Interconnected smoke alarms are hardwired and run off of the 120-volt AC electrical system in a building. Most have backup batteries to power the smoke alarms in the event of a power outage. Nonetheless, hardwired smoke alarms are vulnerable to power surges, which may cause them to fail temporarily or permanently.
Signs of Smoke Alarm Failure
After a power surge, hardwired, interconnected smoke alarms may behave erratically, either beeping every few minutes or going off at inappropriate times. More insidiously, a smoke alarm may fail silently if a large power surge damages the wiring in such a way as to prevent the warning beeps. In such a case, the homeowner may be unaware that the house is unprotected until the next time he tests the smoke detectors, or until there is a fire.
Low Backup Battery
When a power surge trips the circuit breaker controlling interconnected smoke alarms fitted with a battery backup, the smoke alarms should immediately and seamlessly switch to battery power and function as normal. If one or more alarm units begin to beep intermittently instead, the most common cause is a low battery. The beeping is a warning, and replacing the battery with a fresh one will usually solve the problem. If it does not, the circuit may need to be reset.
Resetting the Circuit Breaker
After a power surge, the circuit breaker controlling the smoke alarm system may need to be reset. Some hardwired smoke alarm systems store simple error codes, such as a low battery warning. If replacing the battery does not stop the unit's intermittent beeping, check the breaker box. Reset the circuit breaker, which should reset the error codes in a properly functioning interconnected smoke alarm system. If the unit continues to beep, it will need to be checked by a professional and possible replaced.
Smoke Alarm Testing and Maintenance
Test smoke alarms monthly to ensure proper functioning during an emergency. In addition, test the system after any power surge or electrical storm that results in a power outage or tripped circuit breakers. Keep hardwired smoke alarms clean by vacuuming the exterior vents with the soft brush attachment of a vacuum cleaner. Unlike with battery-operated units, you should not open the casing of a hardwired smoke alarm to clean the interior.