Snohomish County Public Utility District No. 1

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CFL Frequently Asked Questions

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Which CFL should I buy?

All are long-lasting, produce excellent color and are guaranteed.

  • A 13-watt CFL produces the same amount of light as a standard 60-watt incandescent light bulb.
  • An 18-watt CFL produces the same amount of light as a standard 75-watt incandescent light bulb.
  • A 23-watt CFL produces the same amount of light as a standard 100-watt incandescent light bulb.
  • Other styles and sizes are also available.
Where is the best place to use a CFL?

For the biggest energy savings, replace standard incandescent light bulbs that are used for 15 minutes or more, like a porch light or an area light.

Is there any place where I should not use a CFL?

Yes. It should not be used in lighting fixtures with photocells or timers that are not rated for fluorescent lighting. Most CFLs are not rated for fully enclosed indoor lighting fixtures, but CFLs for special lighting (like dimmable or three-way lights) are now available. It is best to read the manufacturer’s recommendation noted on the CFL packaging.

How much money can I expect to save by using a CFL?

It depends on the wattage of the bulb being replaced as well as how long the light stays on each day. Refer to our chart of sample energy savings or use our Lighting Calculator.

Why do CFLs flicker?

Older CFLs may flicker when they are first turned on, and some will flicker when they reach near end of life or are dimmed. One cause of flickering is due to the start-up process in a CFL. When CFLs are turned on, an electrical charge is sent through the glass tubes to excite (light up) the phosphors. This process may take several attempts (due to colder temperatures or end-of-lifespan), which causes the CFL to flicker. Flickering is also caused by using CFLs with electronic controls (such as motion lights, timers and dimmer switches) that are not specifically labeled as approved for fluorescent lighting. These types of electronic controls often do not turn off all the electricity going to the CFL when they are in the ’off’ position. CFLs can detect this small amount of power, causing them to try to turn on. They end up flickering because there is not enough power for them to complete their start-up process of igniting the phosphors. New technology is being developed so that CFLs will no longer flicker.

Can you use a CFL in a three-way lamp or a light fixture with a dimmer switch?

CFLs can now be used in three-way lighting or with dimmer switches. These types of newer CFL technology are clearly marked on their packaging. CFLs not labeled for three-way applications or as "dimmable" will not work properly when using these three- way or dimming types of controls.

What should I do if a CFL breaks?

The Environmental Protection Agency (EPA) recommends the following clean-up and disposal guidelines:  

  • Open a window and leave the room (and restrict access to it) for at least 15 minutes.
  • After 15 minutes, remove all materials you can without using a vacuum cleaner.
    • Wear disposable rubber gloves, if available (do not use your bare hands).
    • Carefully scoop up the fragments and powder with stiff paper or cardboard.
    • Wipe the area clean with a damp paper towel or disposable wet wipe.
    • Sticky tape (such as duct tape) can be used to pick up small pieces and powder.
  • Place all cleanup materials in a plastic bag and seal it.
    • In Snohomish County, broken CFLs properly sealed in two plastic bags should be disposed of at Snohomish County's Hazardous Waste Facilities. Click here for more information about disposal in Snohomish County.
  • Wash your hands after disposing of the bag.
  • Source (click here)
  • The first time you vacuum the area where the bulb was broken, remove the vacuum bag after you are done cleaning the area (or empty and wipe the canister) and put the bag and/or vacuum debris, as well as the cleaning materials, in two sealed plastic bags in the outdoor trash or protected outdoor location for normal disposal.
How long do CFLs last?

There is a big difference in lifespan, depending on the CFL. Six years ago, most CFLs were rated for about 6,000 hours. As technology improved, some CFLs are now rated for 12,000 hours. So, it depends on whether you have a newer or older CFL. On average, CFLs last about seven to ten times longer than their incandescent equivalents.

Why can't I put a burned-out CFL in the garbage?

CFLs contain a small amount of mercury, which if not handled properly, could pose a threat to the health of people who come into contact with it. Particularly, a CFL mixed in with household trash might be crushed during garbage collection, potentially exposing waste handlers to mercury. Mercury should be properly disposed of to protect our natural environment. Click here for information about locations where you can dispose of your burned-out CFL bulbs for free.

Are CFLs dangerous?

CFLs should not be considered dangerous if properly handled and disposed of when they have been spent. CFLs contain a small amount of mercury. According to NW Energy Star, it would take about 100 CFLs to equal the amount of mercury in an older thermometer. However, if a CFL breaks, it is important to follow the proper clean-up procedure to minimize any mercury exposure (see FAQ above "What should I do if a CFL breaks?."

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