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Thread: fluorescent light bulb's don't work with Timer's?

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    DoD Army bjferri's Avatar
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    Default fluorescent light bulb's don't work with Timer's?

    Why is it when I put a fluorescent bulb in a light that is on a timer it starts to blink, even though the timer os off? I have lots of timers around my house instead of the regular switches...does this mean I cannot use this type of bulb?
    Brian

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    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
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    I don't see any reason why this should happen, if everything is properly wired. A switch is a switch. Are these timers mechanical or solid-state?

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    DoD Army bjferri's Avatar
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    The timers are solid state. I don't understand this. Not that I'm an electrician, I don't think I wired them incorrectly.
    Brian

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    Plumber jimbo's Avatar
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    Lighting control devices....timers, photocells, and motion sensors.....can be problematic with fluorescent. Especially electronic devices like your timer.

    Here is the reason......

    Simple electronic in-line devices like maybe your timer are designed to replace a simple on/off switch in a box where only the HOT wire is present, not a ground or neutral. Therefore, they way they work is to "steal" a tiny amount of current. That is when the timer or photocell wants the lights to be OFF it is still passing just a few milliamps of current to operate its circuits, and be ready to switch when the time arrives. For incandescent bulbs, this current just passes through the bulb, and is so small that it does not even cause a little glow. But, flourescent bulbs DO NOT LIKE this set-up. It will cause the flickering etc. that you are seeing.

    The only solution is to get a timer which is specifically rated for fluorescent. They are much more expensive, and often require a neutral and/ or a ground to be present in the switch box, and you may or may not have that.

    Also, you have to look specifically at what kind of lamps/ballasts you have. Some of the timer/photo/motion devices will be rated for MAGNETIC ballast only, some for ELECTRONIC only, and some for BOTH. For a look at some devices and specs, try www.wattstopper.com

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    Moderator & Master Plumber hj's Avatar
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    Default timer

    Many nonmechanical timers are labled specifically that they are not suitable for devices with ballasts.

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    DoD Army bjferri's Avatar
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    I got it! Thanks. I do have the 3-wires needed; however, these timers are new and were expensive (maybe $15 or so) so I'll hold off. Thanks again!!
    Brian

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    Plumber jimbo's Avatar
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    Quote Originally Posted by bjferri View Post
    I got it! Thanks. I do have the 3-wires needed; however, these timers are new and were expensive (maybe $15 or so) so I'll hold off. Thanks again!!
    Unfortunately, @ $15, these fall in to the category of "cheapies". Think $35 to $55 for what you need.

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    They somehow need the closed circuit provided by the incandescant filiment to operate.

    2 wire photo cells are the same way.

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    Senior Robin Hood Guy Ian Gills's Avatar
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    I hate to be a kill-joy but I have the same problem with light switches with LED lights in them (to find them in the dark) and I have found that some brands of CFLs do work and do not flicker.

    It's trial and error, but I have had lots of success with the Lights of America brand.

    Another trick, is that if you have a device that uses more than one bulb, a chandalier for example, you can use CFLs + one ordinary incandescent. The presence of the single incandescent will stop any flickering.
    Last edited by Ian Gills; 06-02-2008 at 02:26 PM.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    CFL could use an electronic ballast or a magnetic one...my guess is a magnetic one might be more likely to work.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Senior Member SteveW's Avatar
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    Intermatic makes a switch capable of use with fluorescent bulbs - EI600. If it's like the model it supersedes, which I have in my house, it has a little motor which mechanically moves a SPST load switch. Mine has a AAA battery which needs to be replaced about once a year, since it operates the switching motor.

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    Computer Programmer Bill Arden's Avatar
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    My X-10 light switches have "latching" relays and work fine.

    My earlier research showed that most inline dimmers and photo cells would slowly charge the 200 volt DC capacitor until the "start up" circuit starts. The bulb would then flash as the switching power supply drained the main capacitor.

    The old style (plug in bulb) CF lights are also ok, but are less efficient.

    motor driven timers are also fine with CF lights.
    Important note Ė I donít know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

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    Senior Robin Hood Guy Ian Gills's Avatar
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    Interesting. What do you mean by "old style plug-in bulb"?

    Are those like the circular CFLs that have four prongs that plug into a plug on the light?

    Like this:

    or

    perhaps these:
    Last edited by Ian Gills; 06-03-2008 at 10:46 AM.

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    Computer Programmer Bill Arden's Avatar
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    Quote Originally Posted by Ian Gills View Post
    Interesting. What do you mean by "old style plug-in bulb"?
    Actually both of those since they tend to use magnetic ballasts and a starter.

    Although I've now seen both with electronic ballasts.
    Important note Ė I donít know man made laws, just laws of physics
    Disclaimer: I'm a big fan of Darwin awards.

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    Plumber jimbo's Avatar
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    Circline bulbs are usually magnetic ballasts. The plug in bulbs...if they have 2 pins that is usually a magnetic ballast, and if they have 4 pins, that is electronic ballast.

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