(1) Lifts and counterweights shall be suspended by steel wire ropes. Only iron (low carbon steel) or steel wire ropes with fiber cores, having the commercial classification of "elevator wire rope" may be used for the suspension of lifts and for the suspension of counterweights.

(2) The minimum number of hoisting ropes is:

(a) Three .5 in. ropes for traction elevators; and

(b) Two .5 in. ropes for drum type elevators.

(3) Fastenings shall be by individual tapered babbitted rope sockets or by other department-approved types.

(4) The rope sockets shall be of a type which will develop at least 80 percent of the breaking strength of the strongest rope to be used in such fastenings. U-bolt type rope clips (clamps) shall not be used for load line fastenings.