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Heat Management Methods for the Efficient Operation of Ceiling-Mounted Fluorescent Residential Luminaires

During the past few years, there has been increasing concern about the premature failure of residential fluorescent lamp luminaires, including those with the ENERGY STAR® label. Lighting manufacturers agree that excessive heat inside the luminaire may be the main cause of their failure. In the round table conference held as a part of the durability testing project with ENERGY STAR partner manufacturers in October 2001, the participants accepted that the premature failures could be reduced by reducing the heat within the luminaires. The hypothesis was that excessive heat reduces the life of the capacitor inside the ballast, resulting in shorter ballast life due to degradation of the capacitor itself or failure of other components inside the ballast that interact with the capacitor.

Following the round table, the LRC measured the ballast case operating temperature inside various ceiling-mounted and recessed downlight luminaires. The results showed that the majority of the luminaires tested had ballast case operating temperatures below the Underwriters Laboratory (UL) limit of 90°C, but were above the limits established by ballast manufacturers (65°C - 70°C). Ballast manufacturers claim a certain life for the ballast. Ideally, none of the ballast components of should have rated life lower than the rated life of the ballast. Hence, it was important to understand the effects of a higher ballast case temperature on its components and devise simple methods to reduce the high temperature.

The objectives of this phase of the project are to:

  • Investigate if capacitor failure is linked to ballast failure and potentially to luminaire failure through literature review on ballast components
  • Investigate the relationship between ballast case temperature and ambient temperature
  • Investigate effective ways to reduce ballast case temperature in ceiling-mounted luminaires
  • Propose guidelines that will help reduce the ballast case temperature



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