US based carrier.
The CAPT & PURS toggle switch is hard wired to the CAPT & PURS position. On our 319/320's (1994 +- Models) a cabin initiated evacuation can be activated by the forward FAP or AFT FA Control Panel. Once activated the EVAC can only be canceled at the panel that initiated the evacuation. The speaker located nearest the panel in the cabin can be silenced from that panel using the RESET button, the other horns will continue to sound. The cockpit horn can be silenced using the HORN SHUT OFF switch. (As an aside the EVAC horn has its own speakers separate from the PA system)
Our manual indicates the CAPT & PURS switch is non functional (the why is it hard wired ? Good question - maybe at one time it was functional...)