The electrical system is designed to protect itself, If you overload the circuit the breaker should trip before anything hazardous can happen. If your house is old than you might have a problem with the older methods of wirring. However I have seen many breakers hold far more than their rating for an extended period of time.
Exactly dont rely on the breaker to hold above its rating or attempt to push it above that.
@Clive_bixby where you're from you have receptacle circuits in your homes that are rated above 15Amp?? the only receptacles in our homes (Canada) that are 20amp are kitchen recepts and they have special T slot receptacles.
clive_bixbyAlright, so, when I say circuits, I mean like every breaker is its own circuit. So if you look in you're breaker box at home, you'll see like kitchen room 1 office etc, and that means its has its own circuit. All of those receptacles fall under the one circuit (i.e. all the receptacles in the office belong to one circuit.) So lf I were you I would go find your 2 or 3 30 amp breakers find out what rooms they are and run cords into wherever this party is going.
Addressing what rusticles said, sometimes lower amperage breakers can pull some more current, but that is pretty stupid to do, especially if you know you are doing it. Depending on the electrician and how tidy his work is, you just really never know because he's the only one who see's it. Don't take chances with it, and as far as him saying the breaker will flip, don't assume anything. Most electrical fires start due to poor joints, or nicks in cable or some other dumb shit. I've seen low voltage commercial grade transformers short and not kick the breaker (an electrician I was with had the heads up to hit it pretty much instantly) in the high voltage panel its being fed from.
Do your house a favor, use the higher breaker. Oh and don't spill mountain dew on the surge protector.