National Electrical Installation Standards

Standards as High as Your Own

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Thursday, August 30, 2018

Question:

Re: CQD answer published August 13 & August 23, 2018-Grounded Conductor Terminations 3

I agree with your answer on this but would like to append it with the need to consider impedance-grounded system. They can have a neutral wire (although mostly delta), but it's not intentionally grounded. So, not all neutrals are necessarily solidly grounded. Since most applications of impedance grounding is industrial and vast majority of electricians are not, but residential and commercial, their in lies the issue of lack of familiarity. Since most NEC classes are geared to residential and commercial, it makes the less covered impedance-grounded system even more mysterious. Lastly, when I used to attend NEC classes and update sessions (now happily retired since 2004, but like to keep an oar in the water), the thing that was always impressed by instructors is that: "The NEC is not an instruction manual"! Electricians need to continuously learn new things as well as keep up with changes. Submitting change proposals to the NEC is always a great way to learn about an issue. Even if your idea is not adopted, the CMP will give you an explanation of why it was rejected, and that is often very valuable since it's almost like getting an interpretation. It's great you encourage that.

Best Regards, Nick Abbatiello

A

Answer:

Hey Nick thanks for your comment. Impedance grounded systems are a type of grounded system. You are correct they are not solidly grounded based on the definition of Grounded, Solidly in Article 100. A lot can be learned by reading resolved Public Inputs and public Comments.

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