What would cause a LED bulb to flash when cold? (120V)

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Andyman
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What would cause a LED bulb to flash when cold? (120V)

I have a few of these bulbs (Polaroid 120V 30W PAR38) in outdoor fixtures around my house. Most of the time, they work great – at least as bright as the incandescent versions, I like the tint, no problems. Until it gets cold. Below about 30F, one of the bulbs starts flashing, it just strobes on about twice per second. Below about 20F, both of them (in the same fixture) flash. Leaving them on for a while (to “warm up”?) doesn’t help. Same bulbs work fine when ambient temp is higher (i.e. no permanent damage from cold). They are not connected to a dimmer or daylight sensor; just a standard household switch controlling a simple floodlight fixture. They are wired downstream of a GFCI outlet, if that might make a difference, but the GFCI is indoors, so I don’t think that should be the culprit.

I also have a few of the “120-watt-equivalent” (23W) versions (link , same brand, same style) in a separate fixture, and they work fine, down to 0F and below – I’ve never seen them flash or act strangely.

Any thoughts on what might cause a low-temperature flash? More to the point, is there any chance of fixing this by replacing any of the components or circuitry? I haven’t looked closely at the bulb to see whether anything can be dissembled, but at this point I’m curious as much as anything.

TIA!

Edited by: Andyman on 01/05/2017 - 18:51
Jerommel
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You’re probably switching the ‘neutral’ in stead of the ‘phase’ or ‘ĺive’.
Due to condensed moisture there’s a little current leak to ‘ground’, so that the electronics accumulate energy until it’s enough to give off a flash.
Try reversing the mains plug.

Andyman
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Jerommel wrote:
You’re probably switching the ‘neutral’ in stead of the ‘phase’ or ‘ĺive’. Due to condensed moisture there’s a little current leak to ‘ground’, so that the electronics accumulate energy until it’s enough to give off a flash. Try reversing the mains plug.

Thanks for the suggestion! I’m confident that switch and fixture are wired properly, but I can double check tonight (some of the wiring is currently accessible). Assuming it’s wired correctly, is it possible that something is reversed inside the light itself to cause this condition?

Andyman
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As I was browsing I found a “cold start LED” (link ) – any idea what would make it better for “cold start” (besides marketing)?

Angler
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To me it sounds like a bad solder joint which is showing itself when it gets cold.

Should be easy enough to open up the fixture and retouch any soldered connections with a soldering iron.

Andyman
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Angler wrote:
To me it sounds like a bad solder joint which is showing itself when it gets cold.

Should be easy enough to open up the fixture and retouch any soldered connections with a soldering iron.


Interesting – that could make sense, if something was contracting when it got cold enough. But wouldn’t a loose connection result in random flickering? What I’m seeing is a very consistent strobe, approx twice per second.
Not much to lose, I suppose – I’ll attempt to pull it apart anyway.
dw911
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Sometimes a fault in the house wiring or light fitting, especially outside in the damp will cause issues when replacing incandescent or cfl bulbs with led bulbs, they were always there but they only make them self evident when leds are used.

But in this case as you say it only does it below a certain temperature id say the problem is likely with the bulbs themself’s, some led bulb modules have switching power supplies which can include capacitors not really rated for operation below a certain temperature and when exposed to lower temperatures they can cause the issues you describe.

Jerommel
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I’m sorry, i thought this occurred when the lights were switched off.
I didn’t read the OP too well apparently…
So forget my comment.