How Linked Smoke Detectors Work

The Basics

• The National Fire Protection Association recommends that homes contain interconnected smoke alarms in each bedroom, outside each sleeping area and on every level of the home. The organization claims that almost two-thirds of fire-related deaths between 2005 and 2009 occurred in homes with no functioning smoke alarms, and linked alarms go above and beyond the function of single smoke alarms. If one alarm goes off, all other alarms inside the home will sound as well, ensuring that nobody misses the warning.

How It Works

• A linked smoke alarm detects the presence of smoke like any other smoke alarm, and it begins to emit a loud sound, warning of a possible fire. At the same time, it sends a signal throughout the home, which is detected by all the other smoke alarms within range. Those smoke alarms begin to sound as well, even if they are located in rooms with no smoke.

The Specifics

• Linked smoke alarms communicate with one another using radio frequencies. In the same way that a radio station satellite transmits music to your FM radio, a linked smoke alarm transmits the same kinds of invisible signals to one another in the event of smoke detection. The alarm that detects the smoke functions as the transmitter, and the other linked alarms function as the receivers, as they detect the invisible radio signals sent by the first alarm.

Additional Information

• Interconnected smoke alarms have become the standard for smoke alarms in the United States, and are, in fact, required by law at the time of publication. Some interconnected smoke alarms, particularly those found in newer homes, are hard-wired into the ceilings and use AC power with a battery backup system. You can also purchase sets of interconnected smoke alarms that use AC power, battery power or both. If using AC power, your alarms should always contain batteries for backup, in the event that a fire breaks out during a power outage.