A compact fluorescent lamp (CFL), also known as a compact fluorescent light bulb is a type of fluorescent lamp designed to replace an incandescent lamp. Many CFLs can fit in the existing incandescent light fixtures.

Spiral CFL

Frequently Asked Questions about CFLs[edit | edit source]

Why use compact fluorescent light bulbs?[edit | edit source]

Compact Fluorescent Light bulbs (or CFLs) use less energy and last longer than conventional incandescent bulbs. They save you money in the long run and you do not have to change them as often. In addition, because they use less energy, they are better for the environment.

Will CFLs work in the home?[edit | edit source]

Yes. They fit in conventional light sockets same as incandescent bulbs. For home use purchase soft white compact fluorescent light bulbs to match incandescent output. When purchasing light bulbs you want to maximize the amount of light (measured in Lumens) and minimize the amount of electricity needed (measured in Watts).

Will CFL bulbs really save me money?[edit | edit source]

YES! For typical electrical rates in Pennsylvania (some of the lowest rates in the world) for example each retrofit CFL will save over $30 over its lifetime.

How does a CFL bulb work?[edit | edit source]

Compact fluorescent lamps are arc discharge lamps that produce light by exciting mercury vapor. Electricity is applied to the electrode at the end of the lamp where it excites the mercury. Once the mercury is excited, it carries the electrical current via an arc across the lamp to the other end. The excited mercury produces most of its energy in the ultraviolet (UV) range. The UV energy stretching across the lamp activates a phosphor, the white coating on the inside of the bulb, which emits visible light.

Are CFLs really good for the environment?[edit | edit source]

Yes! Consider switching a single 100W incandescent bulb for a CFL bulb that produces as much light but uses only a ¼ of the energy. Every CFL bulb assists in reducing climate destabilization caused by greenhouse gas emissions. Here is a list of the pollution prevented by changing only one socket from an incandescent to a CFL bulb:

  • 600 kw-hrs conserved

Pollution prevented[edit | edit source]

  • 490 pounds coal needed
  • 1,269 pounds carbon dioxide (a green house gas contributing to climate change)
  • 3.43 pounds sulfur dioxide (contributes to acid rain and smog)
  • 3.5 pounds nitrogen oxide (contributes to acid rain)
  • 0.17 pounds particulates (aggravates health problems like asthma)
  • 42.9 pounds ash (land filled)
  • 3.86E-05 pounds arsenic (toxic)
  • 1.95E-05 pounds lead (toxic)
  • 6.86E-07 pounds cadmium and other heavy metals (toxic)

377 gallons of water conserved Pollution data from: UCS

Can I use CFL bulbs if I will be turning the lights on and off frequently?[edit | edit source]

Compact fluorescent light bulbs work best if they are left on for over 15 minutes each time they are turned on. CFLs can take up to 3 minutes to warm-up to reach the point of most efficient operation. Frequently switching them on and off can shorten the life of the bulb. If the life of the bulb is shortened significantly, you will not reap the full financial benefits (includes energy and life of bulb).

Don[edit | edit source]

The old ones did but they do not anymore. Due to phosphors in the new bulbs, the quality of light can now be manipulated and three-way CFLs are now available. The greenish cast is gone and the light has the same softness of the conventional bulbs we are used to.

Do CFL bulbs flicker and buzz like the fluorescent lights in old buildings?[edit | edit source]

No. Modern CFL bulbs utilize harmonic technology to eliminate the old problem of flicker and buzzing. This is not true of all compact fluorescents as inferior brands still have that problem.

What should I do if I break a compact fluorescent light bulb?[edit | edit source]

When a bulb is broken, the best thing to do is to wear chemical resistant glove to clean it up. The gloves you buy in the supermarket for household cleaning are sufficient. The gloves protect your skin from absorbing the mercury and from getting cut by the glass. The remains of one lamp can be disposed as normal waste since the amount of mercury is extremely small.

Can I use CFLs with a dimmer?[edit | edit source]

Standard CFLs cannot be used with a dimmer switch. However, there are dimmable bulbs, although they are more expensive. There are also 3-way bulbs.

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CFL savings[edit | edit source]

Assuming you have the lights on for 8 hours a day you will save ~$1.12/month for every 100W fixture you switch to CFLs. The CFL will pay for itself in less than 6 months – and then you reap over 2 years of pure profit while saving planet! CFLs also have a much longer life than conventional incandescents.

Potential problems with fluorescents (including CFLs)[edit | edit source]

Note that the quality of fluorescents can vary enormously. In general to avoid this problem either i) buy from a manufacturer that you trust, ii) purchase from a vendor you can return bulbs to if there is problem, iii) get reliable 3rd party information such as from Consumer Reports or student projects, or iv) buy one bulb test it at home - if it works retrofit your entire home.

  • light quality (spectrum) - this should be on the package as noted as {{WP}color temperature}}
  • flickering, noise (whining) - only in the worst bulbs normally old.
  • unpredictable life span (too sensitive to shocks, surges?) particularly in some cheaper brands.[verification needed]
    • many CFLs are being installed in circuits that are controlled by dimmers, but not all CFLs are designed to tolerate dimmers, which can cause failures in power generation section of the lamp.[1] With the growth of dimmable CFLs and LVDs, this issue is declining.
  • Fluorescent bulbs still contain mercury, a hazard material leading to disposal issues, particularly in less developed regions where disposal is not regulated. The mercury levels in fluorescent lights (including CFLs) are now usually considered to be within safe limits. However you should take care not to break them.
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More information[edit | edit source]

Adapted from a FAQ written by User:J.M.Pearce For details on running a campaign in your school see Joshua Pearce and Chris Russill, "Interdisciplinary Environmental Education: Communicating and Applying Energy Efficiency for Sustainability", Applied Environmental Education and Communication, 4(1), 65-72, 2005.

Some revealing facts about CFLs from Paul Wheaton at richsoil.com: CFL fluorescent light bulbs: more hype than value

Forum at permies.com: CFL brightness and longevity claims

References[edit | edit source]

FA info icon.svg Angle down icon.svg Page data
Authors Joshua M. Pearce
License CC-BY-SA-3.0
Language English (en)
Translations Thai
Related 1 subpages, 3 pages link here
Aliases Compact fluorescent lamps, Compact fluorescent lamp, Compact fluorescent light, CFL
Impact 1,826 page views
Created August 2, 2007 by Joshua M. Pearce
Modified June 8, 2023 by Felipe Schenone
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