The ESP-125 Series operates quartz auxiliary lamps up to 500 W. The device measures the current drawn by the HID circuit rather than voltage across the circuit, allowing use with any type of lamp or ballast circuit. With non-arcing switches, the ESP devices may be used in Class I Division II vapor tight fixtures. High temperature, flameproof plastic enclosure, 90ºC maximum surface temp rating. The quartz restrike controls are UL recognized components for the US and Canada.