Elevator Recall & Shunt Trip Fundamentals (with VESDA + LHD Options)

Elevator recall and shunt trip integration is one of the most scrutinized intersections between fire alarm systems and vertical transportation. When designed incorrectly, it can lead to failed inspections, nuisance shutdowns, or life-safety hazards.

Project Recall Floors: Designated Recall Level (D) = Level 1 | Alternate Recall Level (A) = Level 2

Code edition note: ICC model codes are published on a 3-year cycle (current model edition is 2024). Some jurisdictions refer to “2025 codes” when adopting a 2025 state/local package based on the 2024 I-Codes.

Concept image: elevator hoistway detection options (spot detection, VESDA, and linear heat cable) with recall and shunt trip interfaces.

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Table of Contents

1. Code Framework Overview
2. Elevator Recall Fundamentals (Phase I)
3. Firefighter’s Emergency Operation (Phase I & II)
4. Elevator Shunt Trip (Power Shutdown)
5. Hoistway Protection Requirements
6. VESDA & Linear Heat Options (Testing Without Entry)
7. Mini Sequence of Operations (SOO)
8. Elevator Pit Requirements
9. Machine Room vs Control Room vs Control Space
10. Installation Best Practices
11. Common AHJ Inspection Failures
12. Testing & Commissioning
13. Final Design Checklist

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1) Code Framework Overview

Elevator fire recall and power shutdown requirements come from multiple governing documents. The building/fire codes establish where protection is required, while NFPA 72 defines how the fire alarm system interfaces with elevator controls. ASME A17.1/CSA B44 defines the elevator’s Firefighter’s Emergency Operation (FEO) behavior (Phase I and Phase II).

Standard	What It Governs
IBC (ICC model) Chapter 30	Elevators and conveying systems, machine/control rooms/spaces, hoistway provisions, and related building requirements.
IFC (ICC model) (elevator key/operations references)	Fire code interactions, including standardized fire service key references and fire service operations coordination.
NFPA 72 (2022) Chapter 21	Elevator recall interfaces and elevator power shutdown (shunt trip) signaling rules.
ASME A17.1 / CSA B44	Phase I Emergency Recall and Phase II In-Car operation requirements for elevator controls.
NFPA 13 (as adopted)	Sprinkler rules in hoistways, pits, and elevator equipment/control spaces (where required/allowed).

Code References:

• IBC (ICC model): Chapter 30 (Elevators and Conveying Systems), including Emergency Operations (see “Fire fighters’ emergency operation” sections in adopted IBC). (Example published text: IBC 2024 Ch.30).
• IFC (ICC model): Fire service key and related requirements referenced by IBC Emergency Operations language. (Example published text shows IBC requiring a standardized fire service key per IFC).
• NFPA 72 (2022): Chapter 21 (Elevators). Section families 21.3 (Recall) and 21.4 (Shutdown).
• ASME A17.1/CSA B44: Firefighter’s Emergency Operation (Phase I/II) and relay/access coordination provisions.

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2) Elevator Recall Fundamentals (Phase I Emergency Recall)

Elevator recall is the automatic return of elevators to a designated landing upon actuation of required initiating devices. In most designs, smoke detection at elevator lobbies and certain elevator spaces initiates recall logic.

Designated (Primary) Recall Level = Level 1

• Smoke detection at the Level 1 lobby (D) recalls elevators to the alternate recall level (Level 2).
• Normal call control is removed and elevators transition into Phase I operation.
• Logic must be coordinated to prevent recall into a contaminated lobby condition.

Alternate Recall Level = Level 2

• Smoke detection at the Level 2 lobby (A) recalls elevators to the designated recall level (Level 1), unless the elevator interface documentation requires otherwise.

Machine/Control Room (or Control Space) Smoke Detection

• Smoke detection in elevator equipment/control spaces typically initiates elevator recall.
• If the elevator space is located on Level 1, recall should go to Level 2. If located on Level 2, recall should go to Level 1 (coordinate per elevator interface requirements).

Code References:

• NFPA 72 (2022): Chapter 21 recall provisions (Section family 21.3).
• NFPA 72 lobby detector placement commonly uses the “within 21 ft horizontally of the centerline of elevator doors” rule in older editions and agency guides (example shows 21.3.5).
• ASME A17.1/CSA B44: Phase I Emergency Recall operation requirements and how the elevator controller responds to recall signals.

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3) Firefighter’s Emergency Operation (Phase I & Phase II)

Firefighter’s Emergency Operation (FEO) is defined by ASME A17.1/CSA B44. Fire alarm systems generally provide initiating/control signals that place elevators into Phase I recall. Phase II is manual and controlled by firefighters from the in-car operating panel.

Firefighter’s Hat Indicator (Visual Warning)

Many jurisdictions require a visual indicator at elevator landings that illuminates when smoke detection in the hoistway and/or machine/control spaces operates to warn responders of potential hazards.

Code References:

• IBC (ICC model): Emergency Operations requirements for elevators (Phase I/II language appears in adopted building codes).
• IFC (ICC model): Fire service key reference is explicitly tied into IBC emergency operations language in published ICC text.
• ASME A17.1/CSA B44: Phase I recall and Phase II in-car operation.
• NFPA 72 (2022): Elevator recall signaling/annunciation requirements within Chapter 21 (Section family 21.3).

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4) Elevator Shunt Trip (Power Shutdown)

Shunt trip is the removal of elevator power prior to water discharge onto energized equipment where sprinklers are present. This is coordinated so power can be removed before sprinkler discharge impacts energized elevator equipment.

Heat Detection Near Sprinklers (Spot Heat or Listed Alternatives)

• Provide heat detection used for elevator shutdown within 24 inches (2 feet) of each sprinkler head that could discharge water onto elevator equipment.
• Heat detection used for shutdown must be selected/arranged to operate before the sprinkler (lower temp and higher sensitivity intent).

Waterflow / Pressure Switch Method

• Waterflow switches can be used as an alternate method to initiate shutdown in some designs (less common).
• When used, timing/delay requirements must follow the applicable NFPA 72 elevator shutdown provisions and AHJ requirements.

Code References:

• NFPA 72 (2022): Elevator Shutdown (Section family 21.4).
• Public agency guidance shows the classic subsection structure: 21.4.1 (lower temperature/higher sensitivity intent), 21.4.2 (within 2 ft of sprinklers), and 21.4.3 (waterflow switch option).
• Electrical/elevator coordination: Shunt trip disconnect/breaker interface is an electrical/elevator coordination item; verify labeling, supervision, and responsibilities per project specs and AHJ.

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5) Hoistway Protection Requirements

Hoistway initiating devices are typically driven by sprinkler presence and adopted building/fire code triggers. If sprinklers are installed at the top of the hoistway, detection is commonly provided to initiate recall and coordinate shutdown.

Serviceability note: Spot-type devices at the top of hoistway often require special access procedures. The next section provides alternatives that can allow routine testing from outside the hoistway when engineered correctly.

Code References:

• NFPA 72 (2022): Recall and shutdown signaling in Chapter 21 (21.3 and 21.4).
• NFPA 13 (as adopted): sprinkler rules affecting top-of-hoistway and pit sprinklers (where required/allowed).
• IBC (ICC model): hoistway and elevator space requirements in Chapter 30, including special elevator types (Fire Service Access Elevators / Occupant Evacuation Elevators) that often prohibit sprinklers in certain elevator spaces, removing the shunt-trip driver for those applications.

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6) VESDA & Linear Heat Options (Testing Without Hoistway Entry)

Option A: VESDA / Air-Sampling Smoke Detection for Recall (Top of Hoistway)

VESDA (aspirating smoke detection) can be used to provide smoke detection at/near the top of hoistway while locating the detector in an accessible area, with sampling points in the hoistway. This can support functional testing without entering the hoistway when the manufacturer-approved test method and AHJ acceptance criteria are met.

Option B: Linear Heat Detection (LHD, Protectowire or Equivalent) for Shunt Trip

Listed linear heat detection cable can be positioned near sprinkler locations to provide shutdown-initiating heat detection without relying on a spot-type heat detector mounted at the top of hoistway. Many LHD solutions provide accessible testing methods (manufacturer procedures), supporting serviceability without hoistway entry when properly designed.

Code References:

• NFPA 72 (2022): Recall and shutdown are governed by Chapter 21 (21.3 and 21.4), regardless of whether the initiating device is spot-type or an approved/listed alternative.
• NFPA 72 elevator shutdown spacing intent (public guides show: 21.4.2 within 2 ft of sprinklers; 21.4.1 sensitivity intent).
• Listings & manufacturer instructions: VESDA/LHD must be installed and tested per listing/manufacturer requirements; acceptance testing is AHJ-driven.
• ASME A17.1/CSA B44: Coordination to avoid hoistway interference and ensure elevator controller interface requirements are met.

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7) Mini Sequence of Operations (SOO)

This compact SOO matrix is suitable for drawings and narrative. It assumes: Designated Recall Level (D) = Level 1 and Alternate Recall Level (A) = Level 2. Always confirm final logic with the elevator contractor interface documentation and AHJ requirements.

Initiating Input	Location / Condition	FA System Action	Elevator Output	Annunciation / Notes
Lobby Smoke	Level 1 lobby (Designated D)	Alarm; initiate Phase I recall sequence	Recall to Level 2 (Alternate A)	Prevents recall into smoke condition at Level 1
Lobby Smoke	Level 2 lobby (Alternate A)	Alarm; initiate Phase I recall sequence	Recall to Level 1 (Designated D)	Verify final logic per elevator controller interface documentation
Machine/Control Space Smoke	Machine room / control room / control space	Alarm; initiate Phase I recall; activate hat light where required	Recall to opposite of affected floor (L1 ↔ L2 per location)	Hat light commonly tied to machine/control/hoistway detection
Hoistway Smoke (Spot or VESDA Alarm)	Top of hoistway (where required/used)	Alarm; initiate Phase I recall; hat light where required	Recall to Level 1 (D) unless engineered otherwise	VESDA allows detector/test access outside hoistway with proper design
Hoistway Heat (Spot Heat or LHD Alarm)	Near hoistway sprinklers requiring shutdown coordination	Alarm; initiate elevator power shutdown logic	Shunt Trip Output (disconnect/breaker)	LHD (Protectowire) can support testing without hoistway entry (per manufacturer)
Waterflow / Pressure Switch	Elevator sprinkler branch (where used)	Alarm; initiate power shutdown	Shunt Trip Output	Confirm delay permissibility by method + AHJ (NFPA 72 elevator shutdown rules)
VESDA Trouble/Fault	Detector/airflow/power/pipe fault	Trouble/Supervisory (not alarm)	No recall/shutdown (typical)	Annunciate clearly; maintainability benefit without hoistway access
LHD Trouble/Open	Circuit open/module trouble/cable fault	Trouble/Supervisory (as programmed)	No shunt trip on trouble (typical)	Supervision strategy must be documented and tested

Interface Wiring Responsibilities (typical): Fire Alarm (FA) contractor provides listed modules/relays and terminations at FA equipment; Electrical Contractor (EC) provides conduit, power, and shunt-trip breaker/disconnect wiring; Elevator contractor provides controller terminations/interface points, elevator programming, and final verification of Phase I/II operation. (Final division of scope per project specs/AHJ.)

Mini Point List (Inputs / Outputs / Troubles)

Use this as a compact “point schedule” to align drawings, programming, and acceptance testing. Adjust point names to match your panel database.

Point Type	Point Name (Example)	Class	Function	Notes
Input	SD-L1-ELV-LOBBY (Lobby Smoke, L1)	Alarm	Initiate Phase I recall: Recall to Level 2 (A)	Designated recall lobby smoke causes alternate recall
Input	SD-L2-ELV-LOBBY (Lobby Smoke, L2)	Alarm	Initiate Phase I recall: Recall to Level 1 (D)	Alternate lobby smoke causes designated recall (verify elevator interface)
Input	SD-ELV-MR (Machine/Control Space Smoke)	Alarm	Recall opposite affected floor (L1 ↔ L2); activate FHL (if used)	Also commonly drives firefighter hat light
Input	ASD-ELV-HWY (VESDA Alarm, Hoistway Top)	Alarm	Recall to Level 1 (D); activate FHL (if used)	Alarm threshold used for recall; coordinate threshold level with AHJ/elevator contractor
Input	HD-ELV-HWY (Spot Heat, Hoistway Top)	Alarm	Initiate elevator power shutdown (Shunt Trip)	Used when shutdown coordination is required at sprinklers
Input	LHD-ELV-HWY (Protectowire/LHD Alarm)	Alarm	Initiate elevator power shutdown (Shunt Trip)	Listed LHD cable near sprinkler(s); supports testing without hoistway entry when designed with accessible test method
Input	WF-ELV-BRANCH (Waterflow/Pressure Switch)	Alarm	Initiate elevator power shutdown (Shunt Trip)	If used as shutdown method: typically no delay (confirm method/AHJ)
Output	CR-ELV-RECALL-D (Recall Control)	Control	Phase I recall signal to elevator controller (to Level 1 D logic)	Use elevator contractor interface requirements for exact inputs/terminals
Output	CR-ELV-RECALL-A (Alternate Recall Control)	Control	Phase I alternate recall signal to elevator controller (to Level 2 A logic)	Triggered when Level 1 lobby smoke is in alarm
Output	CR-ELV-FHL (Firefighter Hat Light)	Control	Illuminate firefighter hat indicator (where required/used)	Commonly driven by hoistway + machine/control space smoke conditions
Output	CR-ELV-SHUNT (Shunt Trip Control)	Control	Trip elevator disconnect/breaker via shunt-trip interface	Coordinate delay/sequence with elevator contractor + AHJ (method-dependent)
Trouble	ASD-ELV-HWY-TBL (VESDA Trouble/Fault)	Trouble/Supv	Annunciate aspirating detector trouble (airflow, power, pipe, detector fault)	Should NOT initiate recall/shutdown (typical). Drives prompt service response without hoistway entry.
Trouble	LHD-ELV-HWY-TBL (LHD Trouble/Open)	Trouble/Supv	Annunciate LHD circuit open/module trouble/cable fault	Supervision is critical; do not “fail silent.” Typically no shunt trip on trouble.
Supervisory	ELV-POWER-OFF (Shunt Trip Proof / Aux Contact)	Supervisory	Confirm power removed at elevator disconnect/breaker (status feedback)	Highly recommended for clean acceptance testing documentation

Point List Tip: If your AHJ likes clarity, add a short note in your SoO: “All elevator interface outputs are via listed control relays/modules; all interface troubles are annunciated as supervisory/trouble and recorded in the FA event history.”

Code References:

• ASME A17.1/CSA B44: Phase I Emergency Recall and Phase II In-Car operation.
• NFPA 72 (2022): Elevator Recall (21.3 family) and Elevator Shutdown (21.4 family).
• Agency guidance shows relay location/access constraints and interface considerations (example references relays within 3 ft of controller and access rules tied to ASME A17.1 provisions).

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8) Elevator Pit Requirements

Elevator pits may include sprinkler protection depending on building design, elevator type, and adopted sprinkler rules. Where pit sprinklers exist and require shutdown coordination, heat detection (or approved alternatives such as LHD) may be needed.

Code References:

• NFPA 13 (as adopted): pit sprinkler placement rules (often sidewall and ≤2 ft above pit floor in prior editions) and omission conditions in certain hoistways depending on construction/elevator type (varies by edition and adoption).
• NFPA 72 (2022): if pit sprinkler triggers shutdown coordination, apply elevator shutdown signaling rules (21.4 family).

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9) Machine Room vs Control Room vs Control Space

Elevator Machine/Equipment Room

Houses motors, machinery, controllers, disconnects, and related elevator equipment. If sprinklered, ensure shutdown coordination design is addressed.

Elevator Control Room / Control Space

Control rooms/spaces may house controls without major machinery, but still require the correct detection/recall/shutdown interfaces based on sprinklers and adopted requirements.

Code References:

• IBC (ICC model): machine rooms, control rooms, machinery spaces, control spaces in Chapter 30 (section numbering varies by edition/adoption).
• NFPA 72 (2022): recall (21.3 family) and shutdown (21.4 family) apply based on the interface requirements for those spaces.
• IBC special elevator types: Fire Service Access Elevators (IBC 3007) and Occupant Evacuation Elevators (IBC 3008) often prohibit sprinklers in elevator spaces, removing the shunt-trip driver.

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10) Installation Best Practices

Coordinate Early

• Get elevator contractor interface documentation: required recall inputs, relay types, and where relays must be located/accessed.
• Confirm sprinkler locations that drive shutdown coordination and confirm method (spot heat vs LHD vs waterflow method).
• Confirm AHJ testing expectations, especially for VESDA/LHD “test without hoistway entry” approaches.

Use Dedicated Modules and Relays

• Use separate outputs for designated recall, alternate recall, hat light, and shunt trip activation unless explicitly permitted to combine.
• Keep elevator interface wiring segregated and clearly labeled (panel schedule + riser + controller terminations).

Code References:

• NFPA 72 (2022): Chapter 21 interface requirements (21.2 general, 21.3 recall, 21.4 shutdown).
• Example public guidance shows relay placement intent: relays for connection to elevator controller within 3 ft; access restrictions for relays through hoistway in ASME A17.1 referenced guidance.

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11) Common AHJ Inspection Failures

• Recall floors not clearly documented (Level 1 designated / Level 2 alternate).
• Heat detection method not coordinated to operate before sprinkler discharge (or not installed per listing/manufacturer requirements).
• Incorrect recall logic when the initiating device is on the designated level.
• Improper shunt trip coordination (wrong disconnect, missing proof of power removal, unclear responsibility split).
• VESDA sampling design not engineered/accepted (transport time, sampling point placement, test method).
• LHD not installed per listing or not properly supervised/interfaced.

Code References:

• NFPA 72 (2022): 21.3 family (recall) and 21.4 family (shutdown) drive most test failures.
• ASME A17.1/CSA B44: elevator controller response and Phase I/II behavior.
• IBC/IFC: adopted elevator emergency operations requirements and key coordination references.

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12) Testing & Commissioning

Verify recall and shutdown functions during acceptance and periodic testing with elevator personnel present. Document results, including proof of elevator response, annunciation, and power removal behavior.

• Verify designated recall initiation and recall behavior (D = L1 / A = L2 logic).
• Verify alternate recall initiation and recall behavior.
• Verify hat light operation where required (hoistway/machine/control detection conditions).
• Verify shunt trip initiation and confirm actual power removal at the correct disconnect/breaker.
• VESDA: verify alarm thresholds used for recall and verify trouble/fault reporting.
• LHD: verify activation method used for shutdown and verify supervision/trouble reporting.

Code References:

• NFPA 72 (2022): Acceptance testing and interface performance tied to Chapter 21 functions (21.3/21.4) and applicable testing chapters.
• ASME A17.1/CSA B44: Firefighter’s Emergency Operation functionality.
• Manufacturer listings: VESDA/LHD test procedures and acceptance requirements.

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13) Final Design Checklist

• ✔ Designated Recall Level = Level 1 and Alternate Recall Level = Level 2 clearly documented in SOO
• ✔ Lobby initiating devices located per NFPA 72 lobby rules (commonly within 21 ft of door centerline per guides/legacy numbering)
• ✔ Machine/control space initiating devices and interfaces documented and accessible
• ✔ Hoistway detection method selected: spot smoke/heat or VESDA + LHD alternatives as approved
• ✔ Shutdown method selected and coordinated: spot heat / LHD / waterflow method (as permitted)
• ✔ Shunt trip tied to correct disconnect/breaker and verified during testing
• ✔ Supervision/trouble annunciation implemented for VESDA/LHD interfaces

Code References:

• NFPA 72 (2022): Chapter 21 (21.3 recall / 21.4 shutdown).
• IBC/IFC: adopted elevator emergency operation requirements and keys.
• ASME A17.1/CSA B44: Phase I/II operation requirements.