Recently, I installed a regular light switch with a slide dimmer next to it for my bathroom light (inexpensive 3 40-watt bulbs on a metal box), so when I get up in the night, I can turn the light on and see, without frying my retinas...
But ever since I installed the switch, there is a 'hum' from the lights--even when the dimmer is on full. This did not happen with the ordinary light switch.
Is there anything I can do to keep the dimmer and minimize (or eliminiate) the hum?
Thanks.
If the hum is really coming from the bulbs then it is possible that the filaments are vibrating at 60Hz and this vibration is perhaps amplified by a natural mechanical resonance of the enclosure. The fact that it hums even when it is on-full, indicates that the dimmer is not delivering the full sinewave, in other words is switching at < 180 degree. To prove this point measure the AC voltage (Vrms) before the dimmer and after the dimmer. If this is the case, you should notice a measurable voltage decrease after the dimmer on-full position. To diminish the hum try experimenting by changing the natural frequency of the enclosure.
Gene
A quality dimmer is often the right answer. Very cheap (or no) filtering of the dimmers output causes louder humming. High quality units have an ~1" coil that reduces filament hum dramatically.
Mostly these dimmers come in the large "decorator" style faceplate. Yours sounds like Lutrons "Ariadni" try their "Diva" instead.
Richard Reid, LC
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