Which statement distinguishes a three-phase fault from a single-line-to-ground fault in terms of current path?

• A. Three-phase fault involves all three phases; Single-line-to-ground fault involves one phase and ground.
• B. Three-phase fault involves only one phase; Single-line-to-ground fault involves all three.
• C. Three-phase fault involves no ground; Single-line-to-ground fault involves ground.
• D. Three-phase fault and single-line-to-ground fault have identical current paths.

Answer: (B)

Current path in faults depends on how many conductors are involved. In a three-phase fault, the fault connects the three phase conductors with each other, so current flows in all three lines. The fault current is distributed among the three phases, often in a balanced way for a symmetrical fault, and the return path isn’t limited to ground. In a single-line-to-ground fault, currents flow from the one faulted phase down to the earth and back to the source through the grounding system, so only that one phase carries the fault current with a clear ground path.

So the correct distinction is that a three-phase fault involves all three phases, while a single-line-to-ground fault involves one phase and ground.