Bushing required?

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That's not a "comprehensive" statement. Raceway terminations of types noted by Article hereinbefore are required to have conductor abrasion protection regardless of wire size. If that protection is not integral by design, a bushing is required... even if the wires are smaller than #4 AWG.

You're right, I was referencing raceways that do not require bushings when used with conductors smaller than #4, i.e.- EMT. A 2" EMT filled with #6 and smaller conductors wouldn't require a bushing. Install a #4 and then the bushing is required.