Types of Notification Appliances
NFPA 72 Chapter 18 governs notification appliances — the devices that alert building occupants to a fire alarm condition. The three primary types are:
- Audible appliances (horns) — produce a temporal pattern (T3) sound: three pulses, pause, repeat. Required in all areas where occupants may not see a strobe.
- Visual appliances (strobes) — produce synchronized flashes at 1 Hz. Required in areas where hearing-impaired occupants may be present, and now mandatory in most commercial occupancies under ADA and IBC.
- Combination appliances (horn/strobes) — the most common device in commercial fire alarm design, combining both functions in one unit.
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