Understanding NFPA 72 Notification Appliance Requirements

Audible Notification Requirements

NFPA 72 Chapter 18 establishes specific requirements for audible notification appliances:

Sound Pressure Levels

• General areas: 15 dB above average ambient or 5 dB above maximum ambient (60-second duration), whichever is greater
• Sleeping areas: Minimum 75 dBA at pillow level
• Mechanical rooms: May require higher output due to elevated ambient noise

Temporal Pattern

Fire alarm audible notification must use the standard temporal-three pattern (three pulses, pause, repeat) as specified in ANSI/ASA S3.41.

Visible Notification Requirements

Strobe Flash Rate

All visible notification appliances must flash at 1-2 Hz (1-2 flashes per second) to be effective while minimizing seizure risk.

Candela Ratings

The required candela rating depends on:

• Room dimensions (length and width)
• Mounting location (wall or ceiling)
• Mounting height

Wall-Mounted Strobes

• Must be mounted between 80 inches (2.03 m) and 96 inches (2.44 m) above the floor
• Or not less than 6 inches below the ceiling

Synchronization

Visible notification appliances within the same field of view must flash in synchronization. This is critical to prevent photosensitive seizures.

Combined Audible/Visible Appliances

Many installations use combination horn/strobe units that provide both audible and visible notification in a single device. These must meet all requirements for both functions.

Emergency Voice/Alarm Communications

When voice evacuation systems are used, speakers must provide:

• Intelligible speech in all occupied areas
• Minimum Speech Transmission Index (STI) of 0.45
• Both pre-recorded and live voice capability