An electricity pylon or transmission tower is a tall, usually steel lattice structure used to support overhead electricity conductors for electric power transmission.
Three-phase electric power systems are used for high and extra-high voltage AC transmission lines (50 kV and above). The towers must be designed to carry three (or multiples of three) conductors. The towers are usually steel lattices or trusses (wooden structures are used in Germany in exceptional cases) and the insulators are either glass or porcelain discs or composite Insulators using Silicone Rubber or EPDM rubber material assembled in strings or long rod whose length is dependent on the line voltage and environmental conditions. One or two earth conductors (alternative term: Ground conductors) for lightning protection are often mounted at the top of each tower.
