How Many Smoke Alarms Do I Need in My Home?

By Cathy C. Hall

  • Overview

    Before smoke alarms were introduced, people had to rely on their senses to detect a fire in the home. It's easy enough, of course, to see a fire, or smell smoke. But what about smoke in the basement? Or a fire that starts in the middle of the night? A homeowner needs to be prepared. That's where smoke alarms come to the rescue.
  • Significance

    Where there's smoke, there's fire. But it's oftentimes the smoke, a silent and fast-moving killer, that kills when a fire strikes. That's why a smoke alarm is so important. Its shrill sound can alert residents at the first sign of danger. An alarm installed on every level of a home can reduce risk of death by almost half. And since most deaths from smoke inhalation occur during sleep hours, it is vital to place smoke alarms outside sleeping areas. If bedroom doors are kept closed, it's recommended that smoke alarms be placed in each bedroom.
  • Function

    To get the optimum use from a smoke alarm, proper installation is important, so follow manufacturer's instructions. Placement of smoke alarms can make a difference, too. It's generally best to install an alarm in the center of a ceiling. On a wall, place the alarm 6 to 12 inches below the ceiling. Smoke alarms placed along the evacuation plan route in your home is ideal.


  • Types

    Smoke alarms are classified by the way they detect smoke: ionization or photoelectric sensors. Ionization detectors produce a small, constant electric current. When smoke enters the alarm, the current is disrupted and the alarm is triggered. Photoelectric alarms contain a photocell sensor that detects smoke and triggers the alarm. Although both alarms are effective, there are differences in performance. Ionization alarms respond more quickly to flaming fires, while photoelectric detectors respond more quickly to smoldering fires. Smoke alarms that combine the types, called dual sensor smoke alarms, are also available.
  • Considerations

    Smoke alarms can generally be purchased for less than twenty dollars. Besides being one of the most effective and inexpensive safety features a homeowner can buy, installing smoke alarms can reduce homeowner's insurance. Installation of adequate smoke alarms might also be necessary before selling a home.
  • Warning

    A smoke alarm depends on its working parts as well as batteries to function properly. Test smoke alarms on a regular basis, scheduling one day a year for smoke alarm maintenance. Replace batteries and insure that the alarm is working. Never take the batteries out of a smoke alarm to use in other electronics. Always respond when a smoke alarm goes off.
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