A. The active workings of a mine shall be ventilated by means of main fans.

B. Unless otherwise approved by the Chief, fans shall be (i) provided with pressure-recording gauges, (ii) installed on the surface in fireproof housings, and (iii) equipped with fireproof air ducts.

C. In addition to the requirements of subsection B, main fans shall either:

1. Be equipped with ample means of pressure relief, and be offset not less than 15 feet from the nearest side of the mine opening; or

2. Be directly in front of, or over, the mine opening; however, the opening shall not be in direct line with possible forces coming out of the mine should an explosion occur, and there shall be another opening having a weak-wall stopping or explosion doors that would be in direct line with the forces coming out of the mine should an explosion occur, such opening to be not less than 15 feet nor more than 100 feet from the fan opening; and

3. In mines ventilated by multiple main mine fans, incombustible doors shall be installed so that if any main mine fan stops and air reversals through the fan are possible, the doors on the affected fan automatically close.

D. Main mine fans shall be provided with an automatic device to give alarm when the fan slows down or stops. Unless otherwise approved by the Chief, this device shall be placed so that it will be seen or heard by an authorized person.

E. Main fans shall be on separate power circuits, independent of the mine circuit.

F. The area surrounding main fan installations shall be kept free of combustible material for at least 100 feet in all directions where physical conditions permit.

G. Mine fans shall be operated continuously, except when intentionally stopped for necessary testing, adjustment, maintenance, or repairs while no miners are underground, or as otherwise approved by the Chief. If the main fan is intentionally stopped for testing, adjustment, maintenance, or repairs, the mine operator shall comply with the requirements set forth in the approved fan stoppage plan for that mine. If the main fan is stopped after all miners are out of the mine, the fan shall be operated for a period specified in the approved fan stoppage plan for that mine before any miner is allowed underground.

H. Where electric power is available, main mine fans shall not be powered by means of internal combustion engines; however, where electric power is not available or for emergency use, main mine fans may be powered with internal combustion engines if, unless otherwise approved by the Chief, (i) the fan shall be operated exhausting, and (ii) the engine operating the fan shall be offset at least 10 feet from the fan and housed in a separate fireproof structure.

Code 1950, § 45-60.1; 1954, c. 191; 1966, c. 594, § 45.1-54; 1978, c. 120; 1988, c. 597; 1993, c. 442; 1994, c. 28; 1996, c. 774; 2005, c. 3; 2011, cc. 826, 862.