This study discusses parameters for selecting the most suitable auxiliary lightingsdevice to- operate and control gas-discharge lamps. The devices tested in this studysinclude solid-state, fluorescent, and high-intensity discharge (HID) ballasts;scurrent limiters; and dynamic lighting controls. They have been evaluated whensoperating the standard, 40-W, F-40, T-12, rapid-start, cool-white fluorescent lamps.

Solid-state ballast performance varied widely, from 68 t o 79 lumens per watt (lm/W)sin efficacy, and from 0.83 to 0.98 in ballast factor. System efficacy was measured at up to 26% higher than standard core-coil ballast efficacy.

Current limiters used with standard core-coil ballasts reduce light output and inputspower by 30 to 50% and may be suitable as retrofit devices to reduce light insoverilluminated spaces. In operation a t a constant lamp wall temperature, thesesdevices either maintain or reduce system efficacy.

Dynamic lighting controls (which vary the light output) condition the power to standardscore-coil fluorescent ballasts, and low-voltage-type controls alter the oscillating circuit of solid-state ballasts. Power conditioning systems are generally designed to operate many ballasts and most can dim lamps to 50% of full light output. The solid-state ballasts control individual lamps and can dim them to 10% of full light output.