250 Watt S50 High Pressure Sodium 5-Tap Ballast KitHPS Ballast Cross Reference: Advance Ballast 71A8251 001D Sylvania Ballast LU250 MULTI KIT * Universal Ballast S250ML5AC4M500K Keystone HPS 250A P HP Venture V90D1711K * Sola E 971 W SO250 * (* Quad Tap ONLY) 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