|Khalifa, Mohamed and El-Koshairy, Mahmoud. High-Voltage Engineering:Theory and Practice, vol. 63.Marcel Dekker, 1990: 248.||"The voltage of the majority of transmission lines is in the range of eighty five thousand volts to five hundred and fifty thousand volts."||85–550 kV|
|Brodeur, Paul. The Great Power-Line Coverup, cancer hazards posed by electromagnetic fields. Boston: Little Brown, 1993: 20.||"typically, a hundred and fifteen thousand volts, or two hundred and fifteen kilovolts, or two hundred and thirty-thousand volts, or two hundred and thirty kilovolts"||115–230 kV|
|"Transmission and Distribution Systems." Compton's Encyclopedia Online v3.0. The Learning Company, Inc.: 1999.||"transmission systems operate at voltages from 66,000 to 756,000 volts."||66–765 kV|
|Jacobs, R. The Energy Story. Nevada: Berkeley Publishing, 1977: 308.||"The electricity first goes to a transformer at the power plant that boosts the voltage up to 400,000 volts."||400 kV|
In order for the electrical outlets in our homes to function, they must receive electricity from a power plant. A power plant produces a certain amount of electricity that is then transported by high-tension power lines to substations near residential areas. In order for the electricity to reach the substation economically, it is put through a transformer that increases the voltage to between 66 kilovolts and 765 kilovolts. These voltages make it more efficient to transport electricity over long distances without loss of energy.
There are problems associated with such large voltages being channeled through power lines. Fires can start if trees are too close to such lines. There are mandated guidelines for the distances that must exist between trees and high-tension power lines.
Another serious problem is the occurrence of electromagnetic fields within 20 meters of high-tension power lines. They have been suspected to cause cancer in people living in the immediate vicinity of power lines. Steps have been taken to prevent this, but an alternate method of transmitting electricity over long distances has not been found.
In addition, the obvious and perceptible danger of electrocution exists when people or animals get near the power lines. This is especially true for workers who have to maintain the power lines. There is a slim chance of survival after being shocked by that much voltage.
In conclusion, power transmission lines are a necessary, but sometimes hazardous part of our environment.
Alex Ryabov -- 1999