Greg,
Here is basically what we are told when this comes up at code seminars in my area, and it seems to come up at every one.
Without the outer sheath or jacket, the UL label/mark is now missing and is no longer valid since you have intentionally field altered a listed cable assembly by removing the outer jacket more than is necessary for normal splicing and termination. Without the jacket, there is also no cable or conductor identification as required in 310.11[A] or 310.11[B], [1].
With the outer jacket intact it is the cable assembly SE/SER, designed for use in above ground installations. With the jacket stripped off more than necessary for splicing and termination, it is now scrap since without the jacket it also doesn’t meet NEC 310.11 requirements for individual conductors or cable assemblies.
I’m pretty sure the reason that the conductors aren’t marked individually, is so that it would be obvious that they were designed and listed to be used only as a cable assembly with an overall jacket or sheath. Just like NM-B [Romex].
Anyway, this explanation makes sense to me and has been enforced by inspectors in my area for many years.
