So a circuit in my home is dead. It covers a couple lights and a couple outlets. I plugged a microwave into this circuit and it was more than she could handle. Before this, the circuit worked fine for years, but the lights would noticeably dim when the load from the toaster was applied.
The breaker is not tripped. I replaced the breaker. This particular breaker was different from the others, not labeled on the panel, and the romex enters the panel from a different direction than the other 20amp circuits; I suspect this circuit was added after initial construction.
There is no GFCI on this circuit. The fixtures and outlets are all standard with no obvious fuses. There are no scorch marks, and there was no smell when the circuit cut out.
I worked as an electrician's assistant when I was a teenager. I have basic skills and basic tools. I don't have an outlet tester or a mutimeter.
Everything that was mentioned in the comments are great. I would just add that if you don’t know what wire it is in the attic or elsewhere, you can use a cable tracker. I’ve found that the one from Harbor Freight albeit it cheap and no lasting forever, works better than the Klein ones if you are wearing headphones. It will be able to track the line through the walls, even if it has a break in it. To echo the other person, the circuit will fail in the weakest point, so ideally the breaker is designed to be that. I’d consider changing your old breakers if one failed to trip.