An employer shall ensure, without prejudice to the preceding requirements of this Part, that where a place of work contains an area in which, owing to the nature of the work, there is a risk of any employee suffering personal injury by -
(a) falling a distance, or
(b) being struck by a falling object,
the place of work, so far as is practicable, is equipped with devices preventing unauthorised employees from entering the area and that the area is clearly indicated by warning signs or other appropriate means.