Safe Distances for Blasting Wiring from Commonly Encountered Underground Electromagnetic Energy Sources

The use of electromagnetic field producing equipment in underground coal mining operations can only be expected to grow. The use of these equipment in underground mining operations is hampered by the possibility of their electromagnetic fields interacting with the electric blasting cap operations commonly carried out in the mines. Such interactions can have at least two results bearing directly on mine safety: premature initiation of the cap, either in its normal shot location or during hookup or transportation; and dudding of the cap so that normal firing operations do not cause irritation, thereby leaving unexploded high explosives after normal firing. The experimental work on this project was directed to determining the magnetic field field distribution around typical underground current carrying conductor configurations.