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Smoke Alarms

The Basics

Photoelectric smoke alarms should be placed, at a minimum, on every floor level including the basement, inside every sleeping room, and outside of every sleeping area of all dwellings.
Interconnected photoelectric smoke alarms, either wired or wireless, should be strongly considered. With interconnected alarms, when one smoke alarm sounds, all other smoke alarms in the home sound as well, which creates an early warning to occupants in all areas and allows as much time as possible to escape.
To aid in choosing the correct smoke alarm, consumers should look for the word “photoelectric” or the “P” symbol on the packaging or description of smoke alarms.


 The Details


Sensor Types

There are three types of sensor technology used in smoke alarms: photoelectric, ionization and a combination or dual sensor that incorporates both sensors in one smoke alarm.

  • Photoelectric: The sensor of choice. The photoelectric sensor responds faster to smoldering type fires that cause the most injuries and deaths in residences. It is also less prone to nuisance false alarms from cooking and steam.
  • Ionization: The ionization sensor responds faster to flaming type fires. It is prone to nuisance false alarms from cooking and steam.
  • Combination or Dual Sensor: Contains a photoelectric and ionization sensor. It is still prone to false alarms from cooking and steam due to the ionization component.
  • Smoke alarms should bear the label of an approved testing agency (UL or FM).
  • To aid in choosing the correct smoke alarm, look for the letter “P” or the word “photoelectric” on the packaging or description of the smoke alarm.

Power Types

  • Battery: Uses a 9 volt or AA batteries
  • Long Life Battery: Power may last up to 10 years with a long-life lithium battery.
  • Hardwired: Wired to the home 110 volt electrical service (with battery back-up)
    Battery smoke alarms are readily available and can be installed by a homeowner or tenant. Hardwired alarms must be installed by a qualified electrician but can be easily replaced by the homeowner at the end of their service life or if faulty.


  • Photoelectric smoke alarms should be placed, at a minimum, on every level of the home including the basement, outside every sleeping area and in every bedroom. Smoke alarms should be mounted on the ceiling or high on the wall (smoke rises). Always follow the manufacturer’s instructions.
  • Additional smoke alarms can be added to increase your protection.

 Testing and Maintenance

  • Test each smoke alarm monthly by pushing the button.
  • Replace 9 volt and AA batteries in smoke alarms twice a year.  (Remember: change your clocks, change your batteries.)
  • If the alarm “chirps,” warning that the battery is low, replace the battery right away.
  • All smoke alarms have a recommended service life of 10 years. Replace your smoke alarms at this time or sooner if they are not functioning properly.
  • Vacuum or dust out cobwebs that have accumulated in smoke alarms at least once per year.

Additional Tips

  • Consider installing interconnected photoelectric smoke alarms (wired or wireless). When one detector sounds, every detector throughout the house sounds.  Interconnected Details (369 downloads)
  • In the event of a false alarm, never remove the battery or disconnect the power source. Simply fan the smoke or steam away from the smoke alarm until the alarm stops. Some alarms come with a button you can push to temporarily silence the alarm.
  • If a contractor or supplier is installing your smoke alarm, make sure you are provided with the manufacturer’s instructions.
  • Many communities provide free smoke alarms and batteries to residents who cannot afford them, and may install them for you if you require assistance. Check with your local fire department.
  • Smoke alarms are one component of a complete home fire escape plan. Have a plan and practice it.


Download Residential Smoke Alarm Guide here:
SDBrochureNEOFPA (377 downloads)


How Do I Tell What Type of Smoke Alarm I Have?

To tell if you have a Photoelectric or Ionization type alarm:

  • Look on the front, back or the inside of the unit for the following:
  • The word “Photoelectric” or the symbol “p” or the word “Ionization” or the symbol “i”.
  • Any indication of the unit containing radiation indicates it is an Ionization alarm.


How Do I Tell How Old My Smoke Alarm Is?

Smoke alarms have a service life or expiration date of 10 years. To check the age of your smoke alarm:

  • Look on the back or the inside of the unit for a date of manufacture sticker or stamp.
  • If there is no date listed on your detector it
    Radioactive Label Indicating an Ionization Alarm

    is most likely more than 10 years old and should be replaced.

Ionization Label and Date Code
Radioactive Label Indicating an Ionization Alarm



Photoelectric Label and Date Code



My Smoke Alarm Goes Off When I Burn The Toast Or From Shower Steam. It Must Be Working Fine, Right?

Not Necessarily! The airborne particles from burned toast, ordinary cooking and shower steam are different from the smoke from burning furniture and household items. These nuisance false alarms lead people into a false sense of security that their ionization smoke alarm is ultra-sensitive and will give them an early warning in the event of a fire in their home. In fact, your ionization smoke alarm may not go off early enough to save your family in an actual fire. Ionization smoke alarms are more susceptible to these nuisance false alarms and may alert tens of minutes later than a photoelectric smoke alarm in an actual fire.


Are Officials Listening To The Facts About Photoelectric Smoke Alarms?

Yes! Government officials across the globe are enacting legislation ensuring that photoelectric smoke alarms will be protecting the public in their jurisdictions.
Here are some that have.

Australia: Northern Territory Northern Territory Legislation (418 downloads)

Europe: Cyprus, Luxembourg, Netherlands, Switzerland European Commission Legislation (363 downloads)

United States:

California: Albany, Orange, Palo Alto, Sebastopol Albany Legislation (376 downloads) Palo Alto Legislation (354 downloads)

Iowa (Statewide) Iowa legislation (365 downloads)

Maine  (Statewide) Maine Legislation (381 downloads)

Massachusetts  (Statewide) Mass. Legislation (503 downloads)

Ohio: Brooklyn, Cincinnati (Rental Properties), Chagrin Falls, Lyndhurst, Mayfield Village, Moreland Hills, Shaker Heights Brooklyn Legislation (400 downloads) Chagrin Falls Legislation (344 downloads) Lyndhurst Legislation (365 downloads) Mayfield Village Legislation (352 downloads) Moreland Hills Legislation (405 downloads) Shaker Heights Legislation (353 downloads) Cincinnati Rental Legislation (379 downloads)

Vermont  (Statewide) Vermont Legislation (394 downloads)


What Type of Smoke Alarm is Being Used in Commercial Buildings Like Hospitals, Schools and Nursing Homes Where Our Most At-Risk Citizens Are Located?

Photoelectric smoke detectors are typically used in commercial fire alarm systems because the commercial industry has understood the differences for many years.


Can I Access The Studies That Have Shown The Differences Between Smoke Alarms?

Yes. Here are some of the major studies that have been conducted.

Texas A&M Study 95-01R (1134 downloads) Texas A&M Study Summary Paper (1349 downloads) NIST Smoke Detector Research Summary 2007 (1083 downloads) Tyco Detector Technology Tests (1797 downloads)


Watch the NBC Today Show Video On Photoelectric Smoke Alarms Here


For additional information please go to PhotoelectricSaves.com and also check out the Smoke Alarm Links located on this page.