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Monday, June 3, 2019
Question:
Re: CQD answer published Thursday, May 23, 2019 -Connecting EGC's Together
Good morning, I’m writing to provide a different perspective on the grounding issue in a j-box with multiple branch circuits routed into it. I can see it from the perspective of keeping things separate, for reasons of using a ground crimp and not having #12 and #14 under the same crimp, and keeping it simple for trouble shooting or future work. I would contend, however, that the EGC is the groundING conductor, and intended [per 250.4(A)(5)] as an Effective Ground-Fault Current Path, which in the example given, could mean the #12 current carrying conductor has the possibility to short out onto the #14 grounding conductor. The #14 would most likely provide an adequate path, however, it doesn’t appear to meet the minimum requirements for sizing of most residential branch circuit conductors. I’d also go all the way back to 90.1(A) “Practical Safeguarding: The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity...”If you’re trying to convince your AHJ that tying all grounds together of different circuits that are all somehow terminated or spliced in the same enclosure is onerous or somehow hazardous, than I would ask what that individuals opinion is on the purpose of the code. Thanks Charlie for the daily code lessons. It’s always good to get another perspective.
-James
A
Answer:
Hey James thanks for your comment you have some interesting points. Connecting 14 AWG and 12 AWG equipment grounding conductors together is probably very easily done. What if one circuit was much larger than the other such as a 2 AWG and 14 AWG, although not as common it could happen? What about a larger ungrounded conductor with damaged insulation that contacted a 14 AWG equipment grounding conductor for a different circuit in a cabinet creating a ground fault? There can be a lot of what if's but are they likely to happen, probably not? Copper 14 AWG equipment grounding conductors are commonly used for ungrounded conductors protected by 15 ampere overcurrent devices as shown in Table 250.122. Unless special circumstances exist such as very long circuit length then a larger size might be necessary as stated in the Note to Table 250.122. The word "practical" is a key part of the NEC purpose in 90.1(A).