Lineman (occupation)

A lineman is a tradesman who constructs and maintains electric power transmission and distribution facilities. The term is also used for those who install and maintain telephone, telegraph, and cable TV lines.

Terminology

Not all who work in outdoor tower construction or wire installation are linemen. A crew of linemen will also include several helpers, known as grunts. They help with the on-the-ground tasks needed to support the linemen, but may not do any work off the ground, nor any work which involves electrical circuits.

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Transmission refers to the circuits which carry electric power at high voltages from a generating station, across long distances, to the location where the voltage will be lowered and transferred to distribution circuits, which eventually carry the power to end consumers. A substation is a location where transformers either raise or lower the voltage. A substation at the power generation source will raise the voltage to transmission levels. Distribution substations then lower the voltage from transmission levels down to distribution levels. A feeder is a distribution circuit which carries power from distribution substations, and then feeds lower-voltage distribution lines which serve consumers. Transmission voltages usually range from 138,000 to 765,000 volts, but can be even higher. Distribution voltages can range from the standard United States household current of 120 volts up to 69,000 volts. High-voltage distribution circuits from 600 to 69,000 volts are called primary circuits. There is also a range of voltages in between transmission and distribution, known as sub-transmission.

Related Topics:
Voltage - Transformer

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The terms step up and step down refer to raising and lowering voltage. Step up transformers increase voltage and reduce current, while step down transformers reduce voltage and increase current.

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Most transmission circuits are three phase alternating current. Transmission circuits can also, much less frequently, be direct current. Distribution circuits are either three phase or single phase. Household level voltage is usually single phase alternating current. Three phase circuits can have either three wires (three phase delta) or four wires (three phase wye, with the fourth wire a neutral which may be used in conjunction with any one of the other three to create single phase current.) Often, more than one three phase circuit will use the same transmission towers, so for example you may see a tower with six wires (two circuits). Transmission towers will also typically carry ground wires used to prevent any disruption of the circuit in case lightning strikes a tower.

Related Topics:
Three phase - Alternating current - Direct current - Single phase

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Wood poles can be climbed using tools known as hooks or gaffs.

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In the United Kingdom, the terms earthed and earthing are used, and mean the same thing as grounded and grounding in the United States. When referring to three phase circuits with a fourth neutral wire, star is used in the United Kingdom and has the same meaning as wye.

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