Which NEC table determines the minimum size of a bonding jumper for a water piping system at a separate building?

The correct answer is based on the specific requirements outlined in the National Electrical Code (NEC) for bonding jumpers. Table 250.102(C)(1) is explicitly designed to provide the minimum size for bonding jumpers that are required to connect the grounding system of water piping at a separate building to the grounding system of the main building or structure.

This table considers the size of the largest ungrounded conductor feeding the separately derived system. The purpose of this bonding jumper is to ensure electrical continuity and grounding between the systems to prevent potential shock hazards or differences in electrical potential that could create a safety risk.

Understanding the context of the other tables is essential. For example, Table 250.1 provides general grounding and bonding requirements but does not specify the minimum size for bonding jumpers for water piping systems. Table 250.66 addresses the size of grounding conductors for equipment, while Table 250.122 focuses on the size of equipment grounding conductors for overcurrent devices. Although these tables are relevant to grounding and bonding, they do not directly apply to the minimum size of a bonding jumper specifically for water piping systems in separate buildings, making Table 250.102(C)(1) the most relevant and appropriate choice.