Editing Halogen lamp (section)

== Safety ==
[[File:2010-05-30 Destroyed 300W linear halogen bulb.jpg|thumb|A burned-out R7S form factor halogen lamp]]

Halogen lamps must run at much higher temperatures than regular incandescent lamps for proper operation. Their small size helps to concentrate the heat on a smaller envelope surface, closer to the filament than a non-halogen incandescent. Because of the very high temperatures, halogen lamps can pose fire and burn hazards. In Australia, numerous house fires each year are attributed to ceiling-mounted halogen downlights.<ref>[http://www.theage.com.au/articles/2007/07/21/1184560109174.html Thousands at risk from halogen-light death traps] {{webarchive|url=https://web.archive.org/web/20121218073303/http://www.theage.com.au/articles/2007/07/21/1184560109174.html |date=2012-12-18 }} at The Sunday Age site (accessed 22 Dec. 2012)</ref><ref>[http://www.fire.nsw.gov.au/page.php?id=709 Halogen down light fire safety] {{webarchive|url=https://web.archive.org/web/20130409220132/http://www.fire.nsw.gov.au/page.php?id=709 |date=2013-04-09 }} at Fire and Rescue NSW site (accessed 22 Dec. 2012)</ref> The Western Australia Department of Fire and Emergency Services recommends that homeowners consider instead using cooler-running [[compact fluorescent lamp]]s or [[LED lamp|light emitting diode lamps]].<ref>[http://www.dfes.wa.gov.au/safetyinformation/fire/fireinthehome/pages/downlights.aspx Downlights] {{webarchive|url=https://web.archive.org/web/20130208022139/http://www.dfes.wa.gov.au/safetyinformation/fire/fireinthehome/Pages/downlights.aspx |date=2013-02-08 }} at Western Australia Department of Fire and Emergency Services site (accessed 22 Dec. 2012)</ref> Halogen [[Torchère]] floor lamps have been banned in some places, such as [[dormitories]], because of the large numbers of fires they have caused. They were held responsible by the [[US Consumer Product Safety Commission]] for 100 fires and 10 deaths between 1992 and 1997.<ref name=pop>{{cite journal | title = The Light Stuff| journal = [[Popular Science]] | date = October 1997 | page = 41| url=https://books.google.com/books?id=3aUMamjxVpMC&dq=%22The+Light+Stuff%22.+Popular+Science%3A+41.+October+1997.&pg=PA41}}</ref>  Halogen bulbs operate at high [[temperature]]s and the tall height of the lamps can bring them near [[flammable]] materials, such as [[curtain]]s.<ref>{{cite book| author = Nancy Harvey Steorts | title = Safety and You | isbn = 0815628005 | year = 1999|  page = 15 | publisher = Syracuse University Press | quote = The halogen lamp industry voluntarily undertook an initiative to repair about 40 million halogen torchère floor lamps. The CPSC is aware of 189 fires and eleven deaths that occurred because of these lamps.}}</ref> Some safety codes require halogen bulbs to be protected by a grid or grille, especially for high-power (1–2&nbsp;kW) bulbs used in [[Stage lighting|theatre]], or by the glass and metal housing of the fixture, to prevent ignition of draperies or flammable objects in contact with the lamp.
To reduce unintentional [[ultraviolet]] (UV) exposure, and to contain hot bulb fragments in the event of explosive bulb failure, general-purpose lamps usually have a UV-absorbing glass filter over or around the bulb. Alternatively, lamp bulbs may be doped or coated to [[filter (optics)|filter]] out the UV radiation. With adequate filtering, a halogen lamp exposes users to less UV than a standard incandescent lamp producing the same effective level of illumination without filtering.{{citation needed|date=December 2015}}

Any surface contamination, notably the oil from human fingertips, can damage the quartz envelope when it is heated. Contaminants, because they absorb more light and heat than the glass does, will create a hot spot on the bulb surface when the lamp is turned on. This extreme, localized heat causes the quartz to change from its [[Glass|vitreous]] form into a weaker, [[crystalline]] form that leaks gas. This weakening may also cause the bulb to form a bubble, weakening it and leading to its explosion.<ref>Kremer, Jonathan Z.[http://www.megavolt.co.il/Tips_and_info/types_of_bulbs.html "Types of Light Bulbs and Their Uses"] {{webarchive|url=https://web.archive.org/web/20110629034952/http://www.megavolt.co.il/Tips_and_info/types_of_bulbs.html |date=2011-06-29 }} Megavolt, section "Halogen", Accessed 26 May 2011.</ref>

The small glass envelope may be enclosed in a much larger outer glass bulb, which provides several advantages if small size is not required:<ref name=double/>

* the outer jacket will be at a much lower, safer, temperature, protecting objects or people that might touch it
* the hot-running inner envelope is protected from contamination, and the bulb may be handled without damaging it
* surroundings are protected from possible shattering of the inner capsule
* the jacket may filter out UV radiation
* when a halogen bulb is used to replace a normal incandescent in a fitting, the larger jacket makes it mechanically similar to the bulb replaced
* the inner and outer envelope can be at different pressures, reducing heat dissipation by conduction or convection in order to optimize the trade-off between luminous efficacy and lifetime