National electric code says that outside outlets and bathroom outlets must be protected with GFCI (ground fault circuit interruption) breakers. It's for your protection. When there is a voltage leak from either leg to ground, the circuit will trip. That you changed it to your "pool outlet" and it no longer trips makes me wonder if the "pool outlet" is similarly protected. It DEFINITELY should be if it isn't. All GFCI's have a "test" button. I strongly suggest you try it, if it's there on the circuit protecting the "pool outlet". I can only shudder to think what might happen if that "pool outlet" is actually connected to a swimming pool pump, not protected with a GFCI, and it shorts while people are in the pool.