What is meant by 'ground fault' in an aircraft electrical system?

• A. A fault that occurs when a conductor touches another conductor
• B. An unintentional current path from a conductor to ground, potentially causing equipment fault or fire
• C. A deliberate grounding path to stabilize voltage
• D. A short circuit between two different electrical buses

Answer: (B)

Ground fault means an unintentional current path from a live conductor to the aircraft structure or to ground. In other words, the electrical current that’s supposed to return through the intended circuit instead escapes through the airframe or other ground path. This can energize metal surfaces, lead to equipment faults, overheated wiring, or even start a fire if the fault carries enough current. It happens when insulation breaks down, wiring wears through, or moisture creates a conductive path to the structure.

This is different from a fault where two conductors touch each other, which is a direct short between conductors inside the circuit, not specifically a path to ground. It’s also not a deliberate grounding or bonding path used for safety, nor is it simply a short between two different power buses; those are faults of a different nature. The defining idea is the current taking an unintended route to ground rather than returning through the designed load path.