4.—(1) The owner shall ensure, so far as is reasonably practicable, that the sinking of the shaft is so specified, planned and designed as to be safe, and without risk of injury to persons.
(2) The manager shall ensure, so far as is reasonably practicable, that the shaft is constructed or sunk safely, and without risk of injury to persons.
(3) For the purpose of paragraph (1) or (2), the owner or manager respectively shall take into account risks which (at the time the shaft is specified, planned, designed or, as appropriate, constructed or sunk) it is reasonably foreseeable will arise either while the shaft is being constructed or sunk or during the time it is intended to be used.