30 CFR §75.519
Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
In all main power circuits, disconnecting switches shall be installed underground within 500 feet of the bottoms of shafts and boreholes through which main power circuits enter the underground area of the mine and within 500 feet of all other places where main power circuits enter the underground area of the mine.