46 CFR § 183.220 - General safety provisions.
(a) Electrical equipment and installations must be suitable for the roll, pitch, and vibration of the vessel underway.
(b) All equipment, including switches, fuses, lampholders, etc., must be suitable for the voltage and current utilized.
(c) Receptacle outlets of the type providing a grounded pole or a specific direct current polarity must be of a configuration that will not permit improper connection.
(d) All electrical equipment and circuits must be clearly marked and identified.
(e) Any cabinet, panel, box, or other enclosure containing more than one source of power must be fitted with a sign warning persons of this condition and identifying the circuits to be disconnected.