This free interactive 3D model walks you through a complete fire alarm system in a multi-story building — the fire alarm control panel (FACP), initiating devices like smoke and heat detectors and pull stations, notification appliances such as horns and strobes, and the sprinkler monitoring that ties life-safety together. Click any device to see what it is and what it does. It's a visual learning tool for fire alarm designers, NICET candidates, electrical and fire-protection engineers, AHJs, and students learning how an NFPA 72 system fits together.
The viewer covers the full fire alarm system from panel to riser:
• Fire alarm control panel (FACP) — the brain that monitors initiating circuits and activates notification. • Initiating devices — smoke detectors, heat detectors, manual pull stations, and a projected beam detector for large open spaces. • Notification appliances — horn/strobes and speaker/strobes driven by notification appliance circuits (NACs). • Riser diagram — how circuits run vertically floor-to-floor between the FACP and the devices. • Sprinkler monitoring — the fire department connection (FDC), waterflow switches, and tamper (supervisory) switches that report sprinkler status back to the panel per NFPA 72.
Initiating devices detect a fire condition — smoke, heat, a person pulling a station, or a sprinkler waterflow switch tripping. They signal the FACP, which evaluates the input, logs the event, and activates an alarm. The panel then energizes the notification appliance circuits (NACs) to sound horns and flash strobes for occupant evacuation, and it can transmit the signal to a supervising (central) station and to the fire department. Tamper switches send supervisory signals if a sprinkler valve is closed, and the whole system is continuously monitored so wiring faults are detected — all governed by NFPA 72, the National Fire Alarm and Signaling Code.
1. Drag to orbit the building, scroll to zoom, and pan to move around. 2. Click any device — FACP, detector, pull station, horn/strobe, or sprinkler switch — to highlight it and read what it does. 3. Follow the path from initiating device → FACP → notification appliance, and trace the riser to see how circuits connect the floors.
The FACP is the central controller of a fire alarm system. It continuously monitors all initiating device circuits, processes alarm and supervisory signals, activates notification appliances, and transmits signals off-site to a supervising station or the fire department. It also supervises its own wiring so that any open or ground fault is reported as a trouble condition.
Initiating devices are inputs — they detect a fire and tell the panel (smoke detectors, heat detectors, manual pull stations, waterflow switches). Notification appliances are outputs — they alert occupants once the panel declares an alarm (horns, strobes, speakers). Initiating devices sense; notification appliances signal.
A NAC is a powered, supervised circuit from the FACP (or a NAC power booster) that drives notification appliances such as horns and strobes. NAC design must account for voltage drop along the wire and the synchronization and candela ratings of the strobes so every appliance gets enough voltage to operate per NFPA 72.
In a conventional system, devices are grouped onto zones, so the panel knows only which zone is in alarm. In an addressable system, each device has a unique address on a signaling line circuit (SLC), so the panel can identify the exact device and its status — speeding response and simplifying troubleshooting on larger buildings.
NFPA 72, the National Fire Alarm and Signaling Code, governs the design, installation, inspection, testing, and maintenance of fire alarm and emergency communication systems. It covers detector spacing, notification (audible/visible) requirements, circuit supervision, secondary power, and sprinkler monitoring — and is the primary code basis for the devices shown in this model.