Question ...............

Can you recommend an energy efficient bulb to replace mercury vapor lighting in an indoor rodeo arena? The ceiling is about 30'.

Answer ...............

The existing mercury vapor lighting system is an excellent candidate for an upgrade because mercury vapor lamps experience constant energy consumption over their life, while their light output drops significantly. Many times these lamps are not replaced until well past the time they provide designed light levels because after all, "the lamp is still on." In some cases it gets to the point where it only lights itself.

High pressure sodium is popular in many outdoor lighting applications because it gives off adequate light when excellent color perception is not required, and has good efficacy (providing high lumens per watts). There has been improvement in the color rendering index at the expense of lamp life. A CRI of 100 is the color of standard incandescent lamps, which all others are compared to. The rated life of HPS lamps ranges from 10,000 hours for the color-improved White SON (CRI= 85) models, 15,000 hours for color-improved ceramic models (CRI= 60-65), and 24,000 for the standard models (CRI= 21).

Metal halide lamps provide clear white light-fine for television filming-and would be similar to the new mercury vapor light. If flicker has not been a problem with the current system, it won't be with this system either. Metal halide lamps have a 10,000-hour rated life for standard models and up to 30,000 hours for some pulse start lamps.

A drawback to these high intensity discharge systems is that if the power is interrupted, even briefly, or if someone accidentally turns them off, there is a re-strike time of 6-15 minutes. The shorter times come from the newer pulse start technology. In most public spaces this means that a back-up lighting system is required for safety reasons.

Compact fluorescent lamps gang-mounted in single fixtures of 6-9 lamps each, marketed as Sportlite, are making inroads into former HID territory. They come in many colors (warm to cool) with CRIs as high as 85. They are instant-on with no re-strike time, negating the need for a back-up system. Take care to get a ballast that will operate in the lowest temperatures you expect to have in your facility. There is no flicker, and light distribution is excellent. A further advantage is that if one of the lamps in a fixture fails, there will be enough light from the remaining ones to avoid an interruption in the light distribution pattern.

For answers to your own energy-related questions, call the experts at Western's Power Line. They have a vast library of information-and if they don't know something, they'll find out for you!