Section 11(6)(b) in The Merchant Shipping (Crew Accommodation) Rules, 1960
(b)The electric lighting of the spaces referred to in clauses (d) to (n) (both inclusive) shall be deemed to be adequate for the purposes of these rules, if when the lamp and paintwork are new, the illumination in the horizontal plane when measured at the points and in the manner prescribed in clause (c) is steady and object to a tolerance of 10 percent is maintained at a value not less than that prescribed for every such space.