The building fire alarm signaling system must be arranged to produce a sound level at least 15 decibels (dBA) above the average ambient sound level; the unit system needs to be tested to show that the building fire alarm system can provide the required sound levels inside of the unit with the roof intact (closed).
If the units are only used for employee use areas, a strobe notification appliance is not needed unless the employees in the space are hearing impaired. Since the 2006 edition of the IBC, a 20-percent spare capacity is required to be built into the building fire alarm system to add strobes if needed. If required, the strobe appliance can be located outside of the unit if the strobe light is able to penetrate into the space. The penetration of light can be through glass side panels via a wall mounted appliance or through the skylight roof via a ceiling-mounted appliance. Alternatively, NFPA 72 allows for a performance-based alternative to visible notification appliance location provided it is proven that the design provides a minimum illumination of 0.0375 lumens/ft2 at any point within the unit at all angles.
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