Why do my LED bulbs keep failing?

The advertised life of an LED lamp is the life of the diodes in laboratory conditions. What actually fails is the small switch-mode power supply crammed into the base, and electrolytic capacitors in that supply lose life dramatically with temperature. A lamp that runs 20 degrees hotter can have a fraction of the working life, and nothing about that is visible from the outside.

Step by step

1. Establish whether it is one fitting or all of them.Keep a note of which fitting each failure was in. One fitting eating lamps is a fitting problem. Failures spread across the house are a lamp quality or supply problem. This single observation halves the search.
2. Check whether the fitting is enclosed.A closed glass shade, a bathroom drum, a sealed outdoor lantern or a fully recessed downlight traps heat around the lamp base. Most standard LED lamps are explicitly not rated for enclosed fittings. Look for lamps marked as suitable for enclosed luminaires — they exist and they are what that fitting needs.
3. Check the orientation.A lamp pointing downwards in a closed fitting has its driver above the diodes, so all the heat rises straight into the electronics. Upward-facing lamps in open fittings run far cooler. This is why the same lamp lasts years in one place and months in another.
4. Check the insulation around recessed fittings.Loft insulation laid over a downlight that is not rated for it is both a fire risk and a lamp killer. Fittings must either be insulation-coverable or have a proper clearance or cap. This is worth checking in the loft.
5. Check for a dimmer.A non-dimmable lamp on a dimmer, or a dimmable lamp on a leading edge dimmer, stresses the driver constantly. Repeated failures on a dimmed circuit almost always trace back to this.
6. Check for a switch with a neon indicator.An illuminated switch passes a tiny current through the lamp when off, which trickle-charges the driver's capacitor and can cause both the familiar faint glow and long-term stress. Fitting a non-illuminated switch or a bypass resolves it.
7. Consider the supply.Persistent overvoltage, or repeated switching surges, degrade drivers. If lamps fail across the whole house and the fittings are varied, it is worth having the supply voltage checked at an EICR — and worth asking whether anything else electronic is failing early too.
8. Buy on driver quality, not on price.The cheapest lamps use the smallest capacitors with the lowest temperature ratings. A recognised brand with a genuine multi-year guarantee, kept with the receipt, is the practical answer — and claiming under that guarantee is worth doing.

Tips

• Write the date on the base of the lamp with a marker when you fit it. Two dated failures in one fitting is a diagnosis rather than a suspicion.
• A fitting that has browned the lamp base or the lamp holder is running far too hot, and the fitting itself needs looking at.
• Keep receipts. Most branded LED lamps carry two to five year guarantees, and a genuine early failure is exactly what they are for.

Common mistakes

• Buying the same cheap multipack again — If the driver design is the problem, replacing like with like reproduces the failure. This is one of the few areas where price genuinely correlates with life.
• Using a standard LED lamp in a sealed fitting — Standard lamps assume convection around the base. In a sealed fitting the base runs far hotter than the manufacturer's test conditions and the capacitor life collapses.
• Ignoring a repeatedly failing single fitting — That fitting is telling you something — heat, a poor lamp holder connection, or a loose termination. A loose connection at a lamp holder arcs, and that is not a lamp problem at all.

If it doesn't work

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