Dimming flourescent with motion detector

[yankj]

has anyone had experience with 2 X 4 layins on a dimmer & seperate motion detector? Complaint is lights will suddenly go off or go dim on their own. Lady can hit wall by dimmer switch and they are fine. This is in a conference room at a 1 plus year old elem. school. Supposedly, the original EC has been out checking this in the past. I haven't had a chance to tear into yet, looking for clues...

 

[gar]

100305-2143 EST

Is the ballast in the fluorescent fixture designed for dimmer control? If so then how is the dimming controlled?

To make fluorescents dimmable by controlling the current thru the lamp it is necessary to power the filaments in the bulb. In other words self heating of the filaments will not provide satisfactory dimming range.

So the ballast has to have filament secondaries that provide continuous excitation to the filaments.

Control of lamp intensity is then controlled by the average current thru the bulb. Some ballasts have built in dimming circuitry controlled by a low voltage control signal. There are other communication means to ballasts with built in dimming control. The simplest form uses an ordinary ballast with the addition of the filament secondaries, and then a more or less standard phase shift dimmer control adjusts the average current to the ballast.

You need to know how dimming is controlled in your fixtures.

If an external phase shift controller is used, then you need one designed for fluorescent dimming. Lutron makes at least one and it is about $60.

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[Dennis Alwon]

has anyone had experience with 2 X 4 layins on a dimmer & seperate motion detector? Complaint is lights will suddenly go off or go dim on their own. Lady can hit wall by dimmer switch and they are fine. This is in a conference room at a 1 plus year old elem. school. Supposedly, the original EC has been out checking this in the past. I haven't had a chance to tear into yet, looking for clues...

I suspect the motion sensor is not compatible for these dimmers. Check with Lutron 24/7

 

[nez]

I've installed a system like the one you describe. It was a lutron graffic eye system. Actually the dimmable lights were installed for a while and we went back to install the motion sensor later. I had to call technical support to get everything working right, but the system works fine with no callbacks. Just check everything, including the ballast wiring. once I wired the ballast wrong and they would work, but randomly go off. If she is hitting the wall and they work properly, maybe it is a loose connection or incompatable equipment.

Also if they go off on there own, maybe the sensor is not set right and not picking up motion, when she goes to the wall it picks up her motion?

 

[weressl]

has anyone had experience with 2 X 4 layins on a dimmer & seperate motion detector? Complaint is lights will suddenly go off or go dim on their own. Lady can hit wall by dimmer switch and they are fine. This is in a conference room at a 1 plus year old elem. school. Supposedly, the original EC has been out checking this in the past. I haven't had a chance to tear into yet, looking for clues...

These are rather convoluted, not to mention energy inefficient designs to accomplish a simple task, unless I am missing something.

The task would be to turn off energy use when the room is unoccupied, but allow sufficient lighting for egress - really just that the person does not get scared - when the motion sensor goes off as the result of no movement detected. So one would put ALL the lights on the motion sensor as the ON/OFF control, except a few fixtures to provide the egress lighting. These should also be the ones that are on the emergency circuit or backed up by the generator, emergency supply.