Q: What is the spacing requirement for fire alarm occupant notification devices?
A: The spacing requirements are not listed in a specific distance, but they are listed by their decibel ratings at a specific distance. The Life Safety Code requires compliance with NFPA 72 (1999 edition) for the installation of fire alarm system devices. Section 4-3.3 says:
- Audible devices must have a sound level of not less than 45 dBA at 10 feet or more than 120 dBA at the minimum hearing distance from the audible appliance (10 feet).
- Audible devices must have a sound level at least 10 dBA above the average ambient sound level or 5 dBA above the maximum sound level having a duration of at least 60 seconds, whichever is greater, measured at 5 feet above the floor.
The manufacturer of the audible device will list dBA ratings per feet in a chart so once the installer knows what decibel rating he needs, the manufacturer’s chart will indicate at what distances the device needs to be. It is surprising how many audible devices are needed for an average hospital environment. Many large conference rooms would require multiple devices.