According to NEC Article 250, both the neutral and ground wires must be connected only in the main panel or at the first service disconnect. In my opinion, two locations within the power distribution system present unique challenges for the electrical worker, service entrance equipment and the equipment directly on the secondary of a transformer. 1 (C) provides the designators for raceway trade sizes. All conductors of a circuit, including the neutral and equipment grounding conductors, must be run in the same raceway. From there, it is routed to individual building distribution boxes (secondary distribution boxes), which subsequently supply power to unit-level distribution boxes (tertiary distribution boxes), and finally to household systems. The six disconnect rule per the 2017 version of NEC stated “The. Metal raceways, cable trays, cable armor, cable sheath, enclosures, frames, fittings, and other metal noncurrent-carrying parts that are to serve as grounding conductors, with or without the use of supplementary equipment grounding conductors, shall be effectively bonded where necessary to ensure.
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