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I have 8 CFLs in a circuit of ceiling cans all connected to the same dimmer switch. They buzz all day until I add an incandescent light to one of the cans.

Why does the buzzing stop with the introduction of an incandescent light?

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    Are the CFL bulbs "dimmable CFL"? – mbeckish Nov 6 '14 at 18:16
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    @mbeckish is correct on making sure these are dimmables. If they are all dimmable, then you've found one of the issues with leading edge cut R and RL dimmers. The rise time is so sharp that it causes issues in the electronics, usually the dimmer is what buzzes. Adding some resistance to the circuit will slow the voltage rise. Trailing edge cut dimmers aren't prone to this noise because the front edge of the sine wave is preserved so there's a normal voltage rise. Change out the dimmer control to one the manufacturer specifies for CFL lamps to totally cure the problem. – Fiasco Labs Nov 12 '14 at 2:40
  • sounds like an answer @FiascoLabs. This is also what I did when I added LED bulbs to my existing dimmer circuit. the dimmer was not rated for the low resistance, and needed to add some to the circuit, i.e. added an incandescent. – Hightower Jan 5 '15 at 6:52
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@mbeckish is correct on making sure these are all dimmable CFLs.

If they are all dimmable, then you've found one of the issues with leading edge cut R and RL dimmers. The rise time is so sharp that it causes issues in the electronics, usually the dimmer is what buzzes.

Adding some resistance (an incandescent bulb) to the circuit will slow the voltage rise.

Trailing edge cut dimmers aren't prone to this noise because the front edge of the sine wave is preserved so there's a normal voltage rise. Change out the dimmer control to one the manufacturer specifies for CFL lamps to totally cure the problem.

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