Understanding false alarms

To reduce false alarms, it is essential to understand exactly what a false alarm is, and to know some of the most common causes.

Defining false alarms

A false alarm is a fire signal resulting from any cause other than fire. These may be subdivided into five categories

1. Unwanted alarm
   Where a system has responded as designed, to a fire like phenomenon or environmental influence, or human error
   
   
2. Equipment false alarm
   Alarms resulting from a fault in the system
   
   
3. Malicious false alarm
   Deliberate activation
   
   
4. False alarm with good intent
   An individual activates an alarm believing there is a fire when no fire exists
   
   
5. Unknown
   Where the cause cannot be identified. These should be logged in your Fire Log Book and an engineer called to establish
   the cause.

Likely causes of false alarms

Some of the main causes of false alarms:

• Poorly maintained or non maintained systems
• Insect infestation – such as thrips in rural areas during harvest time
• Build up of dirt and dust in detectors due to lack of maintenance
• Steam ingress into detectors – such as in hotel bedroom ensuites
• Smoke from processes other than fire – such as welding, smoking in poorly ventilated areas
• Badly designed or installed systems
• Aerosols and atmospheric pressures
• Cooking processes – such as flambéing
• Theatrical smoke, dry ice, candles and incense
• External smoke – such as bonfires drifting into a building
• Sudden ingress of heat – such as opening industrial oven doors
• Water ingress into electronics
• Diesel and other vehicle emissions on loading bays enclosed garaging or parking areas
• Cutting, welding and other ’hot‘ work.