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Smoke/Fire Alarm Technology

Wondering what the difference is between smoke detectors with ionization versus photoelectric detectors? Here is the difference between the two.

Which Method is Better?

Both ionization and photoelectric detectors are effective smoke sensors. Both types of smoke detectors must pass the same test to be certified as UL smoke detectors.

Ionization detectors respond more quickly to flaming fires with smaller combustion particles; photoelectric detectors respond more quickly to smoldering fires.

In either type of detector, steam or high humidity can lead to condensation on the circuit board and sensor, causing the alarm to sound. Ionization detectors are less expensive than photoelectric detectors, but some users purposely disable them because they are more likely to sound an alarm from normal cooking due to their sensitivity to minute smoke particles. However, ionization detectors have a degree of built-in security not inherent to photoelectric detectors. When the battery starts to fail in an ionization detector, the ion current falls and the alarm sounds, warning that it is time to change the battery before the detector becomes ineffective. Back-up batteries may be used for photoelectric detectors.

Ionization Detectors

Ionization detectors respond more quickly to flaming fires with smaller combustion particles. Sources of these fires may include paper burning in a wastebasket, or a grease fire in the kitchen.

Photoelectric Detectors

Photoelectric detectors respond more quickly to smoldering fires. Sources of these fires may include cigarettes burning in couches or bedding.

Home Fire Safety Recommendations

  • The Office of the Fire Marshal also recommends that smoke alarms be installed in every room, for maximum protection.
  • A mix of photoelectric and ionization smoke alarms is desirable.
  • As stated by manufacturers of smoke alarms, the most important factor in protecting your family is having the recommended number of working smoke alarms installed in the proper locations.
  • It is also recommended that since you can’t be sure what types of fire might start in your home, you install both ionization and photoelectric smoke alarms in your home, or choose dual sensor smoke alarms which feature both.