30 CFR § 77.1432
After initial rope stretch but before visible wear occurs, the rope diameter
of newly installed wire ropes shall be measured at least once in every third
interval of active length and the measurements averaged to establish a
baseline for subsequent measurements. A record of the measurements and the
date shall be made by the person taking the measurements. This record shall
be retained until the rope is retired from service.
[60 FR 33719, June 29, 1995]