Expands on fundamentals.(Letters)(Letter to the Editor)

Dear Editor:

John Fetters' Applying New Lighting Technology provides very useful information. But his statement, "A common mistake made is to use instant-start ballasts for switching applications when upgrading fluorescent systems," deserves some refinement regarding T8 systems.

Program-start ballasts are not necessarily better than instant-star ballasts lot T8s when controlled by occupancy sensors. Yes, program-start ballasts are recommended when the average on time is less than one hour, which is often the case for many rest rooms, copy rooms, and warehouse rack aisle applications. But if the average on cycle is at least two hours, which is very common in offices and many other applications, long-life T8s and extra-efficient, instant-start ballasts may be a better total solution.

There are several models of high-performance F32T8s that are rated for 24,000 hours life with instant-start ballasts at the industry life-testing standard; longer life is possible with rapid- and program-start ballasts. These lamps are much better than the majority of F32T8s, which are only rated for 15,000 hours life with instant-start ballasts, 20,000 hours with rapid-start ballasts, and 24,000 hours with program-start ballasts.

In general, instant-start ballasts are more efficacious than program-start ballasts for T8s, because instant-start ballasts do not provide any lamp cathode heating after they start, but most, if not all, existing program-start ballasts maintain ...