Talk:Halogen lamp

Controversy?
I've seen references to the fact that halogen lamps aren't very efficient. For example: "But like most conventional forms of domestic lighting, halogen spot lamps are terribly inefficient and use far more power than is necessary since nearly all the energy is wasted as heat, which brings with it the further problem that they run incredibly hot and often require fire-rated covers. They also don’t last that well with bulb replacement required after about 2,000 hours of use." http://www.kulekat.com/led-home-lighting/replacing-12v-halogen-lamps.html

I think it would be useful for someone knowledgeable to discuss this controversy on the page and also clarify the distinction between "efficacy" (as used here) and efficiency, the more generally known engineering term. Is this a US/UK thing, or is a looser sense intended? 96.237.170.55 (talk) 04:01, 2 July 2009 (UTC)
 * All electric lamps - even compact fluorescent, even LEDs - make more heat than light. 2000 hours is a long time for an incandescent lamp and quite standard. "Efficacy" is a perfectly standard bit of jargon when talking about lighting; it's a combination of "how much of the radiation produced by the lamp is visible light" and "how efficient is the lamp at turning wall-plug power into electromagnetic radiation". By definition, for green light at 555 nanometres, the first factor can be no higher than 683 lumens of visible light per watt of electromagentic energy radiated. White light has a much lower lumens/watt efficacy, since the human eye isn't equally sensitive at all visible light wavelengths. Depending on how you define "white" light, the best a white light source can do is around 275 lumens/watt. See luminous efficacy for more.
 * Even a poor fluorescent lamp makes more visible lumens per watt input than the best halogens, but fluorescent lamps aren't the best solution to every lighting problem. --Wtshymanski (talk) 21:14, 28 October 2009 (UTC)


 * Yes, but now ordinary incandescent bulbs are not available in the US (and some other countries) as being too inefficient. Halogen lamps are enough more efficient, and can be used in some places where people might not want fluorescent or LED lamps. Should we add this to the article? Gah4 (talk) 04:29, 8 June 2017 (UTC)
 * I think it is nesessary, but source is needed. Cathry (talk) 07:29, 8 June 2017 (UTC)


 * Some is in: though as with all US government regulations, they could change at any time.  As far as I can tell, halogen lamps have until 2020, when the next level of restriction goes into effect. Gah4 (talk) 08:08, 8 June 2017 (UTC)
 * It is difficult to me to judge whether this source is reliable. Cathry (talk) 08:27, 8 June 2017 (UTC)

Questions
1. If a lamp is referred to as "halogen burner" does that mean it is incandescent or metal halide?

2. What's the temperature range of the filament? Of glass? Quartz?

See reference 1 in the article, which contains a much better description of halogen lamp operation than the entry, and some answers to your questions. (Redcliffe92 (talk) 14:55, 10 March 2008 (UTC))

3. How does a halogen lamp die? —Preceding unsigned comment added by 91.156.21.32 (talk) 21:10, 6 November 2009 (UTC)


 * Halogen lamps are souped-up incandescent lamps. They burn out like other incandescents, the filement "burns out" or evaporates at one point, breaking the filament and the circuit.  OsamaBinLogin (talk) 22:59, 25 November 2023 (UTC)

New
I am unhappy about this Article, which has some inaccuracies, is not very comprehensive and has limited references (ref 2 seems unobtainable) I propose to offer the revision below, retaining the sections headed "Safety" and "Handling Precautions". I am unsure about "Halogen Spectra" as the picture is too indistinct to be readable. The spectra will be fairly similar to a black body at the filament colour temperature.

Any comments would be appreciated. (Redcliffe92 (talk) 15:45, 15 March 2008 (UTC))

PROPOSED REVISION Introduction A halogen lamp is an incandescent lamp wherein a tungsten filament is sealed into a compact transparent envelope filled with an inert gas, which may be argon, nitrogen, krypton or xenon or a mixture, plus a small amount of halogen such as iodine or bromine. The bulb stays clean throughout life. The halogen lamp can operate its filament at a higher temperature than in a standard gas filled lamp of similar wattage without loss of operating life. This gives it a higher efficacy (10-30%). It also gives light of a higher colour temperature (whiter). Alternatively it may be designed to have perhaps twice the life with the same or slightly higher efficacy. Because of their smaller size halogen lamps can advantageously be used with optical systems that are more efficient.

Principle of operation  The function of the halogen is to set up a reversible chemical reaction with the tungsten  evaporating from the filament. . In ordinary incandescent lamps this tungsten is deposited on the bulb. The halogen cycle keeps the bulb clean and the light output remains almost constant throughout life. At moderate temperatures the halogen reacts with the evaporating tungsten, the halide formed being moved around in the inert gas filling. At some time it will reach higher temperature regions, where it dissociates, releasing tungsten and freeing the halogen to repeat the process. In order for the reaction to operate, the bulb temperature, all over, must be higher than in conventional incandescent lamps, necessitating the use of fused silica (quartz) or a high melting point glass (such as aluminosilicate). Quartz being very strong, the gas pressure can be higher, which reduces the rate of evaporation of the filament, permitting it to run a higher temperature (and so efficacy) for the same average life. The tungsten released in hotter regions does not generally deposit on the hotter parts of the filament where failure will eventually take place. Regeneration of the filament is possible with fluorine, but its chemical activity is so great that other parts of the lamp are attacked. .

The first commercial lamps used elemental iodine, and were known as known as Quartz Iodine Lamps, launched by GE in 1959. Later bromine was found to have advantages, but was not used in elemental form., Certain carbon hydrogen bromine compounds  give good results. .  The first lamps used only tungsten for filament supports, but in some designs it has been possible to use molybdenum - an example being the molybdenum shield in the H4 twin filament headlight for the  European Asymmetric Passing Beam.

High temperature filaments emit some energy in the UV region, and doped quartz or optical coatings can be used to block most of the UV, if this is harmful - where people or sensitive material are directly exposed to the lamps. Hard glass blocks UV and has been used extensively for the bulbs of car headlights. Alternatively the halogen lamp can be mounted inside an outer bulb, similar to an ordinary incandescent lamp, which also reduces the risks from the high bulb temperature. Undoped quartz halogen lamps are used in some scientific, medical and dental instruments as a UV-B source.

For a fixed wattage and life, the efficacy of all incandescent lamps increases for lower supply voltages Halogen lamps made for 12 to 24 Volt operation have good light outputs, and the very compact filaments, possible because the voltages gradients are low, are particularly beneficial for optical control. The range of MR16  (50 mm diameter) reflector lamps of 20W to 50W were originally conceived for the projection of 8 mm film, but are now widely used for display lighting and in the home. More recently the wider beam versions are available designed for direct use on supply voltages of 120 or 230V.

The MR16 series uses a multilayer heat transmitting, light reflecting film on the reflector. The idea of putting a light transmitting, heat reflecting film on the bulb has been the subject of research for many years. Lamps are now available using this IRC (Infra- red Reflective Coating) which are generally described as "energy saving" since they offer similar performance for about 30% lower wattage consumption. .

Voltage, Light Output and Lifetime Tungsten halogen lamps behave in a similar manor to Incandescent Lamps, but the light output is reported as proportional to voltage to the power 3 and the efficacy proportional to the power 1.3  The normal relationship regarding life is that it is proportional to voltage to the -14. Halogen lamps are manufactured with a halogen dose to match the rate of tungsten evaporation at their design voltage. Increasing the applied voltage increases the rate of evaporation, so at some point there may be insufficient halogen and the lamp goes black, so over-volting is not generally recommended.. With a reduced voltage the evaporation is lower and there may be too much halogen, which can lead to abnormal failure. At very much lower voltages the bulb temperature may be too low to support the halogen cycle, but by this time the evaporation rate is too low for the bulb to blacken significantly. There are many situations where halogen lamps are dimmed successfully, but whether the very extended lives predicted by the formula are achieved is doubtful, and is in any case dependent on the lamp construction, the halogen additive used and whether dimming is normally expected for this type.

bulb picture
Please provide a better caption for the bulb picture as the proposed caption is not English and does not explain the relevance of the picture to the article. What does "Halogen lamp Replace of incandescent light bulbs Europ < 2009" mean? --Wtshymanski (talk) 15:30, 25 May 2009 (UTC)
 * Now the mystery bulb has gone from 42 watts to 105 watts. *What* is the bulb in the picture, and *why* is it in the article? I've changed the caption again, but I don't know what it is and can't figure out its relevance from the image page. Whoever originally wanted this picture in the article should explain its relevance. --Wtshymanski (talk) 13:48, 27 May 2009 (UTC)

Spectrum
The spectrum picture is not very useful - it doesn't show most of the visible light portion of the spectrum, which is the whole point of a lamp. I'm taking it out till we can find a good line drawing halogen spectrum. --Wtshymanski (talk) 14:33, 11 November 2009 (UTC)
 * I suppose, but since fused silica is transparent somewhat in the UV, and also pretty far into the IR, the spectrum out of the visible is sometimes important. In the IR as the lamps are sometimes used as a (radiant) heat source. In the UV for UV safety reasons. Gah4 (talk) 08:52, 5 June 2021 (UTC)
 * I suppose, but since fused silica is transparent somewhat in the UV, and also pretty far into the IR, the spectrum out of the visible is sometimes important. In the IR as the lamps are sometimes used as a (radiant) heat source. In the UV for UV safety reasons. Gah4 (talk) 08:52, 5 June 2021 (UTC)

Applications: Portable Convection Oven
I just bought one of these and wanted to read up on the science behind it. I was surprised there was no mention of this application of halogen lamps.Janko (talk) 15:48, 21 December 2009 (UTC)

Issues
1. Halogens are low efficacy/efficiency compared to CFLs & many LEDs. A lot of people don't realise this.

2. Halogens are widely used in downlighters, which are very energy inefficient. Its easy for a room that took a 100w incandescent to need 10x 50w = 500w of halogen downlighting to achieve enough light

3. Rubbing alcohol was mentioned to clean the lamps: this is alcohol with added oil, is that not surely the wrong stuff to use? Meths would be more appropriate.

4. Lowish power mains halogens (50w and below on 240v) have much poorer efficacy or life compared to LV ones. They're also very vibration sensitive, and many premature failures occur.

5. Downlighter clusters also suffer high lamp failure rates. 10 lamps of 1500hrs eash will need 10 new lamps per 1500hrs, or on average 150hr relamping interval. 82.31.207.100 (talk) 09:16, 15 February 2010 (UTC)
 * Cite it and write it. Looks like valid points, but do you have a citation? --Wtshymanski (talk) 14:47, 15 February 2010 (UTC)

Yes, but ...
... what TEMPERATURE do they typically run at? That being the precise question I came to this article to look up :-) - David Gerard (talk) 19:25, 11 February 2011 (UTC)

Fair question. I'll do some updating sometime. Vacuum lamps run from perhaps 1500C to 2200C depending on who's talking and on the purpose of the lamp. Halogen lamps From perhaps 2200 C to 3100C. Also depending on function. YMMV. JonRichfield (talk) 20:30, 8 August 2011 (UTC)
 * Is this answerable? Wattage, enclosure / cooling, and many other factors play into this. Where I work I run everything from 35W MR11 lamps to 750W HPL's. I know they don't get equally toasty... LightRobb (talk) 22:03, 18 April 2012 (UTC)
 * Ummm... I read the question as referring to the filament temperature, which is what determines the kind of illumination. In what I regard as the unlikely event that David meant the temperature of the entire unit, could he please repeat his question in more specific detail?

JonRichfield (talk) 12:29, 19 April 2012 (UTC)


 * I believe that 3200K or so is usual. I found that in another page before this one. That is important for some, as it sets the color temperature of the lamp for photographic use. There are 3200K photoflood lamps which have a much shorter lifetime than halogen lamps. Gah4 (talk) 04:21, 8 June 2017 (UTC)
 * my guess is more than 3200K, more like 5500K daylight. That's the whole purpose of having an ultra-hot filament.  The spectrum spreads out in both directions, so you need the UV filter.  Blackbody radiation.  So then you need the halogen cycle as the article says, so the filament rejuvenates and doesn't burn out so quickly.
 * Normal incandescents are cooler, about 3200K, so the filament doesn't burn out so quickly. And, so they don't generate much UV.  Then, color camera film had to come in two kinds: daylight and incandescent light.
 * My dad told me that the outside of a tungsten lamp is so hot, that if you handle it with your fingers, you'll leave fingerprints, they'll get hot and break the glass. Dunno, that's what he said. OsamaBinLogin (talk) 23:14, 25 November 2023 (UTC)

Request for citation
I note my request for a citation was removed without providing a citation, in a series of edits by a single user. The paragraph in which the request was made is unchanged from when I made the request. I have reinstated my request, and am now supporting the template request with more specific details of what I am requesting and how it may be satisfied.

I am requesting a citation from a reliable source allowing verification of the statement:
 * "When this is done correctly, a halogen lamp with UV inhibitors will produce less UV than its standard incandescent counterpart".

The citation should be placed in the article just after the statement, and the cited source should specifically verify the claim made by the above statement – that halogen lamps with UV inhibitors can produce less UV than a standard light bulb if done well – per WP:CHALLENGE. Regrettably this is not a field in which I am expert and my own search for a suitable reference has failed thus far. As the consequences of leaving this statement in the article for a while appear to be mild in all regards, I am content to give a reasonable time for verifiability to be established.

--MegaSloth (talk) 23:46, 16 December 2011 (UTC)
 * In the finest traditions of Wikipedia - "7 is bigger than 3", "Citation needed" and the tag will stay there till the end of time. --Wtshymanski (talk) 04:41, 17 December 2011 (UTC)

Purple flash?
Earlier today the article included: "It is possible to determine whether a particular lamp uses bromine or iodine without breaking the glass envelope. If the current through the lamp is slowly increased from zero to a point just before the lamp starts to emit visible light, there is a short current range where iodine makes itself visible by turning purple. Bromine has no such effect."

Where is this documented? I haven't read everything there is on halogen lamps, but surely this would be noted in several places? I've taken it out. --Wtshymanski (talk) 14:26, 20 March 2012 (UTC)

There isn't that much Iodine in the bulbs for that to happen. Both Iodine (readily sublimes at RTP) and Bromine would be gaseous at cold bulb pressure. Shjacks45 (talk) 01:26, 29 May 2018 (UTC)

Toxicity
I wonder if someone could explain how halogen bulbs are said to be safe for disposal in general waste, and yet halogens are toxic to a varying degree? Is it due to the amounts or are they in fact toxic and the issue is being ignored? Please excuse my lack of knowledge in this field Gwaka Lumpa (talk) 07:42, 27 January 2016 (UTC)

Iodine is commonly used for first aid, and isn't all that toxic. Chlorine for water treatment and especially in swimming pools. There isn't so much in the lamp, iodine is solid at room temperature, and won't move far, in any case. But yes, mostly there isn't all that much of it in the lamp. Gah4 (talk) 04:25, 8 June 2017 (UTC)

External links modified
Hello fellow Wikipedians,

I have just modified one external link on Halogen lamp. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
 * Added archive https://web.archive.org/web/20091230050454/http://www.timessquarenyc.org/nye/2010numerals.html to http://www.timessquarenyc.org/nye/2010numerals.html

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

Cheers.— InternetArchiveBot  (Report bug) 12:42, 28 October 2017 (UTC)

Lumens?
This article gives no information about the lighting flux from halogen lamps. The table at lumen (unit) is notable for its omission of a column for halogen lamps. Or does it come under "incandescent" like tungsten coil? Neither of the citations in the table mention halogen. Would someone rectify both articles, please? --88.97.11.54 (talk) 14:12, 4 February 2018 (UTC)
 * OK, I put some into the lumen (unit) article. Only a small number are available in A (ordinary bulb) shape. Conveniently, they re sized to match the lumen output of traditional bulbs. Gah4 (talk) 00:12, 11 March 2020 (UTC)
 * OK, I put some into the lumen (unit) article. Only a small number are available in A (ordinary bulb) shape. Conveniently, they re sized to match the lumen output of traditional bulbs. Gah4 (talk) 00:12, 11 March 2020 (UTC)

Heating?
Several toaster oven (small countertop ovens) use quartz halogen heating elements. see https://en.wikipedia.org/wiki/Infrared_heater. Touching fused silica and leaving finger oils causes failure? Most animal oils in the human body boil off at below operating temp. Better, see https://www.researchgate.net/publication/251734151_Spherulite-shaped_cristobalite_by_fused_silica_devitrification about damage catalyzed by salt, which is found in human sweat. Shjacks45 (talk) 02:57, 29 May 2018 (UTC)


 * I know many use fuzed quartz tubes, but usually at low (red or orange) temperatures, not the white hot for halogen lamps. The higher temperature is needed for the halogen cycle. Low temperature ones won't have significant evaporation. Gah4 (talk) 03:10, 29 May 2018 (UTC)

Urban myth: Fat/oil burning into the glass
In the safety section, it is written that “surface contamination, notably the oil from human fingertips, can damage the quartz envelope when it is heated” and might eventually lead to the explosion of halogen lamps. This is a common concept, but nonetheless an urban myth. According to Markus Rademacher of lamp manufacturer Osram, not the oil but in fact alkaline minerals from the sweat (most notably sodium chlorite) cause blind spots in the quartz glass. Rademacher also states that bulbs “exploding” because of fingerprints on the glass is a highly unlikely scenario. (Source is in German, see an archived version of the article here.)--Kernpanik (talk) 12:38, 29 July 2020 (UTC)
 * I suspect that you are right that it is sodium, but that may be combined with other chemicals in the fingerprint. I am not sure about explode but they are under pressure when hot. I have seen one with a hole, which might have been a small explosion.  Not one where pieces went all directions. Gah4 (talk) 22:20, 29 July 2020 (UTC)
 * I suspect that you are right that it is sodium, but that may be combined with other chemicals in the fingerprint. I am not sure about explode but they are under pressure when hot. I have seen one with a hole, which might have been a small explosion.  Not one where pieces went all directions. Gah4 (talk) 22:20, 29 July 2020 (UTC)

Jagged spectrum
What is the cause for the peaky spectrum in the illustration Halogen_spectrum.svg? Usually black body spectra are smooth (spectrum in the visible range, scroll down), and peaky spectrum is associated with artificial light sources. Is it caused by glass or an artifact of the measurement method? J7n (talk) 07:57, 19 November 2021 (UTC)
 * Black body radiators are kept in the physics lab on the same shelf as the frictionless planes, the massless pulleys, and the bottle of ideal gas. We know little about our illustration. Possibly it was derived from an experimental measurement of a practical bulb with a real-world measuring instrument, and so does not fit the textbook picture of a black body.  We have illustrations on WP based on what we can get out of copyright, not because they are authoritative or credible. If you have access to a more authoritative spectrum that will not bring down the wrath of the copyright patrollers, please include it! --Wtshymanski (talk) 21:50, 22 November 2021 (UTC)
 * Ideal blackbody radiation (somewhat unrealistic as @Wtshymanski said) generates a smooth spectrum.
 * Low-pressure gas generates a spectrum that only consists of specific lines that the gas's atoms/molecules resonate at. So, like, hydrogen can have its electron jump between shell 2 down to shell 1, or 3 down to 2 or 1, or 7 down to 4 or 3....  But only integer shell numbers.  (Rydberg formula). It can also absorb light at those colors/frequencies.  The atoms are so far apart, they're not affected by surrounding atoms, so there's a sharp spectral line.  (They do get some width from doppler shift, from brownian motion.  Not much.)
 * As the gas is compressed or cooled, the atoms start to stick together or bounce. Those clusters can resonate at other frequencies, and there's so many combinations, esp in a solid/crystal, that you get all sorts of resonances, and a smeared spectrum.  As the diagram shows.  OsamaBinLogin (talk) 23:35, 25 November 2023 (UTC)