Which of the following is true about green main bonding jumper screws in panels?

• A. Main panels only
• B. Sub panels
• C. Meter bases
• D. Main and sub panels

Answer: (A)

In service equipment, the neutral must be bonded to the grounding system at a single point so fault current can return properly and trip the disconnect. The green main bonding jumper screw provides that bond between the panel’s enclosure (or neutral bus) and the grounding path. This bond is required only at the main service panel where the service disconnect is located. In subpanels, neutrals and grounds are kept separate and there’s no main bonding jumper. Meter bases aren’t where the service bond is made unless the service equipment is located there. So green main bonding jumper screws are used in the main panel only.