Methods for locating transpositions of wires and split pairs in telephone and telegraph cables

Author(s): Henry W. Fisher
Publisher: IEEE - Institute of Electrical and Electronics Engineers, Inc.
Publication Date: 1 September 1908
Volume: 27
Page(s): 1,437 - 1,448
ISSN (Paper): 0097-2444
DOI: 10.1109/PAIEE.1908.6741867



Some of the telegraph companies demand that there shall be no transpositions of wires in any of the layers in a telegraph cable. By this is meant that the wires of every layer must have the same relative order at each end of the cable. There is usually a tracer or wire covered with different colored paper from the rest in every layer, and by counting from this tracer any particular wire can be located at any point in the cable. If a wire is fifth from the tracer in a clockwise direction at one end of the cable, it will be fifth from the tracer in a counter clockwise direction at the other end of the cable. By this general plan it becomes possible to identify wires without resorting to some of the common methods of testing. However, in order to be able to place implicit reliance in a scheme of identification of this sort, not only must the cables be manufactured correctly but the jointing must be made by skilled men who are careful to connect the wires of each layer in consecutive order, and as an extra precaution make repeated tests at both ends of the jointed sections as the work of splicing progresses. Even after exercising the greatest care, a transposition may occur. The object of the present article is to show how a fault of this kind can readily be located by some methods devised by the author.