Utility pole

Electrical wires and cables are routed overhead on utility poles as an inexpensive way to keep them insulated from the ground and out of the way of people and vehicles.

[1] Utility poles are usually made out of wood, aluminum alloy,[2] metal, concrete, or composites like fiberglass.

Most utility poles are made of wood, pressure-treated with some type of preservative for protection against rot, fungi and insects.

Traditionally, the preservative used was creosote, but due to environmental concerns, alternatives such as pentachlorophenol, copper naphthenate and borates are becoming widespread in the United States.

In the event of an overload, the fuse melts and the device pivots open to provide a visual indication of the problem.

They can also be opened manually by linemen using a long insulated rod called a hot stick to disconnect the transformer from the line.

If uninsulated conductors touch due to wind or fallen trees, the resultant sparks can start wildfires.

Coaxial or optical fibre cables linking computer networks are also increasingly found on poles in urban areas.

[citation needed] Linemen may use climbing spikes called gaffs to ascend wooden poles without steps on them.

The guys always have strain insulators inserted in their length to prevent any high voltages caused by electrical faults from reaching the lower portion of the cable that is accessible by the public.

In populated areas, guy wires are often encased in a yellow plastic or wood tube with reflectors attached to their lower end, so that they can be seen more easily, reducing the chance of people and animals walking into them or vehicles crashing into them.

He found so many faults with this system that he dug up his cable, stripped off its sheath, bought poles and strung his wires overhead.

On February 7, 1844, Morse inserted the following advertisement in the Washington newspaper: "Sealed proposals will be received by the undersigned for furnishing 700 straight and sound chestnut posts with the bark on and of the following dimensions to wit: 'Each post must not be less than eight inches in diameter at the butt and tapering to five or six inches at the top.

[14] They were used on the Australian Overland Telegraph Line built in 1872 which connected the continent north to south directly through the centre and linked to the rest of the world through a submarine cable at Darwin.

[18] The building of pole lines was resisted in some urban areas in the late 19th century,[citation needed] and political pressure for undergrounding remains powerful in many countries.

In Eastern Europe, Russia, and third-world countries, many utility poles still carry bare communication wires mounted on insulators not only along railway lines, but also along roads and sometimes even in urban areas.

In the United States electricity is predominately carried on unshielded aluminum conductors wound around a solid steel core and affixed to rated insulators made from glass, ceramic, or poly.

Wooden poles have been used for 132 kV for a number of years from the early 1980s one is called the trident they are usually used on short sections, though the line from Melbourne, Cambs to near Buntingford, Herts is quite long.

In many places, as seen in the illustration, providers of electricity, television, telephone, street light, traffic signal and other services share poles, either in joint ownership or by renting space to each other.

Utilities that fall under the Rural Electrification Act must also follow the guidelines set forth in RUS Bulletin 1724E-150[20] (from the US Department of Agriculture) for pole strength and loading.

Steel utility poles are becoming more prevalent in the United States thanks to improvements in engineering and corrosion prevention coupled with lowered production costs.

A rule of thumb for understanding a pole's brand is the manufacturer's name or logo at the top with a two-digit date beneath (sometimes preceded by a month).

Some wood species may be marked "SP" for southern pine, "WC" for western cedar, or "DF" for Douglas fir.

Common preservative abbreviations are "C" for creosote, "P" for pentachlorophenol, and "SK" for chromated copper arsenate (originally referred to salts type K).

In the British region of East Anglia, EDF Energy Networks often add the Ordnance Survey Grid Reference coordinates of the pole or substation to the name sign.

In some areas, utility pole name plates may provide valuable coordinate information: a poor man's GPS.

At electrical operated railways, pole routes were usually not built as too much jamming from the overhead wire would occur.

There was also a long section in place between Wymondham, Norfolk and Brandon in Suffolk, United Kingdom; however, this was de-wired and removed during March 2009.

Some chemicals used to preserve wood poles including creosote and pentachlorophenol are toxic and have been found in the environment[citation needed].

In recent years, concerns have been raised about the toxicity of creosote-treated wood waste, such as utility poles.