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Wednesday, April 6, 2022

Question:

Good Morning Code Friends,

Can the grounded neutral conductor be smaller than the ungrounded service conductors when it is supplied with a 3-phase, 3-wire, corner-grounded delta system?

Dick Sanders

A

Answer:

Hello Dick and thanks for the questions. First, we are a bit confused; it doesn’t take much these days.
In a corner-grounded, 3-phase, 3-wire system, there is no neutral. We’ll answer the question on that basis. The answer is the grounded service conductor for this system must be the same size as the largest ungrounded phase conductor. Remember that the grounded conductor must also meet the identification requirements in 200.6 and overcurrent protection is generally not permitted in accordance with 240.22. See Section 250.24(C)(3).

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