View Full Version : lighting controls with fluorescents
07-23-2008, 11:43 AM
Why can't some lighting controls, like motion or light sensors, work with fluorescents? Is it because of noise on the line? A tendency to flutter on and off when changing modes? Or is it a RFI thing?
07-23-2008, 01:06 PM
My understanding is that the controllers can't handle the reactive load of a fluorescent fixture's ballast, as opposed to an almost purely resistive load of an incandescent bulb's filament.
07-23-2008, 01:12 PM
Solid-state lighting controls use Triacs to switch the load. Triacs handle resistive loads just fine, but a cheap circuit design may be marginal with inductive loads, due to the current and the voltage not being in phase, which can cause turn-off problems. There are solutions to this problem, but it increases the cost a little, and the manufacturer might just not want to deal with all the potential problems.
If you are truly interested in the nitty-gritty, here is a start: http://www.eng.uwo.ca/electrical/information/courses/ece457a/Thyristors.pdf
07-23-2008, 02:53 PM
Many will work fine, if down-rated. Which is easy to do, since CFL bulbs are much lower wattage than the equivalent incandescent bulbs.
I have a motion detector light on my back door; the controller was designed to handle 150 watts (2 75-watt floodlights), but I have since replaced those with 2 CFL lights of 26 watts each. So the controller is handling only 1/3 of it's capacity. That's been working fine that way for several years.
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