Occupancy-Specific Requirements and Interface with Other Systems
Occupancy triggers and interfaces
The adopted building code and NFPA 101 determine when a fire alarm system is required and which occupancy features apply. High-rise buildings, assembly occupancies, hotels, dormitories, health care facilities, and educational occupancies often trigger detection, voice evacuation, or corridor coverage. NFPA 72 then supplies installation and performance rules. Interface with other systems must be coordinated and supervised: elevator recall, HVAC shutdown, sprinkler flow and tamper switches, door hold-open release, access control release, and stairwell pressurization.
Common interface rules
A sprinkler waterflow switch is an alarm signal; a tamper switch is a supervisory signal. Elevator Phase I recall uses lobby smoke detection to send cars to the designated primary floor and machine room or hopper smoke detection to send them to an alternate floor. Duct detector activation commonly shuts down the air-handling unit and transmits an alarm. Relay wiring that controls other systems must be monitored so a broken control circuit does not go unnoticed.
Worked example. In a four-story hotel, a lobby smoke detector operates. The fire alarm system must recall the elevators to the primary floor and notify occupants. If a machine room detector operates, the elevator recall goes to the alternate floor. The interface relay and monitoring circuit must be tested. A sprinkler flow switch in the same building reports an alarm, while a tamper switch reports a supervisory condition. Mixing those two signal types in the report is a documentation error.
Traps that cost marks
Do not treat a tamper signal as a fire alarm. Do not assume smoke alarms satisfy a system-detection requirement. Do not leave interface wiring unsupervised. Do not coordinate elevator recall only with the fire alarm contractor; the elevator inspector and AHJ must be involved. Do not ignore occupancy chapters in the building code.