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  1. #11
    Join Date
    Jan 2011
    Location
    Columbiana, Alabama
    Posts
    721

    Default Re: Motion Detection Switches & CFL Flicker

    Good info Pimba. The 2011 Code now requires a neutral in every switch location, even if it's not used. This was done so electronic occupancy sensor switches could be operated without the ground wire normally carrying current (usually only 0.5 MA).

    If you find a dimmer/CFL combination that works, stick with it..many don't.

    Also, be sure you have a neutral wire on an occupancy sensor you're buying and the box it's going in. Otherwise, it's a Code violation and may not work. Finding a neutral on a occupancy sensor is no easy task, all the supply houses and the big orange or blue stores I've checked don't stock them yet.

    Good Luck from Columbiana, Alabama
    Maurice Turgeon, http://thesemiretiredelectrician.com

  2. #12
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,631

    Default Re: Motion Detection Switches & CFL Flicker

    I think you're on the right track, Maurice.

    In order to power a two-wire motion sensor, it must pass its return current through the light bulb since it doesn't have a connection to the neutral wire. CFLs don't do a good job of allowing this current; they'll flicker because of voltage that passes through the motion sensor when it's off.

    A three-wire motion sensor (not to be confused with 3-way) includes a neutral wire for the return current that must be connected to a neutral line. This allows the load side of the sensor to be completely unpowered when off so the CFL won't flicker.

    Moral of the story is it's best to use a 3-wire motion sensor and run a neutral to the switch box so you can use CFLs with it.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  3. #13
    Join Date
    Aug 2012
    Posts
    1

    Default Re: Motion Detection Switches & CFL Flicker

    I am using a motion detector in my garage with three porcelain ceiling bulb fixtures. I tried an LED for the second time in one of them. The switch will not turn the LED bulb off. The LED will go on when motion is detected but will only dim down (as if it is getting less voltage or current) to a low light and stay that way when the switch stops detecting motion. Is there a trickle current that lets this happen? I like the LED in the garage but cannot see the energy efficiency if the light does not go out.

  4. #14
    Join Date
    Jan 2011
    Location
    Columbiana, Alabama
    Posts
    721

    Default Re: Motion Detection Switches & CFL Flicker

    Sausage, the motion detector uses a transistor (Triac) to turn power on & off to the light bulb but because the CFL or LED draws so little power it can't function.

    As Fencepost said the device w/ 3 wires probably uses a relay output rather than a Triac so they work fine.

    I had a closet w/ two 60W incandescent lights on an occupancy sensor and like yours, the CFL's I installed wouldn't go out.
    I re-installed one of the 60W bulbs (loaded the circuit) and now everything is fine.

    Spending the extra money on CFL's or LED's is hard to recover because the lamps only come on for a few minutes at a time.
    Good Luck from Columbiana, Alabama
    Maurice Turgeon, Hidden Content

  5. #15
    Join Date
    Apr 2012
    Posts
    212

    Smile Re: Motion Detection Switches & CFL Flicker

    Quote Originally Posted by skrillet View Post
    Will led light bulbs also flicker on a motion detecting switch?
    You need a switch rated for LED's. I know Cooper makes some (OS310U).

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