I have been asked to look over some literature on a dimming system for HID lighting. This particular unit, best I can tell dims the voltage level in 15 step increments. Boasting a 40% energy reduction. I am dealing with 400 watt metal halide lamps and understand that by reducing the wattage, but losing light output, to say 350 watts that is saving 50 watts per lamp , adding the ballast factor also in this figure. But I was wondering if someone has had any dealings with dimming HID lights and what pros and cons are associated.