Section 129. The openings of hoistways, hatchways and well holes upon every floor of an industrial establishment shall be protected by sufficient trap doors or self-closing hatches, or by such other safeguards as an inspector directs; and any such openings shall be kept so protected or so safeguarded at all times, except when in actual use, by the occupant of the building having the use and control of the same, or by the owner of the building having such control.