A smoke detector is an electronic fire-protection device that automatically senses the presence of smoke, as a key indication of fire, and sounds a warning to building occupants.
Commercial and industrial smoke detectors issue a signal to a fire alarm control panel as part of a building’s central fire alarm system. By law all workplaces must have a smoke detection system.
Household smoke detectors, or smoke alarms, issue an audible and/or visual alarm locally from the detector itself. They can be battery-powered single units or several interlinked hardwired (mains-powered) devices backed up by batteries. The latter must be installed in all new buildings and after major refurbishments.