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Subchapter 7. General Industry Safety Orders
Group 18. Explosives and Pyrotechnics
Article 114. Storage of Explosives

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§5251. Storage--General Requirements.

(a) All explosive materials as defined in these orders, including industrial high explosives and any newly developed and unclassified explosives, shall be stored in the appropriate magazine as shown in Table EX-3. Magazines shall be constructed in conformity with the provisions of this Article.

(b) The following materials/devices shall be kept in their shipping containers until used:

(1) Explosive materials such as explosive power packs in the form of explosive cartridges or explosive-charged construction devices, explosive rivets, explosive bolts, explosive charges for driving pins or studs.

(2) Cartridges for explosives actuated power devices when in quantities of less than 50 pounds net weight of explosives.

(3) Stocks of small arms ammunition, propellant-actuated power cartridges, small arms ammunition primers in quantities of less than 750,000, and smokeless propellant in quantities of less than 750 pounds.

(4) Fuse lighters and fuse igniters.

(5) Safety fuses.

(c) Detonating cord shall not be kept or stored with blasting caps, but may be stored with other explosives.

(d) All magazines shall be located or protected as to minimize accidental impact from vehicles or falling objects.

(e) Area surrounding magazines shall be kept clear of brush, dried grass, leaves, and other combustible materials for a distance of 50 feet.

(1) Magazine contents shall be protected from flooding. The ground around magazines shall slope away from the magazine or drainage shall be provided.

(f) Electric power lines shall be kept at least 5 feet away from the exterior of any underground magazine except underground service.

(g) Magazines shall be located at least 25 feet from low-voltage electrical lines and 100 feet from high-voltage electrical lines. Care should be taken that they be placed in such a manner that should a line break, it would not fall within this distance except for underground service.

(h) Quantity and Storage Restrictions.

(1) Explosive materials in excess of 300,000 pounds or detonators in excess of 20 million shall not be stored in one magazine.

(2) Detonators shall not be kept or stored in any magazine with other explosive materials, except under any of the following conditions:

(A) In a Type 4 magazine, detonators that will not mass detonate may be stored with electric squibs, safety fuse, igniters, and igniter cord.

(B) In a Type 1 or Type 2 magazine, detonators may be stored with delay devices and any of the items listed in subsection (h)(2)(A) of this Section.

(C) When approved by the Division.

(3) No more than 50 pounds of high explosives shall be stored in an indoor magazine.

(i) Type 3 magazines “Day Box” shall not be used for storage of more than 110 pounds of explosive materials.

(j) All magazines shall be kept closed and locked, except when contents are being removed or replaced. Keys or combinations shall be kept in a safe place. Only persons authorized by the employer or licensed blaster shall be permitted to unlock or remove supplies from a magazine.

(k) Fuse caps with attached safety fuses shall not be stored in an explosives magazine, but may be stored in a magazine with other detonators.

(l) Vehicular storage facilities for Types 2, 4 and 5 magazines shall have wheels removed or shall be immobilized by kingpin locking devices.

(m) Explosive materials shall not be left unattended in Type 3 magazines. The explosive materials shall be removed to a Type 1 or 2 magazine for storage.

(n) A running inventory shall be maintained for the magazine to indicate the quantity of explosive materials in storage, quantity removed, date of removal and the name of the person responsible for transfer/removal of the explosive materials.

Exception: A Type 3 magazine (day box).

(o) Magazines shall not be located within 300 feet of the entrance (portal) of an active tunnel or mine.

(p) Signs shall be posted on the premises where magazines are located with the words “EXPLOSIVES -- KEEP OFF” legibly printed thereon in letters not less than 3 inches high with a 1/2 inch stroke. Such signs shall be within 100 feet of the magazine and so placed that a bullet through the sign will not strike the magazine.

(q) Metal magazines shall be equipped with electrical bonding connections between all conductive portions so the entire structure is at the same electrical potential. Suitable electrical grounding methods include welding, riveting, or the use of securely tightened bolts where individual metal portions are joined. Conductive portions of non-metal magazines shall be grounded.


Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code; and Section 12006, Health and Safety Code.


1. Amendment of subsections (a) and (b) filed 10-17-75; effective thirtieth day thereafter (Register 75, No. 42).

2. Amendments filed 7-16-76; effective thirtieth day thereafter (Register 76, No. 29).

3. Editorial correction restoring missing text in subsection (d) (Register 91, No. 45).

4. Editorial correction reinserting article 114 heading (Register 92, No. 11).

5. Amendment of article heading, section heading and section and new Note filed 7-11-2003; operative 8-10-2003 (Register 2003, No. 28).

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