(1) You must fully enclose elevator cars to car height or to a height of not less than six feet six inches whichever is greater. Elevator cars may be of perforated or solid material provided the material will withstand a horizontal thrust of seventy-five pounds without deflecting one-quarter inch and all openings will reject a one inch ball.

(a) Car frames must be of substantial metal or wood construction with a safety factor of four for metal frames and six for wood frames.

(b) Wood frames must be gusseted and bolted or otherwise secured with large washers and lock washers.

(c) The car platform must not exceed thirty inches inside dimension on each side (6.25 square foot area).

(2) Every car must have a substantial protective top. The front half may be hinged. The protective top may be made from number nine U.S. wire gauge screen, eleven gauge expanded metal, fourteen gauge sheet steel, or three-quarter inch or heavier plywood. If made of wire screen or metal, the openings shall reject a one-half inch diameter ball.