Technical Paper Volume 100-120

Technical Paper Volume 100-120

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1915 edition. Excerpt: ...with weatherproof wire and room switches, about 1,400 Complete with weatherproof wire and no room switches, about.. 1,200 SUMMARY. ESSENTIAL FEATURES OF OUTSIDE SHOT-FIRING SYSTEMS. The recommendations contained in this paper concerning outside shot-firing systems are essentially as follows: CHECKING SYSTEM. An outside firing system shoidd not be used without a suitable checking system. SOURCE OF POWER. The source of power shoidd have a-momentary capacity of not less than 30 kw. for a mine of average size. It may supply either alternating or direct current. FIRING VOLTAGE. It is recommended that 250 volts be used where conditions permit, hut 500 volts must be used where distances or the number of shots to be fired exceed the limits that can be satisfactorily handled by 250 volts. SHOT-FIRING PANEL. The shot-firing panel should be well mounted and housed and should be provided with two single-pole circuit breakers, a doublepole switch, and an ammeter. A switch should also be provided for disconnecting the panel from the source of power. DISTRIBUTING CIRCUITS. Wires of power circuits should not bo used for shot-firing conductors if such a practice reduces the factor of safety of the system. All shot-firing conductors should be insulated. All parts of the shot-firing circuits should be supported on insulators. Dry wood will be satisfactory for the insulators of room wires, but is not recommended for any other part of the circuit. Conductors should not be less than No. 14 (B. & S.) gage in rooms, No. 10 in cross entries, and No. 8 elsewhere. Each system should be considered by itself in the light of the conditions that surround it, and conductors larger than the minimum recommended should be used if the distances and number of shots...
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Product details

  • Paperback | 222 pages
  • 189 x 246 x 12mm | 404g
  • United States
  • English
  • black & white illustrations
  • 1236860748
  • 9781236860743