The system is owned by the facility, patrolled by employees and dispatches in-house fire fighting brigade. Household Fire Warning System - Almost always have internal life safety detectors of smoke and fire. Can be electric connected with battery back-up or independently battery operated with distinctive signal to wake up sleeping people. Must be located directly by bedrooms and detect rapidly rising or smoldering fires. Secondary power is supplied by battery back-up in commercial situations which transmits fire alarm signals and maybe some trouble signals but not supervisory signals.
Batteries can be the primary power source for residential smoke detectors.
They have been used on automatic sprinklers since the 1860s and continue to be used with newer types of systems. They cause an alarm directly or through activating a sprinkler system in which the flow of water activates a fire alarm. Surrounding temperature could be much higher. Fusible Element Type - Eutectic that melt rapidly at known temperatures allow a mechanism to function to alarm or allow flow of fire fighting material. In the first type the material melts while being heated and the two steel wires touch and close a circuit.