Talk:Fluorescent lamp

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Archived discussions[edit]

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)

Mercury. Again.[edit]

A sense of proportion, please. I've seen many broken light bulbs in my day, and I'm going to die, too, but not from mercury. In a world where you can't buy BPA water bottles any more because lab rats get bumps on them, surely the all-seeing nanny state would have banned the killer light bulbs by now? What, specifically, are these lethal compounds in a light bulb? Sure, dimethyl mercury is deadly in tiny quantities, but that doesn't come from light bulbs. That poor woman had 16 milligrams of mercury circulating in her blood, months after exposure...what was left in her blood stream was the equivalent of injecting the mercury content of three bulbs. Corrected after reading [1]. Estimated absorbed dose at the time of the accident was 1344 milligrams of mercury, equivalent to many bulbs. --Wtshymanski (talk) 16:09, 24 February 2011 (UTC)

Addition of Fluorescent versus Neon section[edit]

I know this section doesn't have references but I think it is fairly accurate. It should help people understand the difference, since the two lamp types are very similar. WWriter (talk) 22:26, 28 March 2011 (UTC)

Ballast loss[edit]

The article appears to assign a single percentage for ballast loss (if I read it correctly). Isn’t there a large ballast loss associated with generating the initial striking voltage? In other words, turning on the lamp for only a minute might lead to a larger ballast loss percentage compared to keeping the lamp on for an hour. Should this be in the article?

Psalm 119:105 (talk) 10:55, 1 May 2011 (UTC)

What is your concern here? It takes a fraction of a second to start - I expect the reason no-one tabulates energy lost during startup is that it's a negligable part of the operating life of a lamp. Most of the time, it's running, not starting - so starting losses of a ballast don't consume a lot of energy, at least compared to running loss. --Wtshymanski (talk) 14:53, 1 May 2011 (UTC)
I was under the impression that the amount of energy required to generate the striking voltage was much higher. However, I did a little research and the web site indicates that the initial ballast energy is only equivalent to that needed to operate the lamp for about 5 seconds. Never mind... Psalm 119:105 (talk) 23:24, 2 May 2011 (UTC)

Amperage, not Voltage?[edit]

As I was reading through the Starting section, I was seeing a lot of the use of the word "voltage" especially with reference to the bi-metallic strips found in the starters. I'm no electrician, but I have worked quite a bit with electricity and as far as I've understood the issue, it's not the voltage that heats the bi-metal, it's the amperage (the current) based on the resistance value (ohms) of the metal.

As I've come to learn, amperage is what really effects a load. With electric motors, the movement of the load is engaged by the high amperage, not the voltage. If you clamp an ammeter to the leg of power coming into the motor, at start-up you'll see a huge amp draw of approximately 5 times the normal running amp draw. This difference in amperage is called LRA (locked rotor amps) versus normal running amps, or RLA / FLA (run load amps / full load amps, both the same thing just different abbreviations). Voltage, although important, isn't the driving force of the motor. It's the start-up amperage. This, as far as I knew, dealt with heat motors (bi-metal motors) as well.

It's rather hard for me to believe that it takes thousands of volts to move a bi-metal strip when it would only take a few amps to move it. Additionally, I didn't think it was possible to get that many volts out of the power company without lowering the amount of amps by the hundreds. My understanding comes from Ohm's Law (E over I R).

Can anyone verify this one way or another? — Preceding unsigned comment added by JoeP1983 (talkcontribs) 01:57, 18 July 2011 (UTC)

Bi-metallic strips move due to heating and cooling, not necessarily due to either voltage or current. The only mention of “thousands of volts” that I can find is the “thousand volts” required to strike an arc in the main fluoro tube. According to the article, the starter and its bi-metallic electrode is part of the circuit to generate that voltage. The “thousand volts” is not available until the bi-metallic electrode has already heated up, connected, cooled down, and disconnected from the opposite electrode in the starter. Hope this helps; but what bits needs clarifying in the article? Vadmium (talk) 05:18, 18 July 2011 (UTC).
As the article clearly describes, it is not the current through the bi-metal strip which causes the heating, but the arc in the surrounding gas. Without the high voltage, the arc will not start in the first place. To put it another way, there is no path for current to flow through the bi-metal strip until the contacts have closed.Gutta Percha (talk) 09:01, 7 July 2012 (UTC)

Absolutely, bi-metallic strips move according to heating and cooling. They expand and contract based on the heat gain or heat loss to the strip. But what causes the heat? The heat is generated when the current moving through the metal encounters resistance. It's the same as heating elements. The voltage does the arching, but the arching wouldn't be possible without the strip first moving into place, expansion due to heat caused by the current, aka amperage. So I think the clarification needs to be made that the amperage, or current, causes the metal to heat and expand, thereby moving the element within range to allow for arching, the passing of power. Hope that's clear enough. — Preceding unsigned comment added by JoeP1983 (talkcontribs) 00:36, 5 September 2011 (UTC)

My understanding by reading Fluorescent lamp#Switchstart or preheat is the heat is generated by the glow discharge in the starter. Presumably the the bi-metallic electrode has low resistance (being metallic) and causes little heating directly. Provided there is enough voltage, the glow discharge in the starter occurs immediately, when the bi-metallic electrode is in its cooled position, furthest from the opposite electrode. Is it perhaps that the article is not clearly distinguishing the starter tube, using glow discharge, from the main fluorescent tube, an arc lamp using arc discharge? Vadmium (talk) 06:19, 5 September 2011 (UTC).

I think the problem is first distinguishing, at least in our minds, the difference between current and voltage. Voltage is electric potential while current, or amperage, is the actual work horse of an electric charge. You can have voltage with nearly no amperage. But without amperage, motors won't run, electric fields can't be generated, and heat doesn't exist.

The idea behind bimetallic strips is that it's a multi-layer coupling of metals. Two metals are connected together, flush, and attached at their tips. Because different metals expand and contract at different rates, this is what causes the movement in a bimetallic strip. One side of the strip will expand quicker than the other side, moving the piece of metal from one direction to another when heated. The heat is generated because of the resistance of the metals, each metal heating at a different rate based on their individual ohm ratings, or resistance. The higher the current, or amperage, the faster the circuit or metals will heat.

Most electricians know that with low voltage, amperage starts to jump because resistance in any given circuit will remain constant. The formula is Amperage = Voltage / Ohms. Ohm's Law. If you keep resistance, ohms, constant and decrease voltage, your amperage will increase. This is what burns out circuits and causes brown outs and black outs. When too many people are using appliances and spreading the electric potential (voltage) out over a greater amount of area, such as in the heat of summer, your voltage will decrease and you start to experience brown outs/black outs because the amperage is jumping, heating the circuit and throwing breakers. That's why resisters are used in most circuitry. If they weren't there, then the entire circuit would burn up from the excessive amperage. But amperage isn't all bad in the right situation. This is the idea used to heat bimetallic strips. They allow a greater amount of current, amperage, to flow to the strips in order to heat them. Moving them and allowing them to become an automatic switch as long as amperage is present.

Hopefully that makes sense. — Preceding unsigned comment added by JoeP1983 (talkcontribs) 06:56, 11 September 2011 (UTC)

Electric power is proportional to both voltage and current (have a read of Electric power or Joule's laws). Also, current and voltage are proportional for a constant resistance (read Ohm's law). But even without that knowledge, if there’s a specific bit of this article that is misleading or confusing, then we should fix it. Vadmium (talk) 08:53, 11 September 2011 (UTC).

Here's an introduction of the "improved" me.[edit]

Hello again, everyone. I have changed the way I socialize despite my autism now. First of all, I would like to apologize to Wtshymanski for the conflict two months ago thanks to advice I had received a week later and me deciding to give you a little break. Secondly, many thanks to whoever cited the Hg Law in the USA. Thirdly, I would like to create some new sections to the article due to some new facts I have learned about Fluorescent Lamps. There is some facts about HPF, VHO, LPF etc. that should ideally be written on the "Rapid Start" section. There are some phaseouts going on for the less efficient tubes and control gear in North America and here in Europe. ELIOT2000 and I would like to write about the European Union legislation phaseouts (like the banning of Halophosphate T8's) but other Europeans may also do so. I would also like the North American Wikipedians (including Wtshymanski) to write about the North American phaseouts (like the apparent banning of Magnetic Rapid Start F40T12's?). The section "Instant Start" should ideally mention about connecting the electrodes in parallel (unless untrue). I would also like to write about "Warm Start" which is the most modern form of starting a hot cathode tube. Fourthly, in the light turning pink section, I'd like to mention about technology to prevent this (like Argon and Krypton) but please politely correct me (but don't just remove) if I'm wrong. All of you can feel free to correct any false text but please do not remove any that are true or just delete too much text without permission (a bit like in the conflict two months ago) as you will avoid being reported for vandalism by not doing so. I won't edit just yet, I need permission first to prevent conflict. Autisexp235 (talk) 23:24, 13 August 2011 (UTC)

Proposed opening edit[edit]

Present version says, “A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light.” Is it necessary or correct to say it is a mercury vapor discharge excitation? A white LED that uses a fluorescent phosphor to convert blue emissions into "white" light should also be called a fluorescent lamp as it employs fluorescent conversion. Why not say instead, "A fluorescent lamp is any light source that employs fluorescent conversion of a primary emission into a different spectral region. Typically this means a mercury vapor discharge lamp with a phosphor to convert the UV to the visible range. A white LED is an example of a fluorescent lamp that uses a solid state emission source and a phosphor to produce white light." Paleotechman (talk) 20:53, 1 October 2011 (UTC)

Well, the world seems to be happy calling the mercury-vapor variety a "fluorescent lamp" and the LED variety a "LED lamp" - Wikipedia follows usage, not sets it. I wouldn't recommend this change. Besides, some white LED lamps don't use a phosphor. --Wtshymanski (talk) 22:46, 1 October 2011 (UTC)

Color temperature, Kruithof curve[edit]

I have changed "natural" into "pleasant" and "comfortable" for low CCTs. For 5000 K I left it since high-lux daylight color looks both pleasant and natural. But the statement that only 2700 K looks natural (or even neutral) at low light levels is simply wrong. To me, 2700 incandescent or fluorescent light looks orange-yellowish even at low levels, and many others too. At low light levels, the neutral white (i.e. no apparent color hue) is about 4000 K while being about 6000 K at high (daylight) intensities. Furthermore, the Moon has a CCT of about 4100 K (probably due to its slightly brown surface color), and moonlight does not look unnatural, but unpleasant to many people if it is the only light source. If there are sources which state a natural/neutral color appearance for light CCT below 3000 K at low light levels, please cite them. I am only referring to the Kruithof curve article.--SiriusB (talk) 10:39, 8 November 2011 (UTC)

Tube pressure contradiction?[edit]

The Construction section of the article says the pressure in a fluorescent tube is 0.3% of atmospheric pressure, while the footnote referred to at the end of the sentence says it is 8 Pa or 0.0008% of atmospheric pressure. Which is right? --ChetvornoTALK 08:18, 17 November 2011 (UTC)

Total pressure in the lamp, compared to vapor pressure of the mercury alone. --Wtshymanski (talk) 15:04, 17 November 2011 (UTC)
Thanks, I missed that. --ChetvornoTALK 21:14, 17 November 2011 (UTC)

Fluorescent Lamp starting with heat/steam from stove[edit]

After perusing technical information about Fluorescent lamps, it seems that temperature conditions has something to do with starting the light when the electrical current does not work. My kettle of water for tea starts my bulb over the stove, so my question is whether it is the steam or the heat that causes it to ignite or glow. I am looking for an explanation in layman's terms. Joan in Roswell — Preceding unsigned comment added by (talk) 15:53, 20 January 2012 (UTC)

That's really more a question for the Help Desk; what I understand of your description is at odds with what I understand of the operation of a lamp. --Wtshymanski (talk) 22:44, 31 January 2012 (UTC)


The books say "Efficacy". What we want in lighting is efficacy, not efficiency; an incandescent light bulb is better than 90% efficient at turning electric power into electromagnetic radiation, but we can only *see* a small part of that radiation. Notice the units of efficacy - lumens per watt. Efficiency is dimensionless, a percentage. --Wtshymanski (talk) 22:41, 31 January 2012 (UTC)

There is also the term "luminous efficiency" that only considers visible power output. The luminous efficacy article also uses luminous efficiency. In some contexts, referring to a luminous efficiency can be more approachable because it shows how close to perfect the conversion is. Glrx (talk) 23:21, 7 February 2012 (UTC)

Efficiency Vs Efficacy[edit]

I just noticed that I edited the page for (mis)using the word efficacy instead of the (correct) word efficiency, and that in the process I have unknowingly stumbled into an edit/undo cycle of two people I don't know. So, to explain why I committed the edit...

According to Merriam Webster - Efficacy is a noun meaning the power to produce an effect. They trace the 13th century origin of the word efficacy to efficacious.

According to Merriam Webster - Efficiency is a noun meaning the quality or degree of being efficient. They say the word efficiency was first used in 1633.

Efficacy is is the correct word when discussing whether or not something has a particular effect or does not have that effect.

Efficacy is is the correct word when discussing the relative cost to produce a particular effect.

The source of this Wikipedia "efficacy" vs "efficiency" discourse may be a beaureaucratic decision to name a mandatory performance standard metric for fluorescant ballasts in a revised USA regulatory standard "ballast efficacy". The record suggests that the name was chosen to suggest "efficiency", the regulatory purpose of the rule, although it didn't measure it. (Ballast efficacy is calculated as [(ballast factor × 100) ÷ system watts], where ballast factor is the lamp specifc ratio of the light output of a lamp with a given ballast vs a reference ballast and ignores the power consumption ratio.)

Lastly, to the prior comment and efficiency as dimensionless etc., as a Ph.D. E.E. I have a very clear understanding of efficiency, and there is no reason to only use efficiency as a description of dimensionless ratios. However, it also notable that that in this case both measured quantities are electro-magnetic power and this in fact a dimsionless power ratio multiplied by a unit conversion. — Preceding unsigned comment added by PolychromePlatypus (talkcontribs) 23:36, 31 January 2012 (UTC) --PolychromePlatypus 23:26, 31 January 2012 (UTC)PolychromePlatpus — Preceding unsigned comment added by PolychromePlatypus (talkcontribs)

As Dean of MIT, president and CEO of ABB, owner of General Electric, and a Nobel Prize Winner in Electrical Engineering, you are doubtless also aware that we buy light bulbs to make light, not to make "electro-magnetic power". A watt of green light makes more lumens than a watt of red light. A watt of infrared is useless for illumination. Careful people writing about light sources say "efficacy" when they mean "efficacy", and "efficiency" when they mean "efficiency", and Wikipedia should strive to maintain the distinction where it matters. --Wtshymanski (talk) 21:10, 3 February 2012 (UTC)


The GE fluorescent lamp handbook and other handbooks I've read say that the capacitor in a ballast is for power factor correction. The discussion of different starting methods is out of place and confused. Agapito Flores has nothing to do with the lamps. The discussion of cold cathode lamps is out of place and redundant. A DC ballast must either be an electronic ballast or else must be a resistor - an inductive ballast won't work with DC. The references say the polarity must be reversed on DC to keep the distribution of mercury even in the tube; if there's a reference saying this is to balance erosion of the cathodes, please cite it. Not all the mercury in an operating tube is gaseous - some condenses on the tube wall at the coldest spot and this is a critical mechanism in regulating mercury partial pressure in the tube. --Wtshymanski (talk) 23:31, 8 March 2012 (UTC)

It happens to be the case. Running a tube from a single polarity of DC gives uneven wear on the coated filaments. It is not to do with distribution of the mercury (and this would be the same problem in an AC operated tube - if it was a problem). Thus fluorescent fittings designed for running from a DC supply had to have provision for reversing the polarity of the supply to the tube every time the lamp was switched on. The way it would be done today, of course, is to invert the DC into AC. Unfortunately, as the technique is no longer relevant, references are difficult to impossible to find. I have a very old electrical text book where I had hoped to find it discussed, but sadly it seems to predate the fluorescent light. It was published in 1920. (talk) 09:21, 28 April 2012 (UTC)
It's too bad Messrs. Kane and Sell didn't mention this in their book; they only discuss mercury distribution as the problem in DC lamps. It's also too bad that all the old books on DC lamps were burned in 1987, else we could find references. --Wtshymanski (talk) 13:11, 28 April 2012 (UTC)
Why would they have burned the books in 1987? DC distribution and DC fluorescent lighting was in use in London, England as late as the 1990's. The whole Fleet Street newspaper empire ran from 200 volts DC until its major relocation in that decade. Power was generated in Bankside power station, just across the river, The reason was largely down to the power and clout of the printworkers' union who insisted that all newspapers had to be printed using 1920's hot metal type machines. These ran from 200 volts DC as this was the supply available in that part of London at the time. The reason was that they were not prepared to accept the reduction in manpower that would result from adopting desktop publishing systems.
Your tongue in cheek comment aside, there probably are references available somewhere, but few people bother hanging onto old out of date reference books which makes good references hard to find (I seem to be an exception because I have a modest collection of old reference material). It would be nice if someone did find a reference, because this is the sort of material that should be in article. (talk) 15:59, 28 April 2012 (UTC)
See Fahrenheit 451 . Without references, we can't put it in here. --Wtshymanski (talk) 15:35, 30 April 2012 (UTC)
Where exactly did I suggest otherwise? (talk) 15:39, 30 April 2012 (UTC)
Interesting aside on Bankside. I thought DC had disappeared in the 1950s.
I've just checked Cayless; Marsden (1983) [1966]. Lamps and Lighting (3rd ed.).  and there's no mention in that either. I too have a bit of a gap in my books between 1920 and this. Andy Dingley (talk) 16:20, 30 April 2012 (UTC)
It's quite true. The DC power station had to be maintained to drive the antiquated equipment in Fleet Street. It was why the station was so close to the city of London (DC doesn't travel very well). The electric co. could have installed rectifiers, but I suppose they were ever hopeful that the newspaper boses would one day beat the unions. They did, or rather Rupert Murdock did. Once the newspapers moved to the docklands area, Bankside was immediately decommissioned - the last DC power station in Britain - can't speak for the rest of the world. (talk) 13:38, 1 May 2012 (UTC)

Electronic Ballasts copyedit?[edit]

"inductance" in the first sentence. Should that be inductor? bondolo (talk) 00:34, 16 May 2012 (UTC)

Think you actually mean #Electronic ballasts, second sentence. Probably could be inductor if that helps. Technically inductance is correct also I think, though maybe it sounds a bit smart-arse. Vadmium (talk, contribs) 05:28, 16 May 2012 (UTC).

Switchstart or preheat[edit]

I have removed the phrase "Electronic starters contain a series of capacitors that are capable of producing a high voltage pulse of electricity across the lamp to ensure that it strikes correctly" because it is meaningless, factually incorrect, and at odds with the more detailed explanation below. Gutta Percha (talk) 08:51, 7 July 2012 (UTC)


I think you should include the approximate lifespan of a fluorescent lamp in hours. --Kizar (talk) 00:38, 7 January 2013 (UTC)

Outdated info[edit]

I noticed that pros/cons and life specs were based on mid 20th century materials. I tagged them as update needed. I will work on finding more recent references when I have time. Cantaloupe2 (talk) 19:57, 27 March 2013 (UTC)

Why is the inventor never mentioned?[edit]

Why is the inventor, Agapito Flores, who Filipino scientist that created the Flores-cent lamp not mentioned once in the article?Presidentbalut (talk) 14:33, 29 August 2013 (UTC)

If you could provide some reliable sources, that would be very helpful.
I've never heard of him before. being curious, I just did a pretty thorough search of google books to see what I could dig up. Most mentions are nearly identical stories which give very little in the way of detailed information, but rather have the sense of story being "handed down through the grapevine." All of these accounts come from books which are completely unrelated to either science, inventors, or the lighting industry (ie: children's books and books on literature, etc...) The one book I could find which bears some relevance is Inventions and Innovations By Virgilio L. Malang. On page xiv, he gives the following statement: "By the way, before you miss the fluorescent lamp by the persistent folk creative Agapito Flores, I must apologize for my inability to locate any verifiable information about said invention and inventor. From where I stand, both appear to be simply myths." Zaereth (talk) 18:30, 29 August 2013 (UTC)
its hard to find because the white people cover it up on places like wikipedia. but any1 who is edcated knows this Presidentbalut (talk) 13:11, 18 October 2013 (UTC)
Do you have any reliable sources which report such a cover-up? By the way, what makes you think that any of us are white? Virgilio L. Malang is definitely Filipino, and his book, Inventions and innovations: A Glimpse of the Filipino Legacy is completely dedicated to Filipino inventions. Dr. Malang appears to have done thorough research for his book. If he can't find reliable sources, what makes you think anyone else can? Zaereth (talk) 16:25, 18 October 2013 (UTC)

Why does the article not mention this was invented in the Philippines?[edit]

The florescent lamp was invented in the Philippines by Doctor Flores. Hence the name "Flores-cent". Why is this vital information not mentioned here??? Presidentbalut (talk) 13:09, 18 October 2013 (UTC)

Because WP:V policy forbids it. DMacks (talk) 13:16, 18 October 2013 (UTC)
The term "fluorescence" was coined in 1852 by Sir George Stokes, as a combination of the ancient Greek word, "fluorspar" and "opalescence," in reference to the afterglow produced by some substances. The fluorescent lamps uses such fluorescence, and hence the name, "fluorescent lamp." The powder that coats the inside of the glass is the fluorescent substance, and the term quite literally translates as: The essence of fluorspar. Zaereth (talk) 16:32, 18 October 2013 (UTC)