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Subchapter 7. General Industry Safety Orders
Group 18. Explosives and Pyrotechnics
Article 121. Snow Avalanche Blasting

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§5355.1. Arming Room.

(a) Location of Arming Room.

(1) During arming procedures the arming room shall be located and separated from any building or structure occupied by the public or non-essential personnel the equivalent distance required by the Table of Distances in Article 114 of these Orders, for the maximum amount of explosives that will be allowed in the arming room at any time.

(2) The quantity of explosives used to determine the distances shall be the maximum amount that will be allowed in the arming room at any time.

(3) Only authorized and essential personnel to the operation shall be allowed within the arming room and within the equivalent distance to occupied structures required by the Table of Distances for the amount of explosives present. NOTE:Essential personnel are those individuals directly involved with the arming, the deployment of charges, transportation and site clearing to facilitate transportation. Non-essential personnel are all other individuals.

(b) Arming Room Construction.

(1) Interior of the arming room shall be finished and equipped to the following minimum requirements:

(A) The walls shall be of a smooth finish without cracks or crevices with all nails, screws, bolts and nuts countersunk. Exposed metal or materials capable of emitting sparks shall be covered so as not to come in contact with packages of explosive materials;

(B) The floors shall be constructed of, or covered with, a non-sparking material;

(C) The building and arming room shall be well ventilated, and the ventilation system shall discharge to the outside from the arming room;

(D) The arming table shall be constructed of non-sparking, nonconductive material;

(c) Arming Room Restrictions.

(1) Heating units shall be explosion proof, dust-proof and not depend on a combustion process when properly designed and located. Explosion proof and dust-proof heating units rated for Class II, Division I, Hazardous Locations, pursuant to Article 59, of the Electrical Safety Orders, may be used inside arming rooms.

(2) Temperature control devices shall be adequately designed to prevent overheating of arming rooms when explosives are present.

(3) Lighting fixtures and all wiring shall meet, or shall be equivalent to the requirements for Class II, Division I, Hazardous Location, pursuant to Article 59, of the Electrical Safety Orders, and shall be located a minimum of 5 feet from the explosives. Mine Safety and Health Administration-permissible portable lighting may be used.

(4) All electric control switches, outlet boxes and junction boxes shall be located outside the arming room.

(5) Smoking, matches, open flames, or flame or spark producing devices shall not be permitted inside the arming room.

(6) Flammable and combustible liquids or flammable compressed gases shall not be used or stored in the arming room.

(7) Occupancy of arming room shall be limited to authorized and trained personnel when explosives are present. Trainees shall be permitted in the arming room under the direct personal supervision of a licensed avalanche blaster.

(8) The arming room shall not be used for storage of explosives, detonator systems, or components.

Exception: A maximum total of 5000 caps and capped fuses may be stored in the arming room inside a separate Type 2 magazine. The Type 2 magazine shall be located within 10 feet from an outside exit door at grade level.

(d) Arming Room Housekeeping.

(1) The arming room shall be kept clean and orderly.

(2) Only non-sparking tools and devices shall be used or stored in the arming room.

(3) Brooms used in the arming room shall be made of non-sparking materials.

(4) Sweepings and empty explosive material containers shall be disposed of as recommended by the manufacturer.

(5) The arming room shall be cleaned and all explosive materials shall be removed upon completion of daily arming activities except as provided in the subsection (8) exception. The arming room shall be cleaned and all explosive materials shall be removed when any repairs are made to the arming room.

(6) The arming table or bench shall be cleaned regularly and shall be kept free of any materials or tools not used in the assembly of the charges.

Note: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.


1. New section filed 10-10-2007; operative 11-9-2007 (Register 2007, No. 41).

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