Types of Smoke Alarms

The two most common types of smoke alarms are ionization and photoelectric alarms. 

Ionization alarms: 

  • Respond better to flaming, fast-moving fires.
  • Use ions to detect smoke in the air.


Photoelectric alarms: 

  • Respond better to fires that start with a long period of smoldering.
  • Use a light beam to detect smoke in the air.


As you can never be sure which type of fire you may have in your home, it’s advisable to use both types of alarms in your house or to purchase a combination device that has both technologies in one unit.

Smoke alarms may be battery-powered or they may be hardwired into the home’s electrical systems.

Hardwired alarms:

  • Can be interconnected with other alarms in the house (older houses may require special wiring).
  • May have a battery backup during power outages.
  • Should be installed by a licensed electrician.


Battery-powered alarms: 

  • May not be able to be trigger alarms in other parts of the house.
  • Continue working during power outages.
  • Can be installed using a screwdriver.


Interconnected smoke alarms provide an additional measure of security because the smoke alarms communicate with one another, allowing all alarms to sound if one has detected smoke. They may be connected using wires or wirelessly. Interconnected smoke alarms are best used in multi-story homes as they provide individuals on other floors with the earliest warning possible. The National Fire Protection Association requires that all new homes include interconnected, hardwired alarms.

If a member of your household is deaf or hearing impaired, different types of smoke alarms are available. Detectors with strobe lights are useful in alerting these individuals while they are awake. However, during sleeping hours, additional alert devices are necessary. These devices may include pillow or bed shakers or vibrating bracelets that are activated when a smoke alarm sounds.

All smoke alarms should be replaced every 10 years, cleaned using a vacuum hose attachment every 6 months, and tested every month. For hardwired alarms, the battery backup should be replaced once a year. Battery-powered alarms may come with a 9-volt battery or with a 10-year lithium battery. Replace 9-volt batteries every 6 months and lithium-powered alarms at the end of the 10-year period.

Make it easy to remember when to test alarms or replace batteries by choosing memorable dates. The first Tuesday of every month is an ideal time for alarm testing and Daylight Savings Time is perfect for replacing alarm batteries. When you purchase a new smoke alarm, write the purchase date on the alarm so you can easily remember when you need to replace it.

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