Royce,
The fact is that they always close the circuit after cooling, unless permanently damaged. The proof for that is in the click. There are two kinds of clicks. The first is closing the circuit and remaining closed. The second is closing into a fault condition and reopening. In the latter situation, technically the breaker did indeed close, otherwise it would not have heated up to reopen.
The bi-metallic element is electro-mechanical in nature - once an overcurrent condition trips the breaker, there is no knowledge of the status of the load - whether normalized, marginalized, or a dead short such as in the example you mention. Once the element has cooled off, it WILL close unless it is permanently damaged.
The heating of the element is based on current plus time. Anyone can read up on "time-current curves" if so inclined.
Some examples:
1. The turn signal or emergency flasher use the same bi-metallic electro-mechanical design as many circuit breakers. It is engineered to flash (heat and cool) at a narrow band of rates with a designated load. This is why when you replace incandescent lights with LEDs, which draw less current, cause issues. The element takes much longer to heat up and the flash rate can be painfully slow.
2. When someone installs higher wattage halogen bulbs that run near or slightly over the rating of the circuit breaker that had perhaps a 10-20% margin on traditional bulbs. These will heat up, cool, and repeat the cycle resulting in flashing lights.
3. A dead short. Under this condition the circuit breaker will "trip free". The duration that the contact is closed would be difficult to measure without expensive equipment.
All contacts that interrupt current have a life usually expressed in the number of cycles. Contacts that open under duress (such as a dead short) will lose their life more quickly.
To summarize - we are both right. My perspective was one of the aspect of resetting, whereas yours was from the perspective of a successful reset.
