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-   -   Motion sensor & fluorescent fixture issue (https://www.diychatroom.com/f18/motion-sensor-fluorescent-fixture-issue-70853/)

trclac 05-09-2010 03:58 PM

Motion sensor & fluorescent fixture issue
 
I installed a motion sensor in my garage that automatically turns on the three fluorescent fixtures when we enter the garage. However, I've noticed that lately, one of the fixture's bulbs continue to blink when the sensor switches off. This blinking lasts for about 5 minutes on this one fixture, and the other two fixtures connected to the same wiring don't do this. I thought the motion sensor may be defective and replaced it, but the same thing is occuring, with the same fixture. Why would one of the fixture's bulbs continue to blink when the sensor supposedly shuts the power to the lights off?

Thanks.

Yoyizit 05-09-2010 04:05 PM

Quote:

Originally Posted by trclac (Post 439629)
Why would one of the fixture's bulbs continue to blink when the sensor supposedly shuts the power to the lights off?

I guess when the sensor is off it goes to a high resistance state.
If the fluorescent also has a high resistance at low voltage there might be enough voltage across it to give you your symptoms. Does it use an electronic ballast?

If the sensor uses an electromechanical relay this 'should not be happening'.

You could test this by temporarily wiring a 100w incand. bulb in parallel with the fluorescents.

trclac 05-09-2010 04:13 PM

Thanks. I don't know what type of ballast is used. These fixtures came with the house, but the fixture I'm having an issue with is a smalled fixture in a smaller area of the garage. So the ballasts could definitely be different. As for the sensor, I bought it at Home Depot. It's the 180 degree sensor that they sell. I guess my main concern (or at least the one my wife keeps asking me) is if this is a fire hazard?
One note -- when I turn the sensor to the off position, the flickering stops.

Thanks again.

davidbp 05-09-2010 04:41 PM

The sensor might be for just incand. light fixtures which is what the previous post implied.

Yoyizit 05-09-2010 04:57 PM

Quote:

Originally Posted by trclac (Post 439632)
if this is a fire hazard?

I doubt it but it could possibly cause the Triac in the sensor to fail by overheating.

If you get a chance, measure the sensor output voltage V and output current I with the flickering condition.
Input voltage is assumed to be 120v. If (120-V)xI is more than 5w or so the sensor is likely overheating.

homerb 05-10-2010 11:42 AM

I know it's not the ballast. The motion sensor must just be for an incandescent fixture.

I had the same exact problem with a motion switch I installed in a decora switchplate for my main foyer entrance light. I originally had a compact fluorescent light in that fixture, but with the motion switch, the light would go dim after about 10 seconds (after it didn't notice motion anymore), stayed dim instead of full on (during the countdown period after motion was last detected). I just switched it to a regular bulb. It's a candelabra fixture with a 20W bulb.

I try to have as many compact fluorescent bulbs in my house, but a single 20W incandescent bulb isn't going to make any difference in the power bill. Especially with a motion switch.

Homer


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