wa8yxm wrote:
THere are two types of breakers, Magnetic and thermo. Not all are Thermo.
Virtually all household circuit breakers are thermal-magnetic breakers, combining both thermal trip (for moderate overloads, with some time delay so motors and such can momentarily use more than the rated current to start) and magnetic trip (for instantaneous response to hard, very high current short-circuits).
Thermal only residential circuit breakers (for service panels) do exist, but I think are mostly older/obsolete designs and in any case offer somewhat less protection to connected wiring. I think the little circuit breakers on power strips etc. are often thermal only, but I'm not positive about that.
Magnetic only circuit breakers are primarily used for specialized applications where short-term overloads are neither expected nor permissible. One example I'm aware of is some stage lighting dimmer systems where the individual dimmer output circuits have magnetic only breakers. They're designed to be able to output the full rated load continually, but to trip immediately at a (relatively small) overload. I'm sure there are plenty of other applications, especially in high voltage systems; but they're essentially non-existent for household electric panels.
