Which type of bonding jumper connects different grounding conductors at the main service?

The bonding jumper that connects different grounding conductors at the main service is known as a main bonding jumper. This type of jumper serves a critical role in establishing an intentional electrical connection between the grounded (neutral) conductor and the grounding electrode system at the main service.

The main bonding jumper is essential for ensuring that the entire electrical system is at the same potential ground reference. This helps in providing an effective path for fault currents, thus enhancing safety by reducing the risk of electric shock and preventing damage to equipment.

In contrast, the other options refer to different kinds of bonding jumpers that serve specific functions. System bonding jumpers are used in particular systems to connect grounded conductors but are not typically referenced specifically at the main service. Equipment bonding jumpers connect the ground of individual equipment to the grounding system, while circuit bonding jumpers are used to bond specific conductors within a circuit. Each has its purpose, but the main bonding jumper is unique in its role at the main service, making it the correct answer in this context.