The minimum size bonding conductor for bonding metal parts to the branch circuit equipment grounding conductor is 14 AWG copper.

• A. 12 AWG copper
• B. 14 AWG copper
• C. 16 AWG copper
• D. 18 AWG copper

Answer: (B)

Bonding metal parts to the branch-circuit equipment grounding conductor creates a low-impedance path that keeps normally noncurrent-carrying metal parts at the same electrical potential as the system ground, which helps prevent shock if a fault occurs. The bonding conductor (the bonding jumper) is not a regular current-carrying conductor, but it must be able to carry fault current enough to trip the overcurrent device quickly. For this reason, the code sets a minimum size for that bonding jumper: copper 14 AWG. Using at least 14 AWG copper ensures the jumper can safely carry the fault current without overheating and still provide a reliable path to the grounding conductor. Larger conductors would also meet the requirement, but 14 AWG copper is the smallest size permitted for this purpose.