ELECTRICAL CONTRACTOR Magazine Details Smoke Alarms vs. Smoke Detectors
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Colombo reports that two types of smoke alarms are currently on the market: stand-alone and multiple-station alarms that are connected to form a network to quickly warn a home’s occupants when a fire is detected. A smoke alarm is defined as an autonomous device that contains a smoke sensor with a sounder and power source. It is commonly powered by house power using 120V AC., with a small 9V battery for backup power. An internal sounding device alerts occupants when a fire has been detected. Usually, a tandem line provides connectivity between all of the smoke alarms in the house so that when one goes into alarm, they all do.
According to Columbo, the NFPA 72 National Fire Alarm Code(R) defines a smoke detector as “a device suitable for connection to a circuit that has a sensor that responds to a physical stimulus such as heat or smoke.” It has a more exacting smoke sensor than a smoke alarm, making it more selective in searching for airborne particles such as smoke. Smoke detectors in a home signal a central monitoring or supervising station.
Testing and Replacement
Two types of testing procedures are currently used for both devices: functional and calibrated. With a functional test, the technician often places an object near the detector such as a plastic card or magnet to trip it and/or the unit has a button to trigger a test on itself. By comparison, calibrated testing requires a special tool applied to determine how well it operates by showing how sensitive the unit is to airborne smoke.
For both types of units, homeowners should follow the manufacturer’s instructions for replacement. Colombo said that NFPA 72 places a 10-year limit on smoke alarms because past data shows they’re not maintained as well as smoke detectors. He said that smoke detectors should be replaced when they fail to work properly or cannot be cleaned.
SOURCE ELECTRICAL CONTRACTOR magazine