I own a small industrial park, and needed to replace a 175w mercury fixture over a roll-up door that faces the main driveway entrance. I bought several (6) 70w sodium fixtures previously for entry lighting on units, figured I would try a 100w metal halide for this spot, thinking it would be slightly brighter, but being higher up (25') approx, would be similar light level on the ground, but.... WOW!!! 30 watts in thia case is at least 2x the usable light...even from that high up broadcast point!. It makes defined sharp shadows 150' out. This is a hell of a lot of light for 100w!