46 CFR §183.432

1. (a)Each vessel must have adequate emergency lighting fitted along the line of escape to the main deck from all passenger and crew accommodation spaces located below the main deck.
2. (b)The emergency lighting required by paragraph (a) of this section must automatically actuate upon failure of the main lighting system. If a vessel is not equipped with a single source of power for emergency lighting, it must have individual battery powered lights that:
   1. (1)Are automatically actuated upon loss of normal power;
   2. (2)Are not readily portable;
   3. (3)Are connected to an automatic battery charger; and
   4. (4)Have sufficient capacity for a minimum of 2 hours of continuous operation.