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sub-panel grounding & neutral separation


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Thanks Scott & Mike!

I used the search engine to look for sub-panel grounding neutral & did get there that way. However, I don't see the code reference numbers in that email.

Further enlightenmentis need, I'm afraid.

I do appreciate all the volunteering of time that yo all put into this forum.


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Can someone give me the NEC reference numbers to the requirement for having a separate grounding conductor to a sub panel & the proper ground & neutral separation of the sub panel.

Thanks a Million!


250.24(A)(5) Load-Side Grounding Connections. A grounding connection shall not be made to any grounded conductor on the load side of the service disconnecting means except as otherwise permitted in this article.

250.142(B) Load-Side Equipment. Except as permitted in 250.30(A)(1) and 250.30(B), a grounded circuit conductor shall not be used for grounding non-current carrying metal parts of equipment on the load side of the service disconnecting means or on the load side of a separately derived system disconnecting means or the overcurrent devices for a separately derived system not having a main disconnecting means.

408.40 Grounding of Panelboards. Panelboard cabinets and panelboard frames, if of metal, shall be in physical contact with each other and shall be grounded. Where the panelboard is sued with nonmetallic raceway or cable or where separate grounding conductors are provided, a terminal bar for the grounding conductors shall be secured inside the cabinet. The terminal bar shall be bonded to the cabinet and panelboard frame, if of metal; otherwise it shall be connected to the grounding conductor that is run with the conductors feeding the panelboard.

Exception: Blah, blah, doesn’t apply to our discussion today, blah, blah.

Grounding conductors shall not be connected to a terminal bar provided for grounded conductors (may be a neutral) unless the bar is identified or the purpose and its located where interconnection between equipment grounding conductors and grounded circuit conductors is permitted or required by Article 250.

- Jim Katen, Oregon

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Obviously, I'm not being clear!

I know that subpanels need to be grounded/bonded & that neutrals need to be isolated from grounding/bonding.

Just reading the words "Article 250 – Grounding and Bonding Section 250.54 Supplementary Grounding Electrodes"

does not clearly tell me that this is also the reference for or discussion of the requirement to isolate grounds & neutrals.

Maybe it is but I couldn't tell.

I'm sorry for bothering you.

Please accept my humble apology and my gratitude for your generous wisdom.

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