What are the different subsystems of a fire alarm?

• Main control panel (alarm circuit controls, status indicators and battery backup)
• Detectors and other inputs
• Annunciators and other outputs

Detectors can include

• Smoke and heat detectors
• Water-flow sensors in sprinkler lines
• Supervision circuits for valves and tamper protection
• Inputs from fire extinguisher cabinets and from fixed fire extinguisher (e.g., hoods)
• Manual pull station inputs

Annunciators and outputs can include

• Outputs to horns and strobes
• Outputs to fire-door release mechanisms
• Outputs to remote alarm monitor (dial-out, direct wiring, network)