Photoelectric smoke alarms are generally more responsive to fires that begin with a long period of smoldering also known as “smoldering fires”.
How they work: Photoelectric-type alarms aim a light source into a sensing chamber at an angle away from the sensor. Smoke enters the chamber, reflecting light onto the light sensor; triggering the alarm.
The photoelectric smoke detector can detect fire in an earlier stage than a heat detector. Generally, this detector is installed in spaces such as basements, ordinary floors, corridors, staircases abd elevator shafts.