I'd go a step further with the edit.
Get rid of "grouped".
I still want to see it say, in some fashion, that it's okay to run a switch leg that's not accompanied by the neutral. But I think that's for another thread.
I agree with Kwired's last post that there is the support of the switch loop sans neutral already in 300.20. The key is in the definition of the NFPA Glossary, that Don gave us, of "grouped".
No where have I said they have to be twisted...
Thank you, Don. Now, letting the OP's question rest as answered, by the Forum, IMO, I want to keep poking at "grouped" as you seem to be misreading the very Glossary definition that you provided for us.
I have only said that the code rule requires them to be grouped, and in my opinion one conductor running down the wireway on one side of the panel is not grouped with a conductor running down the wireway on the other side of the panel.
Don, I agree with you that 300.20 DOES tell us to not do that, but, because of the first sentence use of "
arranged" so as to avoid heating the surrounding ferrous metal by induction." When two AC conductors of a single circuit are arranged as you describe in the
bold red of your words, above, their magnetic fields are additive, not canceling, giving rise to induced currents in surrounding ferrous metal. This is a bad ARRANGEMENT giving rise to induction in surrounding ferrous metal.
The words of the first sentence of 300.20 do not give a threshold of heating by induction. I agree with you that this is all-encompassing, unlike the 200 Amp threshold that you report is in the Canadian Electrical Code. BUT, the rule hinges on "heating. . .by induction", NOT grouped. Your quote of the NFPA Glossary of Terms definition for "grouped" for all of NFPA 70 says unambiguously that
grouped conductors are positioned ADJACENT to one another, AND
grouped conductors are NOT in continuous contact with each other.
That NFPA Glossary definition greatly blurs the meaning away from the "singularity" that you appear to claim it has. Especially when you, Don, point to the NFPA Glossary definition of "adjacent" as not applying to grouped, which throws us to the Miriam Webster.
Don, you have been instrumental in answering Rob's OP related question:
I guess that we now need a clear definition of grouped. . .
Will anyone take a shot at defining the word grouped . . .?
There is no need for the last sentence in the code section. If it is to be changed you just delete the following words:
"To accomplish this, all phase conductors and, where used, the grounded conductor and all equipment grounding conductors shall be grouped together"
Including EGCs with CCCs I believe to be important, and removing that is problematic.
There is a real technical issue with how to measure "heating by induction" and to tease it out relative to ambient temps and I squared R heating in the current paths of conductors and terminations, as well as the heat created by all the solid state circuitry that is being placed inside the overcurrent protective devices.
