Abstract

The invention relates to an emergency lighting unit which is used in association with an electric discharge lamp in a fixture. The lamp has a first input terminal and a second input terminal. The emergency lighting unit includes a transformer which has two closely coupled windings constituting the primary of the transformer and a secondary winding. First adjacent ends of the coupled windings constitute the input of the emergency lighting unit, and second adjacent ends of the coupled windings constitute the output terminals thereof. The input terminals are adapted to be connected to a source of ac power, and the output terminals are adapted to be connected to respective ones of the first and second input terminals of the lamp. A rectifier is connected across the output of the secondary winding, and a rechargeable battery is connected across the output of the rectifier to be recharged by the dc output thereof. An inverter is connected in parallel with the battery and adapted to convert the dc output of the battery to an ac signal. A transfer circuit senses the loss of ac power from the source of ac power and, upon sensing the loss, connects the inverter in circuit with the input terminals to provide energy to continue running the lamp.