Electrical – What could cause the oven to trip at a certain temperature

For everyone's info, and because it could help someone else, here is the actual answer in my case.

While I had connected the white wire coming out of the AFCI to the ground bar, I hadn't connected the neutral from the circuit to the AFCI. In my case it was because I didn't realize the extra screw terminal was actually there and the documentation wasn't helpful.

Bottom line: If you install a combination AFCI and connect the hot but not the neutral, it will not pop until there is a load. After the fact, that actually makes sense. This is like a ground fault from the AFCI's point of view because it can't see the current going back through its neutral port.

It doesn't sound like a short. It happens after five minutes... each time. To me it also sounds like loose wiring or a bad breaker. I would turn the circuit off and than I would visually inspect the back of the receptacle first. Are the screws tight? Any burnt looking wires anywhere in the box? Than if that is good I would switch that breaker out for a breaker that works. If it holds, you know your breaker needs to be replaced.

You must have confidence in knowing you know how to turn off circuits to do this. If you are uncomfortable, just call an electrician. I am sure it won't take them that long to figure it out. You could even have a breaker at home for them ready (and return it to a store- if they will let you- if he does not need it.)