Smoke detectors are used to identify smoke early so that fires can be prevented. Among the most commonly used models are photo-electrical devices that are equipment with a light-sensitive sensor. They use the scattered light method, in which infrared light is not reflected in the smoke detector’s optical chamber. Only when smoke particles enter the chamber is the light scattered onto the sensor, triggering the alarm. To ensure that the warning signal of a single smoke detectors is not missed, several of the devices are networked together. This ensures that the alarm is sounded on all connected devices within a very short time. Smoke detectors are primarily used in residential and work buildings.