I have a 500 watt power supply on my computer, and every time I turn it on in the room that I want to keep it in, the breaker goes. Is this normal? I plug the computer into other outlets on other breakers in other parts of my apartment with no problem, but in the 2 bedrooms that the breaker supports, it trips it every time. The other breakers that it does work on are also 20 amps, but this particular breaker that doesn't work looks a little different than the others (meaning looks like a different brand). Is the problem the breaker or the wiring? Any help would be appreciated.

It is possible that that the breaker that trips is an Arc Fault breaker , which are now required for all bedrooms. Is there a test button on the front? It may be defective.

Can you take some pictures of these breakers?

Or the breaker can be a regular breaker and be defective.

I believe the breaker is the issue and not any problem with the wiring or the PC.

Thanks for the reply.

Yes, the breaker has a blue test button. We have 3 bedrooms which seem to be supported by 2 of these blue button breakers. The computer doesn't work in any of the bedrooms so if the breaker is defective, does that mean that both breakers are defective since the PC doesn't work in any bedroom?

OK sounds as if you have Arc Fault breakers, must be a fairly new home, as AFCI were first required back in 2002.

Not really familiar with problems with AFCI breakers, since I have not done residential wiring for several years.

There may be some situation in the PC power supply that the breakers are detecting. Or the breakers may be defective.

There is a recall on Square D AFCI breakers, and they happen to have blue test button.

Review this link; Schneider Electric North American Division Recall of AFCIs

When the breaker trips, how many outlets stop working? What other peripherals are you using? Are they all plugged into a surge suppresser? (If not, they should be unless you are using a UPS device)

A 500 watt power supply is ~4 amps. 2 60 watt light bulbs are 1 amp (Watts/Voltage = Amperage 120 watt bulb/120 volt circuit = 1 amp)
A clock radio is 1-2 amps. A 17" LCD flat panel is 1.5 amps. CRT's are a lot more. Speakers, router, external hard drive, etc probably add up to another couple of amps.

To trip a normal circuit, you would need to be running the PC (4), Display (2) Misc Peripherals (4) and 10 2x60watt bulbs to bring up the load to 20 amps. And even that wouldn't blow the circuit.

Do you have a heated water bed on the same circuit?

It does seem to point to the AFCI as being the culprit. My GE AFCI's are $35 from Menards. Square D are similar. If you are at all uncomfortable at replacing them, call an electrician. Otherwise, de-energize the panel and TEST TO MAKE SURE THE POWER IS OFF, and replace the breaker.

Or, call your landlord and have them do it.

If the new AFCI trips, then, you have a more serious problem.

Have you hung any new pictures, etc? If so, then you may have nicked the electrical wire which is causing the circuit to blow.

Good luck, Dan