8.3.3. Ventilators shall:(a) operate at all times when workers are in the underground work site and if ventilators are stopped while the underground work site is unoccupied, they shall be put into operation for a sufficient period of time prior to the beginning of operations in order to ensure proper ventilation;
(b) be placed in constructions of fireproof materials; and
(c) be equipped with a surface remote control device.