Fire Safety

Basic Alarm Types

Ionization vs. Photoelectric

The two most commonly recognized smoke detection technologies are ionization and photoelectric.
  • An ionization smoke alarm is generally more responsive to flaming fires that spread rapidly but typically have little smoke.
  • A photoelectric smoke alarm is generally more responsive to smoldering fires that produce a lot of smoke.
  • For the best protection, use both types of alarms or use combination alarms, which include both technologies in a single device.
  • Be sure all alarms have the label of a recognized testing laboratory.
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Special Considerations

Be sure you choose alarms that will alert all members of your household and help you deal with nuisance alarms.
  • Smoke alarms with a recordable voice announcement in addition to the usual alarm sound may help wake up children through the use of a familiar voice.
  • Smoke alarms for persons who are deaf or hard of hearing are required to have vibration equipment; some also have strobe lights.
  • Alarms with a hush button allow you to quickly silence nuisance alarms temporarily.


To keep your family safe, make sure you have enough smoke alarms and they are installed correctly.
  • Install alarms in every bedroom, outside every separate sleeping area, and on every level, including the basement.
  • Hard-wired smoke alarms that run on household current should have battery backup in case of a power outage and should be installed by a qualified electrician.
  • Interconnect all smoke alarms in your home, so when one alarm sounds, they all sound.
  • Because smoke rises, mount smoke alarms on ceilings or high on walls.
  • Don’t install smoke alarms near windows, doors, or ducts where drafts might interfere with their operation.
  • Follow the manufacturer’s installation instructions.

Alarm Installation and Placement

Measurements shown are to the closest edge of the detector. Some states and jurisdictions allow smoke alarms to be installed on ceilings only.
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Testing and Maintenance

Smoke alarms save lives, but they can’t protect you if they don’t work properly. Be sure to follow these tips so your smoke alarms are always in top condition:
  • Test alarms at least once a month by pushing the test button.
  • Replace all smoke alarm batteries at least once a year.
  • If an alarm chirps, warning the battery is low, replace the battery right away.
  • Replace all smoke alarms when they are 10 years old or sooner if they do not respond properly.
  • Never paint smoke alarms. Paint, stickers, or other decorations could keep the alarms from working.