Which grounding method allows for the most rapid fault clearing by the system's overcurrent protection equipment?

The phase-to-phase-to-ground grounding method allows for the most rapid fault clearing by the system's overcurrent protection equipment because it creates a low impedance path for fault currents to flow. This method effectively enhances the sensitivity of protective devices, meaning that when a fault occurs, the overcurrent protection can detect the increased current rapidly and isolate the faulted section quickly.

By connecting the phases to ground directly, the system ensures that any imbalances or faults will lead to a significant increase in current that is easily detectable by protective relays. Consequently, this leads to faster operation of circuit breakers or fuses, which is essential for maintaining system reliability and minimizing damage.

In contrast, other grounding methods may not provide such an immediate or robust response to faults due to higher impedance or complexities in fault detection. Single-point grounding, for example, can lead to potential issues with ground loops and may not provide the same low-impedance path. Grounding by equipment enclosure typically serves to protect equipment rather than optimize fault current flow, and isolation grounding is designed primarily for sensitive electronic equipment, potentially delaying the fault clearing process. These differences illustrate why the phase-to-phase-to-ground method is preferred for ensuring rapid fault resolution.