A fire alarm control panel detects the fire. What it does next is set by one document: the cause and effect matrix. The matrix states which signal sounds which alarm zone, which air handling unit stops, which lift is recalled and to which floor, and which door is released. One wrong cell can shut down the stair pressurization fans.
This guide is about the matrix itself, not BMS connections: how to build and review it, turn it into panel programming, and test it cell by cell. That is the core of AZEIDK’s programming and systems integration service, from matrix review to signal testing and documented settings.
Key takeaways
- Rows are inputs (causes), columns are outputs (effects), and every cell is a testable instruction.
- Recent editions of NFPA 72 (including 2019 and 2022) list the sequence of operation, as an input/output matrix or a narrative, in the minimum documentation.
- Chapter 21 of NFPA 72 covers emergency control function interfaces, including where the control relay may sit relative to the equipment.
- Every column needs a named owner for the relay, the cable and the test.
- Any site change needs a new revision and a retest of the affected cells.
In this article
- What is a cause and effect matrix and why is it required?
- Matrix structure: rows, columns and cell codes
- A sample operating matrix
- The main effects and what to write for each
- From matrix to programming: modules and relays
- Reviewing and approving the matrix
- Testing the matrix cell by cell
- Common mistakes in preparing the matrix
- Frequently asked questions
- Conclusion
What is a cause and effect matrix and why is it required?
It links every event the panel can receive to every action that must follow. A cause can be a smoke detector, a manual call point (MCP), a sprinkler flow switch or a gas suppression panel signal. An effect can be sounders, stopping an air handling unit (AHU), starting pressurization fans, lift recall or a signal to another system.
Recent editions of NFPA 72 (including 2019 and 2022) include, in the minimum required documentation, the sequence of operation in the form of an input/output matrix or a narrative, and the 2019 annex shows a sample matrix. As Electrical Contractor magazine notes, a matrix is more useful to the programmer than a narrative because it answers every case explicitly.
In Saudi Arabia, SBC 801, the Saudi Fire Code, is part of the Saudi Building Code, and its 2024 edition has been mandatory since 30 June 2025. Its Chapter 9 covers fire protection and life safety systems, including fire detection and alarm. NFPA 72 is a technical reference the designer adopts; the applicable edition is the one the code, Civil Defense or the project documents accept.
Matrix structure: rows, columns and cell codes
Rows: the causes
Write causes at the level the panel is programmed: a device, a group or a zone. Rows are usually grouped:
- Alarm causes: smoke and heat detectors, manual call points and flow switches.
- Supervisory causes: such as a valve tamper switch. It flags a condition but does not start evacuation.
- Causes from other systems: such as a discharge signal from the gas suppression panel or a fire pump running signal.
- Faults: mains failure, loop fault and battery fault.
Columns: the effects
Each column is one testable output: a sounder group, the shutdown relay for a specific AHU, a lift recall output or a door release output. Do not combine equipment from different systems in one column.
Cells: what does the mark mean?
An “X” alone is not enough. The legend must define each code: immediate, delayed, conditional on a second cause, pulsed, or latched until reset, plus what silence and reset do.
A sample operating matrix
A simplified office-building example showing format only. The real design is set by the consultant per the project code and Civil Defense.
| Cause (input) | Notification | AHU shutdown | Stair pressurization | Lift recall | Door release | Signal to BMS |
|---|---|---|---|---|---|---|
| Smoke detector, 3rd floor | 3rd floor plus whatever the evacuation strategy sets | 3rd floor unit | Start | No (lift lobby detectors only) | 3rd floor doors and exit routes | Status only |
| Manual call point, 3rd floor | As above | 3rd floor unit | Start | No | As above | Status only |
| Sprinkler flow switch, 3rd floor | As above | 3rd floor unit | Start | No | As above | Status only |
| Lift lobby detector on the designated recall floor | Per design | Per design | Per design | To the alternate floor | Per design | Status only |
| Lift lobby detector on any other floor | Per design | Per design | Per design | To the designated floor | Per design | Status only |
| AHU duct smoke detector | Per design (alarm or supervisory) | That unit | Per design | No | No | Status only |
| Valve tamper switch | Supervisory signal, no evacuation | No | No | No | No | Status only |
| Panel mains failure | Fault signal | No | No | No | Per the door’s selected safety category | Status only |
The BMS column reads “status only” throughout: critical commands come from fire alarm relays, not the BMS. See BMS and fire alarm integration.
The main effects and what to write for each
AHU and fan shutdown
The designer decides whether HVAC stops in the affected zone or building-wide, and whether the trigger is the duct detector or any zone alarm. Use the unit tag from the mechanical drawings, not just the relay number.
Stair pressurization and smoke extract fans
These fans must run during a fire, so a “general HVAC stop” command must never stop them. Give them their own column with start/stop conditions and any firefighter panel priority. See smoke control and stair pressurization.
Lift recall
Section 21.3 of NFPA 72 (2025 edition) covers emergency lift recall (Phase I recall), which works together with the lift code, ASME A17.1. Traditionally, recall is initiated only by lift lobby, hoistway and machine room detectors unless the authority requires otherwise. In the recall logic used with ASME A17.1, the lobby detector on the designated recall floor gets its own output, so state explicitly: if the alarm starts at that detector, the lifts go to the alternate floor. Agree the number and type of outputs with the lift contractor.
Door release
This covers releasing door holders so fire doors close, and unlocking access-controlled exit doors. British Standard BS 7273-4 (2015 edition, amended 2023) sets three categories of actuation for door release mechanisms: A (critical), B (standard) and C (indirect), chosen for each door by risk assessment. Its fail-safe principle: the release mechanism operates on specified faults in the critical signal path, such as an open circuit, short circuit or voltage drop, and when power to it is lost. Which doors unlock is for the consultant and authority to decide, not the programmer.
Gas suppression and other systems
Release logic usually stays inside the dedicated extinguishing panel, such as the three-zone Context Plus EP203/CON, which controls the release sequence and monitors hold and abort inputs. Its relays give signals such as “first stage active” and “fault”, a “discharged” output is available with the EP212 expansion relay board, and these signals become rows in the main matrix.
From matrix to programming: modules and relays
Every column needs a physical output, usually an I/O module on the loop. Context Plus examples supplied by AZEIDK:
- SA4700-103IMC: mains switching I/O unit with a volt-free changeover relay rated 250 V AC, up to 5 A, and a fail-safe mode compliant with BS 7273-4. For door holders, AHU/fan shutdown and lift recall.
- SA4700-104IMC: twin I/O unit with two independent circuits and a short-circuit isolator. Its relay outputs are rated 1 A at 30 V: for dry-contact signals, not switching loads.
- 55000-852IMC: sounder control unit that drives a conventional sounder circuit from the loop, in continuous or pulsed mode.
Check each relay rating against its load and record it in the point schedule. FirePlus addressable panels program cause and effect from the panel front or with ConfigManager Plus software. For the product range and commissioning steps, see the Context Plus application guide. Every output adds load on the standby supply, so update the battery calculation once the matrix is approved.
NFPA 72 also limits relay distance. Earlier editions set 3 ft; according to published reviews of the 2025 edition (Security Sales & Integration, Consulting-Specifying Engineer), up to 20 ft is allowed with metal raceway or metal-armored cable. Check the adopted edition’s text for the project before installation.
Reviewing and approving the matrix
Review the matrix in a coordination meeting with the fire alarm, HVAC, lift, door and smoke control contractors. Before submission, check that:
- Every row matches a device or zone on the shop drawings, with the same name and number.
- Every column has a specific piece of equipment, an owner for the output and an owner for the cable to the equipment.
- No command stops equipment that must run during a fire.
- Alternate-floor lift recall cases are written out.
- The legend explains delays, confirmation, silence and reset.
- The matrix has a revision number and date, and changes are logged in a revision table.
Testing the matrix cell by cell
Each row becomes a test step and each cell an expected result, marked pass or fail. A panel display change is not enough: confirm the unit stopped, the door closed and the lift reached the right floor.
NFPA 4 sets a framework for integrated testing of fire protection and life safety systems. According to IAEI’s review of the 2021 edition, the test plan for new systems includes a matrix of all inputs and outputs, and testing is repeated after any change that affects the integrated systems. That makes the approved matrix the basis of the testing, commissioning and handover plan.
The owner keeps the final matrix and panel program backup.
Common mistakes in preparing the matrix
- Copying a previous project’s matrix without matching device and equipment names.
- A “stop all fans” command that includes the stair pressurization and smoke extract fans.
- Switching an electrical load directly on a relay rated 1 A at 30 V.
- Changing the program on site without updating the matrix or retesting the affected cells.
- Each trade testing only its own system, with no end-to-end test.
Frequently asked questions
Who prepares the matrix?
The consultant sets the requirements; the fire alarm contractor usually prepares the detailed matrix with the other trades and submits it. Everyone must work from one approved version.
Is a matrix needed for a conventional system?
Yes. The level of detail is the zone, not the device, and outputs come from panel relays or expansion cards. The matrix is shorter, but the rules for writing and testing it are the same.
What happens to doors on power failure?
It depends on the category selected for the door in the design. The BS 7273-4 principle is that the door mechanism releases on a specified fault or loss of power. Write this behaviour in the matrix and test it.
When should the matrix be updated?
After any change to devices, equipment, programming or the use of the space. Issue a new revision and retest the affected cells.
Conclusion
The cause and effect matrix is the operating contract between the fire alarm and the rest of the building’s systems. Write it precisely, give every column an owner, match each output to its load and test every cell, and the building’s fire response becomes predictable and provable.
Reviewing your project’s matrix before programming? Send us the drawings and the current matrix, and we will review it with the I/O point schedule and the suitable Context Plus modules as part of our fire alarm systems solutions. Talk to the AZEIDK team
