I was removing a small Sony cd player in master bedroom. It made a short/ spark, circuit breaker went off. Removed cd player; Went to pannel and turn on /reset breaker for Masterbderoom; I made a mistake by reset the next AFCI breaker which is for bedroom2 (dont know why,may be itchy finger :o )!
Now Masterbedroom is fine But the light in bedroom 2 are off ;I tried to reset a few more time (with no load i.e. nothing plugged in, only builtin ceiling light) but no luck :confused: ? Is the AFCI of Bedroom 2 went bad? And how do I check it? Thank you for your help..

The only way is to open the panel and check the breaker's output with a voltage tester. Best to be sure what your doing in a live panel if your considering this.

The breaker can be defective, or loose in the panel, or the wire connected to it can be loose. Handling the breaker may have rattled a pre-existing condition.

Thank you for your fast re[ply. :)
The breaker did seem to be a bit loose ! If I turn off the main panel breaker and also stand off- ground... It should be safe , right? How much voltage am I supposed to read? And off which wires? Thanks again.

If you shut off the main, you have no voltage to test at the breakers, so extra caution is needed if you work in a live panel.

You will see the wire connected to the breaker terminal.

Should be 120 volts to ground or neutral.

Or is it easier if I just replace the ARC breaker with the new one?
Thanks again.

It may be easier but that may not be the problem, and Arc Fault breakers are very expensive.

I would test it with a cheap non-arc breaker to determine if the breaker was the problem or even place the suspect breaker to supply a good load.

What makes me suspecious is that you say you saw a spark! An arc breaker should operate too fast for a spark to be visible.

Thank you all for your input.
The spark happened with the Sony CD player (in the master bedroom), and after disconnect the CD player, I reset the Arc breaker, that circuit is OK.
The problem is the Arc breaker (of bedroom 2);in the panel, happen to locate right on top of the Masterbedrom breaker ! Coincident or something make it got loose ? :confused:
Any suggestions? Thanks.

Did you find the cause of the breaker tripping?

Sounds like the suspect breaker is being closed in on a fault. I would look at the breakers that share a common split receptacle that has a fault (perhaps the one that originally tripped the breaker).

I have not yet done it.
Will try your suggestion with a cheaper non ARC breaker first.
I should be able to turn off the master pannel and install the cheap breaker(same voltage and Amp), right?
Thanks again.

Yup. If your careful and you don't want to reset all the clocks, you can turn the trouble breaker off, pull the breaker (pop it out with a flat screwdriver), remove the conductor to the new breaker and plug it back in without tripping the mains.