CHAPTER I
HISTORICAL PERSPECTIVE
OF ELECTRICAL CABLES
Bruce S. Bernstein and William A. Thue
1. DEVELOPMENT OF UNDERGROUND CABLES
[1-1,1-2]
In order to trace the history of underground cable systems, it is necessary to
exatnine the early days of the telegraph. The telegraph was the first device
utilizing electrical energy to become of any commercial importance and its
development necessarily required the use of wires. Underground construction
was advocated by the majority of the early experimenters. Experimentation with
underground cables accordingly was carried on contemporaneously with the
development of the apparatus for sending and receiving signals. Underground
construction was planned for most of the earliest commercial lines. A number of
these early installations are of considerable interest as marking steps in the
development of the extensive underground power systems in operation around
the world.
2.
EARLY TELEGRAPH LINES
In 1812, Baron Schilling detonated a mine under the Neva River at St.
Petersburg by using an electrical pulse sent through a cable insulated with strips
of India rubber. This is probably the earliest use of a continuously insulated
conductor on record.
One of the earliest experiments with an underground line was made by Francis
Ronalds in 1816. This work was in conjunction with a system of telegraphy
consisting of 500 feet of bare copper conductor drawn into glass tubes, joined
together with sleeve joints and sealed with wax. The tubes were placed in a
creosoted wooden trough buried in the ground. Ronalds was very enthusiastic
over the success of this line, predicting that underground conductors would be
widely used for electrical purposes, and outlining many of the essential
characteristics of a modem distribution system.
The conductor in this case was first insulated with cotton saturated with shellac
before being drawn into the tubes. Later, strips of India rubber were used. This
installation had many insulation failures and was abandoned. No serious