1 yr. ago • 100%

Do dimmers affect the life of LED?

In my kitchen I have a flushmount light with an integrated led. I put in an LED dimmer on the switch and all is working well.

However, I had to replace it way sooner than I was expecting. Is there a possibly that the dimmer is hard on it?

I have the exact same one on another non-dimmer switch that is still running fine. That said the other one gets much less use so it could just be that.

25 comments

You need dimmable LED bulbs. Also it’s very likely both the switch and the bulb will be trailing edge, but it’s worth double checking, because having one be leading edge and the other trailing edge can cause issues

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- It is a dimmable fixture. I made sure on that as I’ve run into that problem before.
  
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- Does it matter if it's a rheostat or digital dimmer?
  
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Speaking anecdotally here, but I have about a dozen LED's on dimmers that I use and adjust constantly. No dead bulbs after almost four years. How long did yours last?

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- Further anecdote, I've had a small number of LEDs die early that aren't on dimmers.
  
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- It lasted probably 2 years
  
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A lot of the LED bulbs have very cheap power supplies/control circuits. I've had the best luck with the filament-style LEDs. I remember seeing a video a while back stating filament-style LEDs tend to have better cooling because the driver circuit is surrounded by the metal screw material and the LEDs are separated from the driver PCB. I also haven't had a Phillips Hue bulb die on me yet, but they are quite expensive.

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- This is an in integrated LED fixture. Essentially a LED strip.
  
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I don’t think standard dimmers for incandescent bulbs work well with LEDs. Dimming leds is usually done with pulse width modulation, or turning it off and on very very quickly.

Led bulbs have more components inside to adapt the old school ac current to whatever the LEDs need, you might be killing those components with the dimmer.

Only solution i know off would be using smart bulbs if you want to stick with LEDs, but id imagine theres other ways to go about it, i just dont know

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- Off-the shelf non-smart LEDs are also a thing, they basically read the input voltage as the input for how dim you want them to be. Then adjust themselves as necessary to make less light (as you said, generally by pulsing very quickly). But, you do need ones that specifically say they are dimmable.
  
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- This was a LED specific dimmer
  
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It’s probably the amount of use those lights get. Theoretically it should last longer.

Things to check:

Is your dimmer from a reputable brand, or unknown Chinese origin?

Is your LED bulb compatible with dimmers?

If there is a problem with the dimmer it would be hard to diagnose without an oscilloscope.

Chances are its a dead capacitor on the LED’s driver board. LEDs last for ages, but manufacturers build in planned obsolescence through shitty support components. If you have a multimeter with a capacitor test function you could rip the driver circuit out and test them to confirm.

Other thing to check would be to make sure your lighting circuit has all the lights connected in parallel. Assuming you have more than one bulb on that dimmer, if they are wired in series then the first bulb would be having to handle the current draw for all subsequent bulbs. I imagine if this was the case it would be burning out pretty quick tho. You would know if they were in series though because all your other bulbs would stop working at the same time, and (im not an electrician) i dont think that this would be up to code anyway, so pretty unlikely.
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- I can’t remember the dimmer brand but maybe I can dig it up. It would be an easy swap regardless and maybe worthwhile.
  
  This is the only fixture on this switch.
  
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  I wouldn’t worry too much right now. Just replace the bulb and see if it dies quickly again. Can’t draw too many conclusions from a sample size of one!
  
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I know LED bulbs don't like old-school dimmers, but I haven't really looked into ones made for LED bulbs; I'm assuming they work different and aren't just a variable resistor on a dial.

My guess would be the heat, as you mentioned.

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- As I understand it. LEDs work on PWM. The controllers should regulate it as needed.
  
  So it’s changed from 120 to whatever internal DC current is needed and that’s cycled.
  
  When you use a dimmer you’re lowering/raising that 120v which is messing with the bulbs AC/DC converter which is designed to take 120 and output the applicable DC current for whatever LEDs it has on the circuit.
  
  It definitely won’t adjust the PWM rate or brightness except in some extreme range and I’d personally avoid it unless you have some bulb that says it’s fine (e.g. doing something clever to adjust the DC based on the AC input)
  
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LED's can be very particular about their dimmer. Unfortunately it's not enough just to go to the store and pick up a dimmer switch that claims compatability with LED's .

Fortunately most LED fixtures/bulbs come with a list of recommended dimmers, at least if you stick with larger brands and not cheap LED's from Amazon.

I know a few in my house require ELV dimmers and those sell to the tune of $50/ switch whereas others work fine with a $10 MLV.

Meanwhile my under cabinet lights explicity state not to use an ELV dimmer and to only use MLV or risk damaging the unit.

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