AFCI breakers trip every 6 days like clockwork
I just bought a 3 year old home. The breaker box on the 2nd floor has 3 AFCI breakers (10kA), #10, 8, and 6. EXACTLY and without fail, every 6 days, all 3 trip in the same order (10, then 8, then 6), separated by several hours. There is nothing that we know of on a 6 day timer and the city claims it is not related to the grid. We also can't link the tripping to anything in particular being turned on, and it usually happens when everyone is downstairs and nothing is actively being plugged in or turned on. We have had all outlets and light switches inspected by an electrician and a few nicks were repaired, but the problem continues unabated. There are no junction boxes in the upstairs. Any thoughts about the cause would be greatly appreciated!