46 CFR §129.375

1. (a)If a grounded distribution system is provided, there must be only one connection to ground, regardless of the number of power sources. This connection must be at the main switchboard.
2. (b)On each metallic vessel, a grounded distribution system must be grounded to the hull. On each nonmetallic vessel, the neutral of a grounded system must be connected to a common ground plate, except that no aluminum grounding conductors may be used.
3. (c)On each nonmetallic vessel with a grounded distribution system, the common ground plate must have—
   1. (1)Only one connection to the main switchboard; and
   2. (2)The connection to itself readily accessible for checking.
4. (d)On each nonmetallic vessel with a ground plate provided for radio equipment, the plate must be connected to the common ground plate.
5. (e)Each insulated grounding-conductor of a cable must be identified by one of the following means:
   1. (1)Wrapping of the cable with green braid or green insulation.
   2. (2)Stripping of the insulation from the entire exposed length of the grounding-conductor.
   3. (3)Marking of the exposed insulation of the grounding-conductor with green tape or green adhesive labels.
6. (f)No vessel's hull may carry current as a conductor except for—
   1. (1)An impressed-current cathodic-protection system; or
   2. (2)A battery system to start an engine.
7. (g)No cable armor may be used to ground electrical equipment or systems.
8. (h)Each receptacle outlet and attachment plug, for a portable lamp, tool, or similar apparatus operating at 100 or more volts, must have a grounding-pole and a grounding-conductor in the portable cord.