Quick answer
LED flicker is almost always dimmer incompatibility. Old phase-cut dimmers were designed for the load of an incandescent lamp and cannot regulate the tiny load an LED presents, so the output becomes unstable. Replacing them with trailing-edge, LED-rated dimmers resolves the majority of cases. If new dimmers do not fix it, the next suspect is a loose neutral, which is a different order of problem.
Common causes
- Old phase-cut leading-edge dimmer incompatible with LED loads
- Cheap driverless lamps with poor internal regulation
- Loose neutral connection causing voltage instability
- Minimum load of the dimmer not met by the small LED load
- Mixed lamp makes and models on one dimmed circuit
- Failing driver in an individual LED fitting
What you can do now
- 1Replace the dimmer with a trailing-edge, LED-rated unit
- 2Use identical lamps across the whole dimmed circuit
- 3Check whether the flicker also occurs on non-dimmed circuits, which points at a supply problem
- 4Check the dimmer's minimum load rating against the total wattage of your LEDs
- 5Note whether flicker coincides with large appliances starting
When to call a professional
If a correct trailing-edge dimmer and matched lamps do not fix it, have the neutral connections checked. Flicker across multiple circuits, or flicker with any buzzing, should be looked at within the week — a loose neutral is both a fire risk and a source of voltage swings that damage electronics well beyond the lighting.
Typical cost in Johannesburg
Dimmer R450–R750 fitted
Indicative ranges only. We provide written, itemised quotes before any work.
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