this whole discussion is (...)
If you have nothing to add, please add nothing.
Switched-mode power supplies can be as small as your average Arduino board. They can fit inside the space used for wall outlets or light fixtures. Or you can put the DC transformer inside the light switch.
It's not about DC vs AC, it's high-voltage vs low-voltage. The power dissipation by wire resistance scales with the square of the current ($P=RI^2$), and low line voltage means that you need large currents to transmit the same amount of power.
Also, DC and AC have differences in power transmission independent of resistance, some due to first principles (reactivity), and others related to devices for stepping voltage up or down (eg transformers).
But what about the sub 100W or even 200W applications? That's where I think something like 48VDC would start to shine. Every light in a home, phone chargers, tablet chargers, computer monitors, televisions, computers? (maybe not gaming rigs, but certainly laptops and nucs).
How so? Exactly what benefit does it have over the current AC mains? With 48VDC, you'd still need to use DC-to-DC converters to power everything. I fail to see how that's any kind of improvement over the current switch-mode power supplies used. Instead, it'll just be less efficient because you'll get higher line losses in the power lines in the walls and all the way from wherever that 48VDC is coming from. If that's from a big SMPS in a closet somewhere, that's going to have its own losses. Overall, the entire system will have lower efficiency compared to the current system.
Exactly what problem are you trying to solve with this idea? If you think you're going to eliminate SMPSs in all your electronic equipment, you're not; that's a fantasy. Everything needs a power supply because electronics only work at very low voltages (5V, 3.3V, even 1.8V in places, now 20V with USB3) and most equipment has some kind of peculiar voltage requirements, and usually multiple different requirements inside the same device. There's no improvement in efficiency by running a computer, for instance, from 48VDC vs. 120VAC or 240VAC, in fact it's probably worse.
And since we need high voltage (at least 100V) to keep line losses very low and allow the use of thinner-gauge copper wiring, we need a switching power supply at every light fixture, so it really doesn't matter if it's AC or DC, since modern SMPS (switch-mode power supplies) work equally well with either.
Finally, on top of all that, LEDs are current-driven devices, and need a constant-current power supply. So the power supply must be very close to the diodes, or else fluctuations in supply voltage will have very negative effects.
How about power over ethernet?
I think that non-bulb LED fixtures are relatively common. For example, a style exists where you cut a hole in the ceiling and friction-fit the LEDs with the power supply up in the attic (presumably with infinite convective airflow): https://www.lowes.com/pd/Utilitech-Canless-Color-Choice-Inte...
These power supplies aren't going to die from overheating because the power supply is nowhere near the heat-producing LEDs. And, it's not like $30 for your entire light fixture is going to break the bank.
This is a great idea and I would love it if you would post a Youtube how-to video. It might encourage a bunch of hobbyists to do something useful with those dead bulbs.
I've had a number of LED's fail after only a year or two, in fact more quickly than the average incandescent bulb. Seems like it defeats the whole purpose of "upgrading" and in fact may be more of a downgrade.
LEDs are super cheap. I bought few hundred pre-covid for $3.
LEDs are indeed extremely cheap, but for me, the benefit is reducing the amount of electronic waste I produce, not cost-savings.
I have the exact opposite experience, virtually every single light bulb I have torn down - one LED (all in series) has a black dot, if I shorten it - it will 'work' again. The bulbs I have seen tend to drive the LEDs so hard that some of the latter fail, power supplies might have huge ripple but generally don't fail catastrophically.
Edit: now thinking, it can be a US thing, with the voltage being ~120. Lower AC voltages means worse efficiency for the power supply (and all of them tend to be universal, unless totally cheapen out on the primary capacitor [250V] for the US market). Generally speaking low AC voltages have mostly disadvantages.
I have had lamps that lived long enough to see LED failures (the "black dot of death") but that's not the most usual failure mode that I've personally encountered.
I've been considering following in the footsteps of Big Clive and modifying new LED bulbs to stop them from overdriving the LEDs, but my interest in doing that hasn't yet overcome my inherent laziness.
If the bulb dies but you notice that all of the elements are still just barely on (like a dim spot of light in the middle of each one) then that's a good indication that you have a dead LED.
It's true that the power supply versions are so poorly designed and inefficient that heat is a problem. Design and quality control effort could reduce heat generated by the entire assembly to a fraction of what the socket, fixture, and wiring can sink.
It's more common now to find bulbs that have no power supply at all. They're literally a rectifier made of LED's in series. If the bulb flashes at 2 * mains frequency, that's likely what you have. They die out quickly because the LED strings add up to a maximum voltage a bit over mains voltage, but that's RMS not peak. It's a natural outcome, as using enough LED's to accomodate peak voltage reduces light output by underdriving them, increases obvious flicker from dwell time below minimum voltage, and increases cost.
Hotwired LED strings are cheaper to design, source, assemble, bad parts fail fast more consistently with no effort wasted on quality control, and the market's so flooded and volatile that there's no room for consumer side quality awareness effective enough to make the negative outcomes matter. Power supplies in these bulbs are going away. Ubiquitous 2 * mains frequency strobing, short-lived, hotwired LED bulbs is where the home LED lighting market is taking us.
This is also the same industry and the same players that were perfectly fine with agreeing to not improve incandescent light past 1000 lifetime hours, illegally. I have no doubt that there is a tacit agreement not to make good lighting, as that would extremely disrupt the industry.
No. I like the fixtures I have, and I have no desire to throw them in the landfill so that I can be “environmentally friendly.”
Otherwise, for probably at least 40 or so bulbs swapped for LEDs over the years, I've experienced maybe 4 or 5 failures. The vast majority of my bulbs have been Feit and GE. I never buy smart bulbs. My best experiences have usually been to just buy LED fixtures though, I replaced a lot of my flush mount ceiling fixtures and ceiling fans for ones with integrated LEDs and have not had a single failure so far after a few years, knock on wood.
I had some problems with my old dimmer switches, but upgrading dimmers to newer ones which advertised good LED dimming and ensuring I had bulbs which stated dimming compatibility it eliminated my noise and flicker issues. There's a recent standard out there, NEMA SSL 7A, which seeks to ensure good compatibility. I set my dimmers to this SSL 7A mode and I've had no problems since.
https://www.energystar.gov/sites/default/files/asset/documen...
They're all in freestanding floor lamps installed in a horizontal orientation, which might have something to do with it. That seems like it'd dissipate heat a lot better than e.g. a pot light housing in the ceiling.
They produce great light at the temperature you want and I’ve yet to have one fail after nearly 10 years using them.
Not cheap, but given I’ve never had to replace one maybe in the end they are
https://www.amazon.com/Philips-Hue-Bluetooth-compatible-Assi...
$45 a bulb! That's probably >$2000 to replace a house's worth.
The white, color-temp only ones are about half the price, which is better, but still not cheap:
https://www.amazon.com/Philips-Ambiance-Hue-Equivalent-Assis...
* bulbs with the UK-standard bayonet fitting in light sockets that are suspended from cables from the ceiling with lampshades -- these I don't think I've ever had fail on me yet
* 4.6W bulbs with a GU10 fitting in recessed spotlights -- these fail on me more frequently (perhaps every few years to every five years)
My assumption is that this is all down to the spotlight-fitting bulbs being in a confined space and getting a lot hotter. I use Philips bulbs in both cases.
- Older LEDs house bulbs were much worse than newer ones; far more prone to failure from "things". I had many of them fail after only a few months because our power was "flickery" and their power supplies could not handle it. That's _far_ less common now.
- The power supply / controller circuitry is not a fan of heat. Don't mount them upside down (so the heat floats up to the circuit) and never mount them in a recessed mount. The heat buildup will destroy them a lot quicker. That being said, this advice can be ignored is you're paying attention... mounts that have a way to heat to escape; bulbs that are designed to go in upside-down mounts (maybe?), etc.
- While you certainly don't want to always buy the most expensive bulb, you also don't want to buy the cheap ones. They are far more likely to be made from poor, failure prone components.
It’s not my fixtures’ problem.
It’s these crappy bulbs.
You don't go buy offroad vehicle, then complain it doesn't drive as comfortably on the highway and say it's an objectively worse vehicle. It was designed for a different goal than the 4 door sedan you're comparing it to. It does better at that goal, and worse at others. And, over time, offroad vehicles have gotten better on highways; they'll just never be as good.
The way most people use lighting goes far beyond whatever the manufacturers want to foist.
I don't know if there are any regulations around the 10-year claim, but if there are then I'd expect that it's either an average or something like a one-standard-deviation threshold, like 68% last past that but 32% don't.
"Guaranteed 10 years" doesn't actually say anything about expected lifetime at all, just that they'll do a warranty replacement if it fails sooner.
Personally I'd want a durability guarantee to be more like two standard deviations, on top of replacement in case of early failure.
A lot of this topic smells like typical geek snobbery. They're lights, folks. Cheap consumer products have always been cheap. Halogen bulbs suck too.