What is the minimum size equipment-bonding jumper used to connect a grounding-type receptacle to a grounded metal box where the branch circuit supplying the receptacle is protected by a 30-ampere overcurrent protective device?

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

Answer: (B)

The key idea is how the equipment grounding conductor (the bonding jumper) is sized to handle a fault on the circuit. NEC 250.122 links the circuit’s overcurrent protection to the minimum size of the grounding path. For a branch circuit protected by a 30-amp device, the smallest copper equipment-grounding conductor allowed is 10 AWG. This ensures the fault current has a capable path back to the panel to trip the 30 A breaker quickly, protecting people and equipment. Using a smaller conductor would not meet the requirement and could overheat in a fault, while larger sizes exist but aren’t the minimum. The bonding jumper’s purpose is to connect the receptacle’s ground to the metal box and the circuit grounding conductor so everything shares the same ground potential.