The whole house fire alarms that came with our Van Metre house have just recently started going off by themselves. The last time it went off it lasted for about 30 seconds then just stopped. Because all of them were going off there was no way to figure out which one triggered it. I went around the house and tested all of them and the test switch worked. Batteries were just recently replaced in almost all of them but these are all also on their own power circuit and the batteries are just backup. Really strange situation. In debugging this it seems VM put the attic fan, outlet, and light on the circuit as well. I didn't think they were allowed to do that but that's how things are wired. Doesn't look like anything else is on that circuit. As a precaution I went around the house with a can of compressed air to clean the units. Just wondering if anyone else has had this issue and if they found a cause.