# Dimming and LED lighting



## splatz (May 23, 2015)

Just a reality check. It's my understanding that 

* The most common old fashioned dimmers are resistive, and they work fine with incandescent lighting. 

* Putting a resistive dimmer ahead of an LED driver is no good. 

* Putting a resistive dimmer between an LED driver and the LED light would be OK. 

Is it that simple? 

http://electrical-engineering-portal.com/how-to-dim-led-lighting-in-the-home


----------



## LGLS (Nov 10, 2007)

I've replaced many bulbs in my home with LED conversions, and they all dim fine with the existing dimmers, except that there's a point at about 15-20% output that you can't go below.


----------



## PlugsAndLights (Jan 19, 2016)

https://en.wikipedia.org/wiki/Dimmer
P&L


----------



## V-Dough (Jul 22, 2014)

No, its not that simple. It all depends on the driver. There are drivers that require electronic low voltage dimmers (trailing edge wave chopping), some work well on regular dimmers (leading edge wave chopping), some don't work on dimmers at all. 
As for the low voltage side depending on how LEDs are driven: either constant voltage - dimming is accomplished by lowering voltage, or constant current - dimming works by lowering current. Some of the cheaper LED drivers use PWM dimming - i would not recommend this type. Hopefully that was of some help.


----------



## chicken steve (Mar 22, 2011)

All i know is i have to stock LED *and* non-LED dimmers these days, the specifics of how the triac is configured escapes me.....

ICs Answer the Challenge of Dimming LED Lamps in TRIAC-Driven Circuits

~CS~


----------



## macmikeman (Jan 23, 2007)

A symbol printed boldly on the outside of every dimming led package should be made the industry standard. One that easily details a leading or lagging circuit so that it takes all the research and guesswork on our part to match the fixture and lamp to the dimmer. It should be printed right next to the place where they state that the lamp is dimming able. And , similarly , the dimmer boxes should carry the same symbol on the package to notify the buyer which type methodology they employ as well. That way, the stupid homeowners who buy the dimmers and hand em to me will at least have a better chance to match up the stupid device to the lamp . 

Before everybody screams, it is done basically the same for color choice- that is prominently displayed on each box of dimmer, why not operational configuration?


----------



## Semi-Ret Electrician (Nov 10, 2011)

150W dimmers seem to work OK on LEDs but 600W dimmers have a problem unless there are about six fixtures or more.

Leviton has a list of what devices are compatible. At the bottom of the list is a disclaimer to test the combinations to determine compatibility.


----------

