What amp percentage must be verified for a mechanical jumper to ensure it carries a safe portion of the load before cutting the conductor?

• A. 60%
• B. 30%
• C. 50%
• D. 70%

Answer: (B)

When you place a mechanical jumper to bridge a conductor you’re about to cut, you must verify the jumper can carry a portion of the normal load safely before opening the circuit. This ensures the temporary path will share current during the switching, keeping the remaining conductor from overheating and reducing the risk of a fault rushing through the system.

The minimum you’re checking for is 30% of the circuit’s normal load. This amount provides meaningful current through the jumper to keep service continuous, while not overloading the temporary path. If you tried to transfer a larger fraction, the jumper could overheat or fail; a smaller share might not provide a stable, safe transfer during the cut.