Talk:Fluorescent lamp

Archived discussions

Some of the older discussions have been moved to Talk:Fluorescent lamp/Archive 1 --Wtshymanski (talk) 23:14, 16 August 2009 (UTC) More moved to archive 2, from August 2009 to end of 2010. --Wtshymanski (talk) 03:41, 23 November 2011 (UTC)

More moved from 2011 through early 2017. --Wtshymanski (talk) 02:03, 29 March 2020 (UTC)

Purpose of ballasts

The article mentions ballasts more than 100 times but the only thing it says about them is that they regulate the electricity. That is quite vague. I am interested in a more specific explanation of the purpose of ballasts. The article Electrical ballast just describes how they work but I do not see an explanation for why they are needed. I assume it is due to the material being a gas but I am interested in a more accurate explanation. Sam Tomato (talk) 21:29, 31 July 2019 (UTC)

The ballast is needed due to a funny little phenomenon that occurs in plasma, called negative resistance. In essence, opposite to most conductors, as a plasma gets hotter the resistance decreases. In other words, as current increases both the resistance and voltage decrease. The more current you add, the less resistance there is to block it. Without something to limit the current, the flow will runaway and lead to an arc flash. (I like the analogy of a dam bursting. You can block the flow of water with a dam made of sand, and build up a nice mud puddle, but the second it springs a leak it will melt away. The more water you have on supply, the less dam there is to impede it.)

Cold-cathode fluorescent lamps, which operate like a neon light (typically used as backlighting in flat-screen TVs, or in old exit signs) do not need a ballast because the transformer limits the current, but normal fluorescents are designed to operate directly off of line voltage, and so need something to limit the current and prevent the lamp from destroying itself, and possibly much worse. Zaereth (talk) 23:19, 31 July 2019 (UTC)

In the case of cold cathode lamps, the transformer is designed to limit the current, pretty much transformer and ballast in one case, usually on the same iron core. Also, many fluorescent lamps need more than line voltage, so also a transformer ballast. Rapid start lamps have transformer windings to heat the cathodes while also supplying voltage across the lamp. (It is a convenience of those in 240V countries that you can run a 40W lamp without a transformer. In 120V countries, this works for smaller desk lamp sized lamps.) More modern electronic ballasts use a ferrite core transformer, run at 20kHz or so, and as above use a series capacitor to limit current. Also, multiple-lamp fixtures often run the lamps in series, simplifying the design slightly. (With the inconvenience that all bulbs go out at the same time.) Gah4 (talk) 07:22, 20 September 2019 (UTC)

The problem with very long articles is that it's hard to see the salient facts. The paragraph under Fluorescent lamp#Electrical aspects of operation explains why the ballast is used. --Wtshymanski (talk) 05:34, 3 August 2019 (UTC)

Thanks. I knew it had to be in there somewhere. (For long articles like this, ctrl+F comes in really handy.) The other option would be to operate them like a welder or CO2 Laser, and run the power through a big set of resistors or a space heater, but then we're back to the same problem with incandescent lamps, producing more heat than light. Zaereth (talk) 20:13, 3 August 2019 (UTC)

There are (or were) self-ballasted mercury vapor lamps, which include inside the bulb an incandescent lamp filament that limits the current, and also helps warm the lamp. It is cheap transistors that can run at a few hundred volts that allow the modern electronic ballast, usually at about 20kHz switch frequency. Then a series capacitor is enough to limit current. In addition to all above, the ballast has to keep the lamp within specifications as it ages. Gah4 (talk) 04:49, 16 September 2019 (UTC)

It's funny that you should say that. Around fifty years ago a fluorescent fitting was available in the UK that did precisely that. The resistive ballast was in the form of a 170 Volt, 60 Watt incandescent lamp that also contained the starter (this ran from 240 volts of course). The combination was still more efficient than a 100 Watt incandescent lamp on its own, but not that much less efficient than a fitting with an inductive ballast, bearing mind that an inductive ballast still dissipates a lot of heat. And, of course, fluorescent lamps operated from DC had no alternative but to use resistive ballasts. 86.162.147.218 (talk) 13:30, 5 August 2019 (UTC)

That's not surprising, since the first arc lamps were powered that way, and in many cases still are. Not sure why you never see ballasts in high-powered applications, although it may have something to with limits in efficient heat-dissipation at very high energies. Keep in mind, while some lamps can have wall-plug efficiencies exceeding 70%, the best lamps have luminous efficiencies under 40%. While all power sources lose some energy in the form of heat, every little bit of savings helps. (In fluorescents, the greatest losses occur in the coating itself, due to the Stokes shift.) Zaereth (talk) 21:47, 6 August 2019 (UTC)

There are 120V self-ballasted mercury lamps like this one. Also there were many years ago fluorescent Christmas lamps self ballasted. In the latter case, the filament has to give only a small amount of light, or it will drown out the color. The lamps are white when off, and colored when on. Gah4 (talk) 03:28, 15 December 2019 (UTC)

considerably more complicated than an incandescent bulb

The article says fluorescent lamps, and especially early cold-cathode lamps are considerably more complicated than an incandescent bulb. A cold cathode lamp is very simple, with metal electrodes at each end. An incandescent lamp needs the complication of the filament, system to hold the filament in place (for long ones), and usually coiled or coiled coil filament construction. Hot cathode lamps have heaters which are similar to incandescent lamps, so also similarly complicated. Early fluorescent lamps were fairly simple. Gah4 (talk) 23:53, 14 December 2019 (UTC)

Well, not necessarily. An incandescent lamp is basically just a simple resistor or space heater, so the operation is extremely simple. Granted, the construction was a bit complicated to get down, and there were problems to overcome, such as evaporation of the filament, but all in all it's a pretty straight-forward, simple device that is easy to operate on any type of current.

Fluorescent tubes are much more complicated to operate, as demonstrated by Moore's lamp. The lamps were designed to operate on Edison's DC power supplies, but they needed to be very high voltages, like neon-lighting high (several thousand volts). So first Moore had to develop an interrupter circuit that would switch it on and off really fast, in order to power some large trnsformers. His electrodes were often iron or carbon, but operating as a glow discharge sputter wasn't really a big problem. The biggest problem was that he was using non-noble gases, which react with both themselves and the electrodes, and would quickly run out, so he needed to come up with a pressure regulator valve that would continually feed in new gas. For example, see: this schematic.

While more efficient than incandescents, the units were huge and costly to install, and produced these weird, eerie colors that were often unappealing. To make them marketable, they had to become more appealing, smaller, cost effective, and, most importantly, they needed to be able to run straight off electrical mains power, meaning you needed to take the voltage down into the arc regime. This presented a whole new set of problems, such going from straight arc-lighting to the use of fluorescent coatings, finding a suitable mixture of phosphors, finding a suitable plasma-medium would properly excite the phosphors, a method of coating the glass and sealing it without destroying the phosphors, etc...

And then the problem became sputter, which caused them to fizzle out in no time, that is, until the introduction of the Philips electrode design to lower work function. Then you have to supply some kind of current-limiting device to go with the lamps and a method of striking the lamps with high voltage. You have to consider the plasma dynamics and, very importantly, make sure the lamp has the proper pressure --during operation. In comparison, here is actually a lot to it, even for something as seemingly simple as a flashtube. Zaereth (talk) 01:29, 15 December 2019 (UTC)

I suppose so. I didn't consider the pressure regulation which does complicate things. Otherwise, the statement is about the lamp, so ballast doesn't count. We have a complicated power system designed to generate the constant voltage needed for incandescent lamps. Gah4 (talk) 03:11, 15 December 2019 (UTC)

I get what you're saying. In matters of construction, they're similar. Both are fairly simple designs when you get right down to it, but there were a lot of special innovation needed to get them to work just right. In my experience, that's really the case for any invention. The complicated power supply we have for incandescents (AC) is actually intended to better power everything else. It allowed a safer increase in voltage, because you don't have nearly the amp load with AC, which produced better transmission of current over longer distances. With Edison's power plants, there were so many losses that you would have needed a generator on practically every other street corner. It also allowed things like transformers to function on their own, and better motors to be devised. Not to mention its easier to generate than a DC signal. The thing about incandescents is that you don't need all of that, yet you can run them on it just the same. They're just as happy to run off a couple D-size batteries in my flashlight, or 12 volt DC at my cabin, as they are 120 volt AC in my house. Need to dim it? No problem, just attach a rheostat.

The problem is that the fluorescent tube is just a useless hunk of glass without a way to power it. It doesn't really become a lamp until you're able to plug it into the wall. For example, Harold Edgerton is credited with inventing the flashtube. But Edgerton was no glassblower, so he actually paid General Electric to design and build the first flashtubes, but they were useless things without the power supplies needed to operate them, so he's the one who gets the patent and the credit. In the context of this statement in question, it seems clear to me that it's referring to the lamp, not just the tube itself. But perhaps there's a way to make that clearer? Zaereth (talk) 19:47, 16 December 2019 (UTC)

I once knew the story about the Edison generators, which it seems generate a more constant voltage than other designs of the time, just as is needed for incandescent lamps. Incandescent lamps are about the most voltage-sensitive device run on ordinary power lines. There are voltage regulating (tap switching) transformers to keep the voltage close enough. The statement in question just related to the lamp, not the equipment needed to operate them. One hopes that such equipment lasts for many lamps, though I have found some ballasts in modern lamps not to last so long. Often enough, not even one lamp lifetime. (Partly that is because lamps are getting better.) There are now T5 lamps rated to 90,000 hours. Might also be useful to discuss somewhere the Glass-to-metal_seal needed for fluorescent and incandescent lamps. Gah4 (talk) 02:00, 17 December 2019 (UTC)

HO

There is a section on overdriving normal lamps. I suspect that people do that, though maybe not so easy to find a ballast to do it, but they could just buy and use HO lamps. Well, the easiest way to find a ballast to overdrive seems likely to find an HO ballast, and wire it to non HO lamps. Well, I bought some T5 HO lamps, an amazing amount of light from such a small lamp. Now to install them. But a big advantage of fluorescent lamps is the long lifetime, and if you shorten the life, you lose that. Gah4 (talk) 04:53, 31 March 2020 (UTC)

While possibly interesting to a degree, I notice the source used is about people burning down their own houses trying to modify these lamps for that purpose, yet the addition says nothing about that very real danger. It doesn't take much of an increase in current to arc flash and cause big problems, let alone all the other things that can go wrong when you start tampering with designed safety margins. Personally, I think this is not Popular Mechanics, the Anarchist's Cookbook, or some other how-to manual, so I think this is really irrelevant to this article. If kept, though, we should really try to summarize the sources for better balance, to include the potential hazards of attempting that, especially for those who don't fully understand what they're doing. Zaereth (talk) 05:10, 31 March 2020 (UTC)

Keep in mind that this is coming from someone who regularly overdrives flashtubes to get more power out of my lasers than they were designed for, such as this one, but I wouldn't go recommending that at the flashtube article. For stuff like that you really need to do some deep research, go talk to an expert like Don Klipstein, or start calling manufactures, or even get the guy who invented the lamps on the phone. Wikipedia shouldn't be the place to start getting into those kinds of modifications. Even with something as seemingly simple as a flashtube, the risks involved are extremely high (high voltages, deadly capacitances, and possibility of explosion), and it would be irresponsible and even irrelevant to the article to recommend that to the average reader. Zaereth (talk) 20:53, 31 March 2020 (UTC)

So we don't mention overdriving lamps, but, the reason for this thread, should we mention HO lamps? They seem to be only in the tanning lamp section. I don't actually know what they do to make HO lamps, other than different cathode design. Gah4 (talk) 00:26, 1 April 2020 (UTC)

I think it would be useful to have a brief summary here. I don't know all the details either, but I do know your average 4 foot tube runs on about 400--430 mA or so. For high-output lamps the current is typically in the range of 800 mA for about a 45% increase in light output. Some extremely HO lamps may run as high as 1500 mA for as much as a 60% increase. It's basically increasing the current density by simply adding more current. By doing this, you're running the lamp at a higher temperature and lower voltage, and that will affect things such as electrode design, cooling, etc. It will also affect things like the coating mixture and thickness, because you want enough to prevent transmission of most UV but not so much it blocks visible light from transmitting through. If properly designed, it shouldn't affect lifetime that much.

With things like T5 or T8 lamps, you increase the light output by increasing the overall efficiency of the plasma, by increasing the gas pressure. More or less, your using about the same amount of gas in a smaller space, raising the current density, and this increases efficiency (thus light output) by increasing the overall number of ion transitions per electron. But this comes at a cost in that you need a much higher start-up voltage to strike the lamp and boost the current, so they do wear out much faster than their T12 counterparts. Zaereth (talk) 01:20, 1 April 2020 (UTC)

I believe it is 430mA for all lengths of ordinary lamps, though I haven't thought about it for a while. One that I do remember is that there are some lamps designed to run on higher current but not higher pressure. They have a shape that increases the surface area. With excess liquid, the vapor pressure is that at the coolest part of the tube. Also, T5 lamps have a longer lifetime than T12, but I suspect due to other design differences. F96T12 is about 15,000 hours. F54T5 are 35,000 hours. Some lamps are up to 80,000 hours. Gah4 (talk) 03:49, 1 April 2020 (UTC)

It seems that T8 have longer life than T12 or T5, but they are special double life, or other special lamps. I presume special cathode design that doesn't fit in T5. See this catalog for much of what is available, including life for a variety of lamps. Oh, also, starting method makes more difference in life, with preheat being shorter, rapid start in the middle, and instant start longer. Gah4 (talk) 08:15, 1 April 2020 (UTC)

Indeed, starting has a huge effect on both lifetime and how it wears. I've often found catalogs to be a wonderful sources of basic technical knowledge, such as places like Edmund Optics or CVI Lasers give great tutorials on optics and coatings, but you have to be a lot more suspicious when relying on their proprietary information. Lifetime is one of those things that is really impossible to calculate. Two tubes that come off the production line one after the other can have vastly different lifespans. The tiniest difference between the two, at the start, will have vastly different outcomes in the long run. That's the problem with sputtering, because it's too random, chaotic, and unpredictable. It seems counterintuitive, but if you want to decrease sputter and increase electrode life, then increasing the current is the way to go. It's high voltage and low current that are the enemies there.

In addition, lifespan is highly dependent on how you use it. This also is counterintuitive, you'd think you're measuring those strictly in hours, but it's really the start-up that wears the electrodes out, so those hours are really only good if you lleave them on indefinitely. Everytime you start it it's like striking a match, where a little bit of the surface coating is blown away. So evertime you turn it off you're actually reducing the hours you have, not gaining them. For lamps with higher pressures, starting the lamp is much harder on it than at lower pressures. There's a certain current density, at about 15 A/cm2, where ablation of the glass begins to overtake sputter as the main processs of wear, and then you can calculate the lifetime with pretty good accuracy, but you won't find those kinds of currents in anything but a flashtube (and at that point the lifetime will be extremely short by comparison). As it is, the best you can get for a lifetime is a ballpark range, and you can bet that most catalogs are using the upper end of that range. Zaereth (talk) 22:09, 1 April 2020 (UTC)

Yes, the mentioned catalog gives lifetimes for 3hr and 12hr per start. Older catalogs might only give 3hr numbers. The lifetimes are presumably something like mean, even if it isn't Gaussian. Gah4 (talk) 23:05, 1 April 2020 (UTC)

mercury

The article mentions the mercury emitted by improper disposal. Should we mention the mercury emitted due to the extra power needed, and mercury in coal for coal power plants? Gah4 (talk) 00:29, 1 April 2020 (UTC)

rapid start

There is a {{why}} for the nearby grounded part when starting rapid-start lamps. The requirement for it is often given, but I don't know of any detailed explanation. The one in the article is about the best I have seen. With an AC supply, you will get a small current capacitively coupled through the lamp wall to a nearby ground. That will be enough to ionize a small about of gas near the cathode. That will allow current farther down the lamp. All this is at very low currents, but enough to get things started. Most likely, the lamp will still start, but not as reliably (especially at low temperatures) or as fast, without it. Low temperature starting is important for outdoor lamps. Also, if it starts slow, that defeats the whole idea of rapid-start. Gah4 (talk) 22:47, 29 May 2020 (UTC)

It's basically the same reason you'd wrap a wire around the length of a flashtube to trigger the lamp. Yes, it provides a capacitive coupling. To really understand why, it's necessary to understand the plasma dynamics behind it.

Most lamps would normally strike the arc with a very high-voltage, yet low current signal; basically a spark. This spark bridges the gap, but lacks the current to do much else. The voltage drop between electrodes at this point is greater than the line voltage, so a boost voltage is applied to initiate a mid-voltage glow discharge. As the glow heats up the gas, the resistance drops, until an arc is established and the low line-voltage can take over.

Rapid-start lamps do this a little differently. They pre-heat the cathodes, and continue heating them during operation. This allows the thermionic emission of electrons that characterizes an arc. However, this preheating alone is not enough to cause electrons to be emitted. There still needs to be a potential high enough to get them out of the cathode and on their way to the anode. This potential comes from the ions and the anode, and still requires a voltage high enough to at least sustain a glow discharge. This eliminates the spark and the boost phase of start up, by basically turning the glow into the spark that bridges the gap. Usually a capacitor is used to provide the initial surge of current and provide the necessary potential at each end of the circuit.

When the lamps starts, an initial current is applied to the cathodes, rapidly heating them up. Randomly ionized particles in the vicinity of the cathode then start bombarding its surface. Under cold-cathode conditions this wouldn't be enough to start the lamp (unless the pressure was extremely low, on the order of a few Torr, so that the ions would have sufficient room to accelerate to high enough speeds). However, with the hot cathode, these impacts are enough to begin ejecting electrons from the cathode surface. Most of these electrons don't make it very far, and fall back to the electrode. A few will have sufficient energy to make it out of the pull of the cathode, but they will be dodging ions headed the other way the entire time. Some will combine with those ions, producing whitish continuum-radiation, but many will have near misses, which drag the electrons and slow them down, causing the blue/purplish Bremsstrahlung radiation. When an electron finally makes it out of the glow around the cathode, all of its energy will be pretty much spent. From here, their only motivation is the attraction to the positive side to start them accelerating toward the anode.

The problem is that anode is so far away, and the electrons become stuck in a big pool, or slough, visible as a dark space not far from the cathode. Here, they are spent and don't have much energy to continue on.

At the anode end, however, the anode begins stripping electrons from neutral atoms, which then go rocketing toward the cathode. The problem is getting that charge all the way from the anode down to where the electrons are stuck. The grounded strip along the length of the lamp provides that capacitive coupling that draws the positive charge down the length of the lamp. Suddenly, the electrons have the energy to begin accelerating toward the anode, but at this point they seem to decide that the gas is just in their way, so they divide and go around it, forming an electron sheath around the positively charged gas. This is when the glow discharge is initiated. Nearly all of the current at this point flows around this positively-charged column of gas within this electron sheath. The skin effect of electricity flowing around the gas causes eddy currents within the positive column, which begins to glow with a pinkish light (mostly from ions colliding with atoms (bound-bound transitions, causing spectral-line radiation), although some white light will be produced, coming from areas where ions are able to capture free electrons). These eddy currents create the striations, or the so-called "Faraday cones", in the glow. Nearly all of the glow at this point is strictly from eddy currents, with very little of the positive column actually conducting electricity. Nearly all of the current is flowing invisibly within the sheath surrounding the positive column, making that area electro-negative and protecting the glass from the heat.

At this point, you can call the lamp started. However it's not done yet, and you will likely see the Faraday cones moving across the lamps for up to a few minutes. The glow discharge begins heating up the gas, which causes the resistance to decrease and pressure to build. The hot gas begins heating the mercury, causing it to vaporize, and resistance drops even more as pressure builds even higher. The drop in resistance also causes the voltage to drop, and the glow destabilizes into the arc regime. Then, there is no more differentiating a positive column from a negative one. While the electron sheath still exists, most of the energy is now transmitting through the gas, increasing it to full brightness, while the increase in pressure boosts the efficiency of the discharge. I hope that helps explain. Zaereth (talk) 00:54, 30 May 2020 (UTC)

Sounds good to me, but this is Wikipedia, and you need a W:RS. Also, you mention cathode and anode, but these are switching ends 120 times per second. The ions won't all recombine. Anyway, I suspect that at warmer temperatures they will start, and cold they won't. I suppose I could test one, but that would be WP:OR. Gah4 (talk) 01:50, 30 May 2020 (UTC)

LEDs

There is an edit summary about replacing fluorescent lamps with LEDs. They do make plastic tubes with LEDs the same shape as fluorescent tubes. Some are designed to work with the original balasts, others to be rewired to apply line voltage directly. (And a sticker to warn later users.) I believe for home use, the transition is going pretty fast. I am less sure about industry. Gah4 (talk) 10:51, 13 April 2021 (UTC)

Like you said above, we need sources that say that, otherwise we're just talking from our own pov. From mine, I've seen a big shift in industry, at least locally, but there are problems. So far, LEDs that have a pleasant spectrum and good color rendering are fairly new. Just 10 years ago, most industries I deal with were reluctant just because of the weird, haunted-house lighting effect of older LEDs. That has changed, but the technology is still changing too rapidly, and there is a lack of standardization, so this in itself tends to ward off both consumers and suppliers; nobody wants to stock them because tomorrow they may be obsolete. For he consumer, you either have to change them all at once, to make it look nice, or piece-meal it as they go out with fixtures you may never be able to find again tomorrow, so that's another cost issue to weigh.

These newer replacement tubes certainly are nice, because you can keep your existing fixtures, but often times the cost of new fixture is cheaper, although the ease of changing them makes them attractive over built-in LED fixtures. Lifespan of course is often exaggerated by the manufacturer, although the limiting factor is typically in the drive circuitry rather than the LEDs themselves (quite possibly by design), and there tends to be a lot of bugs they are still trying to work out (as in, there is a lot of inconsistency in reliability). It's always better to go ballast-bypass if at all possible, to eliminate that as a point of failure, but they still haven't been able to fit it all in the T5s. So, in my opinion, while i is a more attractive option, there are still factors that keep many people on both the supply and demand side wary of making the switch. Of course, experiencing that is one thing. Finding it in sources, well, that may take some time and retrospect. Zaereth (talk) 21:22, 13 April 2021 (UTC)

instant start

The article seems to say that instant start single pin lamps are rare since the 1970's. As we have these in our kitchen (installed by the previous owner) and I still buy bulbs for them, I don't think they are so rare. As well as I know, it is only the 8 foot T12 lamps like this one. Common 4 foot lamps are rapid start. There are also some instant start bipin lamps with the two pins shorted together. That might be the HO version. Gah4 (talk) 07:13, 26 August 2021 (UTC)

American names

There seems to be an odd push by one editor to rename everything they perceive to be American, which has been going on slowly for several years now. I don't understand the logic behind this, and in many instances I think the notion is simply a bunch of bologna, such as the idea brought up today that the term "bi-pin" is an American name when in fact it is a very plain description of a tube with two pins at the end. I could call WP:ENGVAR and point out that the article is written in American English, but this seems to go beyond that... for some reason I have not figured out. The logic behind these changes alludes me.

This reminds me of a similar problem over at the Viking article, where a user was continually trying to change the meaning of the word to match what it supposedly meant a thousand years ago, claiming that the English word should match how it's used in all other countries. (Ironically, the word is used in his homeland of Sweden much the same as in English, and the same discussion can be found on their Viking article as in the talk pages of our own.)

As with that article, I fail to see the logic behind most of these changes, nor am I inclined to believe they are in fact words that are strictly American names, but rather words and names that are found in reliable sources. Rather than edit war, I decided to bring it here for discussion so others can chime in. Zaereth (talk) 03:36, 23 September 2022 (UTC)

I am not sure about the American part, but it seems that G13 is the term for 13mm pin spacing. (I suspect 0.5in rounded.) Since T5 uses bipin with a different spacing, but (as far as I know) T8 and T12 both use 13mm, it could be useful to indicate it. Should we use both terms? Or mention bipin 13mm spacing? Gah4 (talk) 03:51, 23 September 2022 (UTC)

Seems too detailed. The purpose of the second pin is to provide heating for the filament, which distinguishes it from single pin or "instant start" lamps. and there are many sizes of bi-pin lamps. The problem is not limited to this one edit, however, For example, this, or this one, which I found particularly amusing since the picture and info were both uploaded by a Russian. There is a lot more in the history. I'm hoping I can get some idea behind the logic of such edits, because perhaps there is something I'm missing. Zaereth (talk) 04:04, 23 September 2022 (UTC)

No comment on the others either way. I suspect giving 13mm spacing seems better than G13, though, and I don't think it is too detailed. Gah4 (talk) 05:57, 23 September 2022 (UTC)

Mercury dosing solutions used in Fluorescent Lamps

This is very important: https://www.researchgate.net/publication/230988669_Mercury_dosing_solutions_for_fluorescent_lamps

I had this pellet in my UV-C lamp and was very confused and tought it would be a manufacutring error. It was very very difficult to find anything about these little pellets. I would be glad, if someone with knowlege in this field would add a section either here or in the UV-C lamp page: https://en.wikipedia.org/wiki/Germicidal_lamp 2A03:7AE0:0:2001:0:0:1:E6 (talk) 08:23, 25 October 2023 (UTC)

Yes, that's actually common, even with the oldest dosing technique of simply adding a liquid drop before vacuuming. In some of the old 8' lamps the drop was large enough to give a good thud when tipped from end to end, but only when new. The first time it's used the mercury vaporizes and doesn't coalesce back into a drop when you turn it off. I'm not familiar with these other techniques. However, an encyclopedia is not a how-to manual, and you'll notice we don't have very much at all about how they're made. It wouldn't hurt to expand the construction section a little, and maybe summarizing this into a sentence or two, but I couldn't see adding an entire section about it. Zaereth (talk) 22:17, 25 October 2023 (UTC)