All power-driven machinery, including all saws, planers, wood shapers, jointers, sandpaper machines, iron mangles, emery wheels, ovens, furnaces, forges and rollers of metal; all projecting set screws or moving parts; all drums, cogs, gearing, belting, shafting, flywheels and flying shuttles; all laundry machinery, mill gearing and machinery of every description; all vats or pans and all receptacles containing molten metal or hot or corrosive fluids in any factory, mercantile establishment, mill or workshop, shall be so located, whenever possible, as not to be dangerous to employees, or, where possible shall be properly inclosed, fenced or otherwise protected. All dangerous places, in or about mercantile establishments, factories, mills or workshops, near to which any employee is obliged to pass or to be employed, shall, where practicable, be properly inclosed, fenced or otherwise guarded. No machine in any factory, mercantile establishment, mill or workshop, shall be used when the same is known to be dangerously defective, and no repairs shall be made to the active mechanism or operative part of any machine, when the machine is in motion. The state commissioner of labor is authorized to adopt the codes promulgated by the American standards association and approved by the United States department of labor, relating to the construction of scaffolding, hoists and temporary flooring of buildings two or more stories in height, in the course of erection. All factories, mills or workshops employing five or more people in the mechanical department shall keep on hand, easily accessible, necessary first aid equipment recommended by the bureau of labor and approved by the state health department.