New aspect of buried urban telephone distribution

In 1955, the Bell System initiated a program for developing the necessary methods, tools, and materials to permit construction of economical buried telephone distribution plant. The buried installations up to that time were generally costly, compared with conventional aerial plant, and were in most instances restricted to very-high-priced residential areas. The postwar development of plastic insulated conductor (PIC) cable and the associated ready-access type of terminations made the prospects quite promising. This paper summarizes results achieved to date and describes those methods, tools, and materials which have produced the best results. The term “telephone distribution” includes the subscriber loop plant from the central office to the customer´s premise. Urban (in contrast to rural) denotes a built-up area, served by a network of metallic underground utility pipes which tends to act as a ground network in the event of lightning. Methods, tools, and materials used in urban and rural installations are basically the same except that added precautions must, in many instances, be included to prevent lightning damage in rural areas.