1910.109(e)(4): Initiation of explosive charges
Key takeaways
- 1910.109(e)(4) is part of OSHA's general industry standards (29 CFR Part 1910, Subpart H).
- Related part: 1910.109(e) Use of explosives and blasting agents.
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In this article
What this rule covers
29 CFR 1910.109(e)(4) ("Initiation of explosive charges") is one requirement inside 1910.109 Explosives and blasting agents, an OSHA general industry standard (Part 1910, Subpart H). It includes 8 sub-paragraphs. The official text below is copied word for word from the Electronic Code of Federal Regulations (eCFR). The numbers, injury cases and training on this page show how OSHA enforces it on real job sites.
Official text
(4) Initiation of explosive charges.
(i) [Reserved]
(ii) When fuse is used, the blasting cap shall be securely attached to the safety fuse with a standard-ring type cap crimper. All primers shall be assembled at least 50 feet from any magazine.
(iii) Primers shall be made up only as required for each round of blasting.
(iv) No blasting cap shall be inserted in the explosives without first making a hole in the cartridge for the cap with a wooden punch of proper size or standard cap crimper.
(v) Explosives shall not be extracted from a hole that has once been charged or has misfired unless it is impossible to detonate the unexploded charge by insertion of a fresh additional primer.
(vi) If there are any misfires while using cap and fuse, all persons shall be required to remain away from the charge for at least 1 hour. If electric blasting caps are used and a misfire occurs, this waiting period may be reduced to 30 minutes. Misfires shall be handled under the direction of the person in charge of the blasting and all wires shall be carefully traced and search made for unexploded charges.
(vii) Blasters, when testing circuits to charged holes, shall use only blasting galvanometers designed for this purpose. Open (e)(4)(vii)
(viii) Only the employee making leading wire connections in electrical firing shall be allowed to fire the shot. Leading wires shall remain shorted and not be connected to the blasting machine or other source of current until the charge is to be fired.
Source: eCFR, text current as of 2026-10-15. Read all of 1910.109.
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OSHA interpretation letters
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About this page
Sources
- 29 CFR 1910.109 (eCFR), text current as of 2026-10-15
- U.S. Department of Labor enforcement data: OSHA inspections, citations and accident records, copied nightly
3-year window. Federal OSHA only; state-plan rules are not counted. Plain-language text is a summary, not legal advice; the official text controls. Black Belt Safety is not part of OSHA or the Department of Labor.