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

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§5257. Makeup or Primer House for Underground Blasting Operations.

(a) When 30 or more primers are required for a single round/shot, the primers shall be made up in advance in a makeup or primer house.

(b) When primers are made up and stored in quantities greater than for immediate need, they must be processed in a separate structure that complies with the Type 1 or Type 2 magazine requirements except as follows:

(1) Electricity for lights will be permitted if the electric wiring is at least 5 feet from explosive materials and complies with Class II, Division I, Hazardous Locations, Electrical Safety Orders.

(2) Not more than 110 pounds of explosive materials other than primers shall be stored in this makeup house.

(3) The number of made-up primers of each delay stored in this makeup house shall not exceed a normal 2-day supply.

(4) Heaters, if installed, shall comply with Section 5254(a).

(c) Makeup or primer houses shall be located no closer than 100 feet from any magazine or inhabited building.

(d) Primers not made up in a makeup or primer house shall be made up at the blasting site.

NOTE: This Section does not prohibit primers being made up in a separate building or area, provided that explosives, detonators, and primers are stored in proper magazines.


Authority cited: Section 142. 3, Labor Code. Reference: Section 142.3, Labor Code.


1. Amendment filed 10-17-75; effective thirtieth day thereafter (Register 75, No. 42).

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

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

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