Leading edge and trailing edge are two different techniques for dimming lighting. It is important to know which technique your lamp uses, as this determines which dimmer is suitable. Using the wrong combination? Then the dimming will not work properly.

Leading edge (leading edge / RL)

Leading edge – also called leading edge or indicated with RL – is an older dimming technique.

• Usually dims down to about 10% of the light level
• Mainly used with incandescent and halogen lamps
• Still sometimes found with LED lamps
• Well-known brands such as Philips regularly apply this technique

So pay close attention when choosing your lamps and dimmer.

Trailing edge (trailing edge / RC)

Trailing edge – also called trailing edge or indicated with RC – is the most commonly used technique in modern lighting.

Advantages:

• Full dimming range (often down to a very low level)
• Smoother dimming
• Quieter in use
• Almost no chance of buzzing noises

Most LED lamps on the market operate with trailing edge.

What should you watch out for?

It is important that your lamp and dimmer use the same dimming technique.

• A trailing edge lamp does not work well with a leading edge dimmer
• And vice versa applies as well

Fortunately, this cannot cause damage. The only consequence is that your lamps will not dim (properly).