What This Guide Covers and Who It Helps
Every electrified door opening -- whether it is an access-controlled entrance at a school, a monitored corridor door in a hospital, or a secured server vestibule in an industrial facility -- requires a document that describes exactly what happens at each event. That document is the sequence of operation. This guide explains what a sequence of operation is, how to read one, what it must include for a compliant submittal, and where hardware specifiers and field installers most often get it wrong.
What Is a Sequence of Operation?
A sequence of operation (sometimes called a theory of operation) is a plain-language or structured statement that describes the step-by-step behavior of every electrified component at a door opening under every foreseeable condition. It is not a wiring diagram and it is not an elevation drawing. Those documents show where things are and how they connect. The sequence of operation answers a different question: what happens, and in what order, when a specific event occurs?
On commercial door hardware submittals, the sequence of operation is typically required under Section 08 71 00 (Door Hardware) for any hardware set containing electrified components. Architects, authorities having jurisdiction (AHJ), and access control integrators all rely on this document to confirm that life safety, egress, and access control requirements are met before a single wire is pulled.
The Six Events Every Sequence Must Address
A complete sequence of operation should document the hardware behavior for each of the following conditions:
- Valid credential presented (access granted): Which device releases? Does the electric strike de-energize, does the latch retract, or does the electromagnetic lock release? What is the time delay, if any, before re-locking?
- Invalid or no credential (access denied): What remains in its locked state? Does the system generate an alarm signal or log the event?
- Occupant egress (free exit): How does the person on the secured side exit without a credential? Describe the mechanical free-egress method -- lever trim on an electrified exit device, push-bar operation, or a request-to-exit (REX) button that interrupts power to an electric strike or magnetic lock.
- Fire alarm activation: Which devices release to allow egress? Which, if any, switch to a locked state? Electrified hardware on fire-rated openings must automatically provide positive latching upon fire alarm signal. Electromagnetic locks and delayed-egress devices must release. Fail-safe locks must drop to the unlocked position.
- Loss of power: For every electrified device at the opening, document whether it is fail-safe (unlocks on power loss) or fail-secure (remains locked on power loss). Life safety codes generally require fail-safe operation on required egress paths. Fail-secure is appropriate for high-security enclosures where unauthorized access is the greater risk.
- System reset or door re-locking: After a timed unlock, an alarm event, or a fire alarm reset, what is the re-locking sequence? Does the system require manual reset by a credential or a supervisory action?
How Sequence Diagrams Are Structured
Sequence of operation documents appear in several formats depending on the project and who is preparing the submittal:
Narrative Format
A numbered or bulleted list, written in plain language, that walks through each event in order. This is the most common format on hardware schedules and is easiest for an AHJ or owner to review. Example: "1. Occupant presents valid card credential to reader. 2. Access control panel verifies credential. 3. Panel sends signal to power supply. 4. Power supply de-energizes electric strike. 5. Occupant operates lever to open door. 6. Door closes; strike re-energizes after 5-second timer."
Matrix Format
A table with events across the top (normal access, fire alarm, power loss, REX) and devices down the left column (electric strike, door position switch, REX button, magnetic lock). Each cell indicates the device state: energized, de-energized, released, or locked. This format is compact and easy to cross-check against a wiring diagram.
Logic Flow Diagram
A flowchart showing decision branches -- credential valid? yes/no; fire alarm active? yes/no -- with hardware states at each branch endpoint. Common in integrated access control submittals where multiple openings share panel logic.
Common Mistakes That Cause Submittal Rejections and Field Problems
- Missing the fire alarm interface: Specifying an electromagnetic maglock or a delayed-egress device without describing how it receives and responds to the fire alarm signal is one of the most frequent submittal deficiencies. The sequence must identify the relay, shunt, or panel output that interrupts power to the lock.
- Fail-safe vs. fail-secure conflicts: A sequence that calls for fail-secure operation on a required means of egress will not pass AHJ review. Confirm each device's power-loss behavior matches the occupancy and egress requirements before writing the sequence.
- REX logic not documented: Request-to-exit devices -- motion sensors, push buttons, or REX contacts built into the lockset -- must be described. Which input triggers them? Does REX signal the panel, shunt the door position switch alarm, or directly interrupt lock power?
- Monitoring outputs not addressed: Door position switches (DPS) and latchbolt monitors generate signals back to the access control panel. If the sequence does not describe what a propped-door or forced-door alarm triggers, integrators will make their own assumptions.
- No description of the mechanical egress backup: Codes require that occupants be able to exit without a credential. The sequence must explicitly describe this -- even if it is simply "occupant depresses exit device touchpad to retract latch mechanically."
Hardware Types That Always Require a Sequence
Any opening specification that includes the following product categories needs a documented sequence of operation:
- Electric strikes -- including latch-retraction and deadbolt-retraction types
- Electrified locksets and mortise locks with electric latch retraction or motor-driven deadbolts
- Electromagnetic locks (maglocks)
- Electrified exit devices with electric latch retraction (ELR) or electric dogging
- Delayed-egress locking systems
- Electrified lever trim on exit devices
- Access-controlled openings with door position monitoring and REX devices
Products from lines such as Sargent, Corbin Russwin, Hager, and PDQ span all of these categories and carry the monitoring, fail-safe/fail-secure options, and fire-alarm interface features that a well-written sequence depends on. Specifying hardware from stable, service-friendly product lines simplifies the sequence because device behavior is consistent across generations and replacement parts remain available without forcing a full hardware change-out.
Who Writes the Sequence of Operation?
On projects with an architectural hardware consultant (AHC), the AHC typically authors the sequence as part of the hardware specification and submittal package. On design-build or contractor-driven projects, the responsibility often falls to the hardware distributor or the access control integrator. Regardless of who prepares it, the sequence must be reviewed by the specifying architect and accepted by the AHJ on fire-rated or life-safety-critical openings before rough-in begins.
Getting this document right before the hardware ships prevents costly field changes, wiring rework, and failed inspections. If you are building out a hardware schedule that includes electrified components and need help structuring the sequence, DoorwaysPlus.com carries the hardware and the product knowledge to support your submittal from spec to closeout.