For nearly 100 years conductor connections have been made by the 

 scarf- joint method, which can be used even when the two conductors are 

 radically different in size. The method has the added advantage of 

 producing only a slight increase in the diameter of the connection. 



Assume two ends of armored cable have been made available for 

 jointing and splicing. On one end the sheathing wires and the jute 

 bedding underneath are unlaid or opened out for about 40 feet. The 

 exposed core (conductor plus insulation) is cut awav, except for 3 to 4 

 feet. On the other end the sheathing wires and the jute bedding under- 

 neath are unlaid for about 8 feet, and 2 feet of the exposed core is cut 

 away. The insulation is stripped off with a sharp knife for about 3 

 inches at both ends of the core. The copper strands are untwisted, with 

 care not to break any of the wires, and each wire is thoroughly cleaned 

 with emery cloth; the wires are then re twisted in the original direction 

 into a strand. The strands of both cable are soldered for about 1 1/2 

 inches from the end and quickly cooled, and both soldered ends are filed 

 to form a scarf or bevel 1 inch long. They are then clamped into the 

 jointer's tray, which is fitted with two small upright vises for holding 

 and properly locating the scarfed ends. 



The scarfed ends then are temporarily bound together by four strands 

 of 0.010-inch copper binding wire (held so as to form a stranded tape) 

 applied in an open helix. The scarfs are then soldered, with care taken 

 that the solder flows between the abutting surfaces. The temporary 

 binding is stripped off, and the soldered surface is smoothed with emery 

 cloth. The soldered surface is then wrapped with four strands of binding 

 wire so that it is entirely covered, with the binding strands close to- 

 gether but not overlapping. This binding is then completely soldered. 

 Next, another wrapping of four strands of binding wire is applied in the 

 opposite direction, over the full length from one vise to the other. This 

 second wrapping, secured by soldering for about 1/2 inch on both ends, 

 serves as a guard wire in case the electrical joint separates. 



Insulation - Universal Method . The method formerly used with gutta- 

 percha insulated cables is not suitable for polvethvlene. As a result, 

 a method has been developed with a special tape that can be used on any 

 kind of insulation. It is sometimes called the "universal" method and 

 utilizes materials obtainable from the Simplex Wire and Cable Company in 

 Cambridge, Massachusetts. It can be used in the jointing of gutta-perchaj 

 rubber, polyethylene, or telecothene insulations to themselves or to one 

 another. The procedure is the same for any of the insulations except 

 that with gutta-percha the K540 cement is not used on the scarfs. 



The end of the insulation is prepared by tapering it over a length 

 of approximately 3 inches, starting approximately 1/4 inch from the edge 

 of the conductor joint. The surface of the scarf is made smooth and 

 symmetrical by scraping with a knife. Loose insulation particles or 

 dust must be removed from the surface. 



On rubber or polyethylene insulation the K540 cement should be thin 

 enough to apply with a small brush. If the cement is too thick it can 

 be thinned with toluol. A second coat is applied after the first one is 

 slightly dried. The scarfs are then placed in an electric heater, where 

 the temperature is brought to 212°F. The scarfs are allowed to cool to 



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