Buyer Beware: This LED Bulb Sold As Germicidal Doesn’t Emit UV-C

Germicidal lamps are designed to destroy viruses and bacteria using ultraviolet light. But not just any UV light will work, and I came across an example of a lamp that was advertised as germicidal but a few things just weren’t right about it.

This is an actual UV-C LED made by CEL (PDF) that emits 275nm. Note the clear glass that covers the LED.

I ordered the UV-C germicidal LED lamp on Amazon, and received it a few days ago. It felt the suspicion from the first moment: playing around with a lot of different UV LEDs, I’ve learnt how the parasitic visible light from different UV ranges should look like to human eye. Also, proper UV-C LED lenses like the one shown here are made of quartz glass. Compare that to the image at the top of the article of the bulb I received that has a soft plastic lens, which is possibly opaque and degradable in the far UV range. The most important clue that something was wrong was the price. It’s hard to imagine that a UV-C LED lamp with the 253.7nm wavelength, made of more than 200 LEDs and in such a robust metal case, can cost only $62.99.

Although there was the risk of being unjust, I decided to return the product. In my message I bluffed that I measured the spectra of the lamp with a spectral emission meter, and that its output was not in the UV-C range. The next day I received confirmation that the bluff paid off: the seller replied that they advertised the product according to information from the supplier, and that the incorrect information was caused by their lack of understanding of product information. They also attached the official datasheet with the measured wavelength: it was not 253.7 nm, as advertised, but with the peak at 394.3 nm, and the dominant wavelength at 413.9 nm. It was not in the far UV-C, but in the near UV-A range and not at all useful for destroying germs! The seller promised that the product would be removed from their store, and kept the promise.

If you are thinking about buying a UV-C LED lamp, maybe you should get the good old CFL germicidal lamp. I don’t think that viruses care too much about the new technology.

131 thoughts on “Buyer Beware: This LED Bulb Sold As Germicidal Doesn’t Emit UV-C

      1. That’s the glass-half-full worldview. :)

        I had a totally safe 1W laser diode for a while. (It was probably static electricity / poor handling.)

        Can I sell you a completely flip-flop-wearer-friendly lawnmower? Guaranteed not to cut your toes off! Of course, if you open the hood and maybe clean some of the gunk out of the carb, our warantee is void.

        1. Obviously I know you were making a joke, but as someone that has used a push mower for years, how does one actually accomplish getting your foot under the mower while it’s running.

          Now I can imagine all sorts of stupid positions to be standing in while holding down the throttle, but you would have to purposely do all of them. And they would require you to actually push your foot under the mower. When used as intended, you always behind the mower, pushing by the handle bar, and the mower is safely a 12″+ from where your feet step as you pushing it. Like I said, it seems like something you would purposely have to do to even think about pulling off.

          1. Heh, I once had the fun of using an electric mower where the safety interlocked switch had failed catastrophically (not fail-safe but fail-dangerously) by shorting itself in the closed position.
            -> the mower was running whenever AC power was connected and the only way to “switch” it off was pulling the plug.

            As it turns out a previous owner/user had let the mower stay in the rain at least once and the water rusted a spring + steel ball combination, keeping the switch in the “on” position.

          2. I know it happened twice. Two different people, years apart. Both were PULLING the mowers backwards (everyody does that occasionally ) tripped over something, held on to the handle to ease their fall (instinctively) pulled mower on foot

          3. I ran a push-mower over my feet once (it only destroyed my army boots, all little piggies were unharmed). I was in a short but steep decline, slipped and the reflex of grabbing hold of something caused me to pull the mower over my feet. I immediately let go of the throttle/dead man switch, but inertia of the blade still kept it spinning for long enough to ruin my boots.

    1. This disclaimer _could_ stand at the place where a real UV-C lamp is sold. But primarily it is not even necessary there. I consider the dangers of UV-C as common knowledge. You also do not see disclaimers on kitchen knives, that you should not stick them into your eyes (or any other body parts).

      1. That’s a pretty short-sighted assumption on your part. Comparing a sharp blade to a lamp that looks really cool when lit on the same level is just silly. Especially when there are other lamps that look very similar that are not dangerous. Put a UV-C tube next to the tube in a bug-zapper and ask random people on the street what the difference is…

        1. Actually, it’s a pretty significant even if they’re not side by side. I have two bug zappers in the house and a “Swordfish” sterilizer on my furnace. The UVA tubes in the bug zappers are still coated on the inside of the glass and “fluoresce” at the 400nm range. The swordfish UVC bulbs are clear and the light is the actual direct UVC generated by the gasses in the tube. (All fluoro tubes work this way, the coating on the glass determines the “colour” of the light. And the UVC is pretty dangerous for the eyes. The WHO is also warning against using UVC lights for sterilizing your hands. At the very least it can cause skin irritation and worst case, skin cancer.

          1. Uh oh. So I ordered a bug zapper lamp off eBay, and comparing pictures online and what you wrote, I am fairly certain the included bulb was UVC. Good thing it failed after a few minutes. Replaced whit a regular fluorescent and later a LED.

      2. Knives are very very old tools that people are usually taught to use safely as kids. They’re everywhere. It’s perfectly normal to have a half dozen for different purposes.

        People wave burning lasers around…. I think the UVC warnings may be needed.

      3. There’s a difference between visible and invisible dangers, and thing which affect you immediately – as you start to hurt yourself with a knife, you realise, and stop before you don serious damage – and things that can do serious damage before you realise. That’s why we don’t have warning on knives or ovens, but do on things like bleach, arc welders, etc.

    2. That was my first thought. I just read n article on Hackaday on how to make your own disinfecting chambers for STUFF not humans. My second thought is: What do they use in bug zappers?

        1. I was thinking about the light used to attract them. You’re right. Then there are those UV lights in food service areas. I’m going to have to do some research. The trouble with a curious mind. Look! Squirrel.

      1. The problem with bug zappers is that they attract the beneficial insects that eat mosquitoes, and don’t attract mosquitoes. So, counterproductive. But people hear the ZAP and think they are effective.

  1. It would be dangerous to use unprotected UV-C lamp as it damages eyes and cause skin cancer.
    UV-C light destroys cell’s DNA/RNA and this is how it kills germs.
    All these gadgets which are with non-protected LEDs are nothing but scam.
    In best case they will be UV-A which is not dangerous.
    Single 30-50mW UV-C LED cost $10-$15 when you buy in 1K lots, so the price should be the first alert that it’s fake.
    Also these LEDs has 5% efficiency, so 50mW LED will dessipate around 1W.
    Lamp with 200 UV-C LEDs would cost $2000-$3000 if real and will use about 200W power.

    1. With 5% efficiency they are a very bad option against a mercury vapor discharge lamp. They are much more efficient. How do you want to “protect” the lamp? If it’s purpose is to kill germs on surfaces, the radiation has to reach them. So the only protection that makes sense is to leave the room where it is in operation.

      1. UV-C lamps are used for water/air cleaning and are encapsulated in tube where the air or water flow around. UV-C is not good for surface cleaning as it damages plastic, rubber, textile same effect as sunburn effect but much faster. And yes, the tubes has 25% efficiency and are widely used. The LEDs has special use in portable devices where you can place as cap on metal bottle with water and disinfect it for few minutes.

          1. My experience using them very effectively in my aquariums to kill parasites and cyanobacteria would suggest that UV-C has no trouble penetrating water, at least as far as the distance between the tube and the edge of the UV sterilizer unit (about 2-3 cm, I think).

            For those concerned, the UV sterilizer unit is separate from the aquarium and has water pumped through it, so the fish are never exposed to the UV in any way.
            Here’s a common type:

        1. Actually, the effectiveness of using germicidal (UV-C) light to decontaminate N95 masks to extend their useful time is well established. In fact, use of Ultraviolet Germicidal Irradiation (UVGI) has been recommended as an emergency measure by the CDC. As you say however, the limiting factor is that UV-C degrades polymers, so it will eventually cause failure to the mask’s structural integrity (Lindsley et al, 2015).

        2. OK, that’s probably the most common way of application. And much safer than open use. I was obviously a little influenced by bigclive’s video in youtube, who obtained a (real, Hg vapor tube type) germicidal lamp. He showed it operating only for a short moment and also emphasized it’s dangers.

        3. Has anyone experience with the use of Far-UV LED? Some sources on the internet classify Far-UV at a wavelength of 222 nm, whilst other go even below 200 nm. All sources claim that the lower wavelength of Far UV LED cannot penetrate human skin or eyes and is therefore less dangerous. Does this also apply for surfaces like plastic, rubber ?

          Many sources claim that Far UV LED is much more efficient in terms of disinfection compared to UV-C. The latter puzzles me, as it is commonly believed that a longer wavelength around 257 nm is most efficient for fluorescent and a wavelength of even 280 nm most efficient for LED light sources.

          1. I use UVC in wound care settings – it works well to disinfect the surface of an infected wound – so I know quite a bit about the tech.
            It’s widely accepted that 254nm is the wavelength of UVC that is most effective at killing microbes. Far UVC is about 222nm and while not as good at killing microbes is still fairly good and supposedly much safer. Far UVC is still being investigated and is not ready for prime-time. 254nm UVC has very little ability to penetrate skin – so little that many experts believe it can’t even get through the layer of dead cells that composes the surface of human skin. 222nm UVC is even worse at penetrating skin – which is actually an advantage because it’s even safer than standard UVC. A study was recently completed using rats that had been genetically modified to be very vulnerable to UV light – to the point that just a few moments of direct sunlight would cause them to develop skin cancer. These rats were exposed to prolonged 222nm light and had no issues. Encouraging result !

            Think of it this way: UVA (in sunlight) penetrates all the way down to the bottom layers of your skin and can cause sunburn with enough exposure. UVB (also in sunlight) will get down to the dermis and while not as deep as UVA, can also cause damage to human cells. UVC at 254nm has almost no ability to get through the top layer of the skin, while Far UVC at 222nm is surface-action only. It can still reach inside a bacteria or virus to damage it’s DNA/RNA because bacteria and viruses are so very tiny – just a few microns in size – so the DNA/RNA has nothing to hide inside of.
            Some free chicken – if you get a UV bulb that puts out a significant amount of light below 200nm, you’ll get some ozone production that can cause irritation to the lungs. Some folks want that for the “deodorizer” effect but usually it’s undesirable. Cleaner bulbs that put out most of their light above 200nm are generally safer.
            Hope that helps!

    2. I’ve tested these lights with a UVC Dose Indicator card from American Ultraviolet, after 30min of exposure the card did NOT change colors. With a real UV-C light, these cards will change colors within seconds to a few min depending on the wattage of the bulb. By comparison, my real UV-C 14 watt bulb changes these cards colors within 15 seconds. I’ve also tested these cards with my UV-C 35w lamp and it changed colors within a few seconds close to the light and with a few minutes a few feet away. This is not a real UV-C light.

    3. I’ve been experimenting with UVC LEDs, as you say they are not very efficient and consume a lot of power. They also generate a lot of heat. Many manufactures provide the UVC/UVB LED with an aluminum substrate PCB to dissipate the heat generated. It’s unlikely you would be able to jamb that many UVC LEDs together in a corn cob tube without significant heat sinking.

  2. To be fair, most of the people who are currently buying UV-C lamps do not fully understand how to use them safely, that exposure to UV-C can cause short term or permanent damage to their eyes (sandman’s eye/potato eye/welder’s flash) and skin exposure can produce rapid sunburn and skin cancer. UV-C breaks double carbon bonds at the molecular level, so anything organic (living or dead – animals, plants, paper, clothes,…) or synthetic (paints, plastics), will be permanently damaged. I’d imagine that the damage they would do trying to protect themselves, by the incorrect use of a UV-C source, would be far greater than the chance of death from COVID-19. At this exact moment in time I’d actually prefer for people who do not understand what they are buying to be sold the wrong product than for them to add unneeded strain to the medical system during this crisis.

    I personally picture the short/long term exposure UV-C to be similar in damage level to that produced by soft X-rays but unlike X-ray damage it is restricted to molecules with double carbon bonds and only to the surface exposed (it does not penetrate deeply beyond the surface).

    1. No, UV-C has no specificity for double carbon bonds, it can break a lot of molecular bonds.

      “Ultraviolet light can dissociate relatively strong bonds such as the double oxygen (O=O) bond in molecular oxygen (O2) and the double C=O bond in carbon dioxide (CO2); ultraviolet light can also remove chlorine atoms from compounds such as chloromethane (CH3Cl).”

      1. Exactly it depend on the energy matching, and yes photolysis applies to more than just some double carbon bonds found in DNA. But carbon bonds are the most directly applicable to human flesh.

        UV-C is from 280nm to 100nm, so in theory it could break any bonds with bond energies from about 427 to 1200 kJ/mol.
        But the reality is that for a typical quartz mercury UV-C lamp there are two main peaks in the UV-C range.
        It has a one peak from 200nm (600kJ/mol) to 160nm (750kJ/mol) with a maximum near 183 nm (655 kJ/mol) and a larger second peak from 260 nm (462kJ/mol) to 230nm (521kJ/mol) peaking near 252 nm (476kJ/mol).

        So any bonds at that bond energy can be broken,
        C=C 602 kJ/mol
        C=N 615 kJ/mol
        O=O 494 kJ/mol

  3. Can anyone please explain to me why on earth you would like to buy an UV-C LED bulb for 4k and not the pl variant for 12 bucks? this sounds ridiculous. the pl tube version is very eficient and a common used type for aquaria. It just seems a waste of money

  4. Actually, my experiences with UV leds in general are bad too. They aren’t able, in 365nM range, to erase UV Eprom and, in other near ranges, are unable to substitute CFL in mosquito killer… So no chance, for now, to replace old CFL lamps with more durable (perhaps)) technology.

        1. Looks a bit like fridge lightbulb. Would be cool to hack the fridge to run UV-C cycle every now and then, so the groceries will stay fresh for longer time. There’s already door switch, so you can turn it off automaticaly if someone opens the fridge during the cycle…

          1. These are not normal bulbs and cannot be directly run off an AC or DC source. These are gas discharge lamps just like a florescent tube. They must be ballasted or they will pop the 1st time you put power on them. I use these exact bulbs in a home made UVC eprom eraser. The way I drive them is with a 120v to 24v 400ma AC transformer. I then have 41ohms of resistance, two 82ohm 5watt ceramic resistors paralleled. This give the bulb the voltage it needs in the upper teens of volts to strike and then the voltage will drop to around the 10v operating voltage of the bulb once the arc is struck.

            One of the bulbs will erase an eprom in about 5 minutes.

            If you look at one of these bulbs at 1st glance they pretty much look like a normal incandescent bulb. The way they work is when they are cool the filament will glow to get the ion emission going then as soon as the bulb strikes the arc across the tips the resistance of the arc is lower than the filament, so the filament is mostly out of circuit. If you watch one of these bulbs start up, (WITH PROPER EYE PROTECTION) you will see this in action. Filament glows for a second or two and as soon as the arc strikes the filament goes out.

            These bulbs will run off AC or DC, but you really should be using AC. With DC you will only see the glow on one side of the tube, No idea if this is bad for them or not, but it is almost certainly cutting your UVC output in half.

        1. Erased EPROMS contain ones (0xFF). So it would not help. At least your test EPROM needs to contain zeros. But you have to compare the necessary dose for erasure of the EPROM to the necessary dose to eradicate the virus (or other pathogen in consideration). I think better sensors exist.

  5. Here’s the real clue that it’s fake: 275nm leds are $18 U.S. apiece, or $10 each in qty of 1000 wholesale. (Mouser) So a lamp with 200 of them should cost at least a couple of grand, minimum.
    CFL style UVC lamps are available on Ali from 8 to 40 watts for $10-$30 ea. U.S. and surprisingly (supposedly) in-stock. I ordered a couple just the other day and received a shipped notice within 24 hrs.

  6. I think the sellers of these items need to be locked in a room with Covid-19 aerosol and one of their lamps.

    This isn’t one of the usual Chinese spec frauds, this might get a lot of people killed.

    An analogy would be disinfectant gels, wipes, or fluid that didn’t contain any actual disinfectant.

    This isn’t simple fraud, this is negligent homicide

  7. And, has the store on Amazon CONTINUED to keep the device out of their store?
    A quick search at Amazon for “UV-C germicidal LED lamp” turns up dozens of hits for lamps that are in this $50-$100USD price range.

  8. If you study nih documents pertaining to UV including 380-400nm, you will find that 300nm @ 21-55 minutes @ .05-.8 joules/watts/cm2, has the highest viral elimination in the solar spectrum vs. illumination on the ground, and 400nm works too it just takes many x longer, think 1-8 hours for viral deactivation at 1-4watts or Joules of 400nm light per cm squared. Instead of 10 milliseconds at 253nm @ .004J/cm2. If you want instant elimination, go with uvc, UVA also deactivates viral strains. So, yes the light will deactivate viruses, but it will have to be on all day, if not 24 hours a day and you’re going to need more than one. Enough viruses will be deactivated to make the remaining viral loads low enough to not be something the body can’t handle. The best frequency range of UV light is 210-222nm it’s wavelength is so short it doesn’t penetrate skin or eyes. 400nm is considered safe too. But for a different reasons.

    1. So you’ll get infected about 4 times over while waiting for this bulb to decontaminate your groceries, lol. So technically, if they took the wavelength off the ad and just advertised it as a germicidal uv lamp they would be covered?

  9. Thank you. I too bought one of these…thought the price was too good, but didn’t let that slow me down. Where can I buy one of those flip-flop friendly mowers? and what can I do with my new paperweight?

    1. While not ‘germicidal,’ these bulbs are a great source of UV-A if you happen to have a bunch of black-light posters lying about. 😋 Also a great UV lamp for your bug-zapper. Should be bright enough in the UV bring ’em all the way in from the next county over. 😄😄

  10. The lamps you want look like a rectangular wound CFL but are clear. The ones we have are either 15W or 25W, they screw into a regular E26 lamp socket. You can tell if you are giving off a lot of UVC by the unmistakable smell of ozone after it is on for a few seconds. These are useful for a lot of things. I keep one on an inverter that is ran for a few minutes a day by a timer in my solar powered cottage in my woods. It kills off mold, it seems to bother bugs and critters, and the place smells fresh and nice when I open it up for the summer.

    1. Mercury-vapor-based UV lamps emit strongly at two UV wavelengths: 253.7 nm (UV-C) and 185 nm (so-called Vacuum-UV or VUV). The latter wavelength generates the ozone that you smell.
      Now some Hg-based UV-C lamps feature a coating on the quartz envelope that blocks 185 nm whilst allowing the other through. You have the uncoated version. Ozone is toxic, and so I hope you’re airing-out the place a bit before occupying it. On the flip side, ozone penetrates areas the light cannot reach, with the combination more effective than either one alone, so it’s a two-edged sword. Best! RE

  11. On the upside, if you or anyone you know has a resin 3d printer, that’s pretty close to the right wavelength to build a post-curing box with it. I can’t find a useful datasheet for how wide the useful bandwidth is to cure 405nm nominal resins, but I’d hazard a guess that bulb is putting out most of its useful light in about the right part of the spectrum.

    If you strike out on 3d printing, could find use in your home laser tag arena, or starting a sweet rave, the possibilities are endless!

    1. I was going to ask if this would serve any other purpose before trying to return it, but you answered it, so they could possibly still have a market for these without lying to people.

  12. You guys are great! Ingenuity, attention to detail, and the documentation!
    Confession, I know very little about this stuff.
    Quick question, is there a way to convert a bulbs wavelength? Ie changing it from 254 to 222 (far UV)

    1. Your question in the visible spectrum would be is there some way to convert red photons (625-740 nm; 1.65-2.00 eV) into shorter wavelength higher energy orange photons (590-625 nm ; 2.00-2.10 eV ). The only way I can think to shift the frequency is to accelerate the light source to near the speed of light and have it travelling towards you (Doppler blue shift). But it is far more energy efficient to just use a different element (and you do not need as much space), which emits and absorbs in the right part of the spectrum. Might I suggest the the equally/more dangerous Deuterium lamp (which emits from about 190 nm to 400 nm – lookup “deuterium emission spectrum” in your browser of choice and compare it to “low pressure mercury emission spectrum”).

      All I ask is that you do not blame me if you fail to take the proper safety measure to protect yourself. If are unable to sleep for weeks because the inside of your eyes feel like sandpaper, not my fault. If you get skin cancer, not my fault.

      1. But aren’t the deuterium lamps what they are using for the far light technology? My understanding is it’s Russian technology and they are using filters with the lamps to focus on the 207-222 range.

  13. I bought one early on, at a pretty steep price, too. contacted the seller via amazon, asked for a return and the next day I did hear back with a credit for the full amount. no directions were given for the return of the unit; so either its too expensive to cover return shipping (on their part) – and what will they do with this (now useless) bit of kit?

    I get the feeling that this is going to be a big loss of face in china, in this industry. given the timing of this and that people can be risking their lives trusting a product that is just placebo, at best; that’s criminal.

    in the end, I wonder how much this Big Mistake(tm) is going to cost? from design to manuf to middle sellers. everyone is going to lose their investment. OR, maybe it was known all along and was meant to be a scam, just to get as much ‘rube’ money as they can, hold it as long as they can and give back only what they are forced to.

    it all looks very bad. so glad that this was posted, to get the word out.

  14. Interestingly, the bulb even says “Germicidal Lamp” on right on the base. But the datasheet shows UVA spectrum, and whether that has some germicidal power or not, it’s not the part of the UV spectrum commonly called germicidal. I feel bad for the many people who have bought these, thinking they’ll disinfect their bedrooms or living rooms in a matter of an hour or two, when it could take days of uninterrupted use in an unoccupied space.

    I’m happy you got confirmation from the seller that their “UVC” “Germicidal Lamp” really isn’t as advertised. I’m not surprised they simply refunded your money, as it’s easier to do that and keep the other sales rolling in for those bulbs. I’d expect a new, suspiciously-similar listing to appear in the near future selling that same bulb or a slight variation of part number, etc.

    Unshielded UVC lights shouldn’t be sold to consumers without a lot of education on the dangers and dosages required for deactivating microbes.

  15. Thanks so much for testing this and posting the result! And thnx to whoever sent the link to me on my Amazn question. After seeing posts there that people had tested them without getting an appropriate reading I tried to cancel my order a few days ago and the seller responded by sending out my package the next day, um thanks. I was going to see if someone had the equipment to test it, now I don’t have to.

    Had some questions if anyone has time. The UVC fish tank bulbs and some of the devices being sold are adverted at 254nm, some state they give off ozone as well, some say they do not but reviewers are stating that they smell ozone. Is there any bad effect from breathing in the air after treating a room with a 254nm bulb. Do they make bulbs that give off both ranges 180nm and 254? Should we be weary that a bulb advertised at 254 might also be producing the range that makes ozone?

    Someone has taken claim to the far-uvc frequencies stating they were the first to separate it, discover it’s usefulness and make products based on that. They posted a response on an article the other week stating that a university doing a lot of research on the safety is working with a foreign competitor and if they produce a product (which they already have) they will protect their patents. I’m guessing that means sue. I haven’t been able to interest anyone in the story but that seems huge to me, considering how beneficial it could be in the epidemic and the safety hazard of people messing around with uvc bulbs. Plus I thought strict mercury import laws were implemented in the last decade.

    I think hobbyists would be able to advance the technology faster than a handful of companies and universities. What are the roadblocks to making an led in the 207-222 nm range, is it even possible?

  16. Amazon is chock full of these bogus LED ‘germicidal’ lamps for sale, and their LED variants. Some even claim their LED bulbs generate ozone which requires an even SHORTER wavelength in the ‘Vacuum-UV’ region under 200 nm (vacuum uv is between UV-C and soft X-rays in terms of wavelength), completely outside the range ANY LEDs can emit (the current record is 210 nm for an experimental aluminum nitride device).
    Commercially-available UV-C LEDs are horrendously expensive – USD $500 PER LED and up, and very low-power, typically under 1 mW.
    So yeah, anybody claiming their $60 LED bulb is germicidal is full of shit, to put it bluntly.

    1. The price quoted is for 255 nm LEDs from Roithner-Laser of Austria. The 275 nm CEL LEDs mentioned in the OP are listed on DigiKey’s website as obsolete. The one model still in stock is $127.40 in unit quantities. As a genenal rule for UV LEDs, the unit price increases exponentially with decreasing wavelength, whilst the radiant power decreases along with expected component lifetime.

  17. There is a difference between GERMicidal and VIRUcidal. In these frenzied days, I think its easy for the layman to get confused. Technically speaking, hand sanitizers are only germicidal. Its takes many years to get a virucidal claim approved by US government agencies. So even though ethyl alcohol can kill viruses (heck even sunlight and time do) no one is going to fork over the monies to get a virucidal claim. It would take two minutes for a competitor to do the ol’ “wink-wink” that their formulation is the same (as most are) so its in essence the same . . . hand sanitizer in this illustration

  18. Great thread. I was just about to fall down this rabbit hole.

    I’m interested in pulsing germicidal light at about let’s say 20hz. Simple square wave on-off. Anybody have thoughts on that?

    I could shell out the $$ for the true UVC LEDs, which are low efficiency, or I’ve wondered if the little 3w E12-base lamps could be effecrively pulsed with the right kind of power supply. Anybody have thoughts?

    1. A quartz low pressure mercury UV-C lamp is the same technology as a normal fluorescent bulb, but without the special Erbium coating inside that converts UV into visible light and with quartz instead of glass, because glass blocks the transmission of UV.

      So what you are asking is can you pulse on and off the arc inside a fluorescent bulb 20 times a second. When a fluorescent bulb is turned on there is a massive current draw, because the initial arc is effectively a short circuit and that is where the maximum amount of power is used, traditionally the magnetic ballasts (large inductor) would limit the current to prevent fuses being blown. So if you are flicking it on and off 20 times a second it will use a crazy amount of power due to the high Inrush current.

  19. This is why you just stick with the tried and true CFL or linear tube UVC bulbs. Much less scamming going on in that space. Even the non-ozone generating ones generate a small amount. Put the UVC bulb in a small room like a bathroom with the door shut and run if for 5 minutes. You’ll be able to smell if it is a real UVC tube. You aren’t going to have true UVC LEDs without either bare exposed dies, or a quartz glass window on it. The few true UVC led’s i’ve seen are usually look like the old style metal can LEDs with the quartz glass window on the end. Expoy is going to both absorb the UVC and degrade very quickly from the UVC. If you see an LED claiming its UVC and it is in the standard epoxy LED casing it is immediately a scam.

    1. I notice the light being a pretty blue when lit, but I also noticed white items having a black light effect. So I did the ole banana tests, leaving a sticker on it, and exposed for 1 hour. Light 5 inches away. After an hour, definite darkening of exposed area. Did same with a piece of regular glass between light and banana for 1 hour. No darkening or color change from the area around the sticker (no difference). There is a smell, but nothing like after a thunderstorm.

  20. I’m seeing numerous comments in here about how dangerous UV-C is. The latest entry in the MedCram series on YouTube specifically covers this topic. “UV-C” is too broad of a term to use when making statements like this. Specifically, UV-C at 200-222 nM has been found to not be dangerous to skin or eyes but highly effective on germs and viruses.

    I’m not saying that all generic UV germicidal lamps are safe, but the opposite is also true. Not all UV-C lamps will give you cancer and cause blindness upon powerup.

    1. If you find out where to find one of those ‘safe’ UV germicidal lamps lmk. I should say if they were in production and cost less than 4000 dollars.

      If this bulb actually killed anything then it would probably be the safest germicidal lamp. One lab test shows 405nm at 15 mW/cm2 for an hour killed a significant amount of ecoli in a petri dish, but 5mw had no effect for 2 hours. An amazon reviewer said this is giving out 3.2 mw/cm2

      At least one of these ads on amazon with a lot of negative evidence has been removed, problem is it took the truthful information down with it.

  21. The majority of UV-C germicidal lamps are in the 250+ nm range that is dangerous to humans (cataracts and skin cancer) and should only be used where humans aren’t present. 200-222 ARE safe, lots of credible science pages where these have been tested. Amazon sellers (almost all) omit the wavelength and very few offer 222nm lamps. Aliexpress and Alibaba sellers show this but in my dealings with both, they don’t usually know much about their product and think UV is UV. Well it isn’t. And Yes Quartz glass is needed so LED’s are suspicious.

  22. I confirmed what everyone else has said. The “corn type” LED UVC bulbs easily found on Amazon and Ebay are fake. I ordered 2 from Amazon and 2 from Ebay. They do not emit UVC or even UVA/UVB light. I confirmed first using agar and a bucal swap, then with a radiation dosimeter dot ( Both methods confirmed that the bulbs were just pretty lights with no smell of ozone.

    Someone should start a class action lawsuit to ensure these disgusting companies stop. Aside from the stolen money, the real issue is the front line clinicians who think they are home sterilizing items after work (phone, keys, personal PPE) and further infecting their friends and family. It’s horrible.

    1. The class action suit should be brought against eBay and Amazon for facilitating fraud. In the case of eBay I have attempted to notify their legal department that their facilitation may result in death if someone relies in the light in lieu of other sanitation methods.

    2. I bought one of these corn cob style LEDs from eBay to sterilized my wife’s scrubs.

      It was a fake as well. There was no smell but I thought nothing of it at the time.

      I just bought some UVC dosimeter dots and found that the light was a fake.

      Stick to bulb style UVC lights. Be sure they give off a smell. And if you are like me and are curious how to know how long to use them, buy dosimeters online FROM US OR EUROPE vendors.

      I will not be buying China crap anymore. They lie and cheat you during a crisis situation. Now how to figure out if these Chinese masks actually work?????

  23. Confirmed that this 60 W germicidal bulb is fake (no UV emissions). I measured a 20 w 20W mercury vapor bulb with a 200-800nm spectrometer and it had a very pronounced spectral line just above 250nm. I then measured this 60w germicidal bulb. It had a spectral peek at 450nm, saturated measurement 500 – 550 nm but nothing above ambient at less than 400 nm. I’ll send my plots to ebay and amazon to see if these can be banned.

    1. Hello
      I bought a Phone UV sterilizer. it was supper fake that makes you laugh. illuminated plastic rods instead of mercury bulb!
      contacted amazon. they said i will get a refund and they the will investigate the issue. but I don’t think they change anything.
      it might seems stupid. but all I could come up with was posting a question under as much as product that i can. i haven’t started yet. please tell me what you think and how can I improve it. I don’t mind spend time to post the question. all I need is to be sure i am posting a true statement.
      Thank you.

      here it is:

      Does these device has a Mercury lamp? because LEDs are not effective for sterilization.
      only Mercury lamp can produce 253.7 nm wave length light which is most effective against microorganisms such as viruses.
      now you know it, it could makes you legally responsible. please do a research about UV sterilization principle and carefully verify the device to avoid any unintentional harm to people. your product is very strategic and important. if it works, it saves lives. if it doesn’t, it takes lives.

  24. I bought 2 of these …oh dopey me….but my problem is I put one in a room downstairs, closed the door and left it on for a half hour and if this is fake, which I believe after reading the comments, then why was there a strong smell …my wife smelled it too…smelled like bleach…I am 73, retired electrician with COPD, so I was worried about ozone but after reading the comments seems as though it couldn’t be….any body help? I don’t want to use it as some “Pretty” $50 mistake if these fumes are harmful…have only used it once…could it be something just burning of on initial use? thanks for listening/reading …any ideas????

    1. I don’t know about harmful, but I don’t know of any affordable LEDs that will put out UV-C. All of the disinfectant UV bulbs that I’ve seen look like fluorescents.

      I also doubt that you’ll successfully disinfect _anything_ in a reasonable timeframe if you’re trying to cover a whole room. Aside from the danger of walking in there while the light is on and UV-irradiating your eyes and skin, what matters for killing viruses is the power per square inch of surface area. Better all around to put the bulb in a small box: you’ll shield yourself from exposure and you’ll get more UV flux onto the things that you want to disinfect.

      If a lightbulb smells like anything, I’d start to worry.

    2. It’s definitely fake. The source of smell is probably some overheated electronic component inside the lamp, especially if it is merged with the low quality FR4 resin or phenolic base, used for printed circuit board. The best option is to return the product (if possible) and to order UV CFL lamp for less money.

      1. Thank you so much….this is by far the most logical explanation….I was an electrician and sometimes new electronic equipment would initially give off a funny odor. We would call it “burning in”….like shellac in a transformer, etc…so if this odor goes away do you think I can use it as a “pretty blue light” conversation piece? By the way it seems like there are even more of these on Amazon……I leave reviews on all that I can to try to stop people from buying these ripoffs…again thank you and let me know if you think I can fire this thing up or just toss it…They won’t take it back or refund

  25. I wish I read this before I bought one from Amazon. I tried returning this yesterday after finding a legit video on youtube. The seller still wont give me a full refund and wanted me to ship the product to China. Whan an opportunist! Thanks for putting the facts out.

  26. These are still all over Ebay in many different shapes and sizes and still in Amazon. Could you please consider writing a a new article describing how to tell the difference between a real uvc bulb and a fake? Just one UVC LED SMD costs five to ten dollars.

    1. after being taken twice I did a lot more research, a lot of it because of this site and a few thing are apparent….If it says LEDs and costs less than at least $500 it’s for sure fake….look up and read about the banana test…it works….I had ordered a bunch of this stuff and was able to return most so far but today I received 2 fold up wands that seem to be the real thing…around $50 each …says it’s UVC and 253.7nm, which is good…3W bulb so only good for small jobs, but if real that’s great….have yet to do the banana test so will get back to you but definitely all the ones that look like a corn cob with a whole bunch of LEDs are all fake so pretty much LED = FAKE

  27. Bought a UVC dose card on eBay and found out some of the lamps were able to kill germs and some weren’t able and sent the ones that didn’t work back to amazon.

  28. One most important thing in all this great and hugeeee article, is that original writer of this article, also the all people here which really posses UV-C Dosimeters, Spectrometer, etc., and really knows this staff in professionally…, the smartest way that they can do to rest of the public readers here, is to give at least a few eBay and Amazon direct link example advices, what UV products is the best buy and certainly not a fake ones!

    For e.g., can someone recommends for the USA and EU market, some really truthful UV lamp on eBay and Amazon, for disinfection the rooms, humidity basements with molds, and for disinfection the masks in this corona crisis now?!

    Thank you and best regards! :)

  29. I purchased one these “UV-C” LED 60W corncob lamps for 30 GBP from ebay and quickly suspected it was fake. I had it checked against a lab quality UV-C meter. At 5 cm it produces almost no UV-C, and measured at 7 microwatts/sq cm. About the same level as a cold white household GU10 LED bulb. Compare that with a mercury vapour 72 watt disinfecting lamp; at 5 cm the UV-C intensity was 7.17 milliwatts.

    1. Ebay has been made aware of these fakes a long time ago yet eBay continues to facilitate this fraud. I would live to see a class action against eBay for this behavior.

  30. I wrote a complaint to the BBB last Spring about ebay allowing these to be falsely advertised, I encourage anyone who has been swindled to do the same. I wasn’t able to do it for amazon but I did receive a full refund from them, but that doesn’t excuse the continued selling of these being allowed. They may be a fire hazard as well. There is a lot more info on the web and tests on youtube about the “uvc” led products now, but 6 months ago there was little information and they sold millions of these products to US consumers in the meantime.
    I have several of the uvc glass compact bulbs, they seem to work well. Killed mold in a humid bathroom ceiling and stayed clear for months. Unfortunate they are not made on shore, often mis-labled (o2 or not) and lots of price gouging still.

  31. 4 different times I bought UVC labeled bulbs off ebay. I Still haven’t received a genuine one yet. More than 50% of the UVC bulbs on ebay right now are only UVA or UVB. Its more than annoying …. I complained twice, but Ebay realy don’t give a shit that people who are counting on UVC for disinfection etc are bieng ripped off.

  32. You never see the visible light of a real UV-C LED. The human eye cannot see UV-C light. I know. I just received my 280nm UV-C two LED strip in the mail. I was wondering why I couldn’t see the UV-C light, like I had seen in the videos. The manufacturer then informed me that I wouldn’t be to visibly see the UV-C light.

    So ANY product that is selling Anti-Viral LED or bulb that they say is UV-C, are not real UV-C frequencies and you are being scammed.

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