Power Circuit
The power circuit providing electricity can be a dedicated circuit, which means it is the only device powered by cables that run directly back to the circuit box. It can also be powered by a circuit that serves outlets and lights if the circuit is not controlled by a switch.
Fuses, Breakers and Interrupters
Although switches aren’t allowed on the circuit serving the smoke detector, it is allowed to be protected by fuses, breakers or Ground Fault Interrupters. Fuses or breakers are mounted in the circuit box and trip or open the circuit in case of an electrical short in the circuit. This prevents fires and lowers the risk of electrical shock in the event of some sort of malfunction. The Ground Fault Interrupter trips so quickly that it prevents the potential of electrical shock during a malfunction.
Battery Backup
Many electrically powered smoke detectors include a battery as a backup power source. This continues the operation of the device even if the power fails in the home. Check the batteries every month or so and replace them on an annual basis to maintain the full operations of the smoke detector.
Interconnected Smoke Alarms
Some electrically powered smoke detectors work in conjunction with other units as a system. They are interconnected so if one device detects smoke or fire the alarm sounds from all devices in the system. These interconnected smoke detector systems require additional wiring for the alarm circuit and may include a control panel or master alarm.