Quick answer
Downlights blow from heat with no ceiling clearance, poor-quality lamps, incompatible dimmers, or loose terminations in the fitting. Heat is the usual culprit — insulation laid over a non-rated downlight traps heat that the fitting was never designed to shed. Switching to LED with correctly rated trims and a compatible trailing-edge dimmer eliminates most cases outright.
Common causes
- Insufficient ceiling clearance, with insulation laid over non-rated fittings
- Cheap lamps with poor thermal management or an inadequate driver
- Incompatible dimmer, particularly an old phase-cut dimmer on LED lamps
- Loose terminals in the fitting arcing and stressing the lamp
- Mixed lamp types on the same dimmed circuit
- Voltage fluctuation on the circuit from a loose neutral elsewhere
What you can do now
- 1Never lay insulation over downlights that are not rated for it
- 2Check the dimmer is a trailing-edge LED-rated unit if the lamps are LED
- 3Use the same make and model of lamp across a dimmed circuit
- 4Note whether it is always the same fitting failing, which points at that fitting's terminals
- 5Keep the lamp packaging so replacements match exactly
When to call a professional
Persistent failures need the fitting, the dimmer and the terminations assessed together rather than another round of replacement lamps. If one particular fitting keeps failing, the termination behind it is the likely cause and that is a heat risk in a ceiling void. An electrician can convert the circuit to properly rated LED fittings with a compatible dimmer.
Typical cost in Johannesburg
LED retrofit R350–R650 per light fitted
Indicative ranges only. We provide written, itemised quotes before any work.
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