The PA/GA industry application is a critical system with respect to personnel safety and, during an emergency situation, needs to be fully operational to allow safe evacuation of the facility, therefore a field proven design shall be provided. The PA/GA distributes alarm tones, pre-recorded messages, emergency voice messages and routine voice messages to all or selected areas of the facility by use of loudspeakers. In areas with a high ambient noise level, flashing lights (beacons) complement voice messages and audible alarms. Alarms can be initiated either manually from any one of the dedicated access panels or automatically from the Fire and Gas Detection System or Emergency Shutdown System main panel via dedicated hardwired interfaces between the two systems. Voice messages can be generated either from the microphones at dedicated access panels or from telephones in the facility.