CHAPTER I 1
CABLE INSTALLATION
James D. Medek and William A. Thue
1.
INTRODUCTION
Thomas A. Edison installed his earliest cables in New York City in 1882. The
cables were placed in iron pipes in the factory and then were spliced together in
the field every 20 feet in an egg-shaped splice casing. Other systems, such as by
Brooks, Callender, and Crompton, were installed by 1885 where they also used
short sections of iron conduit. American Bell Telephone Company installed the
first flexible communication cables in 1882 and 1883 where cables were pulled
into the conduit in the field. “Pumplogs” were first used for water supply lines,
but were used in 1883 in Washington, DC, for telegraph cables. Tree logs were
hollowed out, the exterior was trimmed to make them square, and the entire log
was treated with creosote. These became the conduits of choice! So began the
duct and manhole systems with the need to pull cables.
The Underground Systems Reference Book [ll-11 of 1931 stated that “It is
necessary to inquire into the harmful effects of the pulling stress on the cable
insulation. The conclusion that has been reached, based on tests and experience,
is that satisfactory operation of the cable is assured, provided that it has suffered
no mechanical injury.” It was recommended that a coefficient of friction
between 0.40 and 0.75 should be used and that the total tension should be
limited to 10,000 pounds. Little other advice. was offered.
Significant advances were made in the understanding of cable pulling
calculations with the 1949 paper by Buller [ll-21 and the 1953 work of
Rifenberg [ll-31. These papers provide the basic data for making cable pulls in
all situations encountered in the field. They provide excellent quantitative data
when used to calculate pulling tensions.
Even in the 1957 version of the Underground Systems Reference Book [ll-41,
there was little additional guidance given for such an important consideration as
sidewall bearing pressure for distribution type cables. It was