Effects of ambient temperature on the performance of bent tube fluorescent lamps

The effects of ambient temperature on the system performance characteristics of bent-tube fluorescent lamps for diameters ranging from T5 to T12 are discussed. Measurements were made from +40°F to +120°F ambient temperature with lamp currents ranging from 0.25 to 0.45 A. Results show that the light output and lamp efficacy peak at higher ambient temperatures for the smaller-diameter T5 biaxial lamp types as compared to the larger T8 and T12 diameter lamps. These data are important from a luminaire design standpoint because they indicate how the thermal characteristics of the fixture affect the system performance. It is concluded that be designing the luminaire geometry to give optimal bulb-wall temperatures improved system performance characteristics can be achieved