The product is a hardwired alarm, also confirm if the wiring polarity is correct and that all wire nut connections are secure. A loose neutral (white wire) connection within the home junction box could prompt a device malfunction. Promote greater household safety with the First Alert 9120B Hardwired Smoke Alarm with Battery Backup. This 120-volt AC smoke detector uses an ionization smoke sensor to reliably detect smoke from hot, fast-flaming fires and alerts you with a loud 85-decibel alarm.