30 CFR §75.516
Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
All power wires (except trailing cables on mobile equipment, specially designed cables conducting high-voltage power to underground rectifying equipment or transformers, or bare or insulated ground and return wires) shall be supported on well-insulated insulators and shall not contact combustible material, roof, or ribs.