All elevators shall have car doors, except on fully enclosed hoistways equipped with hoistway gates and enclosed from the top of the hoistway opening to the ceiling on the landing side.

(1) Car doors shall be:

(a) Constructed of solid or perforated material capable of resisting a 75 lb. thrust without deflecting 1/4 in. If perforated material is used, it shall reject a 1 in. diameter ball.

(b) Biparting or otherwise horizontally swung provided the door swings within the elevator car.

(2) Interlocks or a combination consisting of mechanical locks and electric contacts shall be provided on car gates on elevators in unenclosed hoistways unless a safe means of self-evacuation is provided. Such means shall be approved by the department.