How does GFCI protection differ from equipment grounding?

• A. GFCI protects against shock by detecting circuit current imbalance and tripping.
• B. Grounding adds a path for fault current but does not affect shock protection.
• C. GFCI detects imbalance and trips; grounding provides a low impedance path for fault currents to earth to stabilize voltage and facilitate fault clearing.
• D. GFCI and grounding are interchangeable terms.

Answer: (C)

A GFCI protection works by watching the current in the hot and neutral conductors and looking for any imbalance. If some current leaks out, such as through a person who contacts a live part, the GFCI detects that difference and trips within milliseconds, cutting off power to prevent a shock. This is about sensing leakage and interrupting the circuit quickly, even when the total fault current isn’t large.

Equipment grounding provides a physical, low-impedance path from exposed metal parts to earth. Its role is to keep those parts at earth potential and to help fault currents return to the source so that protection devices (like a breaker) will trip. It doesn’t actively sense leakage, and by itself it doesn’t guarantee immediate shock protection unless a protective device intervenes.

These functions are not interchangeable: you can have grounding without a GFCI, and you can have a GFCI without a grounding conductor. The best description is that GFCI detects current imbalance and trips; grounding provides a low impedance path for fault currents to earth to stabilize voltage and facilitate fault clearing.