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Main bonding jumper is the connection between the grounded circuit conductor and the equipment grounding conductor at the service.
The primary function of the main bonding jumper is to connect the grounded circuit conductors and the equipment grounding conductors at the service equipment.
NEC requires the main bonding jumper to be at least the same size as the grounding electrode conductor where the circular mils rating of the service entrance conductors does not exceed1100 kcmil for copper or 1750 kcmil for aluminum.
