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I have a buzzing sound coming from in ceiling light fixtures.
The fixtures are Liton LH1499IC (https://liton.com/ic-double-wall-housing-51083.html)

  • These fixtures are connected to a dimmer switch
  • Buzzing from the fixtures gets worse over time (as the light stays on)
  • Buzzing gets worse with full brightness
  • Buzzing gets worse if I completely remove the bulb but have the dimmer ON
  • Buzzing 100% comes from the fixture itself and not the bulb, I can hear it from inside the fixture and as mentioned, if the bulb is completly removed the fixture buzzes worse
  • Bulbs are 12V 50W which is what the fixture says to use. I tried changing to 12V 30W and 5W just to see what happens and the buzzing actually got much worse with the 5W as well

My first thought was to buy new fixtures and replace the old ones, but looking at the picture of that fixture it looks like its going to be alot of work (i've never replaced light fixtures before).

Next thought was could there be a relationship to the dimmer switch?

To be clear, the dimmer has no sound or buzzing whatsoever. But is it possible the wrong dimmer switch is connected and that is creating a buzz downstream at the fixture?

Dimmer is Lutron SLV-600P (https://www.lutron.com/en-US/Products/Pages/StandAloneControls/Dimmers-Switches/SkylarkDimmer/ModelNumbers.aspx)

  • 120 V / 600 VA (450 W)
  • I have 4 light fixtures connected to it, those are 12V, 50W each. MR-16

Bulbs are Osram 12V 50W MR-16 base bulbs

Is there any rule of thumb I can use in determining if the correct dimmer switch is paired to the correct fixture, or does it not matter? I'm essentially both hoping and wondering there is an easier solution to this problem then changing the fixtures

As you can tell, I'm a total noob.

Any help is much appreciated!

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3
  • What type of dimmer? The older style rotary dimmers won't work well with CFL or LED bulbs. Do you have an LED/CFL compatible dimmer? If you're not sure, remove the cover plate from the switch - there should be labeling stamped into the metal on the front of the switch that says the manufacturer and the model number
    – FreeMan
    Dec 6, 2020 at 18:27
  • @FreeMan Sorry I should have included that. The dimmer is a Lutron SLV-600P. It looks like a Magnetic Low-Voltage dimmer rated to 450 watts. There are 4 lights connected to it each with 50w. Bulbs are all Incandescent
    – Mark
    Dec 6, 2020 at 18:35
  • These are incandescent (halogen=incandescent) lights. LED lights will pay for themselves inside a year from the energy savings, to say nothing of the reduced A/C bill from having to remove 50x8 watts of heat, which is a lot.
    – Harper - Reinstate Monica
    Dec 7, 2020 at 2:50

1 Answer 1

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This is not a simple light fixture. It uses a TRANSFORMER.

Dimmers are tricky devices. While conceptually they adjust the incoming current with a variable resistance, in reality they are far more complex. The end result is that for direct use with incandescent & halogen bulbs, all dimmers work well. For use with dimmer-compatible (some are, some are not) LED or fluorescent bulbs, most modern dimmers (they will specify LED compatibility, as your Lutron does), they will work well.

However, your light fixtures include a transformer. That takes the 120V power and takes it down to 12V needed by the specified bulbs. That process is most definitely not compatible with a typical dimmer. The "right" way to dim such lights would be to dim them after the transformer. There are lights designed to work that way, but not your standard off-the-shelf residential stuff.

Update: Your dimmer (SLV-600P) is supposed to be compatible with Magnetic Low-Voltage fixtures. So it is basically "the right stuff". However, something is clearly going wrong, and my recommendations still stand, primarily because LED lighting has gotten cheaper and better (more reliable, better color) over the last several years and will save a lot in energy costs.

End result: Your dimmer is modern and fine. Your bulbs are "plain" and, in and of themselves, likely dimmer compatible. But your fixtures are not dimmer compatible.

Options:

1 - Replace the dimmer with an ordinary ($1 - $3) switch. No dimming. No buzzing.

2 - Replace the fixtures with your choice of:

  • Ordinary "cans" that will accept ordinary light bulbs and install dimmer-compatible LED lights.
  • Fixtures with integrated dimmer-compatible LED lights.
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  • Wow! Thank you so much for the detailed info. This helps tremendously. Im going to replace my dimmer with a regular on-off switch then. I do have a follow-up question, I actually have 4 separate rows of these lights, and 2 of the 4 are the ones that are buzzing. All 4 are using the same brand fixtures, dimmers, bulbs, etc.. is it just random that 2 are buzzing or do you think its likely those 2 that are buzzing have become damaged from being on a dimmer?
    – Mark
    Dec 6, 2020 at 19:08
  • A separate question, to replace the fixtures, I have to pretty much rip out the ceiling correct? I cant do it from the circular opening port to the fixture housing could I? Because as you mentioned there is a whole transformer attached to the fixture so the whole thing would need to be removed and replaced with an "ordinary can" ?
    – Mark
    Dec 6, 2020 at 19:09
  • Why are only 2 buzzing? Hard to say. But I would expect cumulative damage - i.e., over time the others may start buzzing too. How much to rip/replace is a big question. Depends on how exactly these were installed and how easy access is from above (e.g., attic).
    – manassehkatz-Moving 2 Codidact
    Dec 6, 2020 at 19:13
  • @Mark If you really want to use a mains dimmer for these fixtures, look into a Magnetic Low Voltage (MLV) dimmer, although you will likely need a neutral at the dimmer location for this
    – ThreePhaseEel
    Dec 6, 2020 at 19:30
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    @manassehkatz-Moving2Codidact Ok heres an update. I got new plain old ON/OFF switches (Lutron Claro CA-1PSNL-WH) and the buzzing is still there. So going to a regular switch didn't solve the problem. So it seems like the dimming function is not the source of the problem. Scared this is a much bigger problem. Any other ideas?
    – Mark
    Dec 13, 2020 at 1:36

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