Brief History of Cable Production
Cable came into our life with the use of telegraph machines. The first submarine
cables for telecommunications from 1851 were coated in a protective layer of a
cousin of rubber called gutta percha. In 1795 , Don Francisco Salva presented a
paper to the Academy of Science in Barcelona suggesting paper insulated cable
can be used to transmit telegraph signals. In his words *:
"...it appears , little short of impossible to erect and maintain so many wires ( with the electro static telegraph system that he was contemplating, Salva would require 22 wires, one for each of the 22 letters of the telegraph alphabet) for even with the loftiest and most inaccessible supports, boys will manage to injure them; but as it is not necessary to keep them very far apart, they can be rolled together in one strong cable and placed at a great height. In the first trials made with cable of this kind , I covered each wire with paper coated with pitch or some other ideoelectric substance, then tying them together, I bound the whole with more paper, which eventually prevented any lateral escape of the electricity. In practice, the wire cable could be laid in subterranean tubes, which for greater insulation , should be covered with one or two coats of resin"
In fact , electric cable that we know today , was not much in use or in demand untill Belgian inventor Zénobe Gramme built first Dynamo in 1871.
This is Gramme's Dynamo in picture. It was an electric generator. Once electric current was generated, there was need for cable to transmit electric power. Ancestors of plastic coated cable were paper insulated - covered cables. In most countries , paper insulated telephone wires were still in use until 1970's. Today still paper insulated cables are in use for special applications since dielectric constant of pure cellulose is greater than one.
Eventhough Gutta Percha was used in early sub-marine telecommunication cables. It was not suitable for building wires. In 1882, When Mr. Thomas Edison developed first power distribution system in New York , used copper rods wrapped in jute. Vulcanised Rubber-insulated cable was used for 11,000 volt circuits in 1897 installed for the Niagara Falls power project.
In Mid 1920's PVC was innovated but it would not be used for cable insulation for another 30 years.
Mass-impregnated paper-insulated medium voltage cables were commercially practical by 1895. During World War II several varieties of synthetic rubber and polyethylene insulation were applied to cables
Typical residential and office construction in North America has gone through several technologies:
Early bare and cloth-covered wires installed with staples
1880s-1930s, using asphalt-saturated cloth or later rubber insulation
Rubber-insulated wires with jackets of woven cotton cloth (usually impregnated with tar), waxed paper filler - introduced in 1922
Early two-wire PVC-insulated cable, known by the genericized trademark "Romex", 1950s
Aluminum wire was used in the 1960s and 1970s as a cheap replacement for copper, but this is now considered unsafe due to corrosion. Some countries restrict use of aluminium conductors within the range of 2 kilometers from Sea-water.
Asbestos was used as an Insulatoion material in some cloth wires from the 1920s to 1970s.
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