Put in place to detect the onset of a fire in homes, businesses and other structures, a smoke alarm is instrumental in helping prevent the loss of life and property. While businesses, public buildings, rental homes and apartments are required by law to have a certain number of smoke alarms installed, it is up to a homeowner to outfit their living space with the appropriate alarms. As a general rule, a smoke alarm of one type or another should be installed on every floor of a home in order to ensure timely notification should a fire break out.
Smoke Alarm Types
Two basic types of smoke alarms exist. Ionization smoke alarms work well for detecting trace or near-invisible smoke particles that float through the detection chamber. Using a small chunk of radioactive material, americium-241, an electrical current is created between two metal plates. When smoke enters the chamber, the current is disrupted and the alarm sounds. Photoelectric smoke alarms, by contrast, feature a beam of light in a chamber connected to a perpendicular chamber. When enough smoke enters to block the path of light, portions of the light are deflected into the second chamber where they come into contact with a sensor, setting off the alarm. Smoke alarm/carbon monoxide detector combo units are common as well.
Smoke alarms are available in both DC- and AC-powered varieties. DC-powered smoke alarms operate on 9-volt or AAA batteries most commonly. They can be installed anywhere. AC-powered batteries either plug into a wall outlet or are hardwired into the home circuitry. In both situations they require a backup battery in case the power should fail. Wireless smoke alarms are battery powered, but they are designed to be a part of an interconnected system of alarms. When one alarm goes off, they all do. Wireless smoke alarms may be a part of a full-spectrum home security system.