AEO Answer · Fire Protection & Life Safety

How Does Elevator Recall Integrate With the Fire Alarm System?

By Jeremy Mills, CEO & Founder, Apex Grid Engineering — USAF Veteran. · Updated 2026-09-15

Elevator recall integration uses lobby, machine room, and hoistway smoke detection to automatically return cars to a safe floor on alarm, with shunt trip disconnecting power before sprinklers wet the equipment and Phase II controls for firefighter use.

I'm Jeremy Mills, CEO & Founder of Apex Grid Engineering and a U.S. Air Force veteran. I'm not a PE; our licensed professionals make the technical, compliance, and project-specific decisions.

Illustrative diagram of building MEP systems: ductwork with diffusers, an electrical panel with conduit, and piping runs.

The recall sequence, end to end

I design the recall sequence as a timeline the fire alarm panel executes: lobby smoke detector alarms, the panel initiates Phase I recall on the associated elevator bank, cars return to the designated level (or the alternate if the designated level is the alarm origin), doors open, cars go out of service, and the panel reports recall complete at the fire command center. Machine room or hoistway detection adds the shunt trip step before sprinkler discharge. Every step gets a monitoring point back to the panel — the incident commander needs to see recall status, not assume it. I write the sequence of operations with the elevator contractor and test it as an integrated system, because recall that works in the elevator controller's lab and fails against the real fire alarm panel is a failed design.

Coordination with sprinklers and emergency power

Elevator recall sits at the intersection of three trades, and I coordinate all three. With fire protection: machine room sprinkler heads and heat detectors are positioned and temperature-rated so detection precedes water, and the shunt trip power disconnect is verified to drop the car safely. With electrical: at least one elevator is on emergency power for firefighter service where the code requires it, and the shunt trip arrangement is coordinated with the emergency distribution so the disconnect behaves correctly on both normal and emergency sources. With the elevator contractor: the interface points — who provides what relay, what voltage, what supervision — are nailed down in the submittals, not discovered in the field. Acceptance testing runs the full sequence: alarm, recall, shunt, and Phase II handoff, witnessed by the AHJ.

Elevator recall integration checklist

An elevator recall design is ready when it clears this checklist. Three trades, one sequence — every interface is verified. • Smoke detectors in every elevator lobby, machine room, and hoistway top per code • Phase I recall to designated and alternate levels sequenced and monitored at the fire command center • Shunt trip coordinated so detection and power disconnect precede sprinkler discharge • Phase II firefighter in-car controls verified, with elevator on emergency power where required • Full integrated acceptance test of alarm, recall, shunt, and firefighter handoff witnessed by the AHJ

Which related engineering resources can help?

When should I hire a structural engineer?What does a PE stamp mean?What is MEP engineering?How Does Elevator Recall for Fire Service Work?How Is an Elevator Machine Room Designed?How Is a Commercial Fire Alarm System Designed?Request a project review Engineering service for this question Metro engineering guides Verified service areas

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What triggers Phase I elevator recall?

Smoke detection in an elevator lobby, machine room, or hoistway — any detector associated with the elevator system initiates Phase I, which automatically returns the cars to the designated recall floor, opens the doors, and takes them out of public service. If the smoke is at the designated level itself, the system recalls to the alternate level instead. I also design for the manual recall key at the designated level, which lets firefighters initiate recall themselves. The lobby detectors are the critical ones: they have to be placed so lobby smoke is caught before it enters the hoistway.

What is a shunt trip and why does elevator design need one?

The shunt trip disconnects electrical power to the elevator before sprinkler water discharges onto the machine room or hoistway equipment — water on energized elevator gear is an electrocution and equipment-destruction hazard. The sequence is detection first (a heat detector set below the sprinkler's operating temperature), then shunt trip drops the power, then the sprinklers can wet the space safely. I coordinate the detector temperature rating against the sprinkler temperature rating with the fire protection designer, because if the sprinkler beats the detector, the shunt trip is useless.

What is Phase II firefighter service?

Phase II is the in-car firefighter control that takes over after Phase I recall is complete: a keyed switch in the car lets a firefighter take manual command — holding doors, selecting floors, overriding the automatic sequence. It exists so firefighters can use an elevator deliberately during an incident, with full awareness and control, rather than the public using it blindly. I verify the Phase II controls, the car lighting and communication on emergency power, and the fire alarm panel's monitoring of firefighter service status as part of the acceptance testing.

Where do the elevator lobby smoke detectors go?

In every elevator lobby, positioned to detect smoke before it migrates into the hoistway — which means understanding the lobby's airflow, not just centering a detector on the ceiling. I also place detection in the machine room and at the top of the hoistway where the code requires it, and I coordinate with the sprinkler designer on the machine room head locations for the shunt trip sequence. Lobby detectors near the hoistway doors get priority in the layout, and I keep them clear of HVAC supply diffusers that would blow smoke away from the detector.

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