Information about Smoke Detectors

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An essential safety feature for any home, smoke detectors, when properly installed and maintained, can double your chances of surviving a fire. One half of all home fire deaths occur in homes that do not have working smoke detectors. Also, while it is estimated that 94 percent of U.S. households have at least one smoke detector as many as one half may not be working because the batteries are dead or missing. 

If you live in the City of Fairfax and need smoke detectors (or smoke detector batteries) for your home please visit our Free Smoke Detectors web page.

For additional information visit Smart Alarm Choices Website.

Selecting Smoke Detectors for Your Home

  • Be sure to only use smoke detectors that carry the label of an independent testing laboratory. Some models of smoke detectors are designed to run on batteries while other "hard-wired" smoke detectors use household current as their primary source of power.
  • If electrical wiring is not already provided in your home to accommodate hard-wired smoke detectors, battery-powered smoke detectors can be used. Battery-powered smoke detectors typically use 9-volt batteries as their source of power and can easily be installed by homeowners. Certain models of smoke detectors now also come with 10-year lithium batteries. These smoke detectors are highly reliable, tamper-resistant, and require little maintenance.
  • If the required electrical wiring is provided in your home, hard-wired smoke detectors can be used. Hard-wired smoke detectors run on household current and should be installed by a qualified electrician. Certain hard-wired smoke detectors may use batteries as a back-up source of electricity during power outages. If your hard-wired smoke detectors do not have a battery back up, you may wish to install at least one battery-powered smoke detector in the home for protection in the event that household current is interrupted.
  • If you select a smoke detector that plugs into a wall socket, be sure that the outlet is not connected to a light switch that could allow someone to accidentally turn off the power. Also, make sure that the plug has a restraining device to keep it from being accidentally disconnected.

Smoke detectors use two different types of sensor technologies: 

  • Ionization - Smoke detectors that use ionization technology react most quickly to open flaming fires such as paper or kitchen fires. Recent news reports have indicated concerns with the effectiveness of ionization detectors, which are typically less expensive than other types. The fire service community is evaluating this information so that we can address the issue and make appropriate recommendations.
  • Photoelectric - Smoke detectors that use photoelectric technology react most quickly to smoldering, smoky fires (fires which smolder for hours before bursting into flame.) Sources of such fires might include cigarettes burning in couches or bedding.
  • Combination Ionization/Photoelectric Smoke Detectors - Certain models of smoke detectors incorporate both ionization and photoelectric technologies and provide early warning for both types of fires.
  • Combination Smoke/Carbon Monoxide Detectors - Certain models of smoke detectors also function as carbon monoxide detectors. Remember that unless you purchase one of these special detectors, your regular smoke detector will not alert you to the presence of carbon monoxide in your home. For more information about carbon monoxide, visit our Information About Carbon Monoxide web page.

Where to Install Smoke Detectors 

  • At a minimum, one smoke detector should be installed on every level of your home including the basement and in or near every sleeping area. Follow all manufacturer's instructions and recommendations to ensure the proper installation and placement of your smoke detectors.
  • Smoke detectors should be mounted high on a wall or on the ceiling. A wall-mounted detector should be positioned with the top of the detector 6-12 inches below the ceiling. A ceiling mounted detector should be positioned at least four inches away from the nearest wall.
  • For individuals who are difficult to awaken, it may be necessary to install a smoke detector inside the bedroom.
  • Don't install smoke detectors near windows, doors, or forced-air registers where drafts can interfere with their operation. Moving air can blow smoke away from the detector or result in false alarms.
  • To avoid false alarms, install smoke detectors at least ten feet away from stoves, fireplaces, and steamy showers. In particular, smoke detectors installed too close to the kitchen frequently result in false alarms. Rather than removing the batteries from the detector, try reinstalling it farther away from the kitchen but on the same level of your home.

Smoke Detector Maintenance

  • Test smoke detectors monthly by pushing the "test" button or using other procedures recommended by the manufacturer.
  • Install new batteries annually or whenever the smoke detector makes a "chirping" sound. The chirping sound indicates that the battery in the smoke detector is nearly dead and needs to be replaced immediately.
  • To help you remember to install new smoke detector batteries annually, try changing the batteries every fall when you change your clocks back from daylight savings time.
  • Never "borrow" a battery from a smoke detector. You might forget to replace it in a timely manner.
  • Gently vacuum the outside of smoke detectors monthly to remove dust and cobwebs and to allow for proper airflow through the vent holes.
  • Replace smoke detectors if they are more than ten years old.
  • Residents of the City of Fairfax can now sign up to receive electronic messages reminding them when it is time to change their smoke detector batteries. For more information, please visit our Smoke Detector Reminders web page.

Smoke Detectors for the Hearing Impaired

  • Certain models of smoke detectors come equipped with a built-in strobe light (as well as an audible alarm) that can alert the hearing impaired in the event of a fire.
  • Because the strobes used in such detectors generally require 120 Volts, most smoke detectors for the hearing impaired must run on household current rather than on batteries.
  • For a list of manufacturers that distribute smoke detectors for the hearing impaired, please call the National Fire Protection Association's Center for High-Risk Outreach at 617.984.7826. For more information about smoke detectors, please call the City of Fairfax Fire Department, Office of Code Administration, at 703.385.7830 (TTY 703.293.7120).