Unintentional fire alarm calls in the United States reached 801,500 during 2004, or 38.1 percent of all false fire alarms. Included in this figure are improperly placed automatic smoke detectors and the improper use of heat sensors in specific applications.
Compared to previous years, the 2004 figure is actually 3.7-percent less than 2003. However, compared to 1988, when accurate records were commenced, unintentional false alarms rose more than 188 percent (278,000 in 1988).
According to the National Fire Protection Association (NFPA) of Quincy, Mass., there are two major sources of false fire alarms: steam or smoke from cooking and other activities in the home, and the testing of fire alarm systems without proper notification of fire authorities.
In this month’s “Fire Side Chat,” we will discuss some of the more common sources of false fire alarms. We will also talk about how they can be avoided.
Lack of Notification When Testing
One of the major problems that fire departments have is the testing of residential fire alarm systems without proper notification. In this case, the solution is fairly simple: Let anyone affected by an alarm signal know you intend to conduct a test.
“Before proceeding with any testing, all persons and facilities receiving alarm, supervisory or trouble signals, and all building occupants shall be notified of the testing to prevent unnecessary response. At the conclusion of testing, those previously notified (and others, as necessary) shall be notified that testing has been concluded” (Section 7-1.3.1, NFPA 72, National Fire Alarm Code, 1999 Edition).
To satisfy Section 7-1.3.1, you must notify the central station. However, because central station operators are human, it might be expedient to also call the fire department to let them know. This adds redundancy to the equation and can help to avert an unnecessary response.
The notification of all stakeholders not only applies to fire alarm technicians who routinely conduct fire inspections in homes but also to end users. “The owner or the owner’s designated representative shall be responsible for inspection, testing, and maintenance of the system and alterations or additions to this system … ” (Section 7-1.2, NFPA 72, 1999).
In practice, qualified fire alarm technicians usually inspect such a system on a one-time-per-year basis. In between inspections, end users can do a visual inspection of all components as well as a functional test, which includes sending signals to a central station. The end user must be instructed by the fire alarm firm to call the central station ahead of time to place the system on test.
In addition, they should also call the local fire department. When testing is over, all parties should be notified and the system taken off test with the central station. Improperly Installed Smoke Alarms
Another source of false fire alarms named by NFPA is improperly installed smoke alarms and smoke detectors. NFPA 72 specifically talks about steam and smoke caused by cooking and other activities.
First of all, the individual who designs the residential fire alarm system must choose the correct smoke detector for the application.
According to Section 2-3.6.1 of NFPA 72, 1999, “The selection and placement of smoke detectors shall take into account both the performance characteristics of the detector and the areas into which the detectors are to be installed to prevent nuisance alarms or improper operation after installation.”
A good example of this is the use of ionization-type smoke detectors in or about the location of a kitchen area. Because this technology is more responsive to relatively small airborne particulates, false alarms could occur. In this instance, a photoelectric smoke detector would be more appropriate. It’s important the designer know whether it’s right to use ionization or photoelectric technology to avoid problems.
The issue of detector placement is also important. This can be seen in installations where smoke detectors and smoke alarms are installed too close to cooking appliances and bathroom entrances. In either case, smoke or steam can cause detectors to false alarm.
Section 8-1.4.2 of NFPA 72, 1999, NFPA advises, “Initiating devices shall be located in areas where ambient conditions are within the limits specified by the manufacturer, and smoke alarms or smoke detectors shall not be closer than 3 feet from the door to a bathroom or kitchen. Smoke alarms or smoke detectors that are located within 20 feet of a cooking appliance and are equipped with an alarm silencing means or are of the photoelectric type shall be considered acceptable.”
The installation of smoke detectors must also be correct or false alarms can occur; or worse yet, delays or no alarm could result.
When an automatic smoke alarm or smoke detector is installed on the ceiling, there must be at least 4 inches between the housing and the sidewall. When mounting the same detector/alarm on a sidewall, the distance from ceiling to housing must be at least 4 inches and no more than 12 inches.
For more information on smoke alarm/detector placement in the home, see April 2005’s “Fire Side Chat.”
Using the Right Heat Sensor Another source of false alarms in residences is the use of heat sensors with the wrong heat setting.
I recall a specific case during my field days where I assumed the maintenance responsibilities with regards to an existing fire alarm system in a home. A quick examination of the control panel during the add-on of some burglar equipment revealed that the fire detection circuit had been removed and the end-of-line diode placed over the initiating circuit terminals (yes, a diode).
It was the end of the job when the final connections were made in the alarm panel that we discovered the fire circuit wires were not connected. We installed the end-of-line diode at the last device and restored the system to operational status. Once that was accomplished, we tested our new burglar alarm devices as well as a sampling of the fire sensors and then we called it a day.
It was some time in early to mid-afternoon when the homeowner called to ask for help. After we left, the fire alarm system eventually went into alarm — at the height of the afternoon heat. That was when I knew the disconnected fire circuit was no accident.
Returning to the home, I quickly discovered a fixed heat detector with red lettering in the laundry room, signifying a 190° sensor. Knowing how the distributor packaged its orders, I knew somewhere in the house was a 135° sensor where a 190° model should have been. I quickly found that the 135° unit was in the attic.
The lesson here is to always use the right temperature thermostat for each application. Failure to do so can result either in false or delayed alarms.
