This circuit breaker is a re-settable heat sensitive device designed to protect the blower motor. In a furnace, this heat evidences itself in the form of an amp draw. Therefore, since there are different size motors, there are different amperage ratings on circuit breakers. When replacing a breaker, do so with similar amperage rated breaker. The breakers used on Atwood furnaces are externally mounted and are of a slow blow style. This means that due to their location on the furnace, the heat of the furnace cannot affect their operation. Likewise, short amperage spikes will not cause them to trip either. The motor will have to produce an excessive and prolonged amperage draw to trip it. When the circuit breaker trips, it does so because a problem exists.