One of the most overlooked safety devices in your home is a smoke detector. Simply put, a smoke detector is a device that is used to detect smoke. There are basically two types of smoke detector systems, one that has smoke detector wiring that issues a signal to a monitored fire alarm system and the other, known as smoke alarms, generally issue a local audible and/or visual alarm from the detector itself.
Smoke detectors are typically housed in a disk-shaped plastic enclosure, but the shape may vary by manufacturer or product line. Most smoke detectors work either by optical detection (photoelectric) or by physical process (ionization), while others use both detection methods to increase sensitivity to smoke. Smoke detector wiring can be powered by a central fire alarm system, which uses a battery backup, or as is the case in many single family detached and multi-family homes, a smoke alarm is powered only by a single disposable battery.