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Ask Mr. Tight-Watt: CFL bulbs and dimmer switches  Smart Choices Archive

Ask Mr. Tight-Watt: CFL bulbs and dimmer switches

Mr. Tight Watt says you can use CFL bulbs with a dimmer switch.

Ask Mr. Tight-Watt

Q: I have 5 ceiling can lights at 120v that use 65watt bulbs. This is not enough light and I can’t use CFL (compact fluorescent light) bulbs because of a dimmer switch. Using regular light bulbs, how many watts can I safely increase to? From Herb, a Smart Choices reader

A: Mr. Tight Watt asked for advice from expert Curt Klaassen, former manager of the Energy Resource Station for the Iowa Energy Center. Curt says:

This is a good question with several possible outcomes.  First of all, check the inside of your can light fixture with the bulb removed for a sticker indicating the maximum watts the fixture is rated for.  That maximum watt limit is important in preventing a fire hazard from the heat buildup since an incandescent bulb converts most of the power it consumes into heat.  Another limit would be the size of the bulb that will fit into the fixture while not exceeding the rated watts for the fixture.  Remember that can lights require a reflector type light or flood lamp for the best lighting performance. 
To increase the amount of light, look for a bulb with the highest lumens.  Lumens are a measure of the light output of a bulb.  A typical 65-watt reflector-type incandescent bulb for a can light will produce about 625 lumens of light output.  One option would be a 60-watt Halogen reflector-type bulb, which can produce 700 lumens, providing more light and saving some energy. 
For the most energy savings while keeping the dimmer option, consider a dimming CFL reflector-type lamp.  Most typical retail outlets do not carry a large selection of dimming CFL reflector lamps; however, they are available from electrical suppliers and through the Internet. A high-quality dimming 65-watt equivalent CFL reflector lamp will produce 700 lumens from 16 watts of power—giving you 12 percent more light for one-fourth the energy!  If fixture space allows and more light is important, it may also be possible to use a larger 23-watt reflector-type dimming CFL with over 1,000 lumens light output.
Dimming CFL bulbs
can save significant energy and money, but they are also more fussy to use.  Here are a few important points to remember when using a dimmer with CFL bulbs: 

  1. Use the same model and wattage of CFL bulbs for all lights on the dimmer switch.
  2. All of the bulbs on the dimmer switch circuit should be replaced with CFLs … do not leave any incandescent bulbs on the dimmer since they will interfere with the operation of the dimming CFLs.
  3. The very first time the dimmable CFLs are turned on you should “burn in” the bulbs at full brightness for at least one hour.
  4. Every subsequent time they are used, the dimmable CFL should be turned on to full brightness for a minute or two before dimming down to the desired level; this gives better lighting and avoids flicker. 
  5. Dimmable CFLs will dim down to 20–50 percent of light output, dependent on the type of dimmer switch. They normally do not dim down as low as incandescent bulbs.
  6. Dimmable CFLs do not work with all dimmer switches, so it may be necessary to replace your dimmer switch.
  7. Last, but not least, if you think the dimming feature may not be necessary, install a standard light switch with standard CFL reflector type bulbs and have all the light for one-fourth of the energy. 

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