We have a new addition to our house with its own subpanel. Since it is a bedroom the outlets and lights are on their own two 20Amp AFCI breakers. We now narrowed it down to these two AFCI breakers tripping every 7 days at roughly the same time (from the time they were last reset). In the beginning we did not pay close attention but it always seemed roughly a week. Now it tripped again this evening, 7 days (within the hour) since we last had to reset it. It has been doing this even when the new room was not occupied and there was practically no load. Yesterday I disconnected the Smoke Detector because I thought it might do a self test every 7 days. But it still went out today. We have three dimmers on there and they control recessed lighting as well as one ceiling lamp with 3 or 4 light bulbs. Initially while no one was living there, there was no other load (yet a week later they had tripped). Now there is a small refrigerator in the room, plus a TV, a cable box, a micro wave, toaster and a lamp (there is also a Gas Fire Place with low voltage ignition). One would think that it has to be a device that keeps track of time and does a certain function every 7 days that will trip it. Have you ever heard of such a thing? Are recessed lights that touch the insulation known to cause any trouble? I just don't know of any device in that room that has a circuit that does things on a weekly basis (on the 7th day) after it was turned on. And we replaced both breakers once.