§ 56.6600 30 CFR Ch. I (7–1–10 Edition)

TABLE E–1—SAFETY FUSE—MINIMUM BURNING § 56.6602 TIME—Continued during loading.

Minimum When explosive material is loaded Number of holes in a round burning time pneumatically into a blasthole in a 11 to 15 ...... 5 min. manner that generates a static elec- tricity hazard— 1 For example, at least a 36-inch length of 40--per- foot safety fuse or at least a 48-inch length of 30-second-per- (a) An evaluation of the potential foot safety fuse would have to be used to allow sufficient time static electricity hazard shall be made to evacuate the area. and any hazard shall be eliminated be- (c) Where flyrock might damage ex- fore loading begins; posed safety fuse, the blast shall be (b) The loading hose shall be of a timed so that all safety fuses are - semiconductive type, have a total of ing within the blastholes before any not more than 2 megohms of resistance blasthole detonates. over its entire length and not less than (d) Fuse shall be cut and capped in 1000 of resistance per foot; dry locations. (c) -countered hoses shall not be (e) Blasting caps shall be crimped to used; fuse only with implements designed for (d) Conductive parts of the loading that purpose. equipment shall be bonded and - (f) Safety fuse shall be ignited only ed and grounds shall not be made to after the primer and the explosive ma- other potential sources of extraneous terial are securely in place. electricity; and (g) Safety fuse shall be ignited only (e) tubes shall not be used as with devices designed for that purpose. hole liners if the hole contains an elec- Carbide lights, liquefied gas tric detonator. torches, and cigarette lighters shall not be used to light safety fuse. § 56.6603 Air gap. (h) At least two persons shall be At least a 15-foot air gap shall be pro- present when safety fuse, and vided between the blasting circuit and no one shall light more than 15 indi- the electric source. vidual fuses. If more than 15 holes per person are to be fired, electric initi- § 56.6604 Precautions during storms. ation , igniter cord and connec- During the approach and progress of tors, or other nonelectric initiation an electrical storm, blasting operations systems shall be used. shall be suspended and persons with- drawn from the blast area or to a safe EXTRANEOUS ELECTRICITY location.

§ 56.6600 Loading practices. § 56.6605 Isolation of blasting circuits. If extraneous electricity is suspected and blasting lines shall be in an area where electric detonators isolated and insulated from power con- are used, loading shall be suspended ductors, pipelines, and railroad tracks, until tests determine that stray cur- and shall be protected from sources of rent does not exceed 0.05 stray or static electricity. Blasting cir- through a 1- resister when meas- cuits shall be protected from any con- ured at the location of the electric det- tact between firing lines and overhead onators. If greater levels of extraneous powerlines which could result from the electricity are found, the source shall of a blast. be determined and no loading shall take place until the condition is cor- EQUIPMENT/TOOLS rected. § 56.6700 Nonsparking tools. § 56.6601 Grounding. Only nonsparking tools shall be used Electric blasting circuits, including to open containers of explosive mate- powerline sources when used, shall not rial or to punch holes in explosive car- be grounded. tridges.


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