What is the minimum AWG size allowed for that portion of the bonding jumper that connects to a supplemental grounding electrode if it is a rod, pipe, or plate?

The minimum AWG size allowed for the portion of the bonding jumper that connects to a supplemental grounding electrode, such as a rod, pipe, or plate, is 6 AWG copper. This requirement is established to ensure adequate conductivity and strength in grounding systems, contributing to systems' overall safety and effectiveness.

Using 6 AWG copper provides sufficient current-carrying capacity to handle fault conditions that could arise, ensuring that the bonding jumper can effectively carry any fault current safely to ground. This minimizes the risk of electrical shock and equipment damage while promoting compliance with safety standards outlined in the National Electrical Code (NEC).

In practice, grounding and bonding conductors must be sized properly to prevent overheating and to maintain effective grounding performance. The selection of 6 AWG for copper connections aligns with these necessities, as smaller sizes may not be capable of performing adequately under fault conditions.

Thus, the choice of 6 AWG copper ensures a reliable and safe grounding connection when bonded to supplementary grounding electrodes.