Leading Edge vs Trailing Edge Dimming: Choosing the Right Dimmer for LED Downlights

Q: Can I use a leading edge or trailing edge dimmer with phase-dimmable downlights?

Our phase-dimmable downlights are compatible with both leading edge (TRIAC) and trailing edge (reverse phase) dimmers. However, we strongly recommend trailing edge dimmers for the best performance. Trailing edge dimmers provide smoother dimming, reduced audible buzz, and more stable light output — particularly at low dim levels.

Q: Why is trailing edge dimming preferred over leading edge?

Leading edge dimmers switch on abruptly each cycle, which can cause flicker and audible buzz in LED drivers. Trailing edge dimmers switch off gradually, delivering a smoother and more consistent power supply to the driver. This results in a better dimming experience across the full range.

Q: Will my downlights flicker on a leading edge dimmer?

They may, especially at lower dim levels. While our drivers support leading edge dimming, the sharp switching characteristics of TRIAC dimmers make them more prone to flicker. If you're experiencing flicker, switching to a trailing edge dimmer is the most effective solution.

Q: What about areas with ripple control (e.g., Zellweger) on the mains supply?

In areas where ripple control signals are present on the electrical network — common in parts of Australia — leading edge dimmers are more susceptible to flicker. The ripple signal can interfere with the dimmer's firing point, causing inconsistent light output. Trailing edge dimmers handle this interference significantly better and are strongly recommended in these areas.

Q: What dimmer brands do you recommend?

We recommend using quality trailing edge dimmers from reputable brands such as Clipsal, HPM, or Diginet. Always check the dimmer's rated minimum load and ensure it's suitable for LED use.

Q: What should I do if my downlights are flickering?

First, check that you're using a trailing edge dimmer rated for LED loads. Ensure the total connected load meets the dimmer's minimum load requirement. If flickering persists, try a different dimmer model — not all dimmers perform equally with all LED drivers.