Abstract: This is an emergency lighting system which permits at least one gas discharge lamp to be operated from an AC power source when AC current is present and from a battery when AC signal is not present. The circuit also provides the capability for turning the lamp on under other selected emergency conditions such as in response to an intruder detection, or in response to detection of smoke, heat, water, or some other emergency. In order to converse battery power in the DC mode, controls are also provided for turning off the light or reducing its output level in response to such control inputs as an ambient light detector or manually operated dimmer control. The system also provides a number of other improved features which cause the system to operate more efficiently than prior systems for performing the same function, thus providing greater energy to the lamp with the same source energy input, and reducing the heat generated by the system.