46 CFR §129.370

1. (a)On a metallic vessel each metallic enclosure and frame of electrical equipment must be permanently grounded to the hull. On a nonmetallic vessel each enclosure and frame of electrical equipment must be bonded to each other and to a common ground by a conductor not normally carrying current.
2. (b)Each metallic case of instruments must be grounded. So must each secondary winding of instrument transformers.
3. (c)Each equipment grounding conductor must be sized to comply with section 250-95 of NEC (NFPA 70).
4. (d)Each nonmetallic mast and topmast must have a lightning-ground conductor.