An HPS (High Pressure Sodium) or an MH (Metal Halide) HPS-Conversion Lamp is driven better by indoor hydroponic digital grow light ballasts than by a conventional magnetic ballast. They do this in order to start (fire-up) and subsequently operate HID (High Intensity Discharge) grow lamps by converting mains electricity into the appropriate voltage. Make sure the lamp’s wattage and the ballast’s wattage are always matched. Despite their high efficiency, digital grow light ballasts can still get heated. To avoid a fire, place them away from flammable materials and put them on a hard, flat surface rather than carpet.