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Transformer Bonding conductor size from XO to frame

Question asked by trapp on Apr 3, 2019
Latest reply on Apr 5, 2019 by chiefns830

What is correct table for sizing the conductor between the Neutral and the transformer frame/enclosure for a dry type indoor 480V-208/120V transformer?  The transformer is part of a premises wiring system, not a service entrance, and treated as a separately derived source.  Exhibit 250.14 of the 2014 NEC Handbook identifies this conductor as the system bonding jumper.  The system bonding jumper should be sized according to Table 250.102(C)(1).  Is this conductor correctly labeled in Exhibit 250.14 of the 2014 NEC Handbook? Can this conductor be sized according to Table 250.66?  Are grounding bushings an acceptable method for connecting this conductor between the Neutral and the transformer frame/enclosure?  Please reference specific paragraph from 2014 NEC which is the applicable version in the jurisdiction for this Detail with annotation relating to questionproject.

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