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I installed a dimmer switch in my washroom and it's making a buzzing noise. The more I increase resistance/rotate the dimmer clockwise, the louder it gets.

The humming seems to be coming from the common wire, not from the light fixture, live wire or from the mechanism within the dimmer itself.

The dimmer switch is advertised to hold up to 600w and I'm currently using 340w.

I tried to remove some of the lights and the noise persists.

The one thing I did notice is that the common wire isn't exposed or attached at the end, a section of the wire has been stripped at that's what the original switch was attached to.

How can I lessen or completely rid myself of this humming noise?

Edit: I've since replaced my Leviton rotary dimmer with a high end Lutron sliding dimmer and the problem still persists, at the same loud volume.

Leviton rotary dimmer packaging

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    Just FYI - all dimmers hum. Now some are noticeable unless you are in a completely quiet room with your ear against it.
    – DMoore
    Oct 22, 2014 at 0:32
  • What brand is the dimmer you bought?
    – Eric Lippert
    Oct 22, 2014 at 0:43
  • It's a Leviton single pole rotary dimmer (6681-W), I think it cost around $8. I attached a photo of the packaging to my original post.
    – Orun
    Oct 22, 2014 at 3:10
  • The humming is fairly loud. Almost the same volume as my battery operated electric shaver. I replaced it with a higher-end Lutron slider dimmer.
    – Orun
    Oct 24, 2014 at 4:32
  • Borrow a stethoscope and find out exactly where the hum is coming from.
    – A. I. Breveleri
    Nov 10, 2015 at 21:53

6 Answers 6

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All dimmers buzz a little bit. They "chop up" the AC waveform, which creates mechanical vibration (buzzing) and electrical noise (EMI). Usually they are the most quiet when the lights are fully bright, and get louder as you dim the bulbs. Here is a good page that describes what is happening. A different dimmer may be quieter, although Leviton does make solid products.

I suspect, however, that you may be using the "new" CFL (compact-fluorescent) bulbs? They're the ones with the twisted white glass tube. The electronics in most of these bulbs interact poorly with the dimmers and can cause a lot of noise problems, both audible and electrical.

Now that it has become difficult to find incandescent bulbs (at least here in the USA), a lot of people are having to choose between paying substantially more money for "dimmable" CFL bulbs, or simply replacing their dimmers with simple on/off switches.

Good luck :)

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  • They're incandescent bulbs, not CFL's, but the bulbs are a little larger for aesthetic effect (it's a row of four large bulbs above a washroom mirror, kind of like the ones they had in mid-century makeup rooms). In this case, the buzzing gets really loud; almost the same volume that my battery-operated electric shaver emits! Thanks for that link, I'll read up on dimmers and report on whether it works better with a higher quality dimmer.
    – Orun
    Oct 23, 2014 at 20:58
  • @OrunBhuiyan Oh, that's a lot louder than I expected. It shouldn't be that way, even with a cheap dimmer. Perhaps you just got a bad unit! If you try another dimmer and the problem doesn't go away, let us know :)
    – bitsmack
    Oct 23, 2014 at 21:21
  • Thanks: so I replaced it with a higher end sliding dimmer and it's still happening (same volume). The noise seems to be coming from the red common wire connection, not the actual dimmer itself.
    – Orun
    Oct 24, 2014 at 4:34
  • I'm not sure how a wire, or wire connection, could ever produce a noise like this and so loud. Are you absolutely sure it's not coming from the lamps (light bulbs)??
    – Speedy Petey
    Oct 25, 2014 at 2:05
  • Does the same hold true for LED bulbs?
    – merk
    Aug 26, 2015 at 2:44
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I just installed a Levitron 300w CFL dimmer in my newly renovated bedroom where I installed 4 recessed lights. The two CFL's dim great but the two LED 65w bulbs hum. I switched them around to make sure that it's not the switch but the bulbs that hum. After I switched out the 65w with a lower wattage the humming stopped. Make sure that all your bulb wattage that the dimmer is controlling is NOT higher than what the dimmer is capable of controlling. I hope this helps.

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If the dimmer itself is buzzing my suggestion is to replace the dimmer. I would only use a high quality dimmer like Lutron, Cooper, or a higher end Leviton. Also don't get a rotary dimmer.

Many cheap rotary dimmers are low quality with little filtering.

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  • So I take it I bought a lower quality Levitron? I'll replace is with a higher end dimmer.
    – Orun
    Oct 22, 2014 at 3:17
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    I replaced it with a high end Lutron and I'm still having the issue. The humming is quite loud. I tried this Lutron at another terminal and it works without humming, but the humming isn't coming from the fixture above, it seems to be coming from the [red] common wire.
    – Orun
    Oct 24, 2014 at 4:30
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I noticed that putting a powerful magnet near the cord of my dimmed lights can eliminate the hum. Maybe you could get some semi circular magnets, and place them around the cord?

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  • Doesn't seem likely to me...
    – Daniel Griscom
    Apr 2, 2016 at 18:49
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I have seen cheap light bulbs that hum when dimmed. The problem is with the prongs that hold the filaments. With the cheaper bulbs there are not as many prongs to support the filament and keep from vibrating. Try a more expensive bulb.

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If you read on the package you took a picture of it states incandescent you will get a humming with cfls, or any fluorescent bulbs for that matter due to the igniter that excites the gas inside which produces the light. Incandescent bulbs use filaments which are small pieces of wire that are made to light up when "shorted". Hence the reason for the humming.

-Cjwntaw

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  • 1
    This doesn't really make sense to me...
    – Daniel Griscom
    Apr 3, 2016 at 12:13

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