NFPA 72 code sections · Fire Alarm Design Principles
Elevator recall: which detector sends the car where
Chapter 21 ties the fire alarm to the elevators. Smoke detectors in each elevator lobby, the elevator machine room and the hoistway (where sprinklers are present) initiate Phase I Emergency Recall. A lobby detector on any floor except the designated level recalls cars to the designated level; a detector at the designated level sends them to the alternate level. A machine-room or hoistway detector also causes the fire fighters' hat signal to flash in the car. Where sprinklers protect the machine room or hoistway, a heat detector may be required to shut down power (shunt trip) before the sprinkler operates — with the heat detector rated lower than the sprinkler. The fire alarm system only initiates these functions; the elevator controller performs them under ASME A17.1.
NFPA 72 reference
Chapter 21 — Emergency Control Function Interfaces
21.3 Elevator Phase I Emergency Recall Operation (21.3.1 lobby, machine room, hoistway detectors; 21.3.3 designated vs. alternate level; 21.3.5 fire fighters' hat flashing); 21.4 Elevator Shutdown (shunt trip)
References use NFPA 72 2019/2022 numbering — section numbers can shift between editions, so confirm in the edition your AHJ has adopted.
On the job
An acceptance test recalls the cars when a first-floor lobby detector is tested — but the first floor is the designated level, so they should have gone to the alternate (second) floor. The elevator contractor had wired all lobby detectors to a single recall input. A second input for the designated-level detector is added and the alternate-floor recall works.
Quick check
1. A smoke detector in the elevator lobby on the designated recall level sends the cars to:
2. Which detector activation makes the fire fighters' hat flash in the car?
3. The elevator shunt-trip heat detector must:
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