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BELL SYSTEM TECHNICAL JOURNAL 



resistant to water absorption as the wire itself. The spUce actually 

 developed (see Fig. 1) has two features of interest: the joints in the 

 conductor proper and the method of patching the insulation. The 



Fig. 1 — Splicing buried wire. Top: pressed sleeve joints in conductors, 

 unvulcanized rubber pad in place. Bottom: after vulcanization. 



Center: 



conductor joint is made by pressing a cylindrical sleeve on the abutted 

 ends of the wires to be joined, in this way producing a tight joint of 

 high electrical efificiency and relatively immune to corrosion. The 

 joints in the two wires are staggered and the whole encased in a pad of 

 unvulcanized rubber which is pressed in place and vulcanized in an 

 electrically heated mold, shown in Fig. 2. The vulcanizer is equipped 

 with a thermostatic device to insure proper control of the temperature. 

 This splice is intended for burial directly in the ground without other 

 protection and tests indicate it to be the equivalent of the unspliced 

 wire. 



Electrical Properties and Loading 

 In cross-section, the insulated twin is an oval having a major diam- 

 eter of about .vS3" and a minor diameter of about .165". The cross- 

 section has been designed to give optimum electrical characteristics 

 for the amounts of copper and rubber compound employed per unit 

 length. The average mutual capacitance per thousand pair feet after 

 seven days water immersion is about 0.022 mf. with an average loop 

 resistance \)vr thousand feet of about 10.2 ohms. While the trans- 



