Home Improvement Expert Danny Lipford

How to Fix a Buzzing or Humming Dimmer Switch

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Turning on a dimmer switch

Some dimmers and light bulbs are more prone to buzzing than others.

My dining room chandelier is operated by a dimmer switch, but every time we dim the lights, there’s an annoying buzzing or humming sound. What’s wrong and how can we fix it?

Talk about mood lighting! If you don’t like serving dinner with a nice buzz, the good news is that you can probably fix the problem either by replacing the bulbs or the dimmer switch itself.

Dimmer switches work by chopping up the AC current flowing between the switch and the light. Rather than literally “dimming” the light itself, these switches actually cause the current to undulate or flicker extremely rapidly, so that to our human eyes, it appears that there is less light. The interrupted current can produce a vibration in the electromagnetic field within the light bulb filament or within the switch itself, which can cause a humming or buzzing noise.

Here are some steps you can take to reduce or eliminate the annoying sound:

  • Change Light Bulbs: If the sound is coming from the light fixture itself, you might try a different type of bulb. Decorative bulbs, with their long, delicate filaments, are more susceptible to the changes in magnetic field. Standard and rough service bulbs, such as those used in workshops and appliances, have tougher filaments that might stand up better to the choppy current.
  • Light bulb controlled by dimmer switch.

    Light controlled by dimmer switch.

  • Upgrade Dimmer Rating: If the sound is coming from the dimmer switch, you may be overloading the switch’s capacity. Dimmer switches are rated according to the maximum wattage they can handle. If you’ve installed high wattage bulbs in your chandelier, the switch may be over capacity. You can check this by removing a few bulbs and seeing if the buzzing gets better. Or by checking the wattage rating on the switch against the sum of the wattage of all the bulbs. If so, reduce your overall wattage, or look for a dimmer switch with a higher wattage rating.
  • Upgrade Dimmer Switch: With dimmer switches, you get what you pay for. Buzzing is more common with cheaper triac-based switches (a triac is the gizmo inside the switch that chops up the current). Better quality triac dimmers have an internal choke or filter that evens out the current and can reduce buzzing. Or, you can go for an even higher quality dimmer that uses an autotransformer, rather than a triac, which causes much less interruption to the current.
  • Consider Lighting Usage: If you always use the lights on a dimmed setting, consider installing lower wattage bulbs so the dimmer doesn’t have to work as hard.

Also, don’t forget that incandescent bulbs are phasing out! Dimmer switches won’t work with CFL bulbs unless the bulb is rated as “dimmable,” and even then older dimmer switches may not work properly with CFLs. So if you’re replacing your dimmer switch, be sure to get one that’s designed to work with compact fluorescents and LEDs, such as these from Lutron, and choose bulbs that are rated as dimmable.

Julie

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2 Comments on “How to Fix a Buzzing or Humming Dimmer Switch”

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  1. Patty Kimball Says:
    April 5th, 2013 at 9:57 pm

    Thank you so much for this posting! I’m a single woman and my brother-in-law replaced my kitchen light fixture for me. I had put i the energy saving bulbs and my dimmer switch was buzzing like crazy! Who would have thought it would be such a simple fix. If changing the light bulbs did not work, I was going to have to call an electrician to figure out what the problem was. The buzzing sound made me nervous like my light switch was going to electrocute me or catch on fire or something. Your posting was so helpful and appreciated!

  2. Official Comment:

    Ben Erickson Says:
    April 6th, 2013 at 7:54 am

    Hi Patty,
    Glad we could be of help!

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