What is a main bonding jumper?

A main bonding jumper serves a critical role in ensuring electrical safety by connecting the grounded (neutral) conductor to ground at the service equipment. This connection is vital for establishing a common reference point for the grounded and grounding conductors, which helps to reduce the risk of electric shock and provides a clear path for fault currents back to the source.

By effectively bonding the neutral and ground at the service equipment, the main bonding jumper helps to ensure that under fault conditions, the overcurrent protection devices (like circuit breakers) can operate correctly. This operation is essential for disconnecting the power and preventing potential fire hazards or electrical shock to users.

The proper installation and sizing of the main bonding jumper are specified in the National Electrical Code (NEC), as they must meet specific requirements to ensure the safety and reliability of the electrical system. Additionally, maintaining this bond helps minimize voltage differences that could occur between the grounded and grounding conductors, which can be hazardous in various conditions.

Understanding the function and importance of the main bonding jumper is essential for anyone working with electrical systems, as it is a foundational component of safe electrical service installations.