Melting of led in downlight - Page 1
Forum section: electronics / beginners

author: Ned
author_rank: Newbie
timestamp: August 12, 2025, 03:01:14 pm
content: Hi.I have several ceiling LED downlights. They are powered by 230 V AC connected to a driver, and from the driver, 80 volts and 0.265 amps are supplied to the LED module. The module is made up of Osram Duris 2835 LEDs and does not include the driver internally.The issue is that inside the false ceiling—where both the driver and the LED modules are located—there are pipes carrying slightly flammable air conditioning gas. In case of pipe failure, this gas can be ignited by an open flame or by energetic sparks (from 5 millijoules and above).I assume that the driver could generate sparks way above this value in the event of a failure (in fact, I plan to place the driver inside an aluminum enclosure to prevent problems), but I cannot do the same with the LED module itself.This leads to the following questions:1. What temperature could any of the LEDs in the module reach in the event of a fault or overcurrent, such as if the driver fails and sends 230 V directly to the module (even in a short peak of time)?Any temperature below 400 °C (752 °F) would be acceptable, but if it exceeds that, it would be problematic.From what I understand, most LED failures result in an open circuit. However, could a failure also potentially cause a short circuit — either on the 80 V side or internally within the LED module?Could a failure in the LED module cause any kind of spark inside the led module even short time sparks?Thank you very much.Note: I attach a photo of part of the led module.

author: Zero999
author_rank: Super Contributor
timestamp: August 12, 2025, 03:13:39 pm
content: Sparking will only occur if the LED driver catastrophically fails.The pipes don't pose a fire risk, unless they leak, so long as they're positioned far enough away from the LEDs and drivers.1) Fit a flammable gas detection alarm, possibly with an output signal which turns off the air-conditioning and lighting.2) Keep flammable materials away from the wiring, lighting and driver electronics.4) Don't fit the LEDs and electronics too close to the pipework.3) Fit a fire alarm consisting of:A) A heat sensor.B) A smoke detector.

author: Stray Electron
author_rank: Super Contributor
timestamp: August 12, 2025, 03:31:53 pm
content: Quote from: Ned on August 12, 2025, 03:01:14 pmFirst, what flammable air conditioning gas?? Butane, Propane and some similar gasses can in theory be used for refrigeration but it's illegal to use them in any country that I'm aware because of the flammability. And AFIK they've never been used for refrigeration on a commercial or industrial basis. There are other dangerous gasses used for refrigeration (notably Ammonia) that are regularly used for refrigeration but they're not flammable.The fact that electronic devices or modules can start fires is exactly why the NEC and local building codes typically require that those items be installed inside of aproperly ratedmetal or fire proof plastic enclosure. If you're buying cheap Asian made devices and installing them in your ceiling and not following the proper building codes then you might be signing your own death warrant.

author: jmelson
author_rank: Super Contributor
timestamp: August 12, 2025, 04:06:02 pm
content: Quote from: Stray Electron on August 12, 2025, 03:31:53 pmAmmonia **IS** flammable when mixed with air! Just google it. Beer breweries often used ammonia refrigeration systems, and regularly blew up back when I was a kid.Jon

author: TimFox
author_rank: Super Contributor
timestamp: August 12, 2025, 04:28:43 pm
content: Quote from: jmelson on August 12, 2025, 04:06:02 pmAmmonia gas is also toxic, and not common in domestic air-conditioning systems for that reason.I believe ammonia was used in the first practical refrigeration systems, and is widely used in large-scale refrigerationhttps://www.ammonia.com/ammonia/understanding-ammonia-refrigeration-systemsSide note: Albert Einstein was an expert in thermodynamics, along with his other work, and patented a successful gas-fired refrigeration system with Leo Szilard. Without moving parts, the ammonia-containing heat engine could be sealed to avoid leakage of toxic gas.https://invention.si.edu/invention-stories/einstein-szilard-refrigeratorThis development was just in time for the world economy to collapse, along with opposition to "non-Aryan" science.

author: Zero999
author_rank: Super Contributor
timestamp: August 12, 2025, 04:59:33 pm
content: Quote from: Stray Electron on August 12, 2025, 03:31:53 pmIsobutane is widely used in refrigerators in Europe, but I don't know about air conditioners.https://www.agas.com/au/products-services/refrigerants/r600a/

author: TimFox
author_rank: Super Contributor
timestamp: August 12, 2025, 05:19:53 pm
content: From that datasheet:R600a (isobutane) is a hydrocarbon that is becoming increasingly popular due to its low Global Warming Potential (GWP). It is the refrigerant of choice for domestic and light commercial refrigeration units, including fridges and freezers, drink dispensers and standalone display units.WARNING: hydrocarbon refrigerants are flammable and must be handled in a safe and responsible manner by properly qualified, trained and experienced technicians - relevant regulations or standards should always be adhered to.

author: Siwastaja
author_rank: Super Contributor
timestamp: August 12, 2025, 06:52:58 pm
content: Quote from: Stray Electron on August 12, 2025, 03:31:53 pmNot only they are gradually becoming legal, they are gradually becoming mandatory (e.g. EU). While flammability risk is true, it has been seriously exaggerated as a FUD by trade unions, who have wanted to keep the status quo that refrigerants must be dangerous to environment, such that their use must be regulated to the few professionals. But this "refrigerant mafia" is finally breaking down with environmental concerns exceeding that of lobbying from trade unions; politicians have now accepted even the safety concern, which is partially legit (just greatly overblown).OP is probably talking about R32, though. I would not worry about it, especially if there are no valves or other connections, just uninterrupted pipe close to that point. That kind of pipe starting to leak mid-way is almost impossible; then the LED failing at the same time to produce said 400degC temperature is extremely unlikely - and then if you actually look at videos how R32 behaves is that it makes open flame a bit bigger, so if you already have a fire which just barely is under the threshold of escalating it can then take it over the edge.These factors combined, I believe it is much higher risk that the Moon suddenly explodes and a fragment hits your nose.In fact, I don't think any building code forbids runningeven those fearedR600/R600A (butane/isobutane) refrigerant lines next to a LED lamp fixture, in areas where R600/R600A is applicable, and it is pretty widely in EU: for example the freezers at supermarkets have been R600A for over a decade here (I remember when they appeared in LIDL), small household fridges and dehumidifiers nearly as long already, and even household-size (<1kg or so?) split type air conditioners are finally transitioning into R600A as we speak. I'm pretty certain there are no special requirement not to run the refrigerant lines close to lighting fixtures, but there are limitations for minimum size of enclosed space these units are stored and operated in - that would apply to e.g. the indoor unit of a split air conditioner, because the leak risk is there (in the connections and in the coil), not in contiguous tubes, and the risk is specifically of a small leak filling the room air with the correct explosive mixture, which won't happen in a large room.

author: Ned
author_rank: Newbie
timestamp: August 12, 2025, 07:46:45 pm
content: Ok, long story.It is a false ceiling, but it is completely sealed. The space is approximately 10 square meters in area and 0.3 meters in height. As mentioned, it is fully enclosed with no openings. Two HVAC pipes run through this space: one from the compressor to the evaporator and the other from the evaporator back to the compressor.The refrigerant used is R-32, which is not highly flammable, but it is heavier than air, meaning it will settle at the bottom — where the LED fixtures are located. Moreover, it can be ignited by a spark greater than (depending on the source) 5 mJ, 10 mJ, or 20 mJ.More critically, if ignition occurs, the main risk is not just fire but the production of toxic gases, particularly hydrogen fluoride (HF), as a byproduct of combustion. I have run calculations, and depending on the size of a potential leak, the gas concentration could reach flammable levels. If this happens and there is a simultaneous ignition source, it could result in a fire and the release of large quantities of HF.Given the total charge of R-32 (2.5 kg), the resulting HF produced could exceed the lethal exposure dose if inhaled.So, if there is any chance of a fire or a spark with more than 5 mJ of energy, I will probably not take the risk — I would rather dismount the LEDs and look for an alternative lighting solution.Regarding videos on the internet showing people using torches with R-32 near open flames — the issue is that those scenarios are completely different from one involving a static gas. The speed and movement of the gas play a significant role in whether ignition occurs.I have only found one somewhat relevant video (from someone in Pakistan), where although the setup is not exactly comparable, it can be extrapolated. In that case, gas was released from a plastic bottle and allowed to settle slowly.Additionally, there are laboratory tests where R-32 has been ignited and the flame was self-sustaining.I have other false ceilings in the house, but those are fully ventilated, so I'm not particularly concerned about them. I already have LEDs installed there and plan to keep them.The real issue is the sealed false ceiling in the kitchen.Regarding gas detectors, R-32 is a fluorinated compound, and there are no commercially available detectors suitable for permanent installation inside a false ceiling. If such detectors existed, the solution would be straightforward. However, I haven’t found any, other than the portable units used by HVAC technicians — and those are not designed to be installed permanently in a false ceiling.One more thing — what are the chances of a catastrophic LED failure? I have three LED fixtures mounted in the kitchen’s false ceiling. They are recessed and approximately 20 cm in diameter. While the LEDs themselves are from a well-known brand (Osram), the drivers are of lower quality. I plan to install the drivers in a spark-proof enclosure to reduce the risk.However, since the LED panels are fully recessed into the false ceiling, I can’t take any additional safety measures on the panels themselves.Thank you all.

author: Ned
author_rank: Newbie
timestamp: August 12, 2025, 07:53:58 pm
content: You can see the video here:— around minute 7:40. The guy introduces R-32 into a bottle and leaves the bottle upside down. The flame is self-sustained for a short time.Now imagine a false ceiling with a 15% to 20% gas concentration throughout...