The buzz on dimmable CFL light bulbs
What causes the noise when CFL light bulbs are used with a dimmer?
Star Tribune (Minneapolis
Q: I'm having a hard time finding a good dimmable CFL light bulb, especially for recessed lighting. When I dim the lights, the dimmer makes a loud buzzing noise. The sound is loud enough to be bothersome and sometimes gives me a headache. I've written to both the light bulb and dimmer manufacturers and they haven't offered any solution. What causes the buzzing and how can I fix this problem?
A: The reason you're not getting any answers is because there aren't any yet.
A dimmer typically reduces the effective voltage, which decreases current to the bulb. The science behind fluorescents just isn't meant to work that way, explained Paul McLellan with eLightBulbs, a division of Service Lighting, a Maple Grove, Minn., lighting supply company.
It can cause dimmer switches, or the ballast, to buzz. It can even affect other electronic devices nearby, such as radios. The distortion can even go so far as to cause flickering in the light bulb itself. Occasionally, you may be able to dim by 30 to 40 percent without any adverse reactions.
"We have looked at around 20 different brands and although some of them get close, the science is not yet there," McLellan said. "We do hear of some success, however, usually with high-quality, brand-name bulbs and dimmer switches." Sometimes it's a matter of finding which brand of bulbs works with specific dimmer switches. You may need to change the dimmer.
Remember, not all compact fluorescents are designed to work with dimmers, but CFLs made for dimmers are available. You can use regular compact fluorescent bulbs with dimmer switches, but doing so can shorten bulb life and nullify the bulb's warranty.
Until the technology improves, the best option may be an energy-saver incandescent light. There are 40-watt incandescent floodlights that give off the light equivalent of a traditional 60-watt incandescent flood. By using them with a dimmer, you will use less power and extend the life of the bulb, McLellan said.
These energy-saver incandescent lights comply with the new federal law requiring more efficient light by 2012. (Many people mistakenly believe the law requires a switch to fluorescent lighting. It doesn't. It's just that fluorescent lights, at the time, were the obvious way to comply with the new standard.)
Most light bulb manufacturers offer the new energy-saving incandescent, such as eLogic by Sylvania.
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