109 explicitly permits metal boxes to be part of the ground-fault current path: Metal enclosures shall be permitted to be used to connect bonding jumpers or equipment grounding conductors, or both, together to become a part of an effective ground-fault current path. At the terminal stations where cables transition to overhead lines in systems of. Earthing, also known as grounding, is a critical safety mechanism used in electrical systems and appliances. It involves connecting an appliance's metal parts to the Earth through a low-resistance wire. If a hot or neutral inside the motor touches the casing, the casing will be energized, resulting in a “fault current” through the ground wire. The ground wire (green) safely moves that fault current into the breaker panel, tripping the. Any nonconductive paint, enamel, or similar coating shall be removed at threads, contact points, and contact surfaces or be connected by means of fittings designed so as to make such removal unnecessary. Where necessary for the reduction of electrical noise (electromagnetic interference) of the. NEC 250.
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