504 EM 385-1-1 Sections 27-34

29.G Wiring.

29.G.02 Bus Wiring and insulation.

1. Bus wires must be single solid wires of sufficient current carrying capacity.
2. The insulation on all firing lines must be adequate and in good condition.

29.G.03 The number of electric blasting caps in a circuit must not exceed the capacity of blasting machine or power source.

29.G.04 A power circuit used for firing electric detonators must not be grounded.

29.G.05 Whenever the possibility exists that a leading wire might be thrown onto a live power source by the force of the explosion, care must be taken to see that the total length of wires is kept too short to contact the source or that the wires are securely anchored to the ground. Alternatively, de-energize the live power until it is certain during the post blast inspection that the lines have not crossed. If these requirements cannot be met, a non- electric system must be used.

29.G.06 The manufacturer's shunt must not be removed from the cap leg wires until the cap is connected to the lead line or to another cap in preparation for the assembly of two or more caps into a series circuit or when the cap is to be tested.

29.G.07 Lead wire must not be connected to the circuit until it has been grounded to dissipate any static charge.

29.G.08 The circuit, including all caps, must be tested with an approved blasting instrument (blasting galvanometer, blasting ohmmeter, blaster's ohmmeter, or blaster's multimeter) before being connected to a firing line.

29.G.09 A firing line must not be connected to a blasting machine or other power source until the shot is to be fired. The firing line must be checked with an approved blasting instrument before being connected to the blasting machine or other power source.

29.G.10 When a single series of caps is to be fired, or a number of series of caps is to be fired as a series-in-parallel circuit, the resistance of the circuit must be checked with an approved blasting instrument.

29.G.11 For series-in-parallel circuits, each series must have the same resistance.

29.G.12 Each series circuit must be separately tested for two readings:

1. To ensure that the series is complete; and
2. To ensure that each series shows the same resistance and that this resistance is as close to the calculated resistance for such a series of caps as the testing instrument will read. If the first reading shows a series to be incomplete, the faulty cap or connection must be located and corrected. If the second reading shows incorrect resistance, the cause must be found and corrected.

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