MSHA - Code of Federal Regulations - 30 CFR 77.1912
30 CFR § 77.1912
Ladders and stairways.
(a) Substantial stairways or ladders shall be used during the
construction of all shafts where no mechanical means are provided for men to
travel.
(b) Landings at intervals of not more than 30 feet shall be
installed.
(c) Shaft ladders shall project 3 feet above the collar of the shaft,
and shall be placed at least 3 inches from the side of the shaft.
