29 C.F.R. § 1918.92 – Illumination.

(a) Walking, working, and climbing areas. Walking, working, and climbing areas shall be illuminated. Unless conditions described in the regulations of the U.S. Coast Guard (33 CFR 154.570) exist for specific operations, illumination for cargo transfer operations shall be of a minimum light intensity of five foot-candles (54 lux). Where work tasks require more light to be performed safely, supplemental lighting shall be used.
(b) Intensity measurement. The lighting intensity shall be measured at the task/working surface, in the plane in which the task/working surface is present.
(c) Arrangement of lights. Lights shall be arranged so that they do not shine into the eyes of winch-drivers, crane operators or hatch tenders. On Ro-Ro ships, stationary lights shall not shine directly into the eyes of drivers.
(d) Portable lights. Portable lights shall meet the following requirements:
1. (1) Portable lights shall be equipped with substantial reflectors and guards to prevent materials from coming into contact with the bulb.
2. (2) Flexible electric cords used with temporary lights shall be designed by the manufacturer for hard or extra-hard usage. Temporary and portable lights shall not be suspended by their electric cords unless the cords and lights are designed for this means of suspension. Connections and insulation shall be maintained in safe condition.
3. (3) Electric conductors and fixtures for portable lights shall be so arranged as to be free from contact with drafts, running gear, and other moving equipment.
4. (4) Portable cargo lights furnished by the employer for use aboard vessels shall be listed as approved for marine use by the U.S. Coast Guard or by a nationally recognized testing laboratory (see § 1910.7).
(e) Entry into darkened areas. Employees shall not be permitted to enter dark holds, compartments, decks or other spaces without a flashlight or other portable light. The use of matches or open flames is prohibited.