Some follow up information.
When we have this discussion at work. I like to refer them to Article
250.8 then head over to
314
Part 3
314.40
For some boxes covered in part (C).
Is the catch to how to properly bond to the enclosure with a equipment grounding bar. Some times yes with the screws provided and sometimes no and paint shall be removed and a nut placed on back side. Then I'm fine with it. I also ask them to read 314.41.
Then I like to follow up with 408.40 when installing in a cabinet which contains a panel board.
I get ask a lot why based on 4 square 1-1/2 deep the table only allowed what it does based on the cubic inch of conductors.
Then I go on to explain how this impacts table 314.16(A).
Based on the UL listed box(.0625) and the number of allowed conductors.
The box area is reduce based on the .0625 minimum thickness to comply with 314.40.
I also explain why we use 6/32,8/32,10/32 screws for most of what we do. It's the two threads for the materials thickness for most common applications.
An example would be self grounding devices when installed using the supplied screws, which has two 6/32 screws. The plaster ring (.0625) it fastens to is attached to a four square box (.0625) with two 8/32 which most of the time has an EGC wire type conductor bonded to the box with a 10/32. Then most back that up with a wire type bonding jumper to the device.