T-8 Flourescents and Motion Sensors


I just switched to 3 four foot T8 flourescents from 3 60 watt incandescents in my garage. What a difference! I might just add 2 more. However, there is a problem.
Due to my garage door opener having a permanently broken light, I fixed the problem by putting a motion sensor switch on the incandescents. Car pulls in, light goes on.
The motion sensor and the flourescents don't play well together. If I use just the Off/On it works fine, but in Motion mode I get wierd behavior.
Any thoughts?
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FriscoSoxFan wrote:

I'm not 100% sure. But, the motion sensor probably increases the power to flourescents gradually, instead of instant on. The flourescent lights don't like that. I beleive you would find the same thing true if you tried to connect the flourscents thru a light sensor or a light dimmer. Flourescent need full power.
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Or possibly uses some kind of SRC widget (or similar) that is half-wave rectifying the power. At least, that's my recollection of an explanation I got way back when. Dimmers do things like this too - hence their poor performance with flourescents.
I'd get a single incandescent to run off the motion sensor and separate the flourescents from that circuit. Do you want the motion sensor to operate the lights all the time?
Mike
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Dunno if it's the same thing, but I've got a small fluorescent fixture on the same circuit in the garage as my motion-sensor driveway light. Whenever the fluorescent is switched on, it triggers the sensor. There's no way the sensor is seeing the light from the indoor fixture so it has to be something the fixture is doing to that circuit.
Lee
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1. Older and some newer motion sensors can not be used with fluorescent lamps. It's stated on the package. 2. Solid state ballasts create a lot of line noise that affect other solid state equipment adversely. 3. Fluorescent lights are not what they appear to be (on all the time) they are actually flickering off and on a 60Hz rate. The motion sensor can see this. 4. Try this, put an incandescent (regular light bulb) lamp near the motion sensor so that it out shines the fluorescent lamps. If the motion sensor is still flaky then you'll have to get a sensor rated for fluorescent lamps. Hope this helps dusty
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dusty wrote:

This is likely the cause of problem: Electrical interference

No, they don't. They don't see motion per se, they sense changes in temperature, short term, as one moves across a field divided up like a fly's eye. They detect heat, i.e. infrared radiation.
Assuming you had it adjusted properly, set the temperature in the room you and the switch were in to 98.6 degrees and your body temperature would remain at 98.6 degrees while you were jogging around the room, you could do this all night in the dark since the "motion" sensor would never detect your presence.
My office has motion detection in place for the alarm system. It also has the largest span Hunter fan made (think it's 54" or something) and it sits the path of two of the three sensors in the general office area. It's rarely turned off yet never trips an alarm because it is at the same temperature as its surroundings.
We DID, however, have to install plastic deflectors to dissipate the hot/cold air coming out of the HVAC ductwork as THAT temperature differential would trigger an alarm condition.

Won't make any difference unless the fluorescents are being controlled by the motion sensor, in which case you're correct, they have to be rated to handle fluorescent fixtures.
Still think the answer is RF (radio frequency) interference on the line that's screwing up the detectors. We still occasionally get a false trigger if one of the squad cars triggers his radio when he's right outside the building. Cured that with requiring secondary signals (i.e. multiple zone) to the alarm controller rather than just one hit off the IR sensors.
Anyway, no motion detectors YET in my shop but after following this thread, there are for sure going to be some electronic ballast fixtures out there AND in the garage. They sound really good.
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You are correct when speaking of expensive motion detectors like you find in commercial environments however some of the cheap ones from the BORG can be all over the place on what they detect, I once had one pick up the change in light from a defective street light. Every time the street light went off it would turn on the driveway light.
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dusty wrote:

But I'm NOT necessarily speaking of "expensive" motion detectors. Those used in my alarm system cost something like $35 wholesale and include both coded, multi-frequency capable radio transmitters and relays if I want to run them wired.
That "defective" street light was not, I'll bet, a fluorescent tube device and when it turned OFF or ON (not flickered at 60hz) it created a change in temperature in that zone, hence your motion sensor on the driveway light picked it up. There is generally a sensitivity adjustment on your motion sensor as well as directional "tweaking" that likely could have solved your problem.
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Unquestionably Confused wrote:

FWIW, when CF lamps first came out there were a lot of problems reported with motion sensors, and not just the ones that controlled the lamps. That _may_ have since been addressed in all new production of one or the other but it's something to be aware of.
--
--John
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I've installed several motion sensors and security lights, and like dimmer switches, they all have said "incandescent bulbs only".. Ya can't fool them with fluorescent replacement bulbs, either.. btdt
mac
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I have a fluorescent capable motion sensor in my shop. It's been in use for over 10 years and comes on many times a day. You shouldn't be using a standard sensor to control fluorescents.
Dave
FriscoSoxFan wrote:

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