A. If a supply of explosives or detonators for use in one or more sections is stored underground, it shall be kept in a section box or magazine of substantial construction with no metal exposed on the inside. Such box or magazine shall be located at least 25 feet from any roadway or power wire and in a reasonably dry, well rock-dusted location protected from falls of roof. In a pitching bed, where it is not possible to comply with such location requirement, such box shall be placed in a niche cut into the solid coal or rock.
B. If explosives and detonators are both stored in the section, they shall be kept in separate boxes or magazines not less than 12 feet apart if feasible; if kept in the same box or magazine, they shall be separated by a substantially fastened hardwood partition at least four inches thick or the equivalent. Not more than a 48-hour supply of explosives or detonators shall be stored underground in such box or magazine.
C. If explosives and detonators are kept near the face for the use of miners, they shall be kept in separate individual closed containers, in niches in the ribs, not less than 12 feet apart, and at least 50 feet from the working place and out of the line of blast. Each such container shall be constructed of substantial material and maintained electrically nonconductive. Where it is physically impracticable to comply with such distance requirements, the explosives and detonator containers shall be stored in the safest available places not less than 15 feet from any pipe, rail, conveyor, haulage road, or power line, not less than 12 feet apart, and at least 50 feet from the working face and out of the line of blast.
D. Explosives and detonators shall be kept in their containers pursuant to subsection C until immediately before use at a working face.