What is the minimum sizing requirement for a supply-side bonding jumper when there is no overcurrent protection at the generator?

The minimum sizing requirement for a supply-side bonding jumper without overcurrent protection at the generator is 1/0 AWG. This requirement is grounded in the National Electrical Code (NEC), which specifies sizing based on the size of the largest ungrounded conductor that the bonding jumper connects to.

In situations where there is no overcurrent protection, the bonding jumper must be adequately sized to handle potential fault currents without overheating or failing in a fault condition. The 1/0 AWG size is determined to be sufficient for this purpose, ensuring that the bonding jumper can effectively bond the generator to the grounding system and maintain electrical safety and system integrity.

Sizing smaller than 1/0 AWG wouldn't provide the necessary conductivity and safety margin required in this application, and larger sizes like 2/0 AWG may not be necessary—although acceptable—since 1/0 AWG meets the minimum requirement. Therefore, 1/0 AWG is the correct choice in ensuring compliance with safety standards in these conditions.