There are many causes of failure for LED bulbs.
- Operating Temperature. They are rated at 25degC or 77degF. At higher temperatures, they are dimmer and at even higher temperatures they can fail. I am still hunting for failure curves.
- Mains Voltage. Despite most LEDs using switching power supplies (electronic transformers), I have found that they fail a lot earlier. The LEDS that are solar backed up in the house have failed after 3 years. When I measured the voltage, it was 240V instead of 220V. Maybe your bulbs are rated at 110V.
- Switching Cycles. The LEDs are rated from 20,000 to 100,000 cycles. If you switch them 20 times a day, that's a life of about 3 years.
- Hours of operation - Not an issue in your case. They are rated from 50,000 to 200,000 hours. I am highly critical of these figures. We will find out in 25 years if this is true.
- Production Quality. "Cheaper" bulbs will fail faster. If we are to believe it, cheaper classes of electronics are manufactured with recycled components.
In your case then, it could be a combination of higher voltage, higher operating temperature (if not vented), low-quality products, switching cycles, and maybe loose wires (which may increase switching cycles).
Some references
1. Are LED lights really green
The LED lights are rated for 20,000 to 100,000 switching cycles. This means that they are designed to fail after 11 years (switch the light on and off 5 times a day, for 360 days a year). Did your light supplier tell you this ?
2. How Does Ambient Temperature Affect LED Performance?
LEDs do perform worse the higher the ambient outside temperature. 77 degrees, or 25 degrees Celsius, is the near-universal temperature standard against which L70 ratings are calculated by lighting manufacturers. For instance, if an LED (such as Access Fixtures’ APTA sports lighter) is L70 rated at 200,000 hours, that means that after 200,000 hours of continuous use at 77 degrees Fahrenheit, the lumens will have depreciated by 30%.
3. LED Lifespan: So Long do LED Lights Really Last
The actual light source (light emitting diode) within an LED lamp lasts very long with theoretically 100,000 operating hours and more. However, the lifetime of the LED driver is lower and thus determines the actual lifetime of the entire LED lamp. Apart from the operating hours, the number of switching cycles and the ambient temperature have the greatest influence on the durability.
4. What are switch cycles (Philips)?
Switch cycles indicate the number of times a bulb can be switched on and off before it fails. The room a bulb is being used in can make a big difference to the light bulb's lifespan. This guide shows how LED, halogen and energy-saving light bulbs have different switch cycles and how to compare them.
5. What Happens If You Put Too Much Voltage Through An LED
Generally, excess voltage is dangerous. Voltage surges can have a destructive effect on electronic equipment, including LED light bulbs.