I have four upstairs bedrooms with each bedroom running off an Eaton 20 Amp Arc Fault Breaker. When my 12 Amp vacuum cleaner is plugged into any outlet in three of the bedrooms, it works just fine. However, when plugged into an outlet in the master bedroom, the breaker trips immediately. After several hours of troubleshooting, here is what I have done: 1. Isolate the outlet that is the first one in series from the breaker box from all the other switches and outlets in the master bedroom. I've inspected the wires and replaced the outlet with a new one. 2. I swapped out the current breaker with one from the other bedrooms that works fine with the vacuum -- it still tripped the breaker immediately. 3. I purchased a new Eaton 20 Amp Arc Fault Breaker and same thing --- trips immediately. I'm at a loss...what could I possibly do next?
Honestly, with these kinds of protective-device trips, the problem is often exactly what says on the tin.
An AFCI breaker is designed to look for arc faults, principally in the building wiring. You've swapped breakers around, the problem does not move with the vacuum, it does not move with the breakers, it has stayed with the bedroom. Occam's Razor: it's in the bedroom wiring.
Since wiring problems are almost always at wire ends or devices, I'd preemptively swap every receptacle with a nice contractor grade screw-and-clamp type.