Different countries have different requirements for what goes into the matrix:
The Golden Rule: The matrix must be printed, laminated, and located next to the main fire alarm control panel. If the fire chief arrives at 3 AM and the building manager isn't there, the chief must be able to read the matrix to understand the building's logic.
| Pitfall | Consequence | |---------|--------------| | Undefined reset conditions | Smoke clears but doors stay locked, fans remain off. | | No distinction between alarm & pre-alarm | Stage 1 (staff alert) triggers full evacuation. | | Ignoring multiple simultaneous causes | Two separate fires in different zones – system may lock out second response. | | Effect overwritten by later cause | Fire in lobby recalls lift. Second fire in upper floor – lift already recalled, matrix doesn't say what happens next. | | Manual call point treated same as detector | MCP should usually give no verification delay – many matrices miss this. | fire alarm cause and effect matrix
Instead of just turning on horns, the matrix now selects specific voice messages.
Cause: Firefighter manually overrides automatic mode via key switch. Effect: Matrix logic is temporarily bypassed. All outputs go to manual control (e.g., "Fan On" regardless of smoke location). The Golden Rule: The matrix must be printed,
Auditors and fire marshals will ask for the C&E matrix. Without it, you cannot perform a Commissioning or False Alarm Management procedure. Standards like BS 5839-1:2017 (Clause 16) explicitly require that the design documents include a clear cause and effect description.
Modern systems rarely have a single layer of logic. Usually, the matrix defines three distinct phases: fire alarm cause and effect matrix
This is the most complex section. It defines:
Even experienced engineers get the C&E wrong. Here are the top three failures: