If Fire damper closes, THEN shut down AHU. If AHU shuts down, THEN close fire damper. Result: The panel sends conflicting signals forever, freezing the system. Fix: Always use inputs to control outputs; never use outputs to control outputs directly via secondary logic without a time delay.
To create an effective fire alarm cause and effect matrix, follow these best practices:
: Shuts down air handling units immediately when smoke is detected.
Which (NFPA, EN 54, etc.) applies to your project? fire alarm cause and effect matrix
Automatically flag:
| Cause (Input/Device) | Local Zone Alarm (Sounders + Strobes) | Full Building Evacuation (All Sounders + Strobes) | Door Release (for Zone) | HVAC Shutdown (Entire Building) | Lift Homing | | :--- | :--- | :--- | :--- | :--- | :--- | | Single Smoke Detector (Zone 1) | ✓ | – | – | – | – | | Two Smoke Detectors or a Manual Call Point (Zone 1) | ✓ | ✓ | ✓ | ✓ | ✓ | | Single Smoke Detector (Zone 2) | ✓ | – | – | – | – | | Heat Detector (Any Zone) | ✓ | ✓ | ✓ | ✓ | ✓ | | Sprinkler Flow Switch (Any Zone) | ✓ | ✓ | ✓ | ✓ | ✓ | | Manual Call Point (Any Zone) | ✓ | ✓ | ✓ | ✓ | ✓ |
A common structure is shown below (also referred to in technical Scribd documents for Siemens General Fire Detection): Cause (Input) General Alarm AHU Shutdown Door Release Elevator Recall Manual Call Point Lobby Heat Detector Kitchen Sprinkler Flow (X = The action that occurs) Developing the Matrix: Step-by-Step If Fire damper closes, THEN shut down AHU
This section lists every device or zone capable of sending an alarm signal to the Fire Alarm Control Panel (FACP). Items are usually grouped by floor, zone, or device type: Manual Call Points (MCPs) / Pull Stations Automatic Smoke and Heat Detectors Duct Smoke Detectors Sprinkler System Pressure and Waterflow Switches Clean Agent Suppression Releasing Panels 2. Output / Effect Rows (Horizontal Axis)
Horns, strobes, and voice evacuation announcements.
This comprehensive guide breaks down what a cause-and-effect matrix is, why it is critical for regulatory compliance, how to design one, and best practices for testing it. What is a Fire Alarm Cause and Effect Matrix? Fix: Always use inputs to control outputs; never
Here is a simple example of a fire alarm cause and effect matrix:
Fire alarm programmers use the matrix as a literal instruction manual to write the boolean logic (IF/THEN statements) into the FACP software.
The specific "X" marks or logic that link an input to one or more outputs. System Interfacing
Modern systems (like Honeywell Notifier, Siemens Cerberus, or Hochiki) allow the matrix to change based on time of day.