Editing Fluorescent lamp (section)

{{Short description|Lamp using fluorescence to produce light}}
{{Redirect|Tubelight|other uses|Tubelight (disambiguation)}}
{{For|Lamp sizes and designations|Fluorescent-lamp formats}}
{{Use American English|date = February 2019}}
{{use mdy dates|cs1-dates=ly|date=June 2020}}
[[File:Fluorescent lamps artistic.jpg|thumb|Linear fluorescent lamps illuminating a pedestrian tunnel]]
[[File:Leuchtstofflampen-chtaube050409.jpg|thumb|Top: two non-integrated [[compact fluorescent lamp]]s. Bottom: two fluorescent tube lamps. Both types require a ballast in the [[light fixture]]. A matchstick, left, is shown for scale.]]
{{multiple image
| width             = 220
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| image1            = Compact fluorescent straight crop.jpg
| image2            = Osram Dulux Circolux 24W-7494.jpg
| footer            = Integrated [[compact fluorescent lamp]]s of different shapes with [[Edison screw|E27 socket]] and an [[electronic ballast]] in the base
}}
[[File:tanninglamp.jpg|thumb|Typical [[Fluorescent-lamp formats#Tube designations|F71T12 100 W]] G13 bi-pin lamp used in tanning beds. The (Hg) symbol indicates that this lamp contains [[mercury (element)|mercury]]. In the US, this symbol is now required on all mercury-containing fluorescent lamps.<ref>{{cite web|title=Mercury-containing Lights and Lamps as Universal Waste|url=http://www.ecy.wa.gov/programs/hwtr/dangermat/universal_waste_lamps.html|publisher=[[Washington State Department of Ecology]]|access-date=11 June 2016|archive-date=2016-06-04 |archive-url=https://web.archive.org/web/20160604141653/http://www.ecy.wa.gov/programs/hwtr/dangermat/universal_waste_lamps.html|url-status=live}}</ref>]]
[[File:Fluorescent lamp hold for T8 and T12 lamps.jpg|thumb|upright|A "tombstone" style lamp-holder for [[Fluorescent-lamp formats#Tube designations|T12 and T8]] G13 bi-pin fluorescent lamps]]
[[File:Tanninglampend.jpg|thumb|Inside the lamp end of a preheat G13 lamp. In this lamp, the filament is surrounded by an oblong metal [[cathode]] shield, which helps reduce lamp end darkening.<ref>M. A. Laughton. ''Electrical Engineer's Reference Book Sixteenth Edition'', Newnes, 2003 {{ISBN|0-7506-4637-3}}, pp. 21–12.</ref>]]

A '''fluorescent lamp''', or '''fluorescent tube''', is a low-pressure mercury-vapor [[gas-discharge lamp]] that uses [[fluorescence]] to produce visible light. An electric current in the gas excites mercury vapor, to produce [[ultraviolet]] and make a [[phosphor]] coating in the lamp glow. Fluorescent lamps convert electrical energy into visible light much more efficiently than [[Incandescent light bulb|incandescent lamps]], but are less efficient than most [[LED lamp]]s. The typical [[luminous efficacy]] of fluorescent lamps is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output (e.g. the luminous efficacy of an incandescent lamp may only be 16 lm/w).

Fluorescent lamp fixtures are more costly than incandescent lamps because, among other things, they require a [[electrical ballast|ballast]] to regulate [[Electric current|current]] through the lamp, but the initial cost is offset by a much lower running cost. [[Compact fluorescent lamp]]s (CFL) made in the same sizes as incandescent lamp bulbs are used as an [[energy-saving]] alternative to incandescent lamps in homes.

In the [[United States]], fluorescent lamps are classified as [[universal waste]]. The [[United States Environmental Protection Agency]] recommends that fluorescent lamps be segregated from general waste for [[recycling]] or safe disposal, and some jurisdictions require recycling of them.<ref name =epacfl/>