That is why I posted the question. outside a bare ground wire, when was the last time you seen a bare current carrying conductor? Logistics worked out for me and got my 2012 70E Handbook. In its commentary, under 130.4(C)(3) it states that:
"If a qualified person must approach an energized electrical conductor closer than the restricted approach boundary, Insulating material can be installed material with a define voltage rating must be placed between the person and conductor. The insulating material can take several forms. The insulating material can be installed so that the conductor is insulated from possible contact. The employee can be insulated by wearing appropriately rated PPE or can be insulated from the ground, as in live-line, bare hand work
supposedly, the 2015 70E was going to be clearer on gray areas but I have niot seen anything yet.
As for the extension cord analogy. The conductors are not exposed, The prohibitive approach boundary is to avoid contact with the wires. The outer jacket meets that requirement. If the jacket is damaged, that we must immediately remove it from service.....