Which statement best describes impedance grounding in electrical systems?

• A. Impedance grounding uses a resistor or reactor to limit fault current.
• B. Impedance grounding ties the neutral directly to earth with no impedance.
• C. Impedance grounding disconnects the neutral from earth during faults.
• D. Impedance grounding increases fault current to improve protection.

Answer: (A)

Impedance grounding provides a controlled path to earth by connecting the system neutral to ground through a defined impedance, such as a resistor or reactor. When a ground fault happens, current flows through that impedance to earth, but the magnitude is intentionally limited to a small, preselected value. This limits fault current, reduces damaging arcing, and helps protective devices operate predictably without unnecessarily interrupting the entire system.

That’s why using a resistor or reactor to limit fault current best describes impedance grounding. If the neutral were tied directly to earth with no impedance, that would be solid grounding and would allow a much larger fault current. If the neutral were disconnected from earth during faults, there wouldn’t be a proper ground path for the fault current. And increasing fault current would defeat the protective purpose.