(1) Lift platforms shall be permanently enclosed on all sides and the top.

(2) The enclosure shall be securely fastened to the platform and so supported that it cannot loosen or become displaced in ordinary service.

(3) The enclosure walls shall be of sufficient strength and designed and supported so that when subjected to a pressure of 75 lbs. applied horizontally at any point on the walls of the enclosure, the deflection will not reduce the running clearance to exceed 1 in.

(4) The top of the car enclosure shall be designed and installed so as to be capable of sustaining a load of 300 lbs. on any square area 24 in. on a side and 100 lbs. applied at any point. Simultaneous application of these loads is not required.