Home>Discussions>ELECTRICAL & LIGHTING>Motion Detection Switches & CFL Flicker
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cschofer
Motion Detection Switches & CFL Flicker

A few months ago, I bought a few motion detector switches for the purpose of replacing standard toggle switches in select locations in my home. I don't remember exact details, but the switches cost roughly $20 each from my nearby general home improvement store.

I have noticed that the motion detectors work just fine with normal incandescent bulbs. I have also seen them work with compact flourescents -- but not always. When motion detector switch is set to the "Auto" position, the CFLs (or flourescents in general) have a tendency to flicker. Why is that? Is there anything I can do about it, aside from going back to the standard toggle switches?

BTW, the CFLs usually work fine with the motion detector switch in the "On" position.

Blue RidgeParkway
Re: Motion Detection Switches & CFL Flicker

i don't know why but i notice that a lot of the boxes say they can't be used with timers or light sensors/photo cells to. mabe you need to get ones that can be dimmed or work on sensors. check the box mabe.

canuk
Re: Motion Detection Switches & CFL Flicker

In a nut shell .... it's a compatability issue of electronic circuits between the electronic light controller and the electronic ballast circuit of the lamp.
Many times manufacturers will specify that electronic controllers like timers and or this type of light controller should only be used with incandescent lamps because of the problems you are experiencing.

The reason it seems to work in the "ON" position ....... the switch is bypassing the electronic control ciruit..... in other words acting like a standard switch directing power directly to the lamp.

Hope this helps.:)

JLMCDANIEL
Re: Motion Detection Switches & CFL Flicker

You have to get motion detectors specifically designed and rated for CFLs.
Jack

cschofer
Re: Motion Detection Switches & CFL Flicker
canuk wrote:

In a nut shell .... it's a compatability issue of electronic circuits between the electronic light controller and the electronic ballast circuit of the lamp.
Many times manufacturers will specify that electronic controllers like timers and or this type of light controller should only be used with incandescent lamps because of the problems you are experiencing.

The reason it seems to work in the "ON" position ....... the switch is bypassing the electronic control ciruit..... in other words acting like a standard switch directing power directly to the lamp.

Hope this helps.:)

Why is this an issue? A CFL needs roughly 120VAC to illuminate. The circuit in the motion detector turns that supply on and off. Does that circuit degrade the voltage to a point at or below the threshold that the CFL needs to light up?

This is "troublesome" to me because I have seen the detector switch work with a CFL with no flicker. Did I just get lucky? I had it working with 2 CFLs in parallel, but I added two more CFLs to that circuit, got the flicker, and went back to the toggle switch.

JLMCDANIEL
Re: Motion Detection Switches & CFL Flicker

A CFL rated motion detector has a mechanical switch or equivalent that opens and closes the circuit. The other types have solid state devices to turn the electric on and off. Unfortunately the solid state devices also leak electricity this causes problems with the starter circuits in the CFL. Without a complete turnoff of electricity the starter doesn't fire properly.
Jack

canuk
Re: Motion Detection Switches & CFL Flicker
cschofer wrote:

Why is this an issue? A CFL needs roughly 120VAC to illuminate. The circuit in the motion detector turns that supply on and off. Does that circuit degrade the voltage to a point at or below the threshold that the CFL needs to light up?

Pretty much as JLM metioned.

An incandesent lamp is a resistive load so controllers that use an electronic device to provide the switching this isn't much as a problem.

In the case of the CFL they are more complex because of the requirment to create an arc for igniting the gas inside the lamp.
The electronic"ballast" circuit used for this inside the CFL creates a reactive load and when switched with an electromechanical device has no issues with the load though with common electronic switching components can cause issues.

This is why many devices will clearly state whether or not they can be used with a CFL.

skrillet
Re: Motion Detection Switches & CFL Flicker

I do not know if anyone is still looking at this thread but I have a question regarding it. Will led light bulbs also flicker on a motion detecting switch?

Re: Motion Detection Switches & CFL Flicker

Its my understanding that they will not.

pimba
Re: Motion Detection Switches & CFL Flicker
skrillet wrote:

I do not know if anyone is still looking at this thread but I have a question regarding it. Will led light bulbs also flicker on a motion detecting switch?

Hi,
In order to an occupancy switch work with a CFL and LED bulbs it needs to be relay based.
After buying several switches and having the bulbs flickering a finally found one that works fine with LED and CFL bulbs.
It is part number MSW4KW from BRAZIX and you can Google it to find a place to buy it.
Important to know is that they only work with hot and neutral wires. It took me a while to figure this out despite the fact that it was mentioned on the installation instruction.
Also, they do not work on single pole connection.
I hope it will help.
Pimba

Re: Motion Detection Switches & CFL Flicker

Good info Pimba. The 2011 Code now requires a neutral in every switch location, even if it's not used. This was done so electronic occupancy sensor switches could be operated without the ground wire normally carrying current (usually only 0.5 MA).

If you find a dimmer/CFL combination that works, stick with it..many don't.

Also, be sure you have a neutral wire on an occupancy sensor you're buying and the box it's going in. Otherwise, it's a Code violation and may not work. Finding a neutral on a occupancy sensor is no easy task, all the supply houses and the big orange or blue stores I've checked don't stock them yet.

Good Luck from Columbiana, Alabama
Maurice Turgeon, http://thesemiretiredelectrician.com

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