Abstract: An integral emergency lighting system which utilizes the same branch circuit wiring as main alternating current (AC) power to selectively supply emergency power to light fixtures during an emergency condition such as during an interruption or unavailability of main power from the AC source. The system includes line detection circuitry at the lighting fixtures to enable switching from main AC operation to emergency DC power and also the energizing of the associated egress lighting regardless of the on/off switch settings connected to the branch circuitry. Upon the restoration of main power, the DC battery source automatically switches off and a built-in time delay circuit allows line detection circuitry to stabilize into AC input condition before AC power re-energizes the branch circuit (i.e., switches into the main power mode).