There are two types of dimmer switch for mains dimming, leading edge and trailing edge.  We are often asked whether our dimming drivers are compatible with leading edge or trailing edge dimmers. So let’s take a closer look at these two dimmers here.

Leading Edge Dimmers  – Triac dimmers

  • The electrical current is turned off at the front of the AC input waveform immediately after the zero crossing
  • Traditionally used for incandescent lamps or magnetic low voltage transformers
  • Creates a quick stable of voltage on the circuit and also stabilizes the current in the circuit directly to the light source
  • Causes buzzing sound when dimmed, depending on the quality of the dimmer and whether it is loaded above the prescribed minimum load

Trailing edge dimmers – Electronic dimmers

  • The electrical current (sinusoidal signal) is turned off at the end of the AC input waveform immediately before the zero crossing
  • Traditionally used for electronic drivers or low voltage transformers (capacitive loads)
  • Is not subject to a high inrush of voltage that leads to a high inrush of current
  • Does not cause buzzing sound when dimmed

Now you may ask which dimmer is better for LED lighting, generally, trailing edge is the most popular dimmer with LED light sources. However, when finding the perfect dimmer, you should look at the specifications of LED and driver as well as dimmer to see the compatibility.

If you are concerned about dimmability of Roco’s lighting products with your existing dimmers, always consult us directly.