30 C.F.R. § 75.703-2 Approved grounding mediums.
Title 30 - Mineral Resources
For purposes of grounding offtrack direct-current machines, the following grounding mediums are approved: (a) The grounded polarity of the direct-current power system feeding such machines; or, (b) The alternating current grounding medium where such machines are fed by an ungrounded direct-current power system originating in a portable rectifier receiving its power from a section power center. However, when such a medium is used, a separate grounding conductor must be employed.
Title 30: Mineral Resources
PART 75—MANDATORY SAFETY STANDARDS—UNDERGROUND COAL MINES
Subpart H—Grounding
§ 75.703-2 Approved grounding mediums.
