Abstract: A ground fault circuit interrupter comprises separable contacts for interrupting current flow through a power circuit being protected, trip means operable upon energization to effect separation of the contacts, means for detecting ground fault current, means for monitoring voltage upon the power circuit, and means responsive to the ground fault current detecting means and the voltage monitoring means for energizing the trip means when ground fault current reaches a trip current level. The trip current level varies as a function of the power circuit voltage.

Abstract: To prevent high-intensity-discharge (HID) lamps from extinguishing for prolonged periods due to a power interruption or an appreciable drop in line voltage, a rectifier-battery combination provides standby power for operating a high-frequency inverter. The output of the inverter connects to the HID lamps through impedance means which passes a greatly reduced high-frequency current as compared to the normal lamp operating current, in order to sustain the operation of the lamps at a very reduced power level. Upon restoration of the normal line voltage, the lamps again operate with normal power consumption. The same wiring can be used for both the normal lamp operating current and the high-frequency sustaining current or separate wiring systems can be used if desired. The high-frequency current can be supplied simultaneously with the normal operating current or the high-frequency current can be supplied only during periods of power interruption.

Abstract: Lead-lag, series-sequence starting and operating apparatus for three to six fluorescent lamps comprises two parallel circuit branches, one of which comprises a ballast capacitor and two lamps in series for a three or four lamp apparatus or three lamps in series for a five or six lamp apparatus. The other circuit branch comprises an inductor ballast and one or two lamps in series for a three or four lamp apparatus and two or three lamps in series for a five or six lamp apparatus. An additional ballast inductor connects in series with the two parallel-connected circuits and the AC power source. Starting capacitors parallel individual lamps and means are provided for preheating the lamp electrode coils upon energization of the apparatus. In operation, the lamp electrode coils are all preheated and the lamps which are ballasted by the capacitor, which constitutes the lead circuit, then sequentially start.

Abstract: Outdoor lighting fixture utilizes lamp ballast which includes both solid-state control circuitry and a relatively massive inductor ballast. The solid-state control circuitry is mounted in a separate housing, such as the photocontrol housing, which is affixed to the exterior of the fixture by means of a plug-type receptacle, and the relatively massive inductor portion of the ballast is contained within the fixture body. Those portions of the solid-state control circuitry which require cooling use the separate housing as a heat sink. If troubles are encountered in the solid-state circuitry, the entire circuit can be replaced simply by plugging in a new unit.