46 C.F.R. § 143.410 – Shipboard lighting.

(a) Sufficient lighting suitable for the marine environment must be provided within crew working and living areas.
(b) Emergency lighting must be provided for all internal crew working and living areas. Emergency lighting sources must provide for sufficient illumination under emergency conditions to facilitate egress from each space and must be either:
1. (1) Automatic, battery-operated with a duration of no less than 2 hours; or
2. (2) Non-electric, phosphorescent adhesive lighting strips that are installed along escape routes and sufficiently visible to enable egress with no power.
(c) Each towing vessel must be equipped with at least two portable, battery-powered lights. One must be located in the pilothouse and the other at the access to the engine room.