75.1312—Explosives and detonators in underground magazines.
(a)
The quantity of explosives kept underground shall not be more than is needed for 48 hours of use.
(d)
Magazines shall be substantially constructed and all interior surfaces shall be made of nonconductive material, with no metal or other conductive material exposed inside.
(f)
Magazine locations shall be posted with indelibly marked and readily visible warnings indicating the presence of explosives.