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Comment by parineum | Hacker News Reader

Holds true for a lot of electrical appliances, even lightbulbs. They always blow when you switch the lights on.

I'm not sure whether constant running is worse for wear and tear vs power cycling but power cycling is typically what precedes a failure.

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I expect the main reason incandescents tend to fail when the lights are switched on is because the resistance of the filament is lower when cold, so there's a brief spike in current much higher than steady state as it initially heats up.

The issue is constant running also has thermal cycles, the variance between peaks is just lower, but can be more rapid. (Spikes from particular instructions being more power hungry).

Also in this case we have mechanical components under constant usage (fans), and the effects of long term heat on the thermal compound between the die and cooler plates to consider.

> They always blow when you switch the lights on.

This isn't true at all.

I've never had one fail in a different manner. Modern LED bulbs seem to fail differently. I see lots of power delivery issues before they go

Yeah LED bulbs usually have their power supply go long before the LED itself due to inadequate cooling, LEDs themselves last a long, loooong time if properly driven.

That failure mode is more, it works fine when initially turned on, then starts failing/flickering on and off once it has gotten to temperature.

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