Indoor spaces with high ceilings, such as factories, warehouses, big box retail stores, gymnasiums and all-purpose rooms are often lighted by probe-start metal halide lighting systems. At higher ceiling heights, 350W and 400W units are common …

Advancements in lamp and ballast technology have resulted in two alternatives to this basic system that can significantly reduce energy consumption while providing other benefits. The first alternative is fluorescent T8 or T5HO hi-bay fixtures, which can replace probe-start metal halide fixtures in retrofit or new construction for energy savings up to about 50%. The second alternative is pulse-start metal halide lamp-ballast systems, which can provide up to 25% energy cost savings in existing applications and up to 30% in capital and operating costs in new construction.