46 C.F.R. § 28.360 Electrical distribution systems.
Title 46 - Shipping
(a) Each electrical distribution system which has a neutral bus or conductor must have the neutral bus or conductor grounded. (b) A grounded electrical distribution system must have only one connection to ground. This ground connection must be at the switchboard or, on a nonmetallic vessel, at the common ground point.
Title 46: Shipping
PART 28—REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS
Subpart D—Requirements for Vessels Which Have Their Keel Laid or Are at a Similar Stage of Construction on or After or Which Undergo a Major Conversion Completed on or After September 15, 1991, and That Operate With More Than 16 Individuals on Board
§ 28.360 Electrical distribution systems.

