Safety, Health and Welfare at Work (General Application) Regulations 2007
Natural and artificial lighting.
8. An employer shall ensure that—
(a) places of work receive, as far as possible, sufficient natural light and are equipped with artificial lighting adequate for the protection of the safety and health of the employer's employees,
(b) lighting installations in rooms containing workstations and in passageways are placed in such a way that there is no risk of accident to the employer's employees as a result of the type of lighting fitted, and
(c) places of work in which the employer's employees are especially exposed to risks in the event of failure of artificial lighting are provided with emergency lighting of adequate intensity.