Science Fair Project Encyclopedia
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.
The term refers to those who work in generally outdoor installation and maintenance jobs. Those who install and maintain electrical wiring inside buildings are electricians.
The occupation began with the widespread use of the telegraph in the 1840s. Telegraph lines could be strung on trees, but wooden poles were quickly adopted as the method of choice. The term 'lineman' was used for those who set wooden poles and strung the wire. The term continued in use with the invention of the telephone in the 1870s and the beginnings of electrification in the 1890s.
This new electrical power work proved to be much more hazardous than telegraph or telephone work because of the risk of electrocution. Between the 1890s and the 1930s, line work was considered one of the most hazardous jobs in existence. Approximately 1 in 3 linemen were killed on the job, mostly from electrocution. This led to the formation of labor organizations to represent the workers and advocate for their safety. The most important of these labor organizations in the United States, still in existence today, is the International Brotherhood of Electrical Workers. This also led to the establishment of apprenticeship programs and the establishment of more stringent safety standards, starting in the late 1930s.
In the United States, the rural electrification drive during the New Deal led to a wide expansion in the number of jobs in the electric power industry. Many linemen during that period traveled around the country following jobs as they became available in tower construction, substation construction, and wire stringing. These roving workers or "boomers" as they were called, were known as rowdy risk-takers but also as hard workers with a strong sense of pride in their work. They often lived in temporary camps set up near the project they were working on, or in boarding houses if the work was in a town or city. The occupation was one of the most lucrative at the time, owing to the high level of skill needed and the hazardous nature of the work, but the hazards and the extensive travel limited the appeal of the work to only a hardy few. Often a lineman would finish one job with enough money to live on for several weeks or months before they would "boom up" to another job somewhere else.
A brief drive to electrify some railroads on the East Coast of the U.S. led to the development of a highly specialized branch of linemen who installed and maintained catenary overhead lines. Growth in this branch of line work stalled after most railroads chose to replace their steam engines with diesel, rather than electric, engines.
The occupation evolved during the 1940s and 1950s, as household electricity became more ubiquitous. As the public became more dependent on electricity, it became imperative that damaged power lines be repaired quickly. This led to an increase in the number of linemen needed to maintain power distribution circuits, and to keep them repaired in case of power outages, storms, or other emergencies. These maintenance linemen mostly stayed in one place and could settle down, although sometimes linemen could be called to travel to other states to help repair the damage from major storms such as hurricanes. Also during the 1950s, some electric lines began to be installed in underground tunnels, expanding the scope of the work. Safety standards and equipment have continued to improve; today, while still considered a somewhat hazardous occupation, line work is no longer as dangerous as it once was.
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.
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.
The terms step up and step down refer to raising and lowering voltage. Step up transformers raise voltage and lower current (amperage), while step down transformers lower voltage and raise current.
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.
Wood poles can be climbed using tools known as hooks or gaffs.
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.
What they do
Linemen can work either energized or dead power lines. When working with energized power lines, linemen must use protection to eliminate any contact with the energized line. Some distribution-level voltages can be worked using rubber gloves. The limit of how high a voltage can be worked using rubber gloves varies from company to company according to different safety standards (often negotiated in the union contract) and local laws. Voltages higher than those which can be worked using gloves are worked with special sticks known as hot-line tools, with which power lines can be safely handled from a distance. Linemen must also wear special rubber insulating gear when working with live wires to ensure against any accidental contact with the wire. The buckets from which linemen sometimes work are also insulated using rubber.
Even de-energized power lines can be hazardous, owing to the complex nature of the electrical system. Even though one circuit may be ostensibly shut off, that circuit may still be conducting electricity anyway, because of possible interconnection with other live circuits. Thus, care must be taken to ensure that all possible sources of power to a circuit are removed. This can be especially dangerous when transformers are involved in the connection to another circuit, or one circuit is fed by more than one other circuit. For example: A higher-voltage distribution level circuit may feed several lower-voltage distribution circuits, using step down tranformers. A step down transformer can also act in reverse as a step up transformer. If the higher voltage circuit is de-energized so it can be worked on, but any one of the lower-voltage circuits connected to it via a transformer remains energized, the transformer will convert the power in the lower-voltage circuit back to the higher voltage, and the higher voltage circuit will remain energized. This is known as backfeed. Another potential problem is de-energized wires can become energized through electrostatic induction from energized wires in close proximity. One precaution against this is to ground all the wires in a circuit to each other before working on it, hence the saying, "if it's not grounded, it's not dead."
Incredible as it seems, live high voltage transmission lines can be worked barehanded. This is done with the lineman wearing a special conductive suit which is grounded to the live power line, creating a Faraday shield effect so the lineman is at the same potential as the energized wire, and allowing the lineman to handle the wire safely. Such work is often done from helicopters and is considered a highly specialized area of line work; few linemen have the special training to perform it. Barehanded live-wire work can theoretically be done at any voltage, but because better protective means are available for lower voltages, it is only used for transmission-level voltages and sometimes for the higher distribution voltages.
Telephone and cable TV lines may sometimes be placed on the same poles as electric distribution circuits. They are placed below the electric lines so telephone and cable TV linemen can work those lines without potential contact with high-voltage electricity.
The standard reference book in the field is The Lineman's and Cableman's Handbook. This was first published in 1928 (by Edwin B. Kurtz) and has gone through many editions since, with a new edition appearing as needed to keep up with current technologies. The most recent edition is the 10th edition (2002) (ISBN 0071362401), by Thomas M. Shoemaker and James E. Mack.
Slim (1934) and High Tension (1938) by William Wister Haines are classic portrayals of line work during the Great Depression.
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