⚡Question Of The Week⚡
Question:
An apprentice installs a subpanel in a detached garage. The neutral and ground bars are bonded together in the subpanel. What is the issue?
[Bonus]: What additional conductor is required in this setup?
Drop your answer AND NEC reference if you know it ⚡
Please Comment & Discuss Below.
Disclaimer: As always with my questions, there may be errors or mistakes: feel free to call them out!
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⚡ Credit: TRADEHOG.NET ⚡
250.6
SPOILER: ANSWER KEY BELOW
2023 NEC (NFPA LINK)
250.32 Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s).
(B) Grounded Systems.
(1) Supplied by Feeders or Branch Circuits.
250.6 Objectionable Current.
(A) Arrangement to Prevent Objectionable Current. [as noted by Jonathan]
The Correct answer would be (C). It creates Parallel neutral current paths (the neutral and ground are improperly bonded in the subpanel, creating a parallel neutral current path that allows objectionable current to flow on the equipment grounding conductors and metal parts).