Editing Fluorescent lamp (section)

==Disadvantages==

===Frequent switching===
Frequent switching (more than every 3 hours) will shorten the life of lamps.<ref>{{cite web |archive-url=https://web.archive.org/web/20110511132153/http://www1.eere.energy.gov/femp/pdfs/29267-5.4.3.pdf|archive-date=May 11, 2011|url=http://www1.eere.energy.gov/femp/pdfs/29267-5.4.3.pdf |publisher=eere.energy.gov |title=Compact Fluorescent Lighting |access-date=24 July 2012}}</ref> Each start cycle slightly erodes the electron-emitting surface of the cathodes; when all the emission material is gone, the lamp cannot start with the available ballast voltage. Fixtures for flashing lights (such as for advertising) use a ballast that maintains cathode temperature when the arc is off, preserving the life of the lamp.

The extra energy used to start a fluorescent lamp is equivalent to a few seconds of normal operation; it is more energy-efficient to switch off lamps when not required for several minutes.<ref>{{cite news|title=Science Fact or Science Fiction: Fluorescent Lights|archive-url=https://web.archive.org/web/20111028205846/http://www.cbc.ca/quirks/episode/2011/10/22/october-22-2011|archive-date=October 28, 2011|url=http://www.cbc.ca/quirks/episode/2011/10/22/october-22-2011/|work=Quirks and Quarks|publisher=[[Canadian Broadcasting Corporation|CBC]]|access-date=27 October 2011}}</ref><ref>{{cite web|title=When to Turn Off Your Lights|url=http://energy.gov/energysaver/articles/when-turn-your-lights|website=U.S. Department of Energy|access-date=28 November 2012|archive-date=2012-11-16 |archive-url=https://web.archive.org/web/20121116060834/http://energy.gov/energysaver/articles/when-turn-your-lights|url-status=live}}</ref>

=== Mercury content ===
{{See also|Fluorescent lamps and health|Fluorescent lamp crusher}}
If a fluorescent lamp is broken, a very small amount of [[mercury (element)|mercury]] can contaminate the surrounding environment. About 99% of the mercury is typically contained in the phosphor, especially on lamps that are near the end of their life.<ref name="chem.unep.ch">{{cite report|author=UN Environment|date=January 2017|page=199|publication-date=December 2017|publisher=UN Environment Chemicals Branch|location=Geneva, Switzerland|url=http://wedocs.unep.org/bitstream/handle/20.500.11822/14781/UNEP-Hg-Toolkit-Reference-Report-January2017.pdf?sequence=1&isAllowed=y|title=Toolkit for Identification and Quantification of Mercury Sources, Reference Report and Guideline for Inventory Level 2, Version 1.4|access-date=2019-09-30 |archive-date=2019-09-30 |archive-url=https://web.archive.org/web/20190930070608/http://wedocs.unep.org/bitstream/handle/20.500.11822/14781/UNEP-Hg-Toolkit-Reference-Report-January2017.pdf?sequence=1&isAllowed=y|url-status=live}} Citing Floyd, et al. (2002).</ref> Broken lamps may release mercury if not cleaned with correct methods.<ref>{{cite web|title=Frequently Asked Questions Information on Compact Fluorescent Light Bulbs (CFLs) and Mercury|date=July 2008|url=http://www.energystar.gov/ia/partners/promotions/change_light/downloads/Fact_Sheet_Mercury.pdf|access-date=2020-06-04|archive-date=2021-02-18 |archive-url=https://web.archive.org/web/20210218002047/https://www.energystar.gov/ia/partners/promotions/change_light/downloads/Fact_Sheet_Mercury.pdf|url-status=live}}</ref>{{Failed verification|date=March 2016}}

Due to the mercury content, discarded fluorescent lamps must be treated as hazardous waste in some jurisdictions.<ref name =epacfl>{{cite web | url=https://www.epa.gov/mercury/recycling-and-disposal-cfls-and-other-bulbs-contain-mercury | title=Recycling and Disposal of CFLS and Other Bulbs that Contain Mercury | date=January 22, 2013 }}</ref> For large users of fluorescent lamps, [[Fluorescent lamp recycling|recycling services]] are available in some areas, and may be required by regulation.<ref>{{cite web|url= http://lamprecycle.org/lamprecyclers.shtml|work= LampRecycle.org|title= Commercial Lighting: Lamp Recyclers|access-date= 2010-03-16 |archive-date= 2010-02-01 |archive-url= https://web.archive.org/web/20100201211515/http://www.lamprecycle.org/lamprecyclers.shtml|url-status= live}}</ref><ref name =epacfl/> In some areas, recycling is also available to consumers.<ref name =epacfl/>

===Ultraviolet emission===
Fluorescent lamps emit a small amount of [[ultraviolet]] (UV) light. A 1993 study in the US found that ultraviolet exposure from sitting under fluorescent lights for eight hours is equivalent to one minute of sun exposure.<ref>{{Cite journal|last= Lytle|first= CD |author2=Cyr, WH |author3=Beer, JZ |author4=Miller, SA |author5=James, RH |author6=Landry, RJ |author7=Jacobs, ME |author8=Kaczmarek, RG |author9=Sharkness, CM |author10=Gaylor, D |display-authors=etal |title= An Estimation of Squamous Cell Carcinoma Risk from Ultraviolet Radiation Emitted by Fluorescent Lamps|journal= Photodermatol Photoimmunol Photomed|date=December 1993|volume= 9|issue= 6|pages= 268–274|pmid= 1343229}}</ref> Ultraviolet radiation from compact fluorescent lamps may exacerbate symptoms in photosensitive individuals.<ref>{{cite journal|last1=Nicole|first1=Wendee|title=Ultraviolet leaks from CFLs|journal=Environmental Health Perspectives|date=2012|volume=120|issue=10|page=a387|doi=10.1289/ehp.120-a387|pmid=23026199|pmc=3491932}}<!--|access-date=16 January 2016--></ref><ref>{{cite journal|last1=Moseley|first1=Harry|last2=Ferguson|first2=James|title=The risk to normal and photosensitive individuals from exposure to light from compact fluorescent lamps|journal=Photodermatology, Photoimmunology & Photomedicine|date=2011|volume=27|issue=3|pages=131–137|doi=10.1111/j.1600-0781.2011.00576.x|pmid=21535166|s2cid=9509601|doi-access=free}}<!--|access-date=16 January 2016--></ref><ref>{{cite web|last1=SCENIHR (Scientific Committee on Emerging and Newly-Identified Health Risks)|title=Scientific opinion on light sensitivity|url=http://ec.europa.eu/health/ph_risk/committees/04_scenihr/docs/scenihr_o_019.pdf|access-date=16 January 2016|date=23 September 2008|archive-date=2009-09-02 |archive-url=https://web.archive.org/web/20090902135201/http://ec.europa.eu/health/ph_risk/committees/04_scenihr/docs/scenihr_o_019.pdf|url-status=live}}</ref>

Museum artifacts may need protection from UV light to prevent degradation of pigments or textiles.<ref>Museum Handbook: Museum collections. Part I
 United States National Park Service, Department of the Interior, 1991, p.  K19</ref>

===Ballast===
[[Image:Old USSR Ballast.JPG|thumb|Magnetic [[electrical ballast|ballasts]] have a low [[power factor]], when aren't connected to a power factor correction capacitor. This increases current drawn by the lighting fixture.]]
Fluorescent lamps require a [[electrical ballast|ballast]] to stabilize the current through the lamp, and to provide the initial striking voltage required to start the arc discharge. Often one ballast is shared between two or more lamps. Electromagnetic ballasts can produce an audible humming or buzzing noise. In North America, magnetic ballasts are usually filled with a [[tar]]-like potting compound to reduce emitted noise. Hum is eliminated in lamps with a high-frequency electronic ballast. Energy lost in magnetic ballasts is around 10% of lamp input power according to GE literature from 1978.<ref name=GE1978 /> Electronic ballasts reduce this loss.

===Power quality and radio interference===
Simple inductive fluorescent lamp ballasts have a [[power factor]] of less than unity. Inductive ballasts can be connected to, or may include, power factor correction [[Capacitor|capacitors]]. Simple electronic ballasts may also have low power factor due to their rectifier input stage.

Fluorescent lamps are a non-linear load and generate harmonic currents in the electrical power supply. The arc within the lamp may generate radio frequency noise, which can be conducted through power wiring. Suppression of radio interference is possible. Very good suppression is possible, but adds to the cost of the fluorescent fixtures.

Fluorescent lamps near end of life can present a serious radio frequency interference hazard. Oscillations are generated from the negative differential resistance of the arc, and the current flow through the tube can form a tuned circuit whose frequency depends on path length.<ref>{{cite web|url=https://interferencetechnology.com/rf-emissions-of-compact-fluorescent-lights/|title=RF Emissions of Compact Fluorescent Lights|date=17 December 2012|access-date=2019-03-14 |archive-date=2021-02-27 |archive-url=https://web.archive.org/web/20210227150226/https://interferencetechnology.com/rf-emissions-of-compact-fluorescent-lights/|url-status=live}}</ref>

===Operating temperature===
Fluorescent lamps operate best around room temperature. At lower or higher temperatures, [[Luminous efficacy|efficacy]] decreases. At below-freezing temperatures standard lamps may not start. Special lamps may be used for reliable service outdoors in cold weather.

===Lamp shape===
Fluorescent tubes are long, low-luminance sources compared with [[High-intensity discharge lamp|high intensity discharge lamps]], [[Incandescent light bulb|incandescent]] and [[Halogen lamp|halogen]] lamps and high power LEDs. However, low luminous intensity of the emitting surface is useful because it reduces [[Glare (vision)|glare]]. Lamp fixture design must control light from a long tube instead of a compact globe. The [[compact fluorescent lamp]] (CFL) replaces regular incandescent bulbs in many light fixtures where space permits.

===Flicker ===
Fluorescent lamps with magnetic [[Electrical ballast|ballasts]] flicker at a normally unnoticeable frequency of 100 or 120&nbsp;Hz and this flickering can cause problems for some individuals with [[light sensitivity]];<ref>{{cite web|url=http://www.jan.wvu.edu/soar/vision/light.html|title=Working with Light Sensitivity|access-date=2007-12-28 |archive-date=2008-03-30 |archive-url=https://web.archive.org/web/20080330090508/http://www.jan.wvu.edu/soar/vision/light.html|url-status=live}}</ref> they are listed as problematic for some individuals with [[autism]], [[epilepsy]],<ref>{{cite web|url=http://www.jan.wvu.edu/media/epilepsy.html|title=Accommodation Ideas for Employees with Epilepsy|access-date=2007-12-28 |archive-date=2008-07-25 |archive-url=https://web.archive.org/web/20080725033536/http://www.jan.wvu.edu/media/Epilepsy.html|url-status=live}}</ref> [[Systemic lupus erythematosus|lupus]],<ref>{{cite web|url=http://www.jan.wvu.edu/media/Lupus.html|title=Accommodation and Compliance Series: Employees with Lupus|access-date=2007-12-28 |archive-date=2008-05-09 |archive-url=https://web.archive.org/web/20080509073743/http://www.jan.wvu.edu/media/lupus.html|url-status=live}}</ref> [[chronic fatigue syndrome]], [[Lyme disease]],<ref>{{cite journal|pmid=10610642|title=Musculoskeletal and neurologic outcomes in patients with previously treated Lyme disease | volume=131 | issue=12|date=December 1999|journal=Ann. Intern. Med.|pages=919–26|vauthors=Shadick NA, Phillips CB, Sangha O |display-authors=etal|doi=10.7326/0003-4819-131-12-199912210-00003|s2cid=20746489 }}</ref> and [[Vertigo (medical)|vertigo]].<ref>{{cite web|url=http://www.jan.wvu.edu/enews/2004/Enews_V2-I1.htm#four |title=Accommodating People with Vertigo |url-status=dead |archive-url=https://web.archive.org/web/20080608034400/http://www.jan.wvu.edu/enews/2004/Enews_V2-I1.htm |archive-date=June 8, 2008 }}</ref> 
[[File:Fluorescentfixturebelow20806.JPG|thumb|The "beat effect" problem created when shooting photos under standard fluorescent lighting]]

A [[stroboscopic effect]] can be noticed, where something spinning at just the right speed may appear stationary if illuminated solely by a single fluorescent lamp. This effect is eliminated by paired lamps operating on a lead-lag ballast. Unlike a true strobe lamp, the light level drops in appreciable time and so substantial "blurring" of the moving part would be evident.

Fluorescent lamps may produce flicker at the power supply frequency (50 or 60&nbsp;Hz), which is noticeable by more people. This happens if a damaged or failed cathode results in slight [[Rectifier|rectification]] and uneven light output in positive and negative going AC cycles. Power frequency flicker can be emitted from the ends of the tubes, if each tube electrode produces a slightly different light output pattern on each half-cycle. Flicker at power frequency is more noticeable in the [[peripheral vision]] than it is when viewed directly.

Near the end of life, fluorescent lamps can start flickering at a frequency lower than the power frequency. This is due to instability in the negative resistance of arc discharge,<ref>{{Cite journal |first1=Stanislav |last1=Glozman |first2=Shmuel |last2=Ben-Yaakov |title=Dynamic Interaction Analysis of HF Ballasts and Fluorescent Lamps Based on Envelope Simulation |date= September–October 2001 |journal=IEEE Transactions on Industry Applications |volume=37 |issue=5 |pages=1531–1536 |doi=10.1109/28.952531 }}</ref> which can be from a bad lamp or ballast or poor connection.

New fluorescent lamps may show a twisting spiral pattern of light in a part of the lamp. This effect is due to loose cathode material and usually disappears after a few hours of operation.{{r|GE1978|p=22}}
[[File:Fluorescent beat effect.ogv|thumb|right|The "beat effect" problem created when shooting films under standard fluorescent lighting]]
Electromagnetic ballasts may also cause problems for video recording as there can be a so-called ''[[beat (acoustics)|beat]] effect'' between the video frame rate and the fluctuations in intensity of the fluorescent lamp.

Fluorescent lamps with electronic ballasts do not flicker, since above about 5&nbsp;kHz, the excited electron state half-life is longer than a half cycle,{{Citation needed|date=November 2012}} and light production becomes continuous. Operating frequencies of electronic ballasts are selected to avoid interference with infrared remote controls. Poor quality or faulty electronic ballasts may have considerable 100/120&nbsp;Hz modulation of the light.

===Dimming===
Fluorescent light fixtures cannot be connected to [[dimmer]] switches intended for incandescent lamps. Two effects are responsible for this: the waveform of the voltage emitted by a standard phase-control dimmer interacts badly with many ballasts, and it becomes difficult to sustain an arc in the fluorescent tube at low power levels. Dimming installations require a compatible [[dimming ballast]]. Some models of [[compact fluorescent lamp]]s can be dimmed; in the United States, such lamps are identified as complying with UL standard 1993.<ref>{{cite web|url=https://www.nema.org/Standards/ComplimentaryDocuments/Frequently-Asked-Questions-Regarding-CFLs-and-Dimming.pdf|title=Frequently Asked Questions Regarding CFLs and Dimming|website=www.nema.org|access-date=2020-03-18 |archive-date=2014-05-13 |archive-url=https://web.archive.org/web/20140513210531/http://www.nema.org/Standards/ComplimentaryDocuments/Frequently-Asked-Questions-Regarding-CFLs-and-Dimming.pdf|url-status=live}}</ref>