46 C.F.R. § 111.81-3
Cables entering boxes
Each cable entering a box or fitting must be protected from abrasion and must meet the following:
(a) Each opening through which a conductor enters must be closed.
(b) Cable armor must be secured to the box or fitting.
(c) Each cable entrance in a damp or wet location must be made watertight by a terminal or stuffing tube.