The Most Common Cause - Failing LED Driver
In 70%+ of LED flickering cases, the cause is the LED driver (power supply) failing or degrading. The driver's electrolytic capacitors dry out over time - particularly in India's high-temperature summers - causing the output voltage to ripple instead of remaining steady. The LED responds to this ripple by varying in brightness rapidly - what we perceive as flicker. Test: if the flickering is consistent (rhythmic pulsing rather than random), the driver is almost certainly the cause. Fix: replace the driver with a matching specification unit. The LED chips themselves are usually fine.
Grid Voltage Fluctuation
Rural and semi-urban areas in India often experience voltage fluctuations - grid voltage swinging between 170V and 250V within minutes. An LED driver without a wide input voltage range (or with poor power factor correction) will respond to these swings with output instability, causing visible flicker. Fix: replace the driver with one rated for 100–277V wide input range. Quality drivers from Meanwell, Inventronics, or similar brands handle Indian grid fluctuations without flicker. If multiple lights on the same feeder circuit all flicker simultaneously, grid voltage is the cause - check with a clamp meter at the panel.
Loose or Corroded Connections
A loose terminal at the MCB panel, junction box, or inside the luminaire can cause arcing - intermittent connection that produces irregular flickering (random, not rhythmic). Corroded connections add resistance that causes voltage drop, also causing flicker under varying load conditions. Diagnosis: if the light flickers more when nearby heavy loads (motors, lifts) switch on and off, connection resistance or loose terminals are likely. Fix: tighten all terminals, clean corroded contacts with emery paper, apply antioxidant contact grease. Check the MCB - a failing MCB also causes similar symptoms.
Thermal Shutdown Cycling
If an LED light flickers in a slow cycle - on for several minutes, off for a minute, on again - this is thermal protection cycling. The LED or driver is overheating and the thermal cutoff is activating. Causes: inadequate heat sink (common in cheap fixtures), external heat sources (direct sunlight on the fixture body), blocked ventilation (wasp nests, paint overspray on heat fins), incorrect wattage LED installed in an undersized fixture body. Fix: clean the heat sink fins, check ambient temperature conditions, and for cheap fixtures, replace with a properly sized quality unit. Do not disable thermal protection - it prevents fires.
