30 CFR § 57.19021 - 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).

For rope lengths less than 3,000 feet: Minimum Value = Static Load × (7.0 − 0.001L)

For rope lengths 3,000 feet or greater: Minimum Value = Static Load × 4.0.

(b) Friction drum ropes.

For rope lengths less than 4,000 feet: Minimum Value = Static Load × (7.0 − 0.0005L)

For rope lengths 4,000 feet or greater: Minimum Value = Static Load × 5.0.

(c) Tail ropes (balance ropes).

Minimum Value = Weight of Rope × 7.0