(a) Methane monitors shall be installed on continuous mining machines, longwall mining systems, bench and face drills, and undercutting machines used in or beyond the last open crosscut.
(b) The monitors shall -
(1) Give warning at 0.5 percent methane;
(2) Automatically deenergize electrical equipment, except power to monitoring equipment determined by MSHA to be intrinsically safe under 30 CFR part 18, and prevent starting such equipment when methane levels reach 1.0 percent; and
(3) Automatically deenergize the equipment when power to a sensor is interrupted.
(c) Sensing units of monitors shall be positioned at a location which provides for the most effective measurement of methane.