Addressable fire alarm system 1,NO/NC alarm input 2, four-wire detector 3,Conventional Fire Alarm Addressable fire alarm system with 24-volt operationFeature:1 Sixteen Style B ... Y (Class B) Notification Appliance (Signal) Circuits (NACs).4 Alarm, Trouble and Supervisory, Form-C relays standard.5 24-volt ... not exceed 3.0 amps. .13 Integral Form-C Alarm, Trouble and Supervisory relays,14 rated at: 2.0 ...