How does a compact fluorescent light bulb work?

Fluorescent light bulbs (including compact fluorescents) are more energy-efficient than regular bulbs because of the different method they use to produce light. Regular bulbs (also known as incandescent bulbs) create light by heating a filament inside the bulb; the heat makes the filament white-hot, producing the light that you see. A lot of the energy used to create the heat that lights an incandescent bulb is wasted. A fluorescent bulb, on the other hand, contains a gas that produces invisible ultraviolet light (UV) when the gas is excited by electricity. The UV light hits the white coating inside the fluorescent bulb and the coating changes it into light you can see. Because fluorescent bulbs don't use heat to create light, they are far more energy-efficient than regular incandescent bulbs.

What's the difference between a compact fluorescent light bulb and a fluorescent bulb?

The primary difference is in size; compact fluorescent bulbs are made in special shapes (which require special technologies) to fit in standard household light sockets, like table lamps and ceiling fixtures. In addition, most compact fluorescent lamps have an "integral" ballast that is built into the light bulb, whereas most fluorescent tubes require a separate ballast independent of the bulb. Both types offer energy-efficient light.

What compact fluorescent light bulb do I buy to replace a 60-, 75-, 100- or 150-watt regular bulb? How are the watts calculated?

While a regular (incandescent) light bulb uses heat to produce light, a fluorescent bulb creates light using an entirely different method that is far more energy-efficient — in fact, 4-6 times more efficient. This means that you can buy a 15-watt compact fluorescent bulb that produces the same amount of light as a 60-watt regular incandescent bulb.

Don't worry about the math, though — we make it easy for you to figure out which compact fluorescent bulb to buy by displaying the equivalent regular watts you're used to prominently on the package. Just look for the wattage you would normally buy in a regular bulb.

In case you're curious, here are the watts needed by regular incandescent bulbs and compact fluorescent bulbs to produce the same amount of light.

Because the wattage of a CFL bulb is much lower than that of an incandescent, you can use higher wattage CFL giving you the equivalent light of a higher wattage incandescent. For example: If your fixture says not to exceed 60 watts, you can use a 15 watt CFL to get the same amount of light as an incandescent bulb or use up to a 42 watt CFL and increase the amount of light.

Can I use a compact fluorescent light bulb with a dimmer switch?

To use a compact fluorescent bulb on a dimmer switch, you must buy a bulb that's specifically made to work with dimmers (check the package).

Can I use a compact fluorescent light bulb on my 3-way lamp?

Check the package for this application. If a regular CFL is used in a 3-way switch, it will work on the middle (medium) setting and it should not damage the bulb.

Why does my compact fluorescent light bulb flicker or appear dim when I first turn it on?

The first compact fluorescent bulbs flickered when they were turned on because it took a few seconds for the ballast to produce enough electricity to excite the gas inside the bulb. Today, CFL technology has improved and the flicker that you used to see should not be a factor. However, CFL’s do require a short warm-up period before they reach full brightness, which is why they may appear dim when first turned on. Compact fluorescent bulbs are best used in fixtures that are left on for longer periods of time, rather than in fixtures that are turned off and on frequently.

Can I use a CFL in applications where I will be turning the lights on/off frequently?

Compact fluorescent light bulbs work best if they are left on for more than 15 minutes each time they are turned on. These types of lamps can take up to 3 minutes to warm-up. Warm-up will probably not be noticeable from a users stand point, but the lamp needs to warm-up in order to reach the point of most efficient operation. Frequently switching them on and off will shorten the life of the product. If the life of the lamp is shortened significantly, you will not reap the financial benefits (includes energy & life of lamp), that are common to CFL lamps.

Can I use a CFL in any position?

Yes, CFL bulbs can be used in any operating position unless there is text printed on the lamp or packaging that indicates a required operating position.

Can I use a CFL in applications involving vibration such as a ceiling fan or garage door opener?

Generally it is not recommended to use CFLs in vibrating environments. Vibration can cause the electronics in the CFL to fail. There is one CFL bulb (FLE11) that is available for use in a ceiling fan. Check the package for this application.

Can compact fluorescent bulbs create interference with electronic equipment, such as radios?

Many electronic devices, such as radios, televisions, wireless telephones, and remote controls, use infrared light to transmit signals. Infrequently, these types of electronic devices accidentally interpret the infrared light coming from a compact fluorescent bulb as a signal, causing the electronic device to temporarily malfunction or stop working. (For example, your television might suddenly change channels.) Fortunately, this only happens when light is produced at the same wavelength as the electronic device signals, which is rare.

To reduce the chance of interference, avoid placing compact fluorescent bulbs near these kinds of electronic devices. If interference occurs, move the bulb away from the electronic device, or plug either the light fixture or the electronic device into a different outlet.

Can I use a compact fluorescent light bulb with an electronic timer or photocell (AKA electric eye)?

Some electronic timers and photocells contain parts that are incompatible with compact fluorescent light bulbs; using these bulbs in incompatible products will result in a shorter light bulb life. To find out if an electronic timer or photocell is compatible with compact fluorescent bulbs, check with the manufacturer of the timer or photocell.

Does the EPA recommend the use of CFL bulbs?

Yes. CFLs, when compared with standard incandescent bulbs, offer many benefits. First, they help save energy and money. They use 2/3 less energy than standard incandescent light bulbs, and last up to 10 times longer. Replacing a 60-watt incandescent with a 13-watt CFL can save you at least $30 in energy costs over the life of the bulb. Second, CFLs offer convenience, because they last longer, and come in different sizes and shapes to fit almost any fixture. In addition, CFLs produce about 70% less heat than standard incandescent bulbs, so they're safer to operate and can help cut energy costs associated with home cooling. When shopping, always look for ENERGY STAR qualified CFLs.

Is it true that CFLs contain mercury? Why and how much?

CFLs contain a very small amount of mercury sealed within the glass tubing - an average of 5 milligrams (roughly equivalent to the tip of a ball-point pen). Mercury is an essential, irreplaceable element in CFLs and is what allows the bulb to be an efficient light source. By comparison, older home thermometers contain 500 milligrams of mercury and many manual thermostats contain up to 3000 milligrams. It would take between 100 and 600 CFLs to equal those amounts.

There is currently no substitute for mercury in CFLs; however, manufacturers have taken significant steps to reduce mercury used in their fluorescent lighting products over the past decade.

Should I be concerned about using CFLs in my home or should I take any special precautions?

CFLs are safe to use in your home. No mercury is released when the bulbs are in use and they pose no danger to you or your family when used properly. However, CFLs are made of glass tubing and can break if dropped or roughly handled. Be careful when removing the lamp from its packaging, installing it, or replacing it. Always screw and unscrew the lamp by its base, and never forcefully twist the CFL into a light socket by its tubes. Used CFLs should be disposed of properly.

What do I do with a CFL when it burns out? What is the proper disposal of a CFL bulb?

Follow these guidelines to dispose your CFL properly:

• Our local waste management agency in the Brazos Valley recommends place the CFL in a plastic bag and seal it then place it in the your household waste container.
• ENERGY STAR qualified CFLs have a two-year warranty. If the bulb fails within the warranty period, return it to your retailer.

What should I do if a CFL breaks?

Because there is such a small amount of mercury in CFLs, your greatest risk if a bulb breaks is getting cut from glass shards. Research indicates that there is no immediate health risk to you or your family should a bulb break and it's cleaned up properly. You can minimize any risks by following these proper clean-up and disposal guidelines:

• Sweep up—don't vacuum—all of the glass fragments and fine particles.
• Place broken pieces in a sealed plastic bag and wipe the area with a damp paper towel to pick up any stray shards of glass or fine particles. Put the used towel in the plastic bag as well.
• If weather permits, open windows to allow the room to ventilate.

How much heat (or infrared radiation) is emitted by regular, halogen, and compact fluorescent light bulbs?

Regular light bulbs, known as incandescent bulbs, create light by heating a filament inside the bulb; the heat makes the filament white-hot, producing the light that you see. Halogen light bulbs create light through the same method. Because incandescent and halogen bulbs create light through heat, about 90% of the energy they emit is in the form of heat (also called infrared radiation). To reduce the heat emitted by regular incandescent and halogen light bulbs, use a lower watt bulb (like 60 watts instead of 100).

Fluorescent light bulbs use an entirely different method to create light. Both compact fluorescent bulbs and fluorescent tubes contain a gas that, when excited by electricity, hits a coating inside the fluorescent bulb and emits light. (This makes them far more energy-efficient than regular incandescent bulbs.) The fluorescent bulbs used in your home emit only around 30% of their energy in heat, making them far cooler.

What is the white powder I see inside my fluorescent bulb?

The white powder that you see inside a fluorescent lamp is called phosphor, which is a substance that emits white, visible light whenever it absorbs light waves. Both compact fluorescent bulbs and fluorescent tubes contain a gas that gives off invisible light when excited by electricity. This invisible light travels to the phosphor coating on the bulb, where it is transformed into light visible to the human eye.