(a)
Each conductor or group of conductors that passes through a bulkhead, structural member, junction box, or other rigid surface must be protected from abrasion.
(b)
Each ungrounded terminal or stud that is continuously energized must meet § 183.455 or must have a boot, nipple, cap, cover, or shield that prevents accidental short-circuiting at the terminals or studs.
Code of Federal Regulations
[CGD 81-092, 48 FR 55736, Dec. 15, 1983]