LEDs fail from heat, not hours. Their maximum junction temperature is around 60–80°C (140–170°F), and a closed glass shade traps enough heat to age the driver in months rather than years.
Three fixes: buy bulbs explicitly marked “enclosed fixture rated”, stay at 60W-equivalent or below inside a sealed shade, and stick to brands that publish real specifications.
If you have replaced three bulbs in one fixture in a year, the fixture is almost certainly the problem — not the wiring, not bad luck. Here is what happens inside the shade.
An LED bulb is mostly a small power supply
An incandescent bulb is a filament that wants to be hot. An LED bulb is a semiconductor plus a driver — a small circuit board with capacitors on it — and both hate heat. Every LED bulb has a junction temperature limit, typically 60–80°C. Beyond it, output drops and the driver’s electrolytic capacitors degrade quickly.
Because an LED throws almost no heat forward, what heat it makes has to leave through the base. In open air it does. Inside a sealed globe it recirculates around the components least able to tolerate it.
What “enclosed fixture rated” actually means
It is a manufacturer’s statement that the bulb has been tested inside a sealed housing without exceeding its thermal limits. It is not universal — plenty of ordinary LED bulbs carry an explicit warning against enclosed use in small print on the box.
Look for the phrase on the packaging or spec sheet before buying. If a listing does not mention enclosure, assume it is not rated.
Lower the wattage before you change the brand. A documented comparison: two 40W-equivalent bulbs in an enclosed fixture kept the fixture body at about 95°F and ran for three years. The same fixtures loaded with 100W-equivalent bulbs went through three bulbs in twelve months.
The wattage ceiling inside a sealed shade
Higher-output LEDs draw more power and dump more waste heat into the same small base. In a sealed shade, 60W-equivalent is a sensible ceiling and 40W-equivalent is safer still. If the room needs more light, the answer is another fixture, not a hotter bulb.
Brand variance is real, and larger than you would guess
“100W equivalent” is not a standard. Output, thermal design and driver quality vary widely between models from one manufacturer, let alone between brands. One owner reported testing about fifteen models before settling on three. Off-brand bulbs bought in bulk are the most common cause of repeat failures.
It is also why wiring gets blamed unfairly. Before assuming a fault, try a known-good, enclosure-rated bulb at a lower equivalent wattage in the same socket.
Repeated failures across several fixtures on one circuit, or scorching, discolouration or a smell at the socket, are a different problem. Stop replacing bulbs and have a licensed electrician inspect the circuit — local code and their judgement decide what happens next.
What to take away
- Heat kills LEDs, and the driver in the base fails first.
- Junction temperature limits sit around 60–80°C / 140–170°F.
- Only use bulbs marked “enclosed fixture rated” in sealed shades.
- Stay at 60W-equivalent or below; 40W-equivalent runs cooler still.
- Repeat failures in one fixture point at the bulb or shade, not the wiring.
More in pendants and living room lighting, or see custom design.
Why do my LED bulbs keep burning out in one fixture?
Almost always heat. If the fixture has a closed shade, the bulb’s driver is cooking. Switch to an enclosed-fixture-rated bulb at 60W-equivalent or lower.
Can you put any LED bulb in an enclosed fixture?
No. Many are explicitly not rated for it, and using them there usually voids the warranty as well as shortening their life. Check the packaging for “enclosed fixture rated.”
Do LED bulbs really last 25,000 hours?
Only within their rated thermal conditions. Run the same bulb hot inside a sealed globe and the driver can fail in well under a year.
Fixtures designed around the heat
Shade geometry, socket placement and recommended wattage are decided together at the specification stage rather than left to whatever fits. Ask what a design was tested with.
Explore custom designThermal limits and failure patterns here reflect LED specifications and repeated accounts in home and lighting communities. Suspected wiring faults are work for a licensed electrician.