Dimming LEDs is more demanding than dimming filament lamps because the load is small and electronic. The result is a set of practical rules that, once followed, make dimming boring and reliable.
Leading edge vs trailing edge
Leading-edge dimmers were designed for resistive and wire-wound loads. Trailing-edge dimmers suit electronic drivers and are what most LED installations want — smoother, quieter and less prone to buzz.
Minimum load
Dimmers state a minimum load. Six 4W lamps may total less than that minimum, which produces flicker, a refusal to switch off, or a limited dimming range. Modern LED-rated modules have much lower minimums, which is why they are the correct part for the job.
Two-way and multi-gang considerations
In two-way switching only one location typically carries the dimmer module. Multi-gang plates also derate — four dimmer modules in one plate cannot each carry their full rating. We check both before specifying, because the failure shows up as heat.
Common questions
- Why do my lights glow when switched off?
- Usually a dimmer or a two-way switching arrangement leaking a small current through the driver.
- Can every LED lamp be dimmed?
- No. It must be marked dimmable, and even then compatibility with the specific dimmer matters.
- Can you supply matched dimmers and lamps?
- Yes, and that is the most reliable way to avoid the problem.
- Is smart dimming better?
- It sidesteps some issues by dimming at the driver, but adds its own setup considerations.
Tell us the lamp wattage, quantity and dimmer make and we can usually diagnose it before visiting.
Related guides
- Buzzing Switches, Dimmers and FittingsSome buzz is harmless electronics; some buzz is a connection you should not ignore.
- Smart Lighting: Wired, Wireless and HybridThe most important smart lighting decision is where the intelligence lives.
- LED Downlights, Spotlights and Retrofit LampsThe right choice depends on whether you are replacing lamps or replacing a ceiling's worth of old transformers.