LK, you're a no good low-down dirty liar and I'm going to go do the research to prove it right now...
Uh, oh, never mind...
http://www.sea.siemens.com/reselec/product/rzcbnotacb.html "Short-circuit interrupting ratings: UL 489 requires a minimum short-circuit interrupting rating of 5000A for circuit breakers rated 250V and less, and 10,000A for those rated more than 250V. UL 1077 devices do not have short-circuit ratings, but the standard does required a limited short-circuit test at a maximum current of 5000A. (The actual test value varies from 200A to 5000A, depending on the rating.) The test and acceptable results are also quite different. UL 489 requires the circuit breaker to interrupt the circuit twice; in the first test, the faulted circuit is closed on the circuit breaker and then the same circuit breaker is closed on the fault. After these tests, the circuit breaker must still be functional and pass a dielectric test. UL 1077, on the other hand, requires supplementary protectors be subjected to three operations. However, the supplementary protectors can be wired in series with a fuse or circuit breaker (the branch circuit overcurrent protection), which is allowed to open during the test. While the device cannot become a hazard, it can become inoperable during the tests."
mmkay...
As I was very clearly just saying yesterday at 11:56AM, circuit breakers are not required to interrupt properly after multiple shorts, and it IS possible for properly installed wiring to be damaged from deliberately shorting a branch circuit.
What a half-arsed safety standard. When I finally break down and buy a house, I'm going to replace all the old breakers and rewire it with gold-plated #6. Or maybe install fuses. Do they make fuses in a circuit breaker form-factor? (I can just imagine the look on the salesman's face)