2014 Article 314.16(B)(2)

[kwired]

My confusion started with 'internal cable clamp'.

What is the difference between an internal and an external cable clamp?

IMO any clamp that is primarily inside the box is an internal clamp. A clamp that is inserted in a knockout and only has minimal threads and a locknut or one that just snaps in with minimal penetration in the box is no different then a raceway fitting that does not have to be counted against the box volume.

 

[KP2]

In CT some inspectors will require the clamp on the blue Carlon boxes as an internal clamp, and make you count it, AHJ and all that.

While the gray Slater boxes, my preference, clearly state in the instructions shipped with a case, that the no addition volume deductions are necessary for clamping, or something close to that.

For the new paragraph, I agree with the post about listing a clamp assembly for non-metallic boxes; like the black grommets, they will not snap into a plastic KO.

I think the second sentence may pertain to items like RIB relays and similar products, where the assembly has several wires enter the box, this change requires the conductors to be counted in the fill, while the threaded portion and the lock nut are not. Of course if a larger part needs to be inside the box then it must be deducted from the volume.

Maybe I'm reaching........
Still confused.
Kevin

 

[John120/240]

Here is an Arlington box with a Black Button connector or you could use a T & B 3201.