Among short circuit current and overload current, which is typically greater?

• A. Short circuit current.
• B. Overload current.
• C. They are typically the same.
• D. It depends on the circuit.

Answer: (A)

Short circuit current is typically greater. When a fault creates a path with almost zero impedance, the current is determined mainly by the source voltage and this very small impedance, so the current can surge far above normal operating levels (I ≈ V/Z, with Z very small). Overload current, by contrast, is simply current that goes beyond what the circuit is designed to carry and is limited by the circuit’s impedance and protection settings, so it stays much closer to the normal operating current. This is why protection devices are designed to interrupt the much larger fault (short-circuit) currents to prevent damage.