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I have a couple of outdoor light sockets with built in motion detectors. These seem to work as you'd expect with regular incandescent bulbs- you can set a timer for how long you want them to be on when motion is detected and they light up fine.

When replacing them with LED bulbs however they blink rapidly instead of staying on. I'm not talking about a 50hz buzz or whatever, they completely power off and on rapidly, almost like they are trying to strobe. The blinking is erratic, it will go for 10 seconds then go dark completely, then blink again for varying amounts of time. I see this same behavior with LED bulbs in both of the sockets, which are the same brand and model of motion detector outdoor light sockets.

The bulbs are Verbatim A19 6-Pack Warm White 3000K LED Bulb, Replaces 60W, Non-Dimmable 99072 if that matters.

I want to replace everything in the house with LED, but not sure how to make these two sockets work correctly. Suggestions?

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  • Nothing to do with electronic design. Will be closed. – tcrosley Apr 9 '16 at 3:03
  • tcrosley is right. However, I will take a shot at offering this comment. Maybe there is some kind of dimmer on the circuit that is giving the LED lights fits. Try buying LED lights that are dimmable. The other possibility is that the bulbs are over-heating. Some of them cut in and out when they are too hot. – mkeith Apr 9 '16 at 3:34
  • This is square on-point to diy.se, which despite that name is exclusively about home improvement. – Harper - Reinstate Monica Apr 9 '16 at 4:23
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Are these the the type of motion sensors which use the neutral wire? A motion sensor needs power to work. Ideally it gets always-hot, and neutral, and then provides a switched-hot to the target bulb. Such a unit should work fine, I use them widely.

However some motion sensors are designed like old school dimmers - they are designed to work in old-style "switch loop" wiring which did not provide a neutral. They get power by placing themselves in series with the incandescent bulb - they allow a small amount of current to leak through, not enough for the bulb to light.

This totally falls apart with CFLs or LEDs because their switch mode power supplies do not play nice with that scheme. My suspicion is you have one of these.

You can get new sensor heads that do have neutral wires and attach in the same way (screw into a 1/2" knockout). I use them widely and they play nice with everything.

Or you can get entirely new sensor/lamp combos which are sealed, since the LED emitter is going to outlive us all. Some of those are 12V internally, i.e. the sensor runs on 12V as does the LED emitter head. 12V detector heads are much more economical than 120V ones.

Or you can slap an incandescent into one of the lamp positions. Or a resistor of appropriate size which has the same effect.

  • Thanks, this is super helpful. I was able to test a CFL and it didn't work either, so I'm guessing this is the answer – user1391445 Apr 9 '16 at 14:12
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They are obviously incompatible. Two possibilities come to mind- the bulb does not draw enough current in the right way for the switch in the fixture to stay on, or the bulb is creating so much EMI that it is interfering with the circuit in the fixture.

You could try another brand, preferably something that looks physically different so that they are likely not rebranded identical bulbs. Or you could replace the fixture.

I have replaced our outdoor motion-detector lamp fixtures with ones with built-in LEDs.. More expensive than cheap lamps, but they are lasting better through harsh winter conditions, so I don't begrudge the modest total expense.

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Actually it is because they don't draw the minimum current required for operation of the relay. You can put a LED bulb in one socket and a edison bulb in the other and it will work fine.

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The bulbs being non-dimmable probably matters very much. Buy a dimmable bulb and try that. If it doesn't work you can return the bulb but I think you'll find it's "fixed".

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I second the thought that LED bulbs tend to be more susceptible to voltage fluctuation and will flicker easily. I have a light-sensor driven porch light I bought at Home Depot and for the life of me, I don't know why LED bulbs flicker until one day I tried a set of CFLs and incandescent. Replacing CFL's immediately helped.

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    Hello, and welcome to Stack Exchange. You aren't clear; was it an incandescent or a CFL which worked best in the porch light? (Please edit the information into your answer.) – Daniel Griscom Dec 2 '18 at 4:08
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This is a defect in the manufacturing process. Many of the Verbatim A19 model bulbs will eventually fail with the symptoms of "blinking" or "strobing".

How do I know? Because these poorly made bulbs are cheap and I have seen hundreds of them fail resulting in the flashing or strobing effects before someone complains and they are thrown in the bin and replaced.

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