30 CFR § 56.19021 - Minimum rope strength.
At installation, the nominal strength (manufacturer's published catalog strength) of wire ropes used for hoisting shall meet the minimum rope strength values obtained by the following formulas in which “L” equals the maximum suspended rope length in feet:
(a) Winding drum ropes (all constructions, including rotation resistant).
(b) Friction drum ropes.
(c) Tail ropes (balance ropes).