30 CFR § 75.703-2 - Approved grounding mediums.

---
identifier: "/us/cfr/t30/s75.703-2"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "30 CFR § 75.703-2 - Approved grounding mediums."
title_number: 30
title_name: "Mineral Resources"
section_number: "75.703-2"
section_name: "Approved grounding mediums."
chapter_name: "MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR"
subchapter_number: "O"
subchapter_name: "COAL MINE SAFETY AND HEALTH"
part_number: "75"
part_name: "MANDATORY SAFETY STANDARDS—UNDERGROUND COAL MINES"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "30 U.S.C. 811, 813(h), 957."
regulatory_source: "35 FR 17890, Nov. 20, 1970, unless otherwise noted."
cfr_part: "75"
---


# 75.703-2 Approved grounding mediums.

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.