The current residents report that every clock in the house — battery-powered, plug-in, and phone alarms left charging overnight — stops or resets at approximately 3:15 AM, roughly once a month, with no consistent day-of-month pattern.
An electrician found no wiring fault and no explanation for battery-powered clocks being affected identically to plugged-in ones. We’ve installed a continuously logging clock in the property with owner permission and are waiting for the next occurrence to capture more precise data.