MIKE'S TOOLKIT

False Alarm Calculator

How to Use This Calculator

Enter the total number of false alarms over the last 12 months and the total number of automatic detectors on the system. The calculator will instantly show the system's false alarm rate and the recommended action.

The Calculation & MCPs

A "false alarm" is any fire signal not caused by an actual fire. This includes accidental or malicious activations of Manual Call Points (MCPs). When using this calculator:

Number of False Alarms ($A_{fn}$): This count should include any false alarms from MCPs.
Number of Automatic Fire Detectors ($D_{AF}$): This count should not include MCPs.

$A_{fr} = 100 \times \left( \frac{A_{fn}}{D_{AF}} \right)$

Number of False Alarms ($A_{fn}$) in last 12 months

Number of Automatic Fire Detectors ($D_{AF}$)

Investigation Levels Explained

This calculator assesses the overall system performance. Note that a separate investigation is also triggered if any single device (detector or MCP) has two or more false alarms, regardless of the system-wide rate.

No Action Required: The overall rate of false alarms is within an acceptable tolerance. Continue to monitor the system.
Preliminary Investigation: Triggered when the rate exceeds 4 false alarms per 100 detectors per annum. The user should conduct an initial investigation.
In-depth Investigation: Recommended for systems with over 40 detectors when the rate exceeds 5 false alarms per 100 detectors per annum. This requires a formal investigation by the system's maintenance provider.