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Zaunerstollen 11-28-2010 07:45 PM

Motion sensor causing lights to flicker
I'm having a weird problem with my newly installed garage lights on a motion sensor switch. I have a new, dedicated circuit that was installed this morning. On this circuit I have an always live outlet for the garage door and four porcelain ceiling lamp holders on a motion sensor switch. Each of the lamp holders has a 27W CFL light bulb on it. The lights flicker when the switch is set to AUTO and stop flickering when the switch is set to ON. I also noticed the motion sensor indicator on the switch flickers too on auto. Also the speakers on my computer (which are inside on the other side of the house) hum when the garage lights come on. The computer is on a different circuit altogether. I'm returning the motion sensor tomorrow hoping it is only faulty. You guys have any thoughts or ideas on this? Thanks in advance.

DangerMouse 11-28-2010 08:05 PM

Does the sensor box say anything about using CFL bulbs? That might be the problem.
Buzzing speakers could be a grounding problem.


Zaunerstollen 11-28-2010 09:03 PM

Thanks for the reply DM. The pamphlet sent with the sensor says nothing about CFL lights. That is a good point though and I will ask the guys as the hardware store about it. As far as a grounding problem, the last lamp holder at the end of the series is not grounded. I did not have a screw to attach it to so I capped it off. I have two separate bus bars in my circuit breaker box and I did make sure the ground for this circuit was put on the correct side. If the unattached ground on the last lamp holder is the problem and I do indeed have a grounding issue, can that really cause an issue on a separate circuit? The TV and stereo, which are relatively closer to the garage than the computer did not hum.

On a slightly side note, if I can attach the neutral and ground on the same bus bar in a box with only one, should I attach the ground to the second neutral screw on the last lamp holder? I didn't do it and even think that that is wrong. But then again, I'm not an expert.

AllanJ 11-28-2010 09:12 PM

The neutral may not be connected to ground anywhere except in the panel where the first main disconnect switch (may be a breaker) is located.

Or did the instructions mention any kind of light as preferred or required? Tungsten means incandescent.

Zaunerstollen 11-28-2010 09:42 PM

Thanks Allan. I figured that about the neutral/ground wires. Just wanted to check. I assume I should just leave the last ground wire as is and capped, right?

The specifications for the sensor state:
"Max 500W Incandescent/Halogen"
"Max 500VA Fluorescent (2 tubes min)"
"Must use min 30W load"

The pamphlet that came with the sensor did not specifically mention "CFL" bulbs but they do talk about fluorescent tubes. I'm assuming they are close enough that I can use them. Do you think the possible grounding issue could be causing the flickering?

frenchelectrican 11-28-2010 09:53 PM

Can you expand little more on the motion switch do this motion sensor did use the netural conductor or not if not then that is the issue with electronic ballast.

And the brand name of motion sensor as well.

Before I can rule this out try unscrew one CFL and put in 60 to 100 watt incandescent bulb to see if that clear up the flicking issue if that did stop the flickering then you will need to get a motion switch with real netural connection that will slove the issue pretty much what you have there.


Zaunerstollen 11-28-2010 10:08 PM

Thanks Marc. The name of the company is "Tough and Glow." I went on their website and found a similar motion sensor. The online specs state:

"No Neutral Connection Required"
"Works with CFL, Fluorescents, fans, and motors"

My motion sensor does not have neutral hook ups. I has a black wire (Line), a red wire (Load), and a green wire (Ground). I'll have to reattach the motion sensor to try the incandescent lights. I will give it a try.


frenchelectrican 11-28-2010 10:13 PM

Just try one incandescent bulb and leave the rest { CFL } alone if that did the trick I will give you a trick how to slove it.


Zaunerstollen 11-29-2010 08:52 AM

I reinstalled the motion sensor and turned the circuit back on. The lights still flickered. I then changed the last CFL bulb with a 60W incandescent bulb and the flickering stopped as well as no more humming on the computer speakers. Upside, it worked. Downside, I have no idea what just happened! How did that "fix" it? and What do I need to do so I can put the CFL bulb back?

DangerMouse 11-29-2010 09:05 AM


Originally Posted by Zaunerstollen (Post 542013)
"Must use min 30W load"

I believe this is the key..... the 60w incandescent has a higher load.
Perhaps if you try a higher wattage CFL on one and see if that works?

Of course, I could be wrong, as usual, but when Marc comes back he may have the correct answer.


Zaunerstollen 11-29-2010 09:23 AM

When I saw "min 30W load" for the sensor, I assumed that was 30W total. Do you think they meant per bulb? or Does at least one bulb have to be over 30W? There is no literature I could find in the pamphlet on the company's website.

DangerMouse 11-29-2010 09:40 AM


Originally Posted by Zaunerstollen (Post 542189)
Does at least one bulb have to be over 30W?

That's what I'm thinking. Do you have a higher watt CFL to test with? One that's over 30 actual watts? (equivalent to 150w/200w incandescent, maybe higher.... don't quote me)


DangerMouse 11-29-2010 09:42 AM

It may be too that the incandescent bulb has a different architecture that allows it to work.
Remember, CFL's all have little ballasts built-in, right?


Zaunerstollen 11-29-2010 10:39 AM

I do not know as a fact, but that sounds right. It would have to have a similar inner workings as a tube. Also, the highest CFL I have right now is a 26W.

DangerMouse 11-29-2010 10:46 AM

Marc will likely explain it better, but I think we're onto the culprit here.
Does the 60w do the same trick in any socket, or just the last? Or haven't you tried it in others?


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