Burning issues - false and unwanted fire alarms

Latest Government statistics show that there are approximately 272,000 false and unwanted alarms per annum generated from automatic detectors fitted to fire alarm systems.

The financial annual cost to Britain through these false alarms has been estimated at £1 billion. The higher cost might be loss of life, either from a traffic accident whilst a fire engine is on an unnecessary blue light response, or due to delay where the fire service has to divert from a false alarm attendance to a real fire emergency.

The clear benefits that automatic fire alarm systems can offer, is not disputed. The early warning of fire is essential to protect both life and property and research has proved that AFA-detected fires tend to be smaller than person detected fires and generally require less effort to extinguish when the FRS response arrives.

But the high numbers of false alarms has to be reduced, which is why many brigades are now demanding confirmation of the presence of fire, or refusing to attend unless a 999 call has been made. Some are even considering charging for false alarm attendance under legislation made possible by the Localism Bill, and with costs estimated at £300 per appliance for every 30 minutes in attendance, there could be some large bills to settle.

Defining false alarms

Unwanted alarm - Where a system has responded as designed to a fire like phenomenon such as burnt toast or other environmental influence

Equipment false alarm - Alarms resulting from a fault in the system

Malicious false alarm - Deliberate activation. Usually of a manual call point

False alarm with good intent - An individual activates an alarm believing there’s a fire when in fact none exists

Unknown - Where the cause cannot be identified

In all cases false and unwanted alarm activity should be recorded in the fire log book showing the date and time; the device operated; the location of the device; category and reason for the alarm (if known); any activity in the area; what action was taken; the name of the person making the report.

Likely causes of false alarms

• Poorly maintained systems or lack of maintenance
• Badly designed or poorly installed systems
• Insect infestation, such as thrips in rural areas during harvest time
• Build up of dirt and dust in detector smoke chambers
• Steam ingress into smoke chambers such as from en suite bathrooms in
• hotels
• Smoke from processes other than fire, welding for example
• Aerosols and atmospheric pressures
• Cooking processes such as flambéing
• Theatrical smoke, dry ice, candles and incense
• Sudden heat ingress such as opening industrial oven doors
• Water ingress into electronics
• Diesel emissions on loading bays
• Cutting, welding and ‘hot’ work.

Steps to reduce false alarms

Firstly appoint a Responsible Person to ensure that a risk assessment of the premises is carried out and regularly updated (at least once per annum). The responsible person should be familiar with relevant aspects of BS5839-1 and should ensure that the fire detection and alarm system is regularly maintained by a competent servicing organisation.

Part of the risk assessment must ensure that the correct type of detection is installed throughout the premises and it is applicable to manage the risk from fire and from false alarm potential. Any reputable fire alarm company will be happy to advise.

When buildings are changed in use or shape all interested parties should be consulted. These might include the servicing organisation, the manufacturer of the system, fire prevention officers, insurers, builders, mechanical and electrical engineers and building control officers. There is a likelihood that the system will require to be altered, not only in wiring topography but also detector type or cause and effect programming, as the risk from both fire and false alarm might now change from when the originally designed system was installed.

All persons needing to use the fire alarm system (for weekly sounder tests for example) must be trained in its correct operation.

Upgrade old, obsolete systems. Most modern fire alarm systems use a range of measures to manage out false and unwanted alarms whilst still providing early, reliable detection of genuine fires. Older systems may have become costly to maintain or repair as spares become unavailable. Technology has advanced and offers benefits such as powerful algorithms employing ‘fuzzy logic’ to accurately identify real fire footprints. Time delays, day/night modes, co-incidence detection and verification can all be built into the fire system programming.

The role of the service engineer

Along with correctly designing the detection elements of the fire alarm system, the single most important thing to help prevent false alarms is to have the system regularly maintained by a suitably qualified person.

Depending on the risk, size and complexity of the system, each should be visited either twice or four times per annum but never less than twice. The number of visits should be determined as part of the risk assessment.

At every visit the service engineer will check and test all operations of the control elements of the system, plus the batteries and power supplies and test all sounders. He or she will also test either 50% or 25% of all the field devices such that all are tested once per annum.

The engineer will also check the false alarm record to determine;

• The rate of false alarms expressed as number of false alarms per 100 detectors
• Whether two or more false alarms have arisen from any single device
• Whether any persistent cause of false alarm can be identified
• The dirt build up levels in all detectors and change any which are going out of operational parameters.

If warranted, the engineer and service organisation will carry out further in depth investigation into persistent false alarms and try to establish the technical or environmental causes.

In conclusion

False and unwanted alarms from fire detection and alarm systems are a problem which affects everyone. As such, we all have a collective responsibility to work together to reduce the damaging numbers and financial cost to the country as a whole.

In transport, passenger disruption should a rail station or airport suffer a false alarm can be extremely disruptive and have a negative knock on effect along the transport link by delaying flights, trains and passengers other than those directly involved in the false alarm source building.