30 CFR Part 57Public Domain
§ 57.6403 — Branch circuits
Subpart E — Explosives
(a)If electric blasting includes the use of branch circuits, each branch shall be equipped with a safety switch or equivalent method to isolate the circuits to be used.
(b)At least one safety switch or equivalent method of protection shall be located outside the blast area and shall be in the open position until persons are withdrawn.
Public Domain: 30 CFR Part 57 (MSHA Safety and Health Standards — Underground Metal and Nonmetal Mines) is a U.S. government publication and is not subject to copyright. Text extracted from the official source ↗. Figures are served from the eCFR; if one does not load, use the link in its place.