Ala. Admin. Code r. 480-3-4-.19

Current through Register Vol. 43, No. 1, October 31, 2024

Section 480-3-4-.19 - Electrical Blasting

(1) Connecting

(a) Electric blasting with blasting machines, or special circuits is permissable. With blasting machines, connections shall be made in series or in a combination connection recommended by the manufacturer. With power currents connections shall be made in series, parallel, or a combination of the two.

(b) Where blasting is by means of a special blasting circuit, no one shall enter the place in which the blasting has been done until the permanent blasting wires have been disconnected from the source of electrical energy and the blasting switch has been locked into the open position.

(2) Blasting Machines

(a) All blasting machines for generating or supplying electricity for shot firing shall, when in the pit or quarry, be in charge of a person properly instructed in blasting practice and no other person shall connect the blasting machine to the leading wires, and such connections shall not be made until all other steps preparatory to the firing shall have been completed and the men removed to a safe place.

(b) Electric current from light or power circuits shall not be used for firing shots in a pit or quarry except when the electric connections to light or power circuits are made within the enclosed switch box described in these rules.

(c) Permanent blasting lines shall be kept well in the clear from all power and light circuits and from all pipes, rails, etc., and shall be run or strung at least 20 feet away from all power, lighting, and other electrical circuits.

(3) Blasting Circuits

(a) Grounded circuits or systems shall not be used for electrical blasting.

(b) Permanent blasting lines, safety switches and blasting switches shall be maintained by a competent electrician or other competent and experienced person.

(4) Lead Wires

(a) Leading wires from portable generating blasting devices or approved type batteries shall be not less than #14 A.W.G. insulated wire except that for single shots they shall be not less than #18 A.W.G. insulated wires.

(5) Blasting Circuits

(a) Permanent blasting wires shall be so installed and maintained that they provide the current capacity required by the electrical firing device. All such wires shall be in conduit, shall consist of type "S" cable or equivalent, or shall consist of two rubber covered wires strung on glass insulators or porcelain knobs. If rubber covered wires are used, they shall be kept at least five inches apart.

(6) Connecting Wires

(a) Connecting wires shall be not less than #20 A.W.G. insulated wires. Temporary wires shall be not less than #14 A.W.G. insulated wires. Bus wires shall not be smaller than #16 A.W.G. bare copper wires.

(7) Blasting Switches

(a) At the location where the shot firing is to be controlled, there shall be installed a suitable blasting circuit enclosed, externally operated pole switch with the handle or lever arranged to be locked in the "off" position only.

(8) Single Circuits

(a) Single Blasting Circuit: "Where the blasting lines run to a single face to be blasted, a "safety" switch of the same type as required for blasting switch shall be installed between the switch and the face. This switch shall be installed in a safe location guarded from flying rock.

(9) Multiple Circuits

(a) Multiple Blasting Circuits. Where a single blasting switch is used for several blasting circuits, a safety switch shall be installed in each circuit immediately adjacent to the blasting switch.

(b) In addition, a second safety switch shall be installed in the circuit adjacent to the area to be blasted.

(10) Testing

(a) A blasting galvanometer or circuit tested especially designed for blasting work shall be used for testing.

(11) Shorting

(a) Leg Wires of electric detonator shall be kept short circuited by means of short-circuiting device or by twisting ends of leg wires together, except that the short-circuiting devices may be removed temporarily for the purpose of testing detonators with the galvanometer.

(b) Before connecting the temporary wires to the leg wires, or bus wires, the ends of the temporary wires that are to be connected to the safety switch shall be "shorted" by being twisted together.

(c) The man making or supervising the connection at the face must have the "shorted" ends of the temporary wires in his possession and after making the connections at the face, he shall run the temporary wires to the safety switch. He shall never attach the temporary wires to the safety switch before attaching them to the leg wires, or bus wires.

(d) At the safety switch, he shall untwist the temporary wires, unlock the safety switch, attach the temporary wires to the safety switch and then place the "safety" switch in the "on" position. He shall then proceed or signal to a designated person at the blasting switch and he or such designated person shall unlock the blasting switch, throw it in the "on" position to fire the shot, then immediately return the blasting switch to the "off" position and lock it in that position.

(e) After blasting, no one shall go nearer the place that has been blasted than the safety switch until that safety switch has been opened, the temporary wires disconnected and the safety switch locked in the "off" position.

(f) No blasting or preparation for blasting shall be done during electrical storms.

(12) Workmen

(a) The minimum necessary number of men shall be at the loading places when making the blasting connections. All other men shall be a safe distance away from the loading place when blasting connections are made.

Author: Department of Industrial Relations

Ala. Admin. Code r. 480-3-4-.19

Statutory Authority:Code of Ala. 1975, § 25-2-2(3).

Prior to October 1, 1982, this regulation was designated as General Rule 19.