[Al Skierkiewicz]

These breakers are a thermal reset type. As they have current flowing through them above the trip point, the current flow through the internal resistance causes heat.(Ohm's Law for power(heat) P(watts)=I^2 * R) The switch mechanism is a bimetallic design. The two metals which form the switch expand at different rates when heated and cause the internal parts to deform opening the breaker. When the current flow stops, the metals return to normal shape and the switch closes. However, once the breaker is near to trip temperature, only a little additional current is needed to send it over the edge. So...the breaker is more likely to trip again if it has tripped already in a match. The subsequent trips will occur at lower currents than the initial one. In sustained, high current situations, the reset occurs rapidly sometimes resulting in a buzzing sound from the breaker. Also, breakers that are operating at sustained high temperatures due to high currents, can raise the temperature of nearby breakers as well. The maxi block should help a little with that problem this year. It will be something I am interested in getting feedback on. If any team experiences 40 amp breaker trip during your build time will you post here and let us know the conditions you encountered.
Thanks,