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I have a 14 W LED bulb (no brand name is marked) in a shallow, wide recessed ceiling mount (marked as 60 W) in my kitchen; the bulb is quite a few years old. It is on a regular on/off switch, not a dimmer switch.

Just recently, it's started occasionally turning off for anywhere from half a second to several seconds and then turning back on again. This happens at random intervals, sometimes as close as a dozen or so seconds apart, sometimes several minutes apart. It may happen within a minute or two of when the light is turned on, or the light may be on for many minutes before the first blink appears. It does not appear to be correlated with anything else in my apartment, such as the refrigerator or aircon turning on or off. (The aircon is occasionally being used in heater mode during the very mild +10°C winter here.)

The base of the bulb gets only barely warm to the touch after it's been on for a few minutes, and only slightly warmer after it's been on quite a while. (The kitchen is quite cool, usually less than 20°C.)

Is this merely an indication of an old LED bulb starting to fail, or could it be something else?

I do have electronics test equipment (multimeters, an oscilloscope, etc.) available and I know how to use it, though it appears as if I'd need to destroy the case to get the bulb open.

cjs
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    Is the bulb getting hot when its turning off? – ThreePhaseEel Jan 03 '23 at 03:20
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    Overheating (as implied be ThreePhaseEel's comment, flaky socket...or maybe it is a secret message... – manassehkatz-Moving 2 Codidact Jan 03 '23 at 03:42
  • is it on a dimmer switch ? unscrew it and screw it somewhere else – Traveler Jan 03 '23 at 03:44
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    In my experience with LED bulbs in recessed kitchen mounts during the 2010s era, yes, once a bulb starts going out it only gets worse and usually fails completely within a few months. LED bulbs can be sensitive to heat, and recessed ceiling mounts usually tend to trap heat. – Armand Jan 03 '23 at 06:44
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    This is the bulb's way of telling you it is tired and want's to be retired. – RMDman Jan 03 '23 at 12:56
  • Is it turning off when the refrigerator is turning ON? LED's are very sensitive to even minor voltage changes. – Steve Wellens Jan 03 '23 at 16:58
  • @Armand I've updated the question with further information for all the comments. It's definitely not directly correlated with the (quite low) heat level of the bulb, as in turning off at a given level and turning on after it cools down. – cjs Jan 04 '23 at 00:59
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    My suspicion unencumbered by facts is that thermal expansion/contraction cycles eventually cause a crack in a soldered connection or separation from a heat sink not securely attached (thermal sticky pad instead of screw). That defect progresses and causes more and more frequent outages until the light won't work at all. – Armand Jan 04 '23 at 01:31

1 Answers1

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To summarize the comments into an actual answer:

  • The bulb is likely getting hot in a recessed ceiling fixture and shutting itself off to cool down.
  • The bulb is likely failing and this is the initial indication of that behavior.

To add my own thoughts:

Having gone through more than 20 cheap LED light bulbs over the past couple of years, I can confirm that blinking off then on is the initial signs of death that I've witnessed over the years. You've got anywhere from a few days to a month or two before it blinks off for the last time.

FreeMan
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    These bulbs were advertised to last 20 years, yet my experience with various brands is they only last a few years, barely better than incandescent. – George Anderson Jan 03 '23 at 18:10
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    I agree, @GeorgeAnderson. I'll bet the LEDs themselves will last forever, but not the electronics driving them. – FreeMan Jan 03 '23 at 18:22
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    I do minor volunteer repairs for my church and about 3 years ago I rented a VERY TALL step ladder to replace bulbs in the craftsman style fixtures in our sanctuary. Many of the incandescent bulbs where burned out, so I thought replacing them all with LED (flood lights, BR 40 if I remember right) would be good future proofing, but now, already 4 of them have failed. Very disappointing. – George Anderson Jan 03 '23 at 18:57