Lost power to a few rooms upstairs on Sunday (ran a space heater and hair dryer at some time). I thought we tripped a breaker but nothing was flipped in the electric panel. I reset every breaker to be sure. Then I checked we were getting power to each one with a fuse tester and that looks good. I reset all the GFCIs and found one that wouldn't reset out by the garage. So I replaced it and it reset but it didn't solve the problem.
It just means that a wire termination (where a wire meets a receptacle, wire nut or switch) failed somewhere from the overload. It failed in an arc-fault mode, meaning it burned out like a fuse then arced across the gap, until the arc self-extinguished. If it had not, you'd be seeing your insurance man in the morning.
The connection didn't short against another wire, so it didn't make a short circuit. That's why it didn't trip the breaker. Breakers are not "Magic Master Detect-All's". They make those; they're called dual-mode AFCI/GFCI breakers. The AFCI would have tripped from the arcing, stopping the arc in case it did not self-extinguish.
So now you need to go hunt down the bad connection, starting at the panel. Electrical circuits are wired like a tree, they can have any number of branches, but they never loop back to themselves. Most are wired linear like a vine. The problem is either at the last functioning outlet or the first bad outlet. The top candidates are:
- Backstab connections
- Aluminum wire on old non-aluminum-rated terminations (basically all terminations out there on Al wire)
- Loose amateur-done wirenuts - wirenuts are one of the few times "gorilla tight" is appropriate
- Screws not tightened enough
Non contact testers will give false positives when the dead wire run is parallel to a live run. Verify with a plug in lamp or other device and find the last working outlet On the circuit. Check that and the first non working outlet for a bad connection. If the back stabs on the outlets are used that can be the point of failure on either the black/ hot or white/ neutral wire.
It would be good for me to know how old the house/wiring is..... Off-hand, if wire-connections are all good in the Panel, it is possible that a connection burned/arced-through at the fault location. Note this could be just as easily on the White/Neutral side as the Black/Hot wire. This means that the original connection could have been flaky/NOT secure, and the overload caused the [flaky] connection to fail. This means it could have been arcing for some time, and that being the case you should find discolored wiring at the bad joint/device - either wire-nut, or back-of-the-duplex outlet (for example) connection supplying the loads.