A(n) ? fault condition represents a solid connection of relatively low or zero impedance and is considered the highest magnitude fault condition.

• A. Bolted
• B. Arc
• C. Open
• D. Thermal

Answer: (A)

Short-circuit current depends on fault impedance. A bolted fault creates a direct, near-zero impedance connection, so the current is the largest the system can supply. That near-zero impedance means I = V/Z yields the maximum possible fault current, which is why this type is considered the highest magnitude fault.

An arc fault involves a conductive path through plasma, which adds impedance and can limit current compared to a true zero-impedance short, even though it can be very high. An open fault leaves the circuit open, so no current flows. A thermal fault describes overheating conditions rather than a direct low-impedance connection, so it doesn’t produce the highest instantaneous fault current.