Are steel bushings allowed on rigid pipe terminations for conductors #4 or larger? 300.4(G) appears to say no. When used on smaller conductors, is the steel bushing listed for use without a locknut inside the box?
Also, even though it is not stated in 352.46, I would assume steel bushing would not be allowed on PVC due to a lack of connection to ground. And to be clear, I am refurring to standard/non bond bushings in these post. The Handbook shows bond bushings being used without locknuts so it is probably safe to assume that doesn't violate their UL Listing.
300.4(G) Insulated Fittings. Where raceways contain 4 AWG or larger insulated circuit conductors, and these conductors enter a cabinet, a box, an enclosure, or a raceway, the conductors shall be protected by an identified fitting providing a smoothly rounded insulating surface, unless the conductors are separated from the fitting or raceway by identified insulating material that is securely fastened in place.
They could be listed if they're not intended to put conductors #4 or larger in the conduit.