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Do Dimmable Bulbs Last Longer?
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Mattyuk:
Hi All

I can't seem to find this discussed anywhere online - I was wondering if anyone had a view?

Question - all other things being equal, is a dimmable led 230v bulb likely to be more robust ie. last longer or be better protected against voltage spikes etc. than an equivalent NON-dimmable bulb used in the same lighting circuit? Please assume the lighting circuit is a standard UK domestic circuit and does NOT have any dimmer switches on it.

eg. https://www.screwfix.com/p/lap-0324784031-gu10-led-light-bulb-345lm-3-6w-10-pack/463pp vs. https://www.screwfix.com/p/lap-0318784030-gu10-led-light-bulb-345lm-3-6w-10-pack/186pp

Or conversely does the extra electronics in the dimmable bulb to make the bulb dimmable make it MORE susceptible to failure ie. last less time?

All views welcome. Experience or theory.
Zero999:
If the lamp is dimmed, then it should last longer, otherwise I wouldn't expect there to be a significant difference. It will be the same as anything else. A crap lamp, with overpowered LEDs and inadequate cooling won't last as long, as one with under-driven LEDs and excellent cooling.

I would thought going for as higher lumens per watt as possible, would result in longer life, because less heat will be produced and the LEDs are more likely to be under-drive, as efficiency is higher, at lower current densities. The lamps discussed in the original post have a similar lumens per watt, which isn't great by today's standards. I would recommend looking for something more efficient.
tooki:
Given the OP’s specification that the question is whether a dimmable bulb will last longer on a circuit without a dimmer, I would hazard a guess that it statistically might fail a bit more, since it requires a much more complex circuit to detect the duty cycle and adjust the power to the LEDs. With that said, I would also be very surprised if the failure rate were meaningfully higher, given that other factors (like how hot the bulb is designed to run, how much ventilation is available, etc) surely have a far larger impact.
Whales:
It depends on the exact failure mode of standard (non-dimmable) bulbs and exactly what has changed in the dimmable units.

Is it because of electrolytics drying out in a high-heat environment?  I've seen vented electrolytics in some failed CFLs.  I've not had any compact (bayonet/edison) LED bulbs fail yet to have a look at them.

The dimmable units might need a better switchmode PSU in them to withstand the wider variety of duty cycles.  Perhaps they have better or bigger caps as a result?  Or a higher operating frequency and/or efficiency?  In that case they _might_ last longer.


Regardless: I'm lead to believe the best choices you can make to increase bulb life are:

(1) Run them very well ventilated, ie not inside a glass/plastic enclosures (like a lightshade)
(2) Run multiple, smaller wattage bulbs in a multi-way adaptor.  I run 2x adaptors in edison screw sockets.

As a vague approximation: the Arrhennius equation says that for every 10degC you reduce of operating temp the life is increased by 2x.
Mattyuk:
Thanks all. It sounds like, unless there is a fairly standardised method that manufacturers would use to make their bulbs dimmable, this might be too hard a question to answer as there may be too many variables to know for sure. But thanks for the input regardless!
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