There is an unintended connection between a phase conductor and earth/protective ground. If the system itself is designed to operate ungrounded, no fault current will flow, but it is still a fault in the sense that it is an undesired connection. Two ground faults from different parts of the ungrounded system will usually cause fault current to flow. There is still an environmental ground, usually the bulk of the exposed metal. It is just initially not connected to a circuit conductor.Yes, quite. A fault. But my question remains. How can it be a ground fault if there is no ground?