An overhead power line is an electric power transmission line suspended by towers or utility poles. Since most of the insulation is provided by air, overhead power lines are generally the lowest-cost method of transmission for large quantities of electric energy. Towers for support of the lines are made of wood (as-grown or laminated), steel (either lattice structures or tubular poles), concrete, aluminum, and occasionally reinforced plastics. The bare wire conductors on the line are generally made of aluminum (either plain or reinforced with steel, or sometimes composite materials), though some copper wires are used in medium-voltage distribution and low-voltage connections to customer premises. A major goal of overhead power line design is to maintain adequate clearance between energized conductors and the ground so as to prevent dangerous contact with the line. Today overhead lines are routinely operated at voltages exceeding 765,000 volts between conductors, with even higher voltages possible in some cases.
Read more about Overhead Power Line: Classification By Operating Voltage, Structures, Insulators, Conductors, Compact Transmission Lines, Low Voltage, Train Power, Further Applications, Use of Area Under Overhead Power Lines, History
Famous quotes containing the words overhead, power and/or line:
“During a walk or in a book or in the middle of an embrace, suddenly I awake to a stark amazement at everything. The bare fact of existence paralyzes me... To be alive is so incredible that all I can do is to lie still and merely breathe—like an infant on its back in a cot. It is impossible to be interested in anything in particular while overhead the sun shines or underneath my feet grows a single blade of grass.”
—W.N.P. Barbellion (1889–1919)
“He will deliver you from six troubles; in seven no harm shall touch you. In famine he will redeem you from death, and in war from the power of the sword. You shall be hidden from the scourge of the tongue, and shall not fear destruction when it comes. At destruction and famine you shall laugh, and shall not fear the wild animals of the earth. For you shall be in league with the stones of the field, and the wild animals shall be at peace with you.”
—Bible: Hebrew, Job 5:19-23.
“For almost seventy years the life insurance industry has been a smug sacred cow feeding the public a steady line of sacred bull.”
—Ralph Nader (b. 1934)