(a) Winding drum elevators hereafter installed shall have not less than two hoisting cables and two cables attached to each counterweight. Traction elevators shall have not less than three cables for capacities not exceeding 1,200 pounds. For loads in excess of 1,200 pounds, not less than four cables shall be used.

(b) The hoist and counterweight cables and their fastenings for passenger and freight elevators hereafter installed shall have a safety factor of not less than that given in the following table.

(c) Safety factors shall be computed on the total weight suspended by the cables when the elevator is loaded to its full rated capacity.

(d) Hoisting cables shall be either high grade wrought iron or steel.

(e) Cables shall be replaced when they become unsafe.

(f) The ends of all hoist cables shall be securely fastened and there shall be not less than one full turn on winding drums when the car or weights are at the limits of their travel.

(g) Where installations require that the hoist and counterweight cables pass through the floors outside of the elevator hoistway or enclosure the same shall be boxed in with a solid enclosure on all sides to a height of not less than seven feet.

(h) In future installations of all electric elevators located overhead, where right and left hand single drum grooving is provided, equalizers shall be used for fastening the hoisting and drum counterweight cables to the car and drum counterweight respectively.

(i) On all elevators hereafter installed the diameter of any sheave or drum over which the hoist or counterweight cables pass shall be not less than 40 times the diameter of such hoist or counterweight cables except that sheaves of a minimum diameter of 24 inches may be used for five-eighths inch cable.