False Alarms from Smoke Detectors and Alarms

Canadian Fire Alarm Association – The Journal May 2014


False and nuisance alarms from smoke detectors and smoke alarms continue to be a problem in some buildings. It creates a potentially dangerous situation when the building occupants, residents or management become complacent and say, “Oh it’s just another false alarm”.

There are solutions to these problems and the involvement of property owners and managers is essential in finding the successful solutions.

Several factors other than smoke that can result in nuisance or false alarms include:

  • Dust or particles entering the smoke chamber of the device.

Dust occurring during construction or renovation of buildings is a particular problem. Dry wall installation, sanding, sweeping, vacuuming and spray-painting are examples of activities that create construction dust. The airborne dust particles created during any of these activities might cause an immediate alarm or the dust particles may accumulate within the smoke detector making the smoke detector more sensitive and prone to trigger easily at a later time.

Dust accumulation can also be a problem at times other than during construction. Routine maintenance activities such as sweeping, cleaning or vacuuming may generate airborne particulates.

  • Nuisance smoke

Smoke from abnormal activities in an area of the detector, such as cooking, buffet food heating appliances, barbequing on the patio with open windows, soldering during the installation of plumbing equipment or welding can result in activation of the detector.

  • Humidity

Although smoke detectors and alarms are designed to operate over a large humidity range, the changing humidity or the possibility of small amounts of condensation in the detector can cause an alarm to be activated. Some ceiling locations where the detectors are mounted may be subjected to abrupt changes in ceiling humidity levels due to sudden weather changes.

  • Insects.

Small insects can actually crawl into the smoke detection chamber and initiate an alarm condition. Most establishments discount even the suggestion of insects being a problem without a serious investigation of this possibility. Smoke alarms and smoke detectors have built-in screens to keep insects out but small insects may to pass through the screens. These insects are very small and difficult to detect. Insects may still be present in the building even if it is routinely sprayed. These situations usually turn up as seasonal alarm problems.

  • Vapours

The use of aerosol sprays and vapours from chemical solutions such as cleaners or disinfectants can initiate false alarms.

  • EMF

Electrical interference can cause false alarms on large fire alarm systems. Fire alarm system wiring is spread throughout the building and can act as an antenna that picks up electrical pulses. EMF can activate the sensitive electronic components of the detector. Sources such as nearby radio transmitters or radar systems or areas subject to severe lightning activity are possible considerations as the source of EMF. The use of metallic conduit, shielded wire and proper grounding can reduce or eliminate these problems.

Almost all of the problems with false or nuisance alarms can be resolved. The initial task and first step is to identify the exact cause of the problem. This requires good record keeping from the time the problems first occur. It is frustrating to everyone when there is a continuous history of false alarms and no corrective action is taken to resolve the issue. Complacency by the occupants, possible fire department fines or disconnection of smoke detectors are all unacceptable outcomes.

Property owners and managers play a vital role in finding the solution to the nuisance alarm problems. A detailed record as shown below can be very helpful, particularly when it includes those entries identified as “Detector Location” and “Influencing Elements”.

 The second step in seeking the solution to false or nuisance alarms is comparing the items in the reports over several incidents and answering some simple questions. This is the detective work.

  • Do the alarms always happen about the same time of the day or day of the week or month?
  • What events happened in the building at that time? (i.e. cooking, cleaning, maintenance)
  • Do the alarms coincide with activities of staff or contractors?
  • Do alarms occur at a particular month or season? Could insects entering the smoke detector be the problem?
  • Is the timing related to a heating changeover or seasonal event?
  • Are alarms related to the type of rooms or use of room?
  • Are alarms related to the weather conditions?
  • Are the detectors in high ceiling areas where there could be areas or pockets of high humidity?

There are also questions to consider when implementing a solution.

Would a change from an ionization to photoelectric type detector be effective?

Would a more frequent detector cleaning schedule in that area be effective?

Should a protocol for certain contractor activities be implemented?

Could alterations be made to reduce the effects of sudden humidity changes?

 The solutions may not require a change to the fire alarm system, relocating detectors, changing the type of detector or reprogramming, but rather changes in building procedures or ventilation.

It is time to find the cause of nuisance and false alarms and implement effective solutions. Complacency by the occupants, possible fire department fines or disconnection of smoke detectors are all unacceptable outcomes.