30.-(1) Every fixed vessel, structure, sump or pit of which the edge is less than one metre above the adjoining ground or platform shall, if it contains any scalding, corrosive or poisonous liquid, either be securely covered or be securely fenced to at least that height, or where by reason of the nature of the work neither secure covering nor secure fencing to that height is practicable, all practicable steps shall be taken by covering, fencing or other means to prevent any person from falling into the vessel, structure, sump or pit.
(2) The Chief Inspector may, by certificate in writing, exempt from the requirements of this section any vessel, structure, sump or pit in the case of which he is satisfied that the requirements are unnecessary or inappropriate.