MSHA issues alert on autotransformers and mine equipment

Arlington, VA — Regularly checking equipment that uses autotransformers can help miners and mine operators reduce electric shock risks, the Mine Safety and Health Administration says.

In a recent safety alert, the agency explains that shuttle cars equipped with autotransformers may cause a ground fault that isn’t detected by the ground fault protection circuit because the current is too low. However, the current still carries enough power to shock miners and electricians who contact the shuttle cars.

MSHA offers best practices for working safely with autotransformers:

• Direct coal miners to follow 30 CFR 75.900 and metal/nonmetal miners to follow 30 CFR 57.12003 to ensure adequate protection.
• Train qualified workers conducting electrical examinations to safely identify autotransformer use and potential hazards.
• Consult with machine manufacturers for compliant/approved alternatives.