Ground conductor
From Wikipedia, the free encyclopedia
A ground conductor (also known as an earth conductor, "grounding conductor", "equipment grounding conductor", "earth ground" "ground" "protective earth conductor" and many other names) is an electrically conductive wire or cable, typically green or green with a yellow stripe or even bare copper, that connects the device/ equipment to the protective earth ground of the electrical system.
This conductor is designed to prevent the equipment or device from becoming electrical energized and there by cause a shock hazaard to people or animals or damage to the equipment. This conductor for those reason is sometimes called a protective earth ground.
Details of the use and sizing of this conductor can be found in the National Electrical Code NFPA 70(National Fire Protection Association USA) or in various building electrical codes (globally) and in specific product standards.
A ground conductor also is the tops most conductor on the top of pylons, poles, towers. This ground conductor is designed protect the power conductors from lightning strikes.
Most ground conductors are able to earth electrical strikes via the body of the pylons but in some cases where earthing conditions are poor, specially designed earthing cables are used.
As a general rule, power lines with voltages below 50 kV do not have a ground conductor, but most lines carrying more than 50kV do. This is largely determined by the effectiveness of automatic circuit breakers which are able to protect low voltage installations but which are less efficient at higher voltages because of the persistence of arcing and the distances that need to be travelled by moving parts in a circuit breaker before the circuit is effectively broken.
If there are more demanding requirements for lightning protection, two ground conductors, one on each of the edges of the pylons may be used. In such cases the pylons are either equipped with an additional crossbeam above the conductors, with two tops in form of a letter "V" or the ground conductors are mounted on the top of the topmost crossbeam.
In some parts of the world, the ground conductor cable is used to support fibreoptic cables for data transmission such as on some powerlines in Germany which were built before 1985 by the former EVS AG (nowadays EnBW AG) in Baden-Württemberg.
