Article 200 provides the requirements for using and identifying grounded conductors. But because the term “grounded conductor” is used throughout the NEC, Art. 200 doesn’t define it.
Generally, the Code Making Panels assume that it’s understood that the definition of any special term used in two or more Articles is in Art. 100. In fact, the scope of Art. 100 states this. That’s why you typically don’t see these special terms mentioned with a note that you need to read the Art. 100 definition. But “grounded conductor” is so special that the Informational Note to 200.1 (Scope) explicitly refers you to the Art. 100 definition.
Not only that, this Note also says to see the Art. 100 definition of “Equipment Grounding Conductor” and “Grounding Electrode Conductor.”
For a very long time, the word “grounding” (in its various permutations) has had multiple (and contradictory) meanings in the NEC. This problem is slowly giving way to clarity, and the nexus of the progress is in Art. 100.
IEEE-142 (The Emerald Book) is a useful reference for understanding grounding theory and application; this work is often cited in the NEC terminology reform efforts. Misunderstanding, followed by misapplication, of grounding can and does produce tragic consequences.
