Elevator Shunt Trip Wiring Diagram | Fire Alarm Power Shutdown

An elevator shunt trip is used to automatically disconnect elevator power when required by the approved elevator and fire protection design, typically where sprinkler operation could create an unsafe condition for elevator equipment.

The fire alarm system commonly provides the initiating interface for this function through heat detection and listed control equipment.

This guide explains the basic elevator shunt trip wiring sequence, the purpose of the heat detector, fire alarm control relay, shunt-trip disconnect, power monitoring, and how elevator recall differs from elevator power shutdown.

Important: The diagram below is a typical educational example, not a universal construction detail. Elevator power shutdown must follow the adopted elevator code, NFPA 72, NFPA 13 where applicable, electrical requirements, equipment listings, approved plans, elevator manufacturer's requirements, and the AHJ-approved sequence of operations.

Elevator Shunt Trip Wiring Diagram

The diagram above illustrates a typical concept for interfacing a fire alarm system with an elevator shunt-trip disconnect.

The exact arrangement varies by project. Always use the approved project drawings and equipment-specific wiring diagrams rather than treating a generic diagram as a universal installation detail.

What Is an Elevator Shunt Trip?

An elevator shunt trip is a means of automatically disconnecting electrical power to elevator equipment when required by the elevator/fire protection design.

The objective is not simply to "turn the elevator off."

Where the applicable elevator code requires automatic power shutdown because sprinkler water could create an unsafe elevator condition, the shutdown must occur upon or prior to the application of water.

The fire alarm system commonly interfaces with the electrical disconnect through a control relay or other listed interface equipment.

Elevator Recall and Elevator Shunt Trip Are Different Functions

This distinction is extremely important.

Elevator recall and elevator power shutdown are separate emergency-control functions.

Function	Typical Purpose
Elevator Recall	Causes the elevator system to respond to a fire alarm recall signal and move according to the approved recall sequence.
Elevator Shunt Trip	Disconnects applicable elevator power when automatic power shutdown is required.

A smoke detector used for elevator recall should therefore not be confused with a heat detector used to initiate elevator power shutdown.

Basic Elevator Shunt Trip Sequence

A typical elevator shunt-trip sequence can be understood as:

Heat Detector → Fire Alarm System → Control Relay → Shunt-Trip Disconnect → Elevator Power Removed

The actual system may contain additional monitoring modules, relays, power supplies, disconnects, elevator-controller interfaces, and other components.

Each component serves a specific function and must be coordinated with the approved sequence of operations.

Why Is a Heat Detector Used for Elevator Shunt Trip?

Where automatic elevator power shutdown is required in connection with sprinkler protection, heat detection is commonly used to initiate the shutdown function before sprinkler water is discharged onto elevator equipment.

The purpose is timing.

The shutdown arrangement must coordinate the initiating device and sprinkler so the required power disconnect occurs upon or before water application.

This is different from elevator recall, which is commonly initiated by smoke detection in designated elevator-related locations.

Heat Detector Location Near the Sprinkler

Where heat detection is used to initiate elevator power shutdown, the detector location and temperature characteristics must be coordinated with the sprinkler installation and applicable requirements.

The commonly encountered arrangement places the heat detector within the required proximity of the associated sprinkler so that the detector can respond in time to initiate the shutdown sequence.

Do not simply install one heat detector somewhere in an elevator machine room and assume the requirement has been satisfied. The detector arrangement must correspond with the sprinkler protection and approved design.

Heat Detector Temperature Rating and Sprinkler Temperature

The temperature characteristics of the heat detector and sprinkler are critical.

The goal is for the elevator shutdown sequence to operate before sprinkler discharge when the applicable design requires power removal before water is applied to elevator equipment.

For this reason, the heat detector selection cannot be treated independently from the sprinkler temperature classification and response characteristics.

Design Point: Never select the elevator shunt-trip heat detector solely because a particular temperature rating is normally stocked. Coordinate the detector with the sprinkler and the approved elevator shutdown design.

Fire Alarm Relay for Elevator Shunt Trip

The fire alarm system commonly controls the elevator shunt-trip function through a listed control relay or control module.

When the appropriate heat detector activates, the fire alarm system changes the state of the control output according to the programmed sequence.

That interface then operates the shunt-trip circuit associated with the elevator disconnect.

The exact relay contact configuration, control voltage, wiring method, and fail-safe arrangement depend on the equipment and approved design.

Never assume that normally open or normally closed is universally correct for every shunt-trip installation.

Need the detailed wiring method? For a deeper explanation of ECID placement, supervised control wiring, addressable relay modules, FCM-1 versus FRM-1 operation and external interface relays, see our How to Wire an Elevator Shunt Trip | ECID & Relay Supervision guide.

What Does the Shunt-Trip Breaker or Disconnect Do?

A shunt-trip mechanism allows a circuit breaker or disconnecting means to be electrically operated from a remote signal.

In an elevator power-shutdown application, activation of the required interface causes the applicable elevator power to be disconnected.

The fire alarm control equipment is therefore generally providing the control signal. It is not carrying the elevator motor power through the fire alarm relay.

Critical: Elevator power must never be routed directly through ordinary fire alarm relay contacts unless the equipment is specifically listed and rated for that application. The fire alarm interface normally controls the appropriate listed shunt-trip equipment.

Why Shunt-Trip Control Power Matters

A shunt-trip mechanism needs an available source of control power in order to operate.

That creates an important supervision question:

What happens if the shunt-trip control power is lost before a fire occurs?

If the power necessary to perform the required shutdown is unavailable, the fire alarm system needs to provide the required indication of that impairment where required by the applicable system design and code.

This is why elevator shunt-trip installations commonly include monitoring associated with the availability of the control power.

Monitoring Shunt-Trip Power

A properly designed system should not silently lose the power necessary to perform a required elevator shutdown function.

Depending on the design, the fire alarm system may monitor the availability of the shunt-trip control power through an approved supervisory interface.

If that power becomes unavailable, the fire alarm system can then indicate the abnormal condition rather than leaving a hidden impairment.

The exact monitoring arrangement depends on the disconnect, control-power source, fire alarm equipment, approved plans, and applicable adopted requirements.

What Happens When the Shunt-Trip Heat Detector Activates?

A typical sequence is:

1. The elevator-area heat detector reaches its operating point.
2. The fire alarm control unit receives the detector input.
3. The fire alarm system activates the programmed elevator power-shutdown output.
4. The associated fire alarm control relay or module changes state.
5. The shunt-trip mechanism operates.
6. The applicable elevator power is disconnected.
7. The fire alarm system provides the required event indications according to the approved sequence.

The actual project sequence may contain additional operations and must always be verified against the approved input/output matrix.

Should Elevator Recall Happen Before Shunt Trip?

Elevator recall and power shutdown are coordinated functions, but technicians should be careful with the common field explanation that the fire alarm system simply "recalls the elevator first and then waits to shunt it."

The power-shutdown function is governed by the required response to the sprinkler hazard and the approved elevator-system design.

Do not create an arbitrary fire alarm timer intended to delay required elevator power shutdown unless that exact arrangement is permitted by the applicable codes, elevator equipment, and approved design.

The fire alarm system should execute the approved sequence rather than improvising a delay in the field.

Smoke Detector vs. Heat Detector for Elevator Functions

Device	Common Elevator Function
Smoke Detector	Elevator recall and related Phase I emergency operation inputs where required.
Heat Detector	Elevator power shutdown where required in coordination with sprinkler protection.
Waterflow	Reports sprinkler waterflow but should not automatically be assumed to be the initiating input for the elevator shunt-trip function.

Does Sprinkler Waterflow Shunt Trip the Elevator?

Do not automatically use the sprinkler waterflow switch as the elevator shunt-trip initiating device simply because the shutdown is associated with sprinkler protection.

The purpose of the elevator power-shutdown arrangement is to disconnect the required power upon or prior to the application of water where the elevator code requires that protection.

Waiting for established sprinkler waterflow can be inconsistent with that objective.

Follow the approved heat-detection and shutdown design for the project.

Elevator Machine Room Shunt Trip

Where sprinklers are installed in an elevator machine room, machinery space, control room, control space, hoistway, or other applicable elevator equipment area, the designer must determine whether elevator power shutdown is required by the adopted elevator code and project conditions.

The answer should not be based simply on the fact that the building has elevators or sprinklers.

Modern elevator and sprinkler requirements contain important exceptions and installation options, so each project needs to be evaluated under its adopted codes and elevator design.

Elevator Pit Sprinklers and Shunt Trip

Elevator pits deserve particular attention because the presence of a sprinkler does not automatically mean every pit requires identical fire alarm shutdown equipment.

The sprinkler arrangement, elevator equipment exposure, applicable elevator-code provisions, and approved design determine the required sequence.

Never copy the machine-room shunt-trip design into the pit without verifying the requirements for that specific elevator installation.

NFPA 72 and Elevator Power Shutdown

NFPA 72 addresses the fire alarm system's role in emergency control function interfaces, including elevator-related functions.

The fire alarm system may be responsible for receiving the appropriate initiating-device input, processing the programmed sequence, operating listed control interfaces, supervising applicable pathways or functions, and annunciating abnormal conditions.

However, NFPA 72 is not the only standard involved.

Elevator shunt trip can involve requirements from:

• NFPA 72, National Fire Alarm and Signaling Code
• The adopted elevator safety code, commonly based on ASME A17.1/CSA B44
• NFPA 13 where sprinkler protection is involved
• NFPA 70 / NEC for electrical installation requirements
• The adopted building and fire codes
• Elevator manufacturer requirements
• Fire alarm equipment listings and instructions
• The Authority Having Jurisdiction

Do Not Treat the Fire Alarm Diagram as the Complete Elevator Design

A fire alarm drawing may show a heat detector, control module, monitor module, and interface to the elevator disconnect.

That does not necessarily document every part of the elevator electrical installation.

Coordination may be required between:

• Fire alarm contractor
• Elevator contractor
• Electrical contractor
• Sprinkler contractor
• Mechanical contractor
• Engineer of record
• Fire alarm designer
• Elevator inspector
• Fire marshal or other AHJ

Elevator shunt trip is one of those deceptively small details on a fire alarm drawing that can involve several trades.

Testing an Elevator Shunt-Trip Interface

Testing should verify the complete approved sequence rather than merely checking whether a relay LED turns on.

Depending on the project and applicable requirements, coordinated testing should verify items such as:

• Correct initiating heat detector
• Correct fire alarm input identification
• Correct programmed output
• Operation of the fire alarm control relay or module
• Operation of the approved elevator power-shutdown interface
• Required monitoring of control power
• Correct annunciation at the fire alarm control unit
• Restoration of the system after testing
• Coordination with elevator recall and other elevator emergency functions

Testing Warning: Do not intentionally remove elevator power during testing without coordination with the elevator contractor, building representative, and other responsible parties. An uncontrolled shunt-trip test can trap occupants, interrupt building operations, or create equipment and safety problems.

Common Elevator Shunt Trip Wiring Mistakes

• Confusing recall with shunt trip. They are separate elevator emergency functions.
• Using the wrong initiating device. Smoke detection and heat detection commonly perform different elevator functions.
• Using waterflow as the automatic shutdown trigger without verifying the design.
• Failing to coordinate the heat detector with the sprinkler installation.
• Ignoring loss of shunt-trip control power.
• Using an arbitrary software timer to delay shutdown.
• Assuming every elevator pit or machine room has the same requirements.
• Using a generic wiring diagram instead of the approved project documents.
• Failing to coordinate fire alarm, elevator, electrical and sprinkler trades.
• Testing the fire alarm relay but not the complete integrated function.

Elevator Shunt Trip Quick Reference

Primary Purpose	Automatic elevator power shutdown where required
Typical Initiating Device	Heat detector associated with applicable sprinkler protection
Fire Alarm Output	Listed control relay/module or other approved interface
Controlled Equipment	Approved elevator shunt-trip disconnecting means
Separate From	Elevator recall
Important Coordination	Elevator, fire alarm, sprinkler and electrical systems

Frequently Asked Questions

What is an elevator shunt trip?

An elevator shunt trip is an automatic means of disconnecting applicable elevator electrical power when required by the approved elevator and fire-protection design.

What activates an elevator shunt trip?

Where power shutdown is required in coordination with sprinkler protection, heat detection is commonly used to initiate the fire alarm control sequence that operates the approved shunt-trip interface.

Does a smoke detector shunt trip an elevator?

Smoke detectors are commonly associated with elevator recall functions rather than the sprinkler-related power-shutdown function. The exact operation must follow the approved elevator and fire alarm sequence.

Does a sprinkler waterflow switch shunt trip an elevator?

Waterflow should not automatically be assumed to be the correct initiating input. Where shutdown is required upon or prior to sprinkler water application, the approved design commonly uses heat detection coordinated with the sprinkler rather than waiting for established waterflow.

Is elevator recall the same as elevator shunt trip?

No. Recall commands the elevator system to perform its approved emergency recall operation. Shunt trip disconnects applicable elevator power when power shutdown is required.

Does every elevator require shunt trip?

No. Whether automatic power shutdown is required depends on the elevator equipment, sprinkler protection, adopted elevator code, building conditions, and approved design.

Does every sprinkler in an elevator area require a heat detector?

Not automatically. The required detection and shutdown arrangement depends on whether automatic elevator power shutdown is required for that sprinkler/elevator condition under the applicable codes and approved design.

Why is shunt-trip power monitored?

If electrical power necessary to operate a required shunt-trip function is lost, the shutdown function can become impaired. Where required, monitoring allows that abnormal condition to be reported rather than remaining hidden.

Can the fire alarm relay directly switch elevator motor power?

Ordinary fire alarm control contacts are generally used to interface with the approved elevator power-shutdown equipment, not to carry elevator motor power. Always follow the equipment listings and approved electrical design.

Related Elevator Fire Alarm Guides

• Elevator Shunt Trip Requirements & Codes
• Elevator Recall and Shunt Trip Basics
• Heat Detectors and Elevator Pits
• Elevator Recall Programming and Operation

Final Thoughts

The key to understanding elevator shunt-trip wiring is recognizing that the fire alarm system is only one part of an integrated elevator power-shutdown function.

The heat detector provides the initiating condition. The fire alarm system processes that condition and operates the approved control interface. The shunt-trip equipment disconnects the required elevator power.

Meanwhile, elevator recall remains a separate emergency function with its own initiating devices and sequence.

For a successful installation, the fire alarm, elevator, sprinkler and electrical designs all have to agree on the same sequence of operation.

Technical Disclaimer: This article is intended for educational use by qualified fire alarm and life-safety professionals. Elevator power shutdown is an integrated life-safety function. Always follow the adopted codes and standards, approved construction documents, elevator manufacturer requirements, equipment listings, electrical-safety procedures, and AHJ requirements for the specific installation.

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.

Back to Table of Contents

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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.

Back to Table of Contents

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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.

Back to Table of Contents

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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.

How to Wire an Elevator Shunt Trip | ECID & Relay Supervision

Proper elevator shunt trip wiring involves more than simply connecting a fire alarm relay to a shunt-trip breaker. The fire alarm designer must identify the emergency control interface device (ECID), determine which control pathway requires supervision, verify the electrical characteristics of the controlled circuit, and select an interface device suitable for the application.

This guide focuses specifically on the fire alarm interface and supervision side of elevator shunt-trip wiring, including ECID placement, addressable modules, interface relays and control-circuit supervision.

If you are looking for the complete elevator shutdown sequence instead, including the heat detector, fire alarm relay, shunt-trip disconnect, sprinkler relationship and elevator power removal, see our Elevator Shunt Trip Wiring Diagram & Power Shutdown Guide.

Important: The wiring arrangements shown here are educational examples. Elevator power shutdown is an integrated life-safety function. Always follow the adopted codes, approved drawings, fire alarm and elevator equipment instructions, electrical requirements, equipment listings and the AHJ-approved sequence of operations.

Elevator Shunt Trip Wiring Diagram

The diagram above illustrates two concepts for interfacing a fire alarm system with elevator shunt-trip equipment.

The important concept is not the specific NOTIFIER part number. It is understanding where the emergency control interface occurs and how the fire alarm control pathway is supervised.

What Is an ECID?

ECID stands for Emergency Control Interface Device.

In practical fire alarm design, the ECID is the interface through which the fire alarm system performs the required emergency control function.

For an elevator power-shutdown application, the ECID may be an addressable fire alarm interface located appropriately for the controlled equipment, or the design may use a supervised fire alarm control circuit operating another listed interface relay.

Which device serves as the actual interface depends on the system architecture.

This distinction matters because moving the interface farther away from the addressable fire alarm module can create an additional field-wiring pathway that must be considered in the supervision design.

The Basic ECID Concept

A useful way to visualize the arrangement is:

FACU → Supervised Fire Alarm Pathway → ECID → Controlled Emergency Function

For an addressable fire alarm system, the signaling line circuit itself is supervised by the fire alarm control unit.

However, simply having an addressable module somewhere in the system does not automatically mean every conductor beyond that module is supervised.

That is the key issue this article addresses.

Method 1: Addressable Relay at the Elevator Interface

One approach is to locate an addressable relay module at the point where the fire alarm system interfaces with the elevator power-shutdown control equipment.

The original example used a NOTIFIER FRM-1 addressable relay module.

The FRM-1 communicates with the compatible fire alarm control panel over the SLC and provides isolated Form-C relay contacts for controlling external equipment.

Conceptually:

FACU → Supervised SLC → Addressable Relay at Interface → Shunt-Trip Control Equipment

Locating the addressable interface at the controlled equipment can minimize the amount of unsupervised control wiring between the fire alarm interface and the equipment being controlled.

Important distinction: The FRM-1's addressable SLC connection is supervised by the fire alarm system, but its dry relay contacts do not magically supervise whatever external circuit is connected to those contacts. The complete interface must still be evaluated according to the approved design and applicable supervision requirements.

NOTIFIER FRM-1 Relay Module

The FRM-1 is an addressable relay module that allows a compatible NOTIFIER fire alarm control panel to operate dry relay contacts by command.

It provides two isolated Form-C contact sets that operate together.

This makes the FRM-1 useful for many fire alarm emergency-control interfaces where dry contacts are appropriate.

But there is an important limitation:

The FRM-1 is a relay module, not a universal power-control device.

The circuit being switched must remain within the manufacturer's listed contact ratings for the specific:

• Voltage
• Current
• AC or DC application
• Resistive or inductive load
• Coded or non-coded operation where applicable

Never choose an interface relay based solely on its largest advertised ampere rating.

Why Relay Contact Ratings Matter

Relay contacts are not rated identically for every electrical load.

A contact capable of switching one current at a low-voltage resistive load may have a significantly different rating when switching an inductive load or a different voltage.

Shunt-trip coils and other control equipment can present electrical characteristics that must be checked against the relay manufacturer's published ratings.

Do not assume: A relay marked for a particular maximum current is automatically suitable for every shunt-trip circuit below that current. Verify the actual voltage, current and load type against the manufacturer's listed contact ratings.

What If the Fire Alarm Relay Cannot Directly Control the Load?

If the fire alarm relay contacts are not suitable for the circuit being controlled, the design can use an appropriately rated listed interface relay.

The fire alarm system then controls the interface relay rather than attempting to switch the external control load directly.

Conceptually:

FACU → Supervised Control Module → Interface Relay → Shunt-Trip Control Equipment

This is where the supervision design becomes especially important.

Method 2: FCM-1 With an External Interface Relay

The second arrangement in the original diagram uses a NOTIFIER FCM-1 addressable control module to operate an external interface relay.

This is fundamentally different from using an FRM-1.

The FRM-1 provides addressable dry relay contacts.

The FCM-1 provides a supervised control output designed to monitor the wiring connected to its output circuit.

NOTIFIER documentation describes the FCM-1 as capable of supervising its output wiring and reporting conditions such as normal, open and short to the fire alarm control system.

That capability is why a supervised control-module arrangement can be useful when an external interface relay must be located away from the addressable module.

Why Use an External Interface Relay?

An external interface relay may be necessary when:

• The controlled voltage exceeds the appropriate rating of the fire alarm relay contacts
• The controlled current exceeds the appropriate contact rating
• The load characteristics are not suitable for the addressable relay
• The project design requires a different listed interface
• A supervised control circuit must extend from the fire alarm module to the final interface

The interface relay must itself be properly selected for the electrical characteristics of the controlled circuit.

The original diagram used a PR-1 style interface relay as an example. The exact relay used on a modern project should be selected from the approved equipment for that particular system rather than treating one legacy part number as universally required.

FRM-1 vs. FCM-1 for Elevator Shunt Trip

Feature	FRM-1	FCM-1
Basic Device Type	Addressable relay module	Addressable control module
Typical Output	Dry Form-C relay contacts	Supervised control output
Output Wiring Supervision	Dry contacts do not inherently supervise the external controlled circuit	Designed to supervise connected control wiring when installed as specified
Useful Application	Local dry-contact interface where appropriate	Supervised pathway to an external interface/load where appropriate
Key Design Check	Contact voltage/current/load rating	Compatible external supply, supervised circuit and connected load

Why Module Location Matters

One of the easiest mistakes to make with emergency-control wiring is to focus entirely on the fire alarm panel and ignore where the actual interface device is located.

Consider two arrangements:

Arrangement A:

FACU → SLC → Addressable Interface → Controlled Equipment

Arrangement B:

FACU → SLC → Addressable Module → Long Field Control Circuit → Interface Relay → Controlled Equipment

Arrangement B introduces another pathway between the addressable module and the final interface.

That pathway cannot simply be ignored because the module itself has an address.

If the design requires supervision of that control pathway, the module and circuit architecture must provide that supervision.

What Wiring Is Actually Supervised?

This is the question every technician should ask when looking at an elevator shunt-trip interface.

Do not stop at:

"The module is addressable, so it's supervised."

Instead ask:

• Is the SLC supervised?
• Where is the emergency-control interface located?
• Is there additional wiring between the addressable module and that interface?
• Is that additional wiring supervised where required?
• Is external control power monitored where required?
• Would an open conductor prevent the required emergency function without creating a trouble indication?

Those questions expose the difference between an addressable device and a completely supervised emergency-control interface.

Supervising Shunt-Trip Operating Power

The control pathway is only part of the design.

The shunt-trip mechanism also needs the electrical power necessary to perform its required function.

If that operating power disappears, the fire alarm control relay could function perfectly while the elevator power-shutdown mechanism fails to operate.

Where required by the applicable design and code, loss of power necessary for the emergency control function must therefore be monitored so the impairment does not remain hidden.

The exact method depends on the shunt-trip equipment, control-power source and approved fire alarm design.

Do Not Confuse Control Power With Elevator Motor Power

The fire alarm system normally interfaces with the control side of the elevator power-shutdown equipment.

It is not routing the elevator motor feeder through an ordinary addressable fire alarm module.

The fire alarm interface operates the approved shunt-trip or disconnecting mechanism, which then performs the required power-disconnection function.

This distinction is important both electrically and from an equipment-listing standpoint.

Normally Open or Normally Closed?

There is no responsible universal answer that says every elevator shunt-trip interface should simply use the normally open or normally closed contacts of a relay.

The correct contact arrangement depends on:

• The shunt-trip equipment
• The control voltage
• The approved sequence
• The supervision method
• The interface relay
• The required normal and activated states
• The equipment manufacturer's instructions

Follow the approved wiring diagram rather than selecting NO or NC based on habit.

Do Not Use the SLC as Proof That Everything Is Supervised

This deserves repeating because it is a common misunderstanding.

An addressable module being supervised on the SLC proves that the fire alarm control unit can communicate with that module.

It does not automatically prove that every conductor, relay coil, external power supply, or controlled circuit beyond the module is supervised.

Each part of the emergency-control interface must be evaluated according to what happens if that portion of the circuit opens, shorts, loses power or otherwise becomes impaired.

Common Elevator Shunt Trip Interface Mistakes

• Using a relay without checking its actual contact rating.
• Assuming an addressable relay supervises wiring connected to its dry contacts.
• Installing the addressable module far from the final interface without evaluating the intervening wiring.
• Confusing an FRM-1 relay module with an FCM-1 supervised control module.
• Failing to monitor power required to perform the shutdown function where required.
• Routing loads through fire alarm contacts that are not listed or rated for the application.
• Assuming NO or NC contacts are universally correct.
• Using legacy part numbers without checking current product documentation and compatibility.
• Testing only the fire alarm module rather than the complete emergency-control function.

Testing the Elevator Shunt Trip Interface

Testing should verify more than whether the addressable module changes state.

The complete test should be coordinated with the elevator contractor and other responsible parties and should verify the approved sequence from initiating condition through the final controlled function.

Depending on the installation, this can include:

• Correct fire alarm input
• Correct system programming
• Addressable module operation
• Supervision of the applicable control pathway
• External interface relay operation
• Availability and monitoring of required control power
• Operation of the approved elevator shutdown interface
• Correct trouble indication when a supervised pathway is intentionally opened during testing
• Proper restoration after the test

Testing Warning: Never intentionally interrupt elevator power simply to prove a fire alarm output without proper coordination. Elevator shutdown testing should be performed as an integrated test with the appropriate elevator, electrical, fire alarm and building personnel involved.

Frequently Asked Questions

What is an ECID in a fire alarm system?

ECID stands for Emergency Control Interface Device. It is the interface through which the fire alarm system performs an emergency control function such as an approved elevator power-shutdown operation.

Can an FRM-1 be used for elevator shunt trip?

An FRM-1 provides addressable dry relay contacts and may be suitable for an approved emergency-control interface when its application, contact ratings, location, supervision arrangement and equipment compatibility satisfy the project requirements. It should not be treated as a universal shunt-trip solution.

What is the difference between an FRM-1 and FCM-1?

The FRM-1 is primarily an addressable relay module providing Form-C dry contacts. The FCM-1 is an addressable control module capable of supervising its connected output wiring when installed in accordance with the manufacturer's instructions.

Does an addressable relay automatically supervise the shunt-trip circuit?

No. The fire alarm system supervises communication with the addressable module, but dry relay contacts do not automatically supervise all external wiring connected beyond those contacts.

Why would I use an FCM-1 with an interface relay?

A supervised control module can be useful where the fire alarm system must supervise the control wiring extending to an external interface relay. The external relay can then be selected for the electrical characteristics of the controlled circuit.

Can I use any 10-amp relay for elevator shunt trip?

No. Relay suitability depends on more than a single ampere rating. Verify voltage, AC or DC operation, load type, contact rating, listing, control characteristics and compatibility with the approved design.

Does the fire alarm relay carry elevator motor power?

Normally, no. The fire alarm system interfaces with the control circuitry for the approved elevator power-disconnection equipment. Elevator motor power is not normally routed through an ordinary addressable fire alarm relay.

Related Elevator Fire Alarm Guides

• Elevator Shunt Trip Wiring Diagram | Fire Alarm Power Shutdown
• Elevator Shunt Trip Requirements & Codes
• Elevator Recall and Shunt Trip Basics
• Heat Detectors and Elevator Pits

Final Thoughts

The most important concept in elevator shunt-trip interface wiring is understanding exactly where the emergency control interface occurs.

If an addressable relay is located at the final interface, the supervised SLC brings the fire alarm system directly to that point, but the dry contacts themselves do not automatically supervise the external circuit.

If an external interface relay must be located beyond the addressable device, a supervised control-module arrangement may be appropriate so the wiring to that interface can be monitored.

In either case, the designer must verify the relay ratings, control voltage, supervision requirements, equipment listings and approved elevator shutdown sequence.

Don't ask only, "Is the module supervised?" Ask, "Is the entire required control pathway supervised to the point where the emergency function is actually performed?"

Technical Disclaimer: This article is intended for qualified fire alarm and life-safety professionals. Always follow the currently adopted codes and standards, approved construction documents, equipment listings, manufacturer instructions, electrical-safety requirements and AHJ requirements for the specific installation.

Elevator Shunt Trip Requirements & Codes | NFPA 72 + IBC

Elevator shunt trip is one of the most frequently misunderstood elevator and fire alarm interfaces. In simple terms, elevator shunt trip is used to remove operating power from an elevator before sprinkler water can be discharged onto elevator equipment where energized equipment and water could create an unsafe condition.

The important distinction is that elevator recall and elevator shunt trip are not the same function. Elevator recall is normally initiated by smoke detection and sends the elevator to a designated or alternate recall level. Elevator shunt trip is an elevator power shutdown function associated with sprinkler protection in specific elevator spaces.

Quick Answer:
Where elevator hoistways, machine rooms, control rooms, or control spaces containing elevator equipment are protected by automatic sprinklers and elevator power shutdown is required, the system must be arranged to disconnect elevator power before sprinkler water creates an unsafe condition. NFPA 72 Section 21.4 provides the fire alarm interface requirements for this elevator power shutdown function.

Elevator shunt trip sequence of operations showing heat detection, fire alarm control, power disconnect, elevator shutdown and sprinkler coordination.

What Is Elevator Shunt Trip?

An elevator shunt trip system automatically opens the elevator's main power disconnect when required by the applicable elevator, building, electrical, and fire alarm codes.

The purpose is not simply to turn off the elevator during a fire. The purpose is to coordinate elevator power shutdown with sprinkler operation so that water is not discharged onto certain energized elevator equipment while the elevator remains capable of movement.

A typical elevator shunt trip sequence may include:

1. A heat detector or other approved initiating method operates in a sprinkler-protected elevator space.
2. The fire alarm system processes the elevator shutdown signal.
3. A listed relay or control interface operates the elevator shunt-trip disconnecting means.
4. Main operating power to the affected elevator is disconnected.
5. The disconnecting means remains open until it is manually restored in accordance with elevator and electrical system requirements.

The exact sequence must be coordinated between the fire alarm contractor, electrical contractor, elevator contractor, sprinkler contractor, engineer, and Authority Having Jurisdiction (AHJ).

Elevator Recall vs. Elevator Shunt Trip

Elevator recall and elevator shunt trip work together as part of the overall elevator emergency-control strategy, but they perform completely different functions.

Function	Typical Initiating Device	Primary Purpose
Elevator Recall	Smoke detection or other permitted automatic detection	Moves the elevator to the designated or alternate recall level
Elevator Shunt Trip	Heat detection, pressure/waterflow initiation, or another approved method where applicable	Disconnects elevator operating power before sprinkler discharge creates an unsafe condition

Elevator recall sequence: smoke detection initiates Phase I recall and sends the elevator to the appropriate recall level.

Elevator shunt trip sequence: heat detection or another approved initiating method activates the elevator power shutdown function.

For a complete explanation of recall operation, see our Elevator Recall and Shunt Trip Explained guide.

When Is Elevator Shunt Trip Required?

Shunt trip is generally associated with elevators where automatic sprinklers are installed in elevator hoistways, machine rooms, control rooms, control spaces, or similar elevator equipment locations and the application of sprinkler water could create an unsafe operating condition.

The International Building Code requires elevator power shutdown where specified elevator spaces containing elevator equipment are protected by automatic sprinklers. The shutdown arrangement is coordinated through NFPA 72 Section 21.4.

This means you should not determine whether shunt trip is required simply by asking whether the building itself is sprinklered.

Instead, determine:

• Whether sprinklers are installed in the applicable elevator space.
• Where the sprinkler is located.
• Whether elevator equipment could be exposed to sprinkler water.
• Whether the elevator is a standard passenger elevator, Fire Service Access Elevator, Occupant Evacuation Elevator, or another elevator type.
• Which editions of the building, fire, elevator, electrical, sprinkler, and fire alarm codes have been adopted by the jurisdiction.

2024 IBC Requirements for Elevator Shunt Trip

IBC Section 3005.5 addresses elevator shunt trip.

Where elevator hoistways, machine rooms, control rooms, and control spaces containing elevator control equipment are protected by automatic sprinklers, the IBC requires a means arranged in accordance with NFPA 72 Section 21.4 to automatically disconnect main-line elevator power before the application of water.

The disconnecting means is also required to be non-self-resetting. In other words, power should not automatically restore when the fire alarm initiating condition clears.

Sprinkler activation elsewhere in the building is not intended to indiscriminately shut down elevator power. The shutdown function is associated with sprinkler protection affecting the elevator equipment areas addressed by the applicable code.

NFPA 72 Section 21.4: Elevator Power Shutdown

NFPA 72 Chapter 21 covers emergency control function interfaces. Section 21.4 specifically addresses Elevator Power Shutdown.

Heat Detectors Used for Shunt Trip

When heat detectors are used to initiate elevator power shutdown, they must be selected and arranged so that elevator power is removed before sprinkler operation.

The heat detection must be coordinated with the sprinkler system so that the detector operates sooner than the sprinkler under the conditions anticipated by the design.

NFPA 72 requires heat detection used for this purpose to have a lower temperature rating and greater response sensitivity than the associated sprinkler.

24-Inch Heat Detector Placement

When spot-type heat detectors are used for elevator power shutdown, NFPA 72 requires them to be located within 24 inches of each sprinkler associated with the shutdown function unless an approved engineering method is used to demonstrate that the required operating sequence will occur.

This is why elevator machine rooms and hoistways may have heat detectors positioned immediately adjacent to sprinkler heads rather than laid out using ordinary area heat-detector spacing.

Important: A heat detector used for elevator shunt trip is performing an emergency control function. Do not treat its location as ordinary area heat detection spacing. Its relationship to the sprinkler is critical.

Waterflow or Pressure Switch Initiation

Where an approved pressure switch or waterflow switch is used to initiate elevator power shutdown, NFPA 72 does not permit the use of a time-delay function in that initiating path.

This is very different from ordinary sprinkler waterflow alarm applications where retard or time-delay arrangements are commonly encountered.

Can Elevator Shunt Trip Be Delayed?

Some elevator shutdown designs using heat detection may incorporate a coordinated delay intended to provide additional opportunity for the elevator to complete recall before power is removed.

However, this is not a universal permission to program an arbitrary shunt-trip delay. The sequence must remain coordinated with the elevator safety requirements so that power is removed before sprinkler water creates the hazardous condition the shutdown function is intended to prevent.

Any proposed delay should therefore be reviewed with the elevator contractor, design engineer, and AHJ.

If a pressure or waterflow switch is being used as the elevator shutdown initiating device, the NFPA 72 restriction on time-delay capability still applies.

Shunt Trip Control Circuit Supervision

This requirement is frequently overlooked in both design and installation.

The control circuit used to operate the elevator disconnecting means must be monitored for the presence of the operating voltage needed to perform the shutdown function.

If that operating voltage is lost, the fire alarm system must indicate the required supervisory condition so building personnel know that the elevator shutdown function may no longer be available.

A typical addressable fire alarm installation may use a monitor module and appropriately listed relay or interface arrangement to supervise the availability of the shunt-trip control voltage.

Field Tip: Functional testing should include more than simply tripping the elevator breaker. Verify loss-of-voltage supervision, fire alarm annunciation, relay operation, elevator recall sequence, shutdown sequence, and proper manual restoration.

Smoke Detectors Do Not Normally Initiate Elevator Shunt Trip

One of the most common design mistakes is assuming that the smoke detector used for elevator recall should also operate the shunt-trip breaker.

These are separate functions.

Smoke detection is generally associated with elevator recall.

Heat detection or another approved sprinkler-related initiating method is generally associated with elevator power shutdown.

The final design must follow the adopted elevator, fire alarm, building, sprinkler, and electrical codes for the project.

Fire Service Access Elevators and Occupant Evacuation Elevators

Fire Service Access Elevators and Occupant Evacuation Elevators require special treatment and should not be designed using the ordinary passenger-elevator shunt-trip assumptions.

Under the 2024 IBC:

IBC Section 3007.4 prohibits installing the ordinary elevator shutdown means described by Section 3005.5 on Fire Service Access Elevators.

IBC Section 3008.4 provides the corresponding restriction for Occupant Evacuation Elevators.

The IBC also restricts automatic sprinklers in their associated elevator hoistways and specified elevator equipment spaces.

Always identify the elevator type before designing the fire alarm interfaces.

Elevator Pit Sprinklers and Shunt Trip

Elevator pits create another common area of confusion because the required shutdown arrangement depends on the sprinkler location, elevator configuration, adopted elevator code, and applicable exceptions.

A sprinkler located very low in an elevator pit can be treated differently from a sprinkler located higher in the hoistway because the potential for sprinkler discharge to affect energized elevator equipment is different.

For a detailed explanation, see:

Do You Need a Heat Detector in the Elevator Pit?

California Elevator Shunt Trip Requirements

California deserves special attention because elevator installations are regulated by the California Division of Occupational Safety and Health, commonly known as Cal/OSHA, through its Elevator Unit, in addition to the applicable California Building Standards Code.

Older guidance sometimes stated that elevator shunt-trip equipment had to be located outside the elevator machine room. That is not an accurate blanket statement under current California Elevator Unit guidance.

The California Elevator Unit issued a memorandum clarifying the location of shunt-trip equipment.

California permits shunt-trip devices that are incorporated into the design and function of the listed equipment serving as the single main-line disconnecting means to be located in elevator machine rooms, control rooms, and control spaces.

However, shunt-trip equipment that is not incorporated into that listed single disconnecting means is treated differently and is not permitted by that Elevator Unit policy to be located in those elevator equipment spaces.

See the official California Elevator Unit memorandum here:

California Elevator Unit – Location of Shunt Trip Equipment

California projects should also be reviewed against the current edition of the California Building Standards Code and any local amendments adopted by the AHJ.

Where Should the Elevator Shunt Trip Disconnect Be Located?

There is no universal rule stating that every elevator shunt-trip disconnect or breaker must always be located in one particular location.

Location depends on the electrical code, elevator code, equipment listing, elevator configuration, jurisdiction, and whether the shunt-trip components are incorporated into the elevator's listed main-line disconnecting means.

For California installations, follow the California Elevator Unit guidance described above rather than relying on the older assumption that every shunt-trip device must automatically be located outside the machine room.

Resetting an Elevator Shunt Trip Disconnect

Elevator power shutdown is intended to be a non-self-resetting function.

After the initiating condition has been investigated and the fire alarm and elevator systems are ready to be restored, the elevator disconnect must be manually restored using the proper procedure for the specific listed equipment.

Do not assume that resetting the fire alarm control unit should automatically restore elevator power.

Restoration should be performed by qualified personnel in accordance with the elevator equipment manufacturer's instructions, electrical safety requirements, elevator contractor procedures, and AHJ requirements.

Who Is Responsible for the Elevator Shunt Trip Wiring?

Responsibilities vary by project, but the interface normally involves several trades.

Trade	Typical Responsibility
Fire Alarm Contractor	Initiating devices, monitor modules, control modules, relay interfaces, programming, annunciation, and fire alarm testing
Electrical Contractor	Elevator disconnect and shunt-trip power wiring and associated electrical distribution work
Elevator Contractor	Elevator controller interface, recall operation, elevator safety functions, and elevator-side testing
Sprinkler Contractor	Sprinkler locations, temperature ratings, waterflow or pressure interfaces where applicable, and sprinkler system coordination

The construction documents should clearly identify responsibility rather than leaving the trades to determine the interface during final testing.

Typical Elevator Shunt Trip Sequence of Operations

A common sequence for a sprinkler-protected elevator equipment space may look like this:

1. Smoke detection initiates elevator Phase I recall when required.
2. The elevator begins traveling toward the applicable recall level.
3. A heat detector associated with the sprinkler operates.
4. The fire alarm system initiates the approved elevator power-shutdown sequence.
5. The shunt-trip disconnect removes the required elevator operating power before sprinkler discharge creates an unsafe condition.
6. The fire alarm system supervises the availability of the shutdown control circuit.
7. Elevator power remains disconnected until manually restored by qualified personnel.

This is only a general example. The project-specific sequence must match the elevator type, sprinkler configuration, adopted codes, equipment listings, engineering documents, and AHJ requirements.

Common Elevator Shunt Trip Design Mistakes

• Using the elevator recall smoke detector to initiate shunt trip.
• Installing the shunt-trip heat detector using ordinary room spacing instead of coordinating it with the sprinkler.
• Failing to supervise shunt-trip control voltage.
• Using an improper delay on a waterflow or pressure-switch shutdown circuit.
• Allowing sprinkler operation elsewhere in the building to shut down elevator power.
• Assuming every sprinklered building automatically requires elevator shunt trip.
• Failing to distinguish standard elevators from Fire Service Access Elevators or Occupant Evacuation Elevators.
• Failing to coordinate sprinkler temperature ratings and heat detector response characteristics.
• Failing to coordinate fire alarm, electrical, sprinkler, and elevator contractor responsibilities.
• Using outdated California guidance regarding shunt-trip equipment location.

Elevator Shunt Trip Wiring

This article focuses on the code requirements and operating principles behind elevator shunt trip.

For the actual fire alarm control wiring and relay arrangement, see:

How to Wire Elevator Shunt Trip

If you are looking specifically for a diagram, see:

Elevator Shunt Trip Wiring Diagram

Codes and Standards Commonly Used for Elevator Shunt Trip

Elevator power shutdown is a coordinated function involving several different codes and standards rather than a single fire alarm section.

Common references include:

• NFPA 72 – Section 21.4, Elevator Power Shutdown
• International Building Code – Section 3005.5, Shunt Trip
• ASME A17.1/CSA B44 – Safety Code for Elevators and Escalators
• NFPA 70 / NEC Article 620 – Elevators and associated disconnecting means
• NFPA 13 – Sprinkler protection and sprinkler installation requirements
• California Title 24 and California Elevator Safety Orders for California projects

Always verify the exact code editions adopted by the project jurisdiction. A project designed under an older adopted code cycle may not use the same edition referenced by a newly permitted project.

Final Elevator Shunt Trip Checklist

Before approving an elevator shunt-trip design, confirm:

☐ Is sprinkler protection installed in the applicable elevator space?

☐ Is elevator power shutdown actually required for that location?

☐ Is the elevator type clearly identified?

☐ Are recall and shunt trip being treated as separate functions?

☐ Is heat detection properly coordinated with each applicable sprinkler?

☐ Are heat detector temperature and response characteristics coordinated with the sprinkler?

☐ Is the shutdown control circuit supervised for operating voltage?

☐ Are prohibited time delays avoided?

☐ Is the disconnecting means non-self-resetting?

☐ Have the fire alarm, electrical, elevator, and sprinkler contractors coordinated responsibilities?

☐ Have the applicable adopted codes and local amendments been confirmed?

More Elevator Fire Alarm Resources

Continue learning with these Fire Alarms Online resources:

Elevator Recall & Shunt Trip Explained

Elevator Recall & Shunt Trip Fundamentals

How to Wire Elevator Shunt Trip

Elevator Shunt Trip Wiring Diagram

Is a Heat Detector Required in the Elevator Pit?

Important: Fire alarm, elevator, sprinkler, building, and electrical requirements vary by adopted code edition and jurisdiction. Always verify the applicable project documents, equipment listings, local amendments, elevator authority requirements, and AHJ interpretation before construction or modification.