What minimum gauge is recommended for bonding jumpers for detachable metallic parts of equipment cabinets?

• A. #8 AWG
• B. #10 AWG
• C. #12 AWG
• D. #14 AWG

Answer: (C)

Bonding jumpers are used to keep all detachable metallic parts of an equipment cabinet at the same electrical potential, preventing dangerous voltage differences if panels are opened or touched. The path created must stay intact even when parts are removed and reattached, and it has to carry any fault current long enough for the protection devices to trip, all with a low impedance.

For this application, a copper conductor sized at 12 AWG provides a good balance of electrical capacity and practical installability. It is thick enough to carry fault currents without excessive voltage rise and is robust against mechanical wear from frequent panel removal. Using a smaller size could raise the impedance of the bonding path and potentially allow a hazardous voltage to appear during a fault, while larger sizes would be more than necessary for typical cabinet bonding needs. Thus, 12 AWG is the recommended minimum.