406.4(C) compared to 404.9(B)1

[MiElectrician]

A long time ago someone told me that using a bonding jumper from a metal box to a receptacle was required because the plaster ring or raised industrial cover isn't listed as part of the equipment grounding conductor. I was reading in the switch part of the nec (2014) and it explicitly allows this, so I figured I'd just look at the same code number for the receptacles and read similar verbage. I'm then directed to 250.1469(A) which allows using the screw to bond as long as there is good contact between the box and the yoke but not there is a cover used unless "the box and cover combination are listed as providing satisfactory ground continuity between the box and the receptacle."
The question is, are there any box cover combinations that are listed as satisfactory?

 

[tom baker]

Yes, those box covers have what is call crush corners, and the 8/32 screws have ridges under the head to get a good bite on the cover. This was put in to the code about ten years ago, and its hard to find a straight raised cover today. Yes this is a switch cover and the recpt covers are similar.
Its great to see someone dig into the code and not rely on what "someone once said"

 

[MiElectrician]

Thanks a lot tom baker, I really went far down this rabbit hole, and as just a worker, if I've run a copper ground 99% of the way I'll just take it the rest of the way, but maybe if I ever bid work I'll consider this to save time.

 

[don_resqcapt19]

A revision to 250.109 will be made for the 2023 code to make it clear that plaster rings and things like that can be used a the effective ground fault clearing path.