Annunciators and graphic display panels disclose the layout and sound the status and measurement parameters of industrial processes, security and fire alarms of buildings and manufacturing facilities, power distribution networks, and other operations.  They are specified by the number of zones or alarm points covered.  Zones are groups of initiating annunciators and graphic display panels wired on a common circuit. Each wiring circuit is used to relay information to the display panel regarding the condition of the initiating devices, which can include smoke, heat, or fire detectors, manual pull stations or any circuit closure device.  A circuit that connects automatic and/or manual signal-initiating devices, such as fire alarm manual boxes (pull stations), heat and smoke detectors and water flow alarm devices.