The situation: I want to replace incandescant bulb in a ceiling socket with LED or CFL.

The conditions:

  1. When I plug in a CFL, it glows when the wall switch is in the off position, gets brighter when turned on, and makes ominous hissing / crackling sound.
  2. When I plug in an LED, it is on when the wall switch is in the off position, gets brighter when turned on, makes an ominous hissing / crackling sound, and flickers.
  3. Pre-existing condition: With incandescent, wall switch position doesn't always determine on/off status (i.e., sometimes have to toggle several times)
  4. The switch is not a dimmer switch and does not have a timer.

The questions:

  1. Does the hissing / crackling sound indicate danger?
  2. What accounts for the pre-existing condition? Is it simply a faulty switch?
  3. Does the pre-existing condition explain the CFL / LED issues?

and, of course

  1. Is there a solution?
  • It sounds like there is a ballast in the fixture.
    – Ed Beal
    Aug 28, 2020 at 14:12
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    – isherwood
    Aug 28, 2020 at 16:15

2 Answers 2


You have problems,all right. Almost certainly your wall switch is broken, which is why you had to toggle it repeatedly w/ the incandescent bulb in place. Replace the switch first.

In all likelihood all the other problems resulted from your broken switch providing voltage but very little current when in a "not quite on OR off" state.


Switch the Switch

I suspect you have one (or more) of the following:

  • Timer
  • Motion Sensor
  • Dimmer
  • Lighted Switch (light is on when switch is off)
  • Smart Switch

Many of these work by leaking current through when "off" in order to power themselves, or do other strange things (particularly older dimmers) that are incompatible with many LED and CFL light bulbs.

If you have any of the above, switching to a simple switch will do the trick. Alternatively, if you want the "features", look for a switch that requires neutral (of course, that will only work if neutral is available in your switch box). Next best choice would be a switch that specifically claims compatibility with LED and CFL. In addition, an LED bulb that specifically claims "dimmer compatible" will often help as well.

If this is already "just a truly ordinary switch", then swapping it for another one (some are less than $ 1) is worth a try.

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