Design & Engineering Services - Southern California Lighting Technology Center

After many T5 undercabinet fluorescent lights failed prematurely in the Southern California Lighting Technology Center's kitchen, researchers conducted accelerated life cycle tests on the fixtures.

The typical rated life of 8-Watt and 13-Watt T5 lamps (F8T5 and F13T5) ranges from 5000 hours to 7500 hours. Out of the 24 one and two-lamp fixtures installed, two failures were noticed within the first 300 hours of operation. The accelerated rated life test was conducted on the F8T5 and F13T5 lamps using the standard testing protocol of 3 hours on and 20 minutes off to allow the lamps to cool back to room temperatures. A number of the F8T5 and F13T5 systems were left continuously on as a control group.

When the actual rated life was measured, it was found that 50 percent of the cycling lamp population failed at about 1650 hours. The expected typical rated life was 5000 to 7000 hours, 22 percent to 33 percent of the average rated life of the typical T5 lamps.

It was noticed that of all the cycling lamp failures, all were F8T5s and none were F13T5s, regardless of the ballast type. This is due to the higher arc resistance in the 21" F13T5 lamp, which makes it more durable than the smaller 12" F8T5. A graph of the cycling system failures after 4729 hours is shown. More efficient under-cabinet lighting systems are being both pushed and pulled into the residential market by utilities, governmental agencies, and consumers. The under-cabinet lighting fixture's usage hours, demand, market availability, and new codes make it one of the best fixture's to look at in terms of overall residential energy savings potential.

The durability of residential fluorescent under-cabinet lighting fixtures will have significant impact on future residential energy savings. If the fluorescent under-cabinet light fixtures are failing more than or even as much as their incandescent counterparts, then there is a possibility of increased use of much less energy efficient lighting, such as incandescents, as consumers grow frustrated with replacing failed fluorescents. The premature failure mechanisms must be determined and understood in order to find a solution to the problem. The sustainability of the residential fluorescent under-cabinet and valence lighting market is dependent on the customers' reactions and whether there is a solution to the premature failures.

View the graphical representation of the table.