Autotransformers - MSHA Safety Alert

"Autotransformers being used by machine manufacturers pose a potential ground fault hazard. It is hazardous when a ground fault within the autotransformer occurs and goes undetected by the ground fault protection circuit. Miners and electricians have reported being shocked when contacting shuttle cars. Shuttle cars equipped with autotransformers may cause a ground fault condition that goes undetected. These hazards exist when an autotransformer ground fault occurs, and the ground fault protection circuit is inadequate because the ground fault current is too low to be detected..."

https://www.msha.gov/news-and-updates/alerts-hazards/filter/autotransformers-safety-alert