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Minnesota Administrative Rules

7500.1500 INITIATION OF EXPLOSIVES CHARGES.

Subpart 1.

Electric blasting detonators.

Only electric blasting detonators may be used for blasting operations in congested districts, in highways, or adjacent to highways open to traffic, except where sources of extraneous electricity make this use dangerous.

Subp. 2.

Using fuses.

When a fuse is used, the blasting detonator must be securely attached to the safety fuse with a standard ring-type detonator crimper. Primers may only be assembled at least 50 feet from any magazine.

Subp. 3.

Primers.

Primers may be made up only as required for each round of blasting.

Subp. 4.

Inserting detonator into explosive.

A blasting detonator must not be inserted in the explosives unless a hole is first made in the cartridge for the detonator with an approved punch of proper size or standard detonator crimper.

Subp. 5.

Extracting explosives from hole.

Explosives must not be extracted from a hole that has once been charged or has misfired unless it is impossible to detonate safely the unexploded charge by inserting a fresh additional primer.

Subp. 6.

Misfires.

If a misfire occurs while using a detonator and a fuse or an electric blasting detonator, all persons shall remain away from the charge for at least 30 minutes. A misfire may be handled only under the direction of the person in charge of the blasting, the wires must be carefully traced, and a search must be made for unexploded charges.

Subp. 7.

Testing circuits.

When testing circuits to charged holes, blasters shall use only blasting galvanometers or other instruments approved for testing circuits.

Subp. 8.

Lead wire connections.

Only the person making the lead wire connections in electrical firing shall fire the shot. Connections should be made from the bore hole back to the source of firing current. The leading wires must remain shorted and must not be connected to the blasting machine or other source of current until the charge is to be fired.

Statutory Authority:

MS s 299F.71 to 299F.83

History:

11 SR 6

Published Electronically:

July 26, 2007

700 State Office Building, 100 Rev. Dr. Martin Luther King Jr. Blvd., St. Paul, MN 55155 ♦ Phone: (651) 296-2868 ♦ TTY: 1-800-627-3529 ♦ Fax: (651) 296-0569