The pool pump motor has vent holes to prevent the motor from overheating. Sometimes the equipment area may be flooding, or the house gutters need to be cleaned so water from the roof gets displaced properly. Usually the breaker does what it is designed to do and trips to the off position. Once the moisture dissipates in the motor the breaker will be able to be reset and pump operates properly again. It is possible to purchase a motor cover at our retail store if it becomes a persistent problem.