Elevator Recall Detection in an Existing Building: Lobby Omission and Machine Room Devices
A six-story existing office building, fully sprinklered, is installing a new traction elevator. The fire alarm submittal shows smoke detectors in the elevator machine room and at the first-floor elevator lobby only. A 135 F heat detector in the machine room is wired to the shunt-trip relay for the machine room sprinkler head. Phase I recall is programmed to initiate on any of these three devices. The designer's cover letter states that lobby detectors on floors 2 through 6 are unnecessary because those lobbies are sprinklered with quick-response heads and the building is fully sprinklered. The elevator contractor has installed the ASME A17.1 interface and is waiting on the fire alarm to finish so the elevator can be turned over.
1. Evaluate the decision to omit elevator lobby smoke detectors on floors 2 through 6.
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Treat the omission as unproven until the AHJ accepts it in writing.
The lobby detector is not primarily a fire alarm design choice - it is a Phase I recall input required by the elevator code and by the building code's elevator provisions, and the fire alarm is only the vehicle that delivers it. A sprinkler-based exception to lobby detection does exist in some editions of the building code, but it is narrow, edition-specific, and conditioned on details of the sprinkler design and the presence or absence of smoke barriers at the lobby. It does not automatically satisfy the elevator code's recall input requirement.
Action items:
- Identify the editions actually adopted by this AHJ (building code, elevator code, NFPA 72) and read the exception text, not the cover letter.
- Submit a formal code-modification/variance request if the designer wants to rely on the exception. Silence is not approval.
- If the variance is not granted, add lobby detection on floors 2-6 and verify the recall sequence groups the floors so a single lobby detector recalls the car to the designated alternate floor.
- Record the resolution in the sequence of operations, not just in correspondence.
2. The machine room has both a smoke detector and a 135 F heat detector. Explain the role of each and whether the programming is correct.
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They are two different functions and should not be lumped together.
- Machine room smoke detector - provides elevator recall (Phase I) and general building alarm. This is the detection the elevator code and NFPA 72 contemplate for recall.
- 135 F heat detector - provides the shunt trip that removes power to the machine room sprinkler control (or to the elevator) before a 165 F sprinkler head fuses, so the elevator does not operate with water on it. Its set point is deliberately below the sprinkler's.
Programming Phase I recall to initiate on "any of these three devices" incorrectly makes the heat detector a recall trigger and blurs the shunt-trip function. Correct the sequence so that:
- Lobby detectors and the machine room smoke detector initiate Phase I recall;
- The heat detector initiates shunt trip and reports as its own distinct zone/address;
- Both report distinctly at the panel and to the supervising station so a responder can tell which device operated;
- The shunt-trip output is supervised and its activation is verifiable at acceptance test.
Confirm the arrangement with the elevator contractor and the sprinkler designer before final programming.
3. What acceptance evidence should you require before the elevator is turned over?
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Recall is a life-safety interface between two trades, so test it as one system, not two.
Require:
- A written sequence of operations signed by the designer showing every recall and shunt-trip input and output.
- A witnessed test of each lobby detector, each machine room device, and each hoistway device, with the elevator contractor present, demonstrating Phase I recall to the designated floor and correct behavior on the alternate-floor designations.
- A test of the heat detector's shunt trip showing power removal and a distinct supervisory/alarm indication at the panel.
- Verification that the signals reached the supervising station (a live test signal, not a simulated one).
- Signed and dated test records identifying the devices, results, and any deficiencies, plus the completed elevator interface checklist.
If the AHJ granted a lobby-detection variance, attach the written approval to the acceptance package - otherwise the record set will not match the installed system.