Hello, I have a condo with 2 bedrooms. The circuit for both bedrooms is on 1 AFCI breaker. The one bedroom works fine but the other does not. If I plug anything into the second bedroom it trips the breaker. I have tried a single light, a radio, a vacuum cleaner. These items all work in the other bedroom. If I plug in a simple tester it shows everything is okay. The electrician who wired it has washed his hands of the problem.
Help!
Thanks
Corvette

Just a few questions:

1. have you tried replacing the afci breaker?
2. is it a certain outlet that you plug into that causes the breaker to trip or is it every outlet in that room¿
3. do you know how the afci breaker works? ( if not here's a link: HandymanWire - AFCI Arc Fault Circuit Interrupters )

Did the electrician push wire things or are ALL the connections on the screws? If it is push wired, you might as well just redo the whole circuit. Then redo the rest of the house. If he used the screw terminals then figure out the route of the wiring and the outlet closest to the breaker in the chain where the problem occurs is most likely the culprit. See if there is a conductor that isn't caught in a wire nut, a loose wire nut, or a loose screw connection in that box. I've seen all three of those things. Sometimes electricians will use the screws for everything until they need that one extra conductor connection and then they will push wire that one. If it is push wired, redo things on the screws or with a wire nut and pigtail on the screw. Push wiring on power distribution should be illegal!

One other possibility I can think of. Are the receptacle boxes in the wall plastic or metal? I won't go into the metal box thing here, check one of my early posts about an AFCI for that one!

Make sure the neutral from the AFCI is connected to the neutral bar and the neutral from the circuit is connected to the AFCI.

If those outlets worked before, then likely a connection as mentioned, if this always happened since the AFCI's was installed, then the other bedroom's neutral may be on another circuit.
Everything on that arcfault HAS to draw only from AFCI's hot and neutral, no other neutral can be connected.