When you go to a job to replace a bunch of incandescent bulbs for LED bulbs, don’t forget to check what kind of dimmer is present, if there is one at all. I’ve made this mistake in the past.

So LED dimming is different than incandescent dimming. LED lamps have a driver, which is a nonlinear load, that is controlled to dim the lights, whereas an incandescent lamp is pure resistance. The dimmers for each of these loads must take that into consideration when designing the technology that allows them to dim, and for the most part, one won’t work with the other.

As a young apprentice, I didn’t realize this at first. I went to a job and installed dozens of brand new LED bulbs to replace the old incandescents that were onsite. I thought everything was gravy until I turned the dimmer on and saw the bulbs not responding, then flickering. It did this in the entire house…everywhere there was a dimmer and a new bulb. Then I realized I never checked to see if the dimmers in the house were rated for combo incandescent/cfl/led – and of course, they weren’t. They were all incandescent only! So I had to go and replace all of the dimmers throughout the house, which nearly doubled the cost of the job. The customer was not too happy.

Nowadays what I do is open the plate up at the switches to check the dimmers first. I never relamp or retrofit a fixture with an updated lamp without checking the switches/dimmers first.