400 Watt M59/H33 5-Tap Metal Halide Ballast KitMetal Halide Ballast Cross Reference: Advance Ballast 71A6051 001D Universal Ballast M400ML5AC4M 500K Howard M0400 81C 211 Sola E MCAWDD400 High Intensity Discharge (HID) lamps require a ballast to apply starting voltage to the lamp and establish current flow an arc between the lamp electrodes. Without a ballast, the arc will extinguish or draw increasing current until some circuit element burns up. Ballasts provide system stability by limiting the