1. mmoathudi

    Thread Starter New Member

    May 9, 2008
    Why is it that CFLs (Compact Fluorescent Light Bulbs) are not suitable for use with light sensors (daylight switches)? From all the literature available to me I can't find the reason they can;t work. Help.

    "Still trying to find my feet, but forced to run".
  2. jpanhalt


    Jan 18, 2008
    How about providing a reference for your original premise? There are a lot of myths out there.

  3. HarveyH42

    Active Member

    Jul 22, 2007
    I switched over from the old incandescent types, and found that my solar calculator no longer works. Had it for more then 20 years now, it was great, never needed batteries, nothing to plug in. Wonder if it's the pulsating light, or weak in the infrared area...
  4. thingmaker3

    Retired Moderator

    May 16, 2005
    Last Friday I bought a CFL with daylight sensor built into it. It works just fine.
  5. jpanhalt


    Jan 18, 2008
    The question may not be whether a daylight sensor will continue to work with daylight to turn the CFL on, but whether the CFL will self-activate those photosensors.

    In other words, I wonder whether the OP meant that CFLs didn't work with light sensors because they were so bright as to turn the sensor off again. Thus the lights would go on, then turn off because of the detected light, etc. unless the photosensor was physically shielded, had a light filter to prevent/reduce detection of the CFL light, or a built-in time constant to prevent reacting to pulsating light. A CFL with a built-in light sensor would be expected to include such design features.

    I did a couple of searches and found nothing. I suspect CFL's light emission is biased toward shorter wavelengths, hence the bleaching effect on paintings and photographs. By itself, that should not reduce photocell sensitivity to them. It might actually increase photocell sensitivity to them.


    That leaves HarvyH42's suggestion that maybe there is something also to do with pulsations. Does your calculator work with regular fluorescent lights?