28 (A) allows us to use wire, bus, a screw or other similar conductor in this critical role. The main bonding jumper is a critical safety component in an electrical service, responsible for creating a reliable, low-impedance path for fault current to travel back to its source. According to the National Electrical Code (NEC), this connection is made between the grounded conductor (typically. In an electrical panel or load center, the Main Bonding Jumper (MBJ) is the conductive connection that bonds (connects) the grounded conductor (neutral) to the equipment grounding conductor and the metal enclosure of the panel. To catch up on Lorenzo Mari's series on grounding and bonding, please follow these links: Section 250. What material can be used? Let's start with what.