The Mine Safety and Health Administration has issued a safety alert advising employers to take precautions when storing, handling, transporting, and using explosives and detonators in underground coal mines near energized equipment or electrical systems. These include communications and tracking system infrastructure, electronic components worn or carried by miners, and the like.
Employers should remember that it is important to maintain appropriate separation distances between electric blasting circuits and all potential sources of electrical current including equipment that emits radio frequency (RF) energy, MSHA said. It advised following manufacturer recommendations on storage, handling, transportation, and usage.
MSHA also recommended certain best practices, including:
- Protect electric blasting circuits from all sources of stray electric current.
- Maintain a minimum 50-foot distance from RF energy, unless other means are provided and approved. Other means may include placing detonators in a container compliant with 30 C.F.R. 75.1311 and housed in a fully enclosed metallic structure to provide shielding from RF energy.
- Consider and manage all sources of stray electric current, including portable and RF emitting devices to which electric detonators may be exposed when stored, transported, handled, and used.
- Maintain detonators in their original containers, coiled, shunted, and folded as received from the manufacturer until ready for use.
- Review and update, as necessary, the Emergency Response Plan (ERP) to ensure that proper procedures are in place to prevent exposure to RF energy during storage, handling, and transportation and use of explosives and detonators.