What pikachu said, plus:

The (US) national electric code says the maximum CONTINUOUS current draw is 80% of the breaker rating. In this case, the highest continuous current for a 15 amp breaker is 12 amps total. Don't forget to include anything thing else on the breaker like lights or electronics.

If you are going into full power extraction mode, you might want to check that the labeling on your junction box is correct. If a particular breaker has scattered outlets, you may want to also map them out.

One last thing, I would talk to an electrician if you house has 14 gauge aluminum wiring. This is a problem.