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I’m trying to pick some LED light bulbs for outdoor use. I live in Canada and we can get temperatures below -40°C. On all the bulbs I look at, there is the disclaimer:

Minimum starting temperature -25°C (-13°F).

What does this mean? Will the bulbs not work reliably below this temperature? I’ve tried searching the internet and everybody (albeit of indeterminate knowledge) is saying that LEDs will actually work better at cold temperature.

For what it’s worth, I did come across one bulb labelled “COLDSTART” and “-40°F” but, unfortunately, it is not as bright as I would like.

  • The LEDs themselves likely will work fine. But there could be issues with the driver circuits, which convert ~120V AC to low voltage DC. – manassehkatz Oct 28 '18 at 0:34
  • Is this listed as the storage temperature or operating temperature? – Someone Somewhere Oct 28 '18 at 0:46
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    @blacksmith37 Home freezers are typically 0 F = -18 C, which is > -25 C (i.e., within stated range). -40 C is a lot colder. – manassehkatz Oct 28 '18 at 1:08
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    As a general rule, many types of electronic components are designed to actually work across a wide range of temperatures and other conditions (e.g., humidity). Depending on the type of component and the manufacturer, they may be tested and binned based on quality (e.g., mil-spec gets the best, everything else goes to ordinary usage and likely to fail at extremes), or they may simply never be tested beyond the stated limits (and then anyone's guess as to whether they will work well or not). My general suggestion would be to spend a little extra for a good quality brand and hope for the best. – manassehkatz Oct 28 '18 at 1:46
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    Cold is likely much less of a problem than heat. But there may be issues with some components not producing the right voltage/current at extreme temperatures. The other factor is thermal expansion - the circuit might go from -40 C to 30 C in a relatively short amount of time. If it does that every day (or worse, several times a day) then that could lead to cracks or other problems. – manassehkatz Oct 28 '18 at 1:48
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It is exactly what it states. That’s the minimum temperature for the bulb to start. It doesn’t necessarily mean the bulb won’t work below that temperature. It probably will light. Rather it means either that some of the electrical components will not perform within specs below that temperature, it simply wasn’t tested below that temperature, or use below that temperature will cause damage and limit it’s lifespan. If you’re going to regularly use the bulb at -40, get one rated for that for lower temperatures. If nothing else, it will likely mean replacing the bulb less often.

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