Show eliminating MISFIRING OF CENTER SHOTS As a means toward the elimination of misfiring of u f center shots in large lare scale blasting in coal mines the bureau of mines recommends the following practices be used whenever shots are to be fired in wet holes use waterproofed water proofed electric detonators with enameled leg wires when making connections connection with enameled leg wires care must be taken to scrape the ends of the wires well otherwise the enamel will prevent good electrical contact fire shots from an underground power circuit that has a capacity of at least 30 kw use extra care when tamping the holes in order not to damage the insulation of the leg wires arrange the connections between the detonators so that they are supported clear of the earth or any other conducting medium further details given in serial 2384 failure of center shots in blasting which may be ob bained from the bureau of mines washington D C |