57.22207—Booster fans (I-A, II-A, III, and V-A mines).
(a)
Booster fans shall be approved by MSHA under the applicable requirements of 30 CFR part 18, and be—
(1)
Provided with an automatic signal device located so that it can be seen or heard by a person designated by the mine operator to give an alarm when the fan stops or when methane reaches the following levels:
(2)
Equipped with a device that automatically deenergizes power in affected workings should the fan stop; and
(3)
Equipped with starting and stopping controls located at the fan and at another accessible remote location.