In the example where the DC grounding electrode conductor is six AWG copper and the AC grounding electrode conductor is one AWG copper, what is the minimum size for the bonding conductor that must connect the two electric systems together?

• A. 1 AWG copper
• B. 4 AWG copper
• C. 6 AWG copper
• D. 8 AWG copper

Answer: (A)

Bonding two electrical systems requires a bonding conductor that can carry fault current without becoming a bottleneck, so its size must be at least as large as the largest grounding path involved. In this case, one system has a 6 AWG copper grounding electrode conductor and the other has a 1 AWG copper grounding electrode conductor. The bonding jumper must be sized no smaller than the larger of the two, which is 1 AWG copper. Therefore, the minimum bonding conductor size is 1 AWG copper. Smaller options would not provide a sufficient, low-impedance path for fault conditions.