An overhead line is an essential part of electrical power transmission and distribution systems. It refers to a set of conductors, support structures, insulators, and related equipment installed above ground to deliver electricity from generating stations to substations and then to consumers. Overhead lines are widely used because they are relatively economical, easy to inspect, and suitable for long-distance power transfer.The main components of an overhead line include conductors, poles or towers, insulators, crossarms, and grounding devices. Conductors are the wires that carry electrical current. They are usually made of aluminum, copper, or aluminum alloy, depending on the required strength, conductivity, and cost. Support structures such as wooden poles, steel poles, lattice towers, or concrete poles hold the conductors at a safe height above the ground. Insulators are used to separate the live conductors from the supporting structures and prevent unwanted current flow. Crossarms help maintain the correct spacing between conductors, while grounding systems improve safety by directing fault currents into the earth.Overhead lines are designed to withstand a variety of environmental and mechanical conditions. These include wind, rain, ice, temperature changes, lightning, and mechanical tension. For this reason, engineers carefully calculate conductor sag, tension, and clearance. Sag is the slight downward curve in the conductor between two supports. It is necessary to allow for thermal expansion and to ensure the line remains safe under different weather conditions. Proper clearance is important to avoid contact with buildings, trees, vehicles, or people.One of the major advantages of overhead lines is their lower installation cost compared with underground cables. They are also easier to extend, repair, and modify. Faults can often be located and fixed more quickly because the equipment is visible and accessible. In addition, overhead lines can be used in rural, suburban, and some urban areas where land is available.However, overhead lines also have disadvantages. They are more exposed to weather and external damage, which can lead to outages. They may also affect the visual appearance of an area and require regular maintenance such as vegetation control, inspection of insulators, and replacement of damaged parts. Despite these drawbacks, overhead lines remain a vital and widely used solution for power delivery around the world.In modern power systems, overhead lines continue to play an important role in connecting generation sources, substations, and distribution networks. Their simple structure, cost-effectiveness, and adaptability make them one of the most common methods of electrical energy transmission.