1926.909: Blasting Warning Signals
Employers must post a code of blasting signals equivalent to Table U-1 and require employees to know it, and place danger signs. Before a blast, the blaster in charge must give a loud warning after making sure explosives are safe and everyone is at a safe distance or under cover. Flagmen must stop highway traffic in the danger zone.
Key takeaways
- 1926.909 is part of OSHA's construction standards (29 CFR Part 1926, Subpart U).
- OSHA cited it 2 times in the last 3 years, in 2 inspections, with $0 in current penalties.
- Free 5-minute toolbox talk for your crew below.
In this article
What this rule covers
29 CFR 1926.909, "Firing the blast", is an OSHA construction standard (Part 1926, Subpart U). It has 5 numbered 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
Show the full text of 1926.909 (5 paragraphs)
(a) A code of blasting signals equivalent to Table U-1, shall be posted on one or more conspicuous places at the operation, and all employees shall be required to familiarize themselves with the code and conform to it. Danger signs shall be placed at suitable locations.
(b) Before a blast is fired, a loud warning signal shall be given by the blaster in charge, who has made certain that all surplus explosives are in a safe place and all employees, vehicles, and equipment are at a safe distance, or under sufficient cover.
(c) Flagmen shall be safely stationed on highways which pass through the danger zone so as to stop traffic during blasting operations. 2 citations
(d) It shall be the duty of the blaster to fix the time of blasting.
(e) Before firing an underground blast, warning shall be given, and all possible entries into the blasting area, and any entrances to any working place where a drift, raise, or other opening is about to hole through, shall be carefully guarded. The blaster shall make sure that all employees are out of the blast area before firing a blast.
Warning Signal—A 1-minute series of long blasts 5 minutes prior to blast signal.
Blast Signal—A series of short blasts 1 minute prior to the shot.
All Clear Signal—A prolonged blast following the inspection of blast area.
Source: eCFR, text current as of 2026-10-15.
Where and how often it was cited
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OSHA interpretation letters
None exist. OSHA has not published a letter of interpretation for 1926.909.
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Frequently asked questions
What is the warning signal?
A 1-minute series of long blasts 5 minutes prior to blast signal.
What is the blast signal?
A series of short blasts 1 minute prior to the shot.
What is the all clear signal?
A prolonged blast following the inspection of the blast area.
About this page
Sources
- 29 CFR 1926.909 (eCFR), text current as of 2026-10-15
- U.S. Department of Labor enforcement data: OSHA inspections, citations and accident records, copied nightly; data as of 2026-10-19
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.