Per 250.190(B), when grounding a 5kV rated service disconnect operating at 4.16kV, what is the minimum size grounding electrode conductor for this service to connect the non-current metal parts of the metal-clad enclosure to ground?
Per 250.190(B), when grounding a 5kV rated service disconnect operating at 4.16kV, what is the minimum size grounding electrode conductor for this service to connect the non-current metal parts of the metal-clad enclosure to ground? Assume the largest service-entrance phase conductor is 350kcmil and the equipment involved is fixed equipment.
350kcmil aluminum
3/0 AWG copper
1/0 AWG copper
2 AWG copper
Answer: D
Per this new section of the Code, the minimum size of the grounding electrode conductor is based on the size of the largest ungrounded phase conductor. A quick check of Table 250.66 reveals that a 350kcmil copper phase conductor requires a minimum size 2 AWG copper grounding electrode conductor.
Owen is the owner and president of National Code Seminars and the holder of master electrician certifications in 46 states. He can be reached at [email protected].