1926.906: Electric Blasting
Electric caps may not be used where extraneous electricity makes them dangerous, and leg wires stay shunted until connected. The blaster must survey for and eliminate dangerous currents before loading. All caps in a blast must be the same style or function and maker, firing must follow the maker's recommendations with insulated wires in good condition, and firing power circuits must not be grounded. Underground power firing needs lockable-off safety switches and a lightning gap of at least 5 feet.
Key takeaways
- 1926.906 is part of OSHA's construction standards (29 CFR Part 1926, Subpart U).
- Most-cited part: 1926.906(q).
- Free 5-minute toolbox talk for your crew below.
In this article
What this rule covers
29 CFR 1926.906, "Initiation of explosive charges—electric blasting", is an OSHA construction standard (Part 1926, Subpart U). It has 20 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 1926.906 (20 paragraphs)
(a) Electric blasting caps shall not be used where sources of extraneous electricity make the use of electric blasting caps dangerous. Blasting cap leg wires shall be kept short-circuited (shunted) until they are connected into the circuit for firing.
(b) Before adopting any system of electrical firing, the blaster shall conduct a thorough survey for extraneous currents, and all dangerous currents shall be eliminated before any holes are loaded.
(c) In any single blast using electric blasting caps, all caps shall be of the same style or function, and of the same manufacture.
(d) Electric blasting shall be carried out by using blasting circuits or power circuits in accordance with the electric blasting cap manufacturer's recommendations, or an approved contractor or his designated representative.
(e) When firing a circuit of electric blasting caps, care must be exercised to ensure that an adequate quantity of delivered current is available, in accordance with the manufacturer's recommendations.
(f) Connecting wires and lead wires shall be insulated single solid wires of sufficient current-carrying capacity.
(g) Bus wires shall be solid single wires of sufficient current-carrying capacity.
(h) When firing electrically, the insulation on all firing lines shall be adequate and in good condition.
(i) A power circuit used for firing electric blasting caps shall not be grounded.
(j) In underground operations when firing from a power circuit, a safety switch shall be placed in the permanent firing line at intervals. This switch shall be made so it can be locked only in the “Off” position and shall be provided with a short-circuiting arrangement of the firing lines to the cap circuit.
(k) In underground operations there shall be a “lightning” gap of at least 5 feet in the firing system ahead of the main firing switch; that is, between this switch and the source of power. This gap shall be bridged by a flexible jumper cord just before firing the blast.
(l) When firing from a power circuit, the firing switch shall be locked in the open or “Off” position at all times, except when firing. It shall be so designed that the firing lines to the cap circuit are automatically short-circuited when the switch is in the “Off” position. Keys to this switch shall be entrusted only to the blaster.
(m) Blasting machines shall be in good condition and the efficiency of the machine shall be tested periodically to make certain that it can deliver power at its rated capacity.
(n) When firing with blasting machines, the connections shall be made as recommended by the manufacturer of the electric blasting caps used.
(o) The number of electric blasting caps connected to a blasting machine shall not be in excess of its rated capacity. Furthermore, in primary blasting, a series circuit shall contain no more caps than the limits recommended by the manufacturer of the electric blasting caps in use.
(p) The blaster shall be in charge of the blasting machines, and no other person shall connect the leading wires to the machine.
(q) Blasters, when testing circuits to charged holes, shall use only blasting galvanometers or other instruments that are specifically designed for this purpose. Open (q)
(r) Whenever the possibility exists that a leading line or blasting wire might be thrown over a live powerline by the force of an explosion, care shall be taken to see that the total length of wires are kept too short to hit the lines, or that the wires are securely anchored to the ground. If neither of these requirements can be satisfied, a nonelectric system shall be used.
(s) In electrical firing, only the man making leading wire connections shall fire the shot. All connections shall be made from the bore hole back to the source of firing current, and the 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.
(t) After firing an electric blast from a blasting machine, the leading wires shall be immediately disconnected from the machine and short-circuited.
[44 FR 8577, Feb. 9, 1979; 44 FR 20940, Apr. 6, 1979, as amended at 63 FR 33469, June 18, 1998]
Source: eCFR, text current as of 2026-10-15.
Free toolbox talk
A 5-minute crew talk on 1926.906, plus alerts when this rule changes. Free.
OSHA interpretation letters
- Blasters Circuit Testers. (1990-09-17)
- Use of silver chloride dry cells as a power source for testing electric blast caps. (1977-11-18)
- Carbon zinc batteries in blasting galvanometers. (1977-10-12)
- Electric blasting machine. (1976-01-08)
Most-cited parts of this rule
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Frequently asked questions
When must the blaster survey for extraneous electricity?
Before adopting any system of electrical firing, and all dangerous currents must be eliminated before any holes are loaded.
Can different caps be mixed in one electric blast?
No. All caps in a single blast must be the same style or function and the same manufacture.
Can a power circuit used for firing be grounded?
No. A power circuit used for firing electric blasting caps shall not be grounded.
About this page
Sources
- 29 CFR 1926.906 (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.