insulated fittings?

[guschash]

When do you use insulated fittings? I always used them when using any wire except NM cable. But reading 300.4(G) it says 4awg or larger. How about manufacture fittings they have smoothly rounded surfaces. I was told once that these fittings because of the smooth surface that we didn't have to use a brushing. What do you think?

gus

 

[infinity]

What kind of manufactured fittings are you referring to? Here's a graphic from Mike Holt:

 

[guschash]

I was thinking Emt, their connectors have smooth surfaces. I don't see how putting a brushing on them would make much differences.