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Wednesday, May 22, 2019
Question:
I have a situation where in a residential kitchen I have a 2-gang fiberglass box wired for a switch with 14-2 NM (15-amp) for an over the sink light and 12-2 NM (20-amp GFCI) for a counter receptacle. The inspector hit me with article 250.148 saying all grounds that enter a box are to be spliced together. My counter argument is doing so is a violation of article 310.10(H) which prohibits conductors under 1/0 from being run in parallel. By splicing the grounds from two different circuits the grounds become paralleled due to the splice in the box at one end and both of them being on the ground bar in the panel. What is one to do here? Thanks!
Richard Cressotti
A
Answer:
Hey Richard thanks for your question. The wording for conductors in parallel, with the1/0 limitation, applies to each phase, polarity, neutral, or grounded conductor, but not to equipment grounding conductors, as stated in 310.10(H)(1). The wording in 310.10(H)(2) is somewhat problematic because it includes the term "equipment grounding conductor". Equipment grounding conductors of different sizes are often connected together at both the beginning and ends of runs in a variety of different applications. This might be a good situation for a Public Input for the 2023 NEC to remove the equipment grounding conductor term, at least for non-parallel applications of other conductors. There is some relief in 310.10(H)(5) for the sizing issue but for paralleled equipment grounding conductors.
Besides all that there was a change to 250.148 for the 2017 NEC that many are interpreting as requiring all equipment grounding conductors in boxes to be connected together but the word "together" is not in the actual NEC wording. Stay tuned for the 2020 NEC which has wording that hopefully is a little clearer about only requiring equipment grounding conductors associated with those circuit conductors needing to be connected. The word "together" does not exist in the proposed final wording (to this point) even though it was added during the first draft. Additional Public Inputs to this section for the 2023 NEC could also help improve the wording
For now, it is the AHJ's decision to make the determination and it might be easiest to connect them all together.