A utility pole , commonly referred to as a transmission pole , telephone pole , telecommunication pole , power pole , hydro pole , telegraph pole , or telegraph post , is a column or post, usually made out of wood or aluminum alloy , used to support overhead power lines and various other public utilities, such as electrical cable , fiber optic cable , and related equipment such as transformers and street lights while depending on its application. A Stobie pole is a multi-purpose pole made of two steel joists held apart by a slab of concrete in the middle, generally found in South Australia .
111-567: 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. Utility poles can be made of wood, metal, concrete, or composites like fiberglass . They are used for two different types of power lines: sub transmission lines , which carry higher voltage power between substations, and distribution lines , which distribute lower voltage power to customers. The first poles were used in 1843 by telegraph pioneer William Fothergill Cooke , who used them on
222-566: A coordinate plane used in geometry, X increases as one travels east and Y increases as one travels north. The upper two tags are specific to the sub transmission section of the pole; the first refers to the route number, the second to the specific pole along the route. However, not all power lines follow the road. In the British region of East Anglia , EDF Energy Networks often add the Ordnance Survey Grid Reference coordinates of
333-424: A glass with no true melting point, can be used as a glass fiber for fiberglass but has the drawback that it must be worked at very high temperatures. In order to lower the necessary work temperature, other materials are introduced as "fluxing agents" (i.e., components to lower the melting point). Ordinary A-glass ("A" for "alkali-lime") or soda lime glass, crushed and ready to be remelted, as so-called cullet glass,
444-475: A silicate in which some [SiO 4 ] units are replaced by [BO 4 ] centers, together with additional cations to compensate for the difference in valence states of Si(IV) and B(III). Because this substitution leads to imperfections, the material is slow to crystallise and forms a glass with low coefficient of thermal expansion , thus resistant to cracking when heated, unlike soda glass . Common borate salts include sodium metaborate (NaBO 2 ) and borax. Borax
555-496: A wood preservative or fungicide. Zinc borate is used as a flame retardant . Some borates with large anions and multiple cations, like K 2 Al 2 B 2 O 7 and Cs 3 Zn 6 B 9 O 21 have been considered for applications in nonlinear optics . Borate esters are organic compounds , which are conveniently prepared by the stoichiometric condensation reaction of boric acid with alcohols (or their chalcogen analogs ). Metal borate thin films have been grown by
666-434: A "static line" or a "neutral", suspended above them. The OGW acts like a lightning rod, providing a low resistance path to ground thus protecting the phase conductors from lightning. Distribution lines use two systems, either grounded-wye ("Y" on electrical schematics ) or delta (Greek letter "Δ" on electrical schematics). A delta system requires only a conductor for each of the three phases. A grounded-wye system requires
777-400: A 40-mile telegraph line between Baltimore , Maryland and Washington, D.C. Morse began by having a lead-sheathed cable made. After laying seven miles (11 km) underground, he tested it. 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
888-539: A 5 mg/m total limit. As of 2001, the Hazardous Substances Ordinance in Germany dictates a maximum occupational exposure limit of 86 mg/m . In certain concentrations, a potentially explosive mixture may occur. Further manufacture of GRP components (grinding, cutting, sawing) creates fine dust and chips containing glass filaments, as well as tacky dust, in quantities high enough to affect health and
999-602: A November, 2011 modification to its Proposition 65 listing to include only "Glass wool fibers (inhalable and biopersistent)." Therefore a cancer warning label for biosoluble fiber glass home and building insulation is no longer required under federal or California law. As of 2012, the North American Insulation Manufacturers Association stated that fiberglass is safe to manufacture, install and use when recommended work practices are followed to reduce temporary mechanical irritation. As of 2012,
1110-439: A binder. It is typically processed using the hand lay-up technique, where sheets of material are placed on a mold and brushed with resin. Because the binder dissolves in resin, the material easily conforms to different shapes when wetted out. After the resin cures, the hardened product can be taken from the mold and finished. Using chopped strand mat gives the fiberglass isotropic in-plane material properties. A coating or primer
1221-417: A chemical solution. The individual filaments are now bundled in large numbers to provide a roving . The diameter of the filaments, and the number of filaments in the roving, determine its weight , typically expressed in one of two measurement systems: These rovings are then either used directly in a composite application such as pultrusion , filament winding (pipe), gun roving (where an automated gun chops
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#17328766425281332-401: A combined stream from a chopper gun. Workers roll out the spray-up to compact the laminate. Wood, foam or other core material may then be added, and a secondary spray-up layer imbeds the core between the laminates. The part is then cured, cooled, and removed from the reusable mold. Pultrusion is a manufacturing method used to make strong, lightweight composite materials. In pultrusion, material
1443-667: A commercial basis. With Charles Wheatstone he invented the Cooke and Wheatstone telegraph and founded the world's first telegraph company, the Electric Telegraph Company . Telegraph poles were first used on the Great Western Railway in 1843 when the Cooke and Wheatstone telegraph line was extended to Slough . The line had previously used buried cables but that system had proved troublesome with failing insulation. In Britain,
1554-537: A form of visual pollution . Many lines are placed underground for this reason, in places of high population density or scenic beauty that justify the expense. Architects design some pylons to be pretty, thus avoiding visual pollution. Some chemicals used to preserve wood poles including creosote and pentachlorophenol are toxic and have been found in the environment. The considerable improvement in weathering resistance offered by creosote infusion has long-term drawbacks. In recent years, concerns have been raised about
1665-430: A fourth conductor, the neutral , whose source is the center of the "Y" and is grounded. However, "spur lines" branching off the main line to provide power to side streets often carry only one or two phase wires, plus the neutral. A wide range of standard distribution voltages are used, from 2,400 V to 34,500 V. On poles near a service drop , there is a pole-mounted step-down distribution transformer to transform
1776-460: A lightning arrester) may also be installed between the line (ahead of the cutout) and the ground wire for lightning protection. The purpose of the device is to conduct extremely high voltages present on the line directly to ground. If uninsulated conductors touch due to wind or fallen trees, the resultant sparks can start wildfires . To reduce this problem, aerial bundled conductors are being introduced. The communications cables are attached below
1887-941: A line along the Great Western Railway . Utility poles were first used in the mid-19th century in America with telegraph systems, starting with Samuel Morse , who attempted to bury a line between Baltimore and Washington, D.C. , but moved it above ground when this system proved faulty. Today, underground distribution lines are increasingly used as an alternative to utility poles in residential neighborhoods, due to poles' perceived ugliness, as well as safety concerns in areas with large amounts of snow or ice build up. Utility poles are commonly used to carry two types of electric power lines : distribution lines (or "feeders") and sub transmission lines . Distribution lines carry power from local substations to customers. They generally carry voltages from 4.6 to 33 kilovolts (kV) for distances up to 30 mi (50 km), and include transformers to step
1998-430: A liner to prevent gas leakage or as a barrier to protect the composite from the fluid to be stored. Filament winding is well suited to automation, and there are many applications, such as pipe and small pressure vessels that are wound and cured without any human intervention. The controlled variables for winding are fiber type, resin content, wind angle, tow or bandwidth and thickness of the fiber bundle. The angle at which
2109-952: A mixture of B(OH) 3 , [B(OH) 4 ] , [B 3 O 3 (OH) 4 ] , and [B 5 O 6 (OH) 4 ] . These ions, similarly to the complexed borates mentioned above, are more acidic than boric acid itself. As a result of this, the pH of a concentrated polyborate solution will increase more than expected when diluted with water. A number of metal borates are known. They can be obtained by treating boric acid or boron oxides with metal oxides. Some chemicals contain another anion in addition to borate. These include borate chlorides , borate carbonates , borate nitrates , borate sulfates , borate phosphates . More complex anions can be formed by condensing borate triangles or tetrahedra with other oxyanions to yield materials such as borosulfates , boroselenates , borotellurates , boroantimonates , borophosphates , or boroselenites . Borosilicate glass , also known as pyrex , can be viewed as
2220-402: A mixture of both, can be used in borate fusion sample preparation of various samples for analysis by XRF , AAS , ICP-OES and ICP-MS . Borate fusion and energy dispersive X-ray fluorescence spectrometry with polarized excitation have been used in the analysis of contaminated soils. Disodium octaborate tetrahydrate Na 2 B 8 O 13 ·4H 2 O (commonly abbreviated DOT) is used as
2331-774: 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. The conductors on these are bare metal connected to the posts by insulators. Wood poles can also be used for low voltage distribution to customers. Today, utility poles may hold much more than the uninsulated copper wire that they originally supported. Thicker cables holding many twisted pair , coaxial cable , or even fibre-optic , may be carried. Simple analogue repeaters or other outside plant equipment have long been mounted against poles, and often new digital equipment for multiplexing /demultiplexing or digital repeaters may now be seen. In many places, as seen in
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#17328766425282442-516: 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). Below the date is a two-character wood species abbreviation and one- to three-character preservative. 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). The next line of
2553-913: A post-exposure recovery period." Historic reviews of the epidemiology studies had been conducted by Harvard's Medical and Public Health Schools in 1995, the National Academy of Sciences in 2000, the Agency for Toxic Substances and Disease Registry ("ATSDR") in 2004, and the National Toxicology Program in 2011. which reached the same conclusion as IARC that there is no evidence of increased risk from occupational exposure to glass wool fibers. Genetic and toxic effects are exerted through production of reactive oxygen species , which can damage DNA, and cause chromosomal aberrations , nuclear abnormalities, mutations, gene amplification in proto-oncogenes , and cell transformation in mammalian cells. There
2664-415: A thermoplastic inner tank which acts as a preform during construction. Much more reliable tanks are made using woven mat or filament wound fiber, with the fiber orientation at right angles to the hoop stress imposed in the sidewall by the contents. Such tanks tend to be used for chemical storage because the plastic liner (often polypropylene ) is resistant to a wide range of corrosive chemicals. Fiberglass
2775-399: A variety of techniques, including liquid-phase epitaxy (e.g. FeBO 3 , β-BaB 2 O 4 ), electron-beam evaporation (e.g. CrBO 3 , β-BaB 2 O 4 ), pulsed laser deposition (e.g. β-BaB 2 O 4 , Eu(BO 2 ) 3 ), and atomic layer deposition (ALD). Growth by ALD was achieved using precursors composed of the tris(pyrazolyl)borate ligand and either ozone or water as
2886-403: A weak Brønsted acid , that is, a proton donor, with p K a ~ 9 . However, it more often acts as a Lewis acid , accepting an electron pair from a hydroxide ion produced by the water autoprotolysis : This reaction is very fast, with characteristic time less than 10 μs . Polymeric boron oxoanions are formed in aqueous solution of boric acid at pH 7–10 if the boron concentration
2997-422: Is a common type of fiber-reinforced plastic using glass fiber . The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth . The plastic matrix may be a thermoset polymer matrix —most often based on thermosetting polymers such as epoxy , polyester resin , or vinyl ester resin —or a thermoplastic . Cheaper and more flexible than carbon fiber , it
3108-427: Is a fabrication technique mainly used for manufacturing open (cylinders) or closed-end structures (pressure vessels or tanks). The process involves winding filaments under tension over a male mandrel. The mandrel rotates while a wind eye on a carriage moves horizontally, laying down fibers in the desired pattern. The most common filaments are carbon or glass fiber and are coated with synthetic resin as they are wound. Once
3219-545: Is also indirect, inflammation-driven genotoxicity through reactive oxygen species by inflammatory cells . The longer and thinner as well as the more durable (biopersistent) fibers were, the more potent they were in damage. In the US, fine mineral fiber emissions have been regulated by the EPA , but respirable fibers (“particulates not otherwise regulated”) are regulated by Occupational Safety and Health Administration (OSHA); OSHA has set
3330-432: Is also used for septic tanks . Glass-reinforced plastics are also used to produce house building components such as roofing laminate, door surrounds, over-door canopies, window canopies and dormers, chimneys, coping systems, and heads with keystones and sills. The material's reduced weight and easier handling, compared to wood or metal, allows faster installation. Mass-produced fiberglass brick-effect panels can be used in
3441-401: Is applied to the chosen mold to allow the finished product to be cleanly removed from the mold. Resin—typically a 2-part thermoset polyester, vinyl, or epoxy—is mixed with its hardener and applied to the surface. Sheets of fiberglass matting are laid into the mold, then more resin mixture is added using a brush or roller. The material must conform to the mold, and air must not be trapped between
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3552-479: Is applied to the roving to help protect the glass filaments for processing and manipulation and to ensure proper bonding to the resin matrix, thus allowing for the transfer of shear loads from the glass fibers to the thermoset plastic. Without this bonding, the fibers can 'slip' in the matrix causing localized failure. An individual structural glass fiber is both stiff and strong in tension and compression —that is, along its axis. Although it might be assumed that
3663-419: Is attached to the side of the first and runs at an angle to the ground. If there is no space for a lateral support, a stronger pole, e.g. a construction of concrete or iron, is used. The system of suspending telegraph wires from poles with ceramic insulators was invented and patented by British telegraph pioneer William Fothergill Cooke . Cooke was the driving force in establishing the electrical telegraph on
3774-483: Is called pultrusion . The manufacturing process for glass fibers suitable for reinforcement uses large furnaces to gradually melt the silica sand, limestone , kaolin clay , fluorspar , colemanite , dolomite and other minerals until a liquid forms. It is then extruded through bushings ( spinneret ), which are bundles of very small orifices (typically 5–25 micrometres in diameter for E-Glass, 9 micrometres for S-Glass). These filaments are then sized (coated) with
3885-579: Is credited with producing the first composite boat in 1937 but did not proceed further at the time because of the brittle nature of the plastic used. In 1939 Russia was reported to have constructed a passenger boat of plastic materials, and the United States a fuselage and wings of an aircraft. The first car to have a fiberglass body was a 1946 prototype of the Stout Scarab , but the model did not enter production. Unlike glass fibers used for insulation, for
3996-432: Is developing inspection, maintenance, and prevention procedures similar to those used on wood utility poles to identify and prevent decay. British Telecom posts are usually marked with the following information: The date on the pole is applied by the manufacturer and refers to the date the pole was "preserved" (treated to withstand the elements). In the United States, utility poles are marked with information concerning
4107-401: Is essentially an entire two-dimensional plane; with woven fabrics or unidirectional layers, directionality of stiffness and strength can be more precisely controlled within the plane. A fiberglass component is typically of a thin "shell" construction, sometimes filled on the inside with structural foam, as in the case of surfboards. The component may be of nearly arbitrary shape, limited only by
4218-526: Is higher than about 0.025 mol/L. The best known of these is the tetraborate ion [B 4 O 7 ] , found in the mineral borax: Other anions observed in solution are triborate(1−) and pentaborate(1−), in equilibrium with boric acid and tetrahydroxyborate according to the following overall reactions: In the pH range 6.8 to 8.0, any alkali salts of "boric oxide" anions with general formula [B x O y (OH) z ](( q ) where 3 x + q = 2 y + z will eventually equilibrate in solution to
4329-513: Is pulled through forming machinery using either a hand-over-hand method or a continuous-roller method (as opposed to extrusion , where the material is pushed through dies). In fiberglass pultrusion, fibers (the glass material) are pulled from spools through a device that coats them with a resin. They are then typically heat-treated and cut to length. Fiberglass produced this way can be made in a variety of shapes and cross-sections, such as W or S cross-sections. People can be exposed to fiberglass in
4440-639: Is required, such as equipment cabinets and steel support structures, due to the ease with which it can be molded and painted to blend with existing structures and surfaces. Other uses include sheet-form electrical insulators and structural components commonly found in power-industry products. Because of fiberglass's lightweight and durability, it is often used in protective equipment such as helmets. Many sports use fiberglass protective gear, such as goaltenders' and catchers' masks. Storage tanks can be made of fiberglass with capacities up to about 300 tonnes . Smaller tanks can be made with chopped strand mat cast over
4551-561: Is soluble in water, so mineral deposits only occur in places with very low rainfall. Extensive deposits were found in Death Valley and shipped with twenty-mule teams from 1883 to 1889. In 1925, deposits were found at Boron , California on the edge of the Mojave Desert . The Atacama Desert in Chile also contains mineable borate concentrations. Lithium metaborate , lithium tetraborate, or
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4662-505: Is sometimes referred to as "fiberglass", the composite is also called fiberglass-reinforced plastic ( FRP ). This article uses "fiberglass" to refer to the complete fiber-reinforced composite material, rather than only to the glass fiber within it. Glass fibers have been produced for centuries, but the earliest patent was awarded to the Prussian inventor Hermann Hammesfahr (1845–1914) in the U.S. in 1880. Mass production of glass strands
4773-635: Is stronger than many metals by weight, non- magnetic , non- conductive , transparent to electromagnetic radiation , can be molded into complex shapes, and is chemically inert under many circumstances. Applications include aircraft, boats, automobiles, bath tubs and enclosures, swimming pools , hot tubs , septic tanks , water tanks , roofing, pipes, cladding, orthopedic casts , surfboards , and external door skins. Other common names for fiberglass are glass-reinforced plastic ( GRP ), glass-fiber reinforced plastic ( GFRP ) or GFK (from German : Glasfaserverstärkter Kunststoff ). Because glass fiber itself
4884-402: Is that the resins used are subject to contraction during the curing process. For polyester this contraction is often 5–6%; for epoxy, about 2%. Because the fibers do not contract, this differential can create changes in the shape of the part during curing. Distortions can appear hours, days, or weeks after the resin has set. While this distortion can be minimized by symmetric use of the fibers in
4995-528: Is the most significant cause of pole deterioration in the U.S. Other common utility pole materials are aluminum, steel and concrete, with composites (such as fiberglass ) also becoming more prevalent. One particular patented utility pole variant used in Australia is the Stobie pole , made up of two vertical steel posts with a slab of concrete between them. On poles carrying both electrical and communications wiring,
5106-427: Is the most widely used species in the United States; however, many species of long straight trees are used to make utility poles, including Douglas fir , jack pine , lodgepole pine , western red cedar , and Pacific silver fir . Traditionally, the preservative used was creosote , but due to environmental concerns, alternatives such as pentachlorophenol , copper naphthenate and borates are becoming widespread in
5217-460: Is used when tensile strength (high modulus) is important and is thus an important building and aircraft epoxy composite (it is called R-glass, "R" for "reinforcement" in Europe). C-glass ("C" for "chemical resistance") and T-glass ("T" is for "thermal insulator"—a North American variant of C-glass) are resistant to chemical attack; both are often found in insulation-grades of blown fiberglass. Fiberglass
5328-433: Is versatile because it is lightweight, strong, weather-resistant, and can have a variety of surface textures. During World War II, fiberglass was developed as a replacement for the molded plywood used in aircraft radomes (fiberglass being transparent to microwaves ). Its first main civilian application was for the building of boats and sports car bodies, where it gained acceptance in the 1950s. Its use has broadened to
5439-564: The International Agency for Research on Cancer (IARC) as "not classifiable as to carcinogenicity to humans" ( IARC group 3 ). "Epidemiologic studies published during the 15 years since the previous IARC monographs review of these fibers in 1988 provide no evidence of increased risks of lung cancer or mesothelioma (cancer of the lining of the body cavities) from occupational exposures during the manufacture of these materials, and inadequate evidence overall of any cancer risk." In June 2011,
5550-620: The oxidant to deposit CaB 2 O 4 , SrB 2 O 4 , BaB 2 O 4 , Mn 3 (BO 3 ) 2 , and CoB 2 O 4 films. Borate anions are largely in the form of the undissociated acid in aqueous solution at physiological pH. No further metabolism occurs in either animals or plants. In animals, boric acid/borate salts are essentially completely absorbed following oral ingestion. Absorption occurs via inhalation, although quantitative data are unavailable. Limited data indicate that boric acid/salts are not absorbed through intact skin to any significant extent, although absorption occurs through skin that
5661-712: The telephone exchange to local customers is a thick cable lashed to a thin supporting cable, containing hundreds of twisted pair subscriber lines . Each twisted pair line provides a single telephone circuit or local loop to a customer. There may also be FOCs interconnecting telephone exchanges. Like electrical distribution lines, communication cables connect to service drops when used to provide local service to customers. Utility poles may also carry other equipment such as street lights , supports for traffic lights and overhead wires for electric trolleys , and cellular network antennas. They can also carry fixtures and decorations specific for certain holidays or events specific to
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#17328766425285772-539: The European Union and Germany have classified synthetic glass fibers as possibly or probably carcinogenic, but fibers can be exempt from this classification if they pass specific tests. A 2012 health hazard review for the European Commission stated that inhalation of fiberglass at concentrations of 3, 16 and 30 mg/m3 "did not induce fibrosis nor tumours except transient lung inflammation that disappeared after
5883-526: The UK, boots fitted with steel loops that go around the pole (known as "Scandinavian Climbers") are also used for climbing poles. In the US, linemen use bucket trucks for the vast majority of poles that are accessible by vehicle. The poles at the end of a straight section of utility line where the line ends or angles off in another direction are called dead-end poles in the United States. Elsewhere they may be referred to as anchor or termination poles. These must carry
5994-553: The US National Toxicology Program (NTP) removed from its Report on Carcinogens all biosoluble glass wool used in home and building insulation and for non-insulation products. However, NTP still considers fibrous glass dust to be "reasonably anticipated [as] a human carcinogen (Certain Glass Wool Fibers (Inhalable))". Similarly, California's Office of Environmental Health Hazard Assessment (OEHHA) published
6105-535: 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. However, premature failure due to corrosion is a concern when compared to wood. The National Association of Corrosion Engineers Archived 2010-06-19 at the Wayback Machine or NACE
6216-505: The US). For economic or practical reasons, such as to save space in urban areas, a distribution line is often carried on the same poles as a sub transmission line but mounted under the higher voltage lines; a practice called "underbuild". Telecommunication cables are usually carried on the same poles that support power lines; poles shared in this fashion are known as joint-use poles, but may have their own dedicated poles. The standard utility pole in
6327-475: The United Kingdom, utility poles have sets of brackets arranged in a standard pattern up the pole to act as hand and foot holds so that maintenance and repair workers can climb the pole to work on the lines. In the United States, such steps have been determined to be a public hazard and are no longer allowed on new poles. Linemen may use climbing spikes called gaffs to ascend wooden poles without steps on them. In
6438-608: 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. Telephone, CATV, and FOCs are generally attached directly to the pole without insulators. In the United Kingdom, much of the rural electricity distribution system is carried on wooden poles. These normally carry electricity at 11 or 33 kV (three phases) from 132 kV substations supplied from pylons to distribution substations or pole-mounted transformers. Wooden poles have been used for 132 kV for
6549-486: The United States is about 35 ft (10 m) tall and is buried about 6 ft (2 m) in the ground. In order to meet clearance regulations, poles can, however, reach heights of at least 120 feet (40 meters). They are typically spaced about 125 ft (40 m) apart in urban areas, or about 300 ft (100 m) in rural areas, but distances vary widely based on terrain. Joint-use poles are usually owned by one utility, which leases space on it for other cables. In
6660-770: The United States, the National Electrical Safety Code , published by the Institute of Electrical and Electronics Engineers (IEEE) (not to be confused with the National Electrical Code published by the National Fire Protection Association [NFPA]), sets the standards for construction and maintenance of utility poles and their equipment. Most utility poles are made of wood, pressure-treated with some type of preservative for protection against rot, fungi and insects. Southern yellow pine
6771-479: The United States. In the United States, standards for wood preservative materials and wood preservation processes, along with test criteria, are set by ANSI , ASTM , and American Wood Protection Association (AWPA) specifications. Despite the preservatives, wood poles decay and have a life of approximately 25 to 50 years depending on climate and soil conditions, therefore requiring regular inspection and remedial preservative treatments. Woodpecker damage to wood poles
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#17328766425286882-589: 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. Six hundred and eighty of said posts to be 24 feet in length, and 20 of them 30 feet in length.'" In some parts of Australia, wooden poles are rapidly destroyed by termites , so metal poles must be used instead and in much of
6993-1152: The absorption of low frequency sound in seawater. Borates also occur in plants, including almost all fruits. The main borate anions are: In 1905, Burgess and Holt observed that fusing mixtures of boric oxide B 2 O 3 and sodium carbonate Na 2 CO 3 yielded on cooling two crystalline compounds with definite compositions, consistent with anhydrous borax Na 2 B 4 O 7 (which can be written Na 2 O·2B 2 O 3 ) and sodium octaborate Na 2 B 8 O 13 (which can be written Na 2 O·4B 2 O 3 ). Borate anions (and functional groups) consist of trigonal planar BO 3 and/or tetrahedral BO 4 structural units, joined together via shared oxygen atoms (corners) or atom pairs (edges) into larger clusters so as to construct various ions such as [B 2 O 5 ] , [B 3 O 8 ] , [B 4 O 12 ] , [B 5 O 6 (OH) 5 ] , [B 6 O 13 ] , etc. These anions may be cyclic or linear in structure, and can further polymerize into infinite chains, layers, and tridimensional frameworks. The terminal (unshared) oxygen atoms in
7104-458: The air near manufacturing facilities or when they are near building fires or implosions . The American Lung Association advises that fiberglass insulation should never be left exposed in an occupied area. Since work practices are not always followed, and fiberglass is often left exposed in basements that later become occupied, people can get exposed. No readily usable biological or clinical indices of exposure exist. Fiberglass will irritate
7215-599: The automotive and sport equipment sectors. In the production of some products, such as aircraft, carbon fiber is now used instead of fiberglass, which is stronger by volume and weight. Advanced manufacturing techniques such as pre-pregs and fiber rovings extend fiberglass's applications and the tensile strength possible with fiber-reinforced plastics. Fiberglass is also used in the telecommunications industry for shrouding antennas , due to its RF permeability and low signal attenuation properties. It may also be used to conceal other equipment where no signal permeability
7326-710: The borate anions may be capped with hydrogen atoms ( −OH ) or may carry a negative charge ( −O ). The planar BO 3 units may be stacked in the crystal lattice so as to have π-conjugated molecular orbitals , which often results in useful optical properties such as strong harmonics generation, birefringence , and UV transmission . Polymeric borate anions may have linear chains of 2, 3 or 4 trigonal BO 3 structural units, each sharing oxygen atoms with adjacent unit(s). as in LiBO 2 , contain chains of trigonal BO 3 structural units. Other anions contain cycles; for instance, NaBO 2 and KBO 2 contain
7437-483: The bottom connected to a metal rod driven into the ground. Some countries ground every pole while others only ground every fifth pole and any pole with a transformer on it. This provides a path for leakage currents across the surface of the insulators to get to ground, preventing the current from flowing through the wooden pole which could cause a fire or shock hazard. It provides similar protection in case of flashovers and lightning strikes. A surge arrester (also called
7548-427: The brand is usually the pole's ANSI class, used to determine maximum load; this number ranges from 10 to H6 with a smaller number meaning higher strength. The pole's height (from butt to top) in 5-foot increments is usually to the right of the class separated by a hyphen, although it is not uncommon for older brands to have the height on a separate line. The pole brand is sometimes an aluminum tag nailed in place. Before
7659-465: The cables would be expensive. Another situation in which pole routes were extensively used were on the railways to link signal boxes . Traditionally, prior to around 1965, pole routes were built with open wires along non-electrical operated railways; this necessitated insulation when the wire passed over the pole, thus preventing the signal from becoming attenuated. At electrical operated railways, pole routes were usually not built as too much jamming from
7770-843: The city where they are located. Solar panels mounted on utility poles may power auxiliary equipment where the expense of a power line connection is unwanted. Streetlights and holiday fixtures are powered directly from secondary distribution. The primary purpose of pole attachment hardware is to secure the cable and associated aerial plant facilities to poles and to help facilitate necessary plant rearrangements. An aerial plant network requires high-quality reliable hardware to Functional performance requirements common to pole line hardware for utility poles made of wood, steel, concrete, or Fiber-Reinforced Composite (FRC) materials are contained in Telcordia GR-3174, Generic Requirements for Hardware Attachments for Utility Poles . In some countries, such as
7881-550: The complexity and tolerances of the mold used for manufacturing the shell. The mechanical functionality of materials is heavily reliant on the combined performances of both the resin (AKA matrix) and fibers. For example, in severe temperature conditions (over 180 °C), the resin component of the composite may lose its functionality, partially due to bond deterioration of resin and fiber. However, GFRPs can still show significant residual strength after experiencing high temperatures (200 °C). One notable feature of fiberglass
7992-412: The construction of composite housing, and can include insulation to reduce heat loss. In rod pumping applications, fiberglass rods are often used for their high tensile strength to weight ratio. Fiberglass rods provide an advantage over steel rods because they stretch more elastically (lower Young's modulus ) than steel for a given weight, meaning more oil can be lifted from the hydrocarbon reservoir to
8103-587: The cyclic [B 3 O 6 ] ion, consisting of a six-membered ring of alternating boron and oxygen atoms with one extra oxygen atom attached to each boron atom. The thermal expansion of crystalline borates is dominated by the fact that BO 3 and BO 4 polyhedra and rigid groups consisting of these polyhedra practically do not change their configuration and size upon heating, but sometimes rotate like hinges, which results in greatly anisotropic thermal expansion including linear negative expansion. In aqueous solution, boric acid B(OH) 3 can act as
8214-973: The design, a certain amount of internal stress is created; and if it becomes too great, cracks form. The most common types of glass fiber used in fiberglass is E-glass , which is alumino-borosilicate glass with less than 1% w/w alkali oxides, mainly used for glass-reinforced plastics. Other types of glass used are A-glass ( A lkali-lime glass with little or no boron oxide), E-CR-glass ( E lectrical/ C hemical R esistance; alumino-lime silicate with less than 1% w/w alkali oxides, with high acid resistance), C-glass (alkali-lime glass with high boron oxide content, used for glass staple fibers and insulation), D-glass (borosilicate glass, named for its low D ielectric constant), R-glass (alumino silicate glass without MgO and CaO with high mechanical requirements as R einforcement), and S-glass (alumino silicate glass without CaO but with high MgO content with high tensile strength). Pure silica (silicon dioxide), when cooled as fused quartz into
8325-433: The early 1940s, and many sailing vessels made after 1950 were built using the fiberglass lay-up process . As of 2022, boats continue to be made with fiberglass, though more advanced techniques such as vacuum bag moulding are used in the construction process. Though most bullet-resistant armours are made using different textiles, fiberglass composites have been shown to be effective as ballistic armor. Filament winding
8436-587: The electric power distribution lines and associated equipment are mounted at the top of the pole above the communication cables, for safety. The vertical space on the pole reserved for this equipment is called the supply space . The wires themselves are usually uninsulated, and supported by insulators , commonly mounted on a horizontal beam ( crossarm ). Power is transmitted using the three-phase system, with three wires, or phases, labeled "A", "B", and "C". Sub transmission lines comprise only these 3 wires, plus sometimes an overhead ground wire (OGW), also called
8547-657: The electric power lines, in a vertical space along the pole designated the communications space . The communications space is separated from the lowest electrical conductor by the communication worker safety zone , which provides room for workers to maneuver safely while servicing the communication cables, avoiding contact with the power lines. The most common communication cables found on utility poles are copper or fibre-optic cable (FOC) for telephone lines and coaxial cable for cable television (CATV). Coaxial or optical fibre cables linking computer networks are also increasingly found on poles in urban areas. The cable linking
8658-420: 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. The pole may be grounded with a heavy bare copper or copper-clad steel wire running down the pole, attached to the metal pin supporting each insulator, and at
8769-562: The eyes, skin, and the respiratory system. Hence, symptoms can include itchy eyes, skin, nose, sore throat, hoarseness, dyspnea (breathing difficulty) and cough. Peak alveolar deposition was observed in rodents and humans for fibers with diameters of 1 to 2 μm. In animal experiments, adverse lung effects such as lung inflammation and lung fibrosis have occurred, and increased incidences of mesothelioma , pleural sarcoma , and lung carcinoma had been found with intrapleural or intratracheal instillations in rats. As of 2001, in humans only
8880-563: The fiber has an effect on the properties of the final product. A high angle "hoop" will provide circumferential or "burst" strength, while lower angle patterns (polar or helical) will provide greater longitudinal tensile strength. Products currently being produced using this technique range from pipes, golf clubs, Reverse Osmosis Membrane Housings, oars, bicycle forks, bicycle rims, power and transmission poles, pressure vessels to missile casings, aircraft fuselages and lamp posts and yacht masts. A release agent, usually in either wax or liquid form,
8991-434: The fiber is weak in compression, it is actually only the long aspect ratio of the fiber which makes it seem so; i.e., because a typical fiber is long and narrow, it buckles easily. On the other hand, the glass fiber is weak in shear—that is, across its axis. Therefore, if a collection of fibers can be arranged permanently in a preferred direction within a material, and if they can be prevented from buckling in compression,
9102-415: The fiberglass and the mold. Additional resin is applied and possibly additional sheets of fiberglass. Hand pressure, vacuum or rollers are used to be sure the resin saturates and fully wets all layers, and that any air pockets are removed. The work must be done quickly before the resin starts to cure unless high-temperature resins are used which will not cure until the part is warmed in an oven. In some cases,
9213-420: The final structure to be strong, the fiber's surfaces must be almost entirely free of defects, as this permits the fibers to reach gigapascal tensile strengths . If a bulk piece of glass were defect-free, it would be as strong as glass fibers; however, it is generally impractical to produce and maintain bulk material in a defect-free state outside of laboratory conditions. The process of manufacturing fiberglass
9324-882: The functionality of machines and equipment. The installation of effective extraction and filtration equipment is required to ensure safety and efficiency. Borate A borate is any of a range of boron oxyanions , anions containing boron and oxygen , such as orthoborate BO 3− 3 , metaborate BO − 2 , or tetraborate B 4 O 2− 7 ; or any salt of such anions, such as sodium metaborate , Na [BO 2 ] and borax (Na ) 2 [B 4 O 7 ] . The name also refers to esters of such anions, such as trimethyl borate B(OCH 3 ) 3 but they are alkoxides. Borate ions occur, alone or with other anions, in many borate and borosilicate minerals such as borax , boracite , ulexite (boronatrocalcite) and colemanite . Borates also occur in seawater, where they make an important contribution to
9435-459: The gas content of the material was replaced by plastic. This reduced the insulation properties to values typical of the plastic, but now for the first time, the composite showed great strength and promise as a structural and building material. Many glass fiber composites continued to be called "fiberglass" (as a generic name) and the name was also used for the low-density glass wool product containing gas instead of plastic. Ray Greene of Owens Corning
9546-473: The glass into short lengths and drops it into a jet of resin, projected onto the surface of a mold), or in an intermediary step, to manufacture fabrics such as chopped strand mat (CSM) (made of randomly oriented small cut lengths of fiber all bonded together), woven fabrics, knit fabrics or unidirectional fabrics. Chopped strand mat (CSM) is a form of reinforcement used in fiberglass. It consists of glass fibers laid randomly across each other and held together by
9657-467: The high distribution voltage to the lower secondary voltage provided to the customer. In North America , service drops provide 240/120 V split-phase power for residential and light commercial service, using cylindrical single-phase transformers. In Europe and most other countries, 230 V three phase (230Y400) service drops are used. The transformer's primary is connected to the distribution line through protective devices called fuse cutouts . In
9768-534: 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. In the United States, ANSI standard 05.1.2008 governs wood pole sizes and strength loading. Utilities that fall under the Rural Electrification Act must also follow the guidelines set forth in RUS Bulletin 1724E-150 (from
9879-531: The interior wooden poles are vulnerable to fire. The Oppenheimer pole is a collapsible wrought iron pole in three sections. It is named after Oppenheimer and Company in Germany, but they were mostly manufactured in England under license. 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
9990-597: The lateral tension of the long straight sections of wire. They are usually made with heavier construction. The power lines are attached to the pole by horizontal strain insulators, either placed on crossarms (which are either doubled, tripled, or replaced with a steel crossarm, to provide more resistance to the tension forces) or attached directly to the pole itself. Dead-end and other poles that support lateral loads have guy-wires to support them. The guys always have strain insulators inserted in their length to prevent any high voltages caused by electrical faults from reaching
10101-441: The legal limit ( permissible exposure limit ) for fiberglass exposure in the workplace as 15 mg/m total and 5 mg/m in respiratory exposure over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 3 fibers/cm (less than 3.5 micrometers in diameter and greater than 10 micrometers in length) as a time-weighted average over an 8-hour workday, and
10212-425: 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. Another means of providing support for lateral loads is a push brace pole, a second shorter pole that
10323-413: The mandrel is completely covered to the desired thickness, the resin is cured; often the mandrel is placed in an oven to achieve this, though sometimes radiant heaters are used with the mandrel still turning in the machine. Once the resin has cured, the mandrel is removed, leaving the hollow final product. For some products such as gas bottles, the 'mandrel' is a permanent part of the finished product forming
10434-641: The manufacturer forces preservatives into the wood, until it refuses to accept more, but performance is not guaranteed. Some of these were still in service after 80 years. The building of pole lines was resisted in some urban areas in the late 19th century, 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. Errant traffic being uncommon on railways, their poles are usually less tall. In
10545-455: The manufacturer, pole height, ANSI strength class, wood species, original preservative, and year manufactured (vintage) in accordance with ANSI standard O5.1.2008. This is called branding, as it is usually burned into the surface; the resulting mark is sometimes called the "birth mark". Although the position of the brand is determined by ANSI specification, it is essentially just below "eye level" after installation. A rule of thumb for understanding
10656-449: The material will be preferentially strong in that direction. Furthermore, by laying multiple layers of fiber on top of one another, with each layer oriented in various preferred directions, the material's overall stiffness and strength can be efficiently controlled. In fiberglass, it is the plastic matrix which permanently constrains the structural glass fibers to directions chosen by the designer. With chopped strand mat, this directionality
10767-586: The more biopersistent materials like ceramic fibres, which are used industrially as insulation in high-temperature environments such as blast furnaces , and certain special-purpose glass wools not used as insulating materials remain classified as possible carcinogens ( IARC Group 2B ). The more commonly used glass fibre wools including insulation glass wool , rock wool and slag wool are considered not classifiable as to carcinogenicity to humans ( IARC Group 3 ). In October 2001, all fiberglass wools commonly used for thermal and acoustical insulation were reclassified by
10878-605: The overhead wire would occur. To accomplish this, cables were separated using spars with insulators spaced along them; in general four insulators were used per spar. Only one such pole route still exists on the UK rail network, in the highlands of Scotland. 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. Utility poles are used by birds for nesting and to rest on. Utility poles and related structures are regarded by some to be
10989-418: 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 . A pole route (or pole line in the US) is a telephone link or electrical power line between two or more locations by way of multiple uninsulated wires suspended between wooden utility poles. This method of link is common especially in rural areas where burying
11100-417: The practice of branding, many utilities would set a 2- to 4-digit date nail into the pole upon installation. The use of date nails went out of favor during World War II due to war shortages but is still used by a few utilities. These nails are considered valuable to collectors, with older dates being more valuable, and unique markings such as the utilities' name also increasing the value. However, regardless of
11211-626: The rest of the world through a submarine cable at Darwin . The Stobie pole was invented in 1924 by James Cyril Stobie of the Adelaide Electric Supply Company and first used in South Terrace, Adelaide . One of the early Bell System lines was the Washington DC–Norfolk line which was, for the most part, square-sawn tapered poles of yellow pine probably treated to refusal with creosote . "Treated to refusal" means that
11322-628: The surface with each stroke, all while reducing the load on the pumping unit. Fiberglass rods must be kept in tension, however, as they frequently part if placed in even a small amount of compression. The buoyancy of the rods within a fluid amplifies this tendency. GRP and GRE pipe can be used in a variety of above- and below-ground systems, including those for desalination, water treatment, water distribution networks, chemical process plants, water used for firefighting, hot and cold drinking water, wastewater/sewage, municipal waste and liquified petroleum gas . Fiberglass composite boats have been made since
11433-520: The toxicity of creosote-treated wood waste, such as utility poles. Specifically, their biodegradation can release phenolic compounds in soil, which are considered toxic. Research continues to explore methods to render this waste safe for disposal. Historically, pole-mounted transformers were filled with a polychlorinated biphenyl (PCB) liquid. PCBs persist in the environment and have adverse effects on animals. Fiberglass Fiberglass ( American English ) or fibreglass ( Commonwealth English )
11544-616: The trees used for telegraph poles were either native larch or pine from Sweden and Norway. Poles in early installations were treated with tar, but these were found to last only around seven years. Later poles were treated instead with creosote or copper sulphate for the preservative. Utility poles were first used in the mid-19th century in America with telegraph systems. In 1844, the United States Congress granted Samuel Morse $ 30,000 (equivalent to $ 981,000 in 2023) to build
11655-423: The value to collectors, all attachments on a utility pole are the property of the utility company, and unauthorized removal is a misdemeanor or felony. A practice in some areas is to place poles on coordinates upon a grid. The pole at right is a Delmarva Power pole located in a rural area of the state of Maryland in the United States. The lower two tags are the "X" and "Y" coordinates along said grid. Just as in
11766-606: The voltage down from the primary voltage to the lower secondary voltage used by the customer. A service drop carries this lower voltage to the customer's premises. Subtransmission lines carry higher voltage power from regional substations to local substations. They usually carry 46 kV, 69 kV, or 115 kV for distances up to 60 mi (100 km). 23 kV lines are often supported on H-shaped towers made with two or three poles. Transmission lines carrying voltages of above 230 kV are usually not supported by poles, but by metal pylons (known as transmission towers in
11877-482: The work is covered with plastic sheets and vacuum is drawn on the work to remove air bubbles and press the fiberglass to the shape of the mold. The fiberglass spray lay-up process is similar to the hand lay-up process but differs in the application of the fiber and resin to the mold. Spray-up is an open-molding composites fabrication process where resin and reinforcements are sprayed onto a mold. The resin and glass may be applied separately or simultaneously "chopped" in
11988-415: The workplace during its fabrication, installation or removal, by breathing it in, by skin contact, or by eye contact. Furthermore, in the manufacturing process of fiberglass, styrene vapors are released while the resins are cured. These are also irritating to mucous membranes and respiratory tract. The general population can get exposed to fibreglass from insulation and building materials or from fibers in
12099-490: Was accidentally discovered in 1932 when Games Slayter , a researcher at Owens-Illinois , directed a jet of compressed air at a stream of molten glass and produced fibers. A patent for this method of producing glass wool was first applied for in 1933. Owens joined with the Corning company in 1935 and the method was adapted by Owens Corning to produce its patented "Fiberglas" (spelled with one "s") in 1936. Originally, Fiberglas
12210-425: Was a glass wool with fibers entrapping a great deal of gas, making it useful as an insulator, especially at high temperatures. A suitable resin for combining the fiberglass with a plastic to produce a composite material was developed in 1936 by DuPont . The first ancestor of modern polyester resins is Cyanamid 's resin of 1942. Peroxide curing systems were used by then. With the combination of fiberglass and resin
12321-443: Was the first type of glass used for fiberglass. E-glass ("E" because of initial Electrical application), is alkali-free and was the first glass formulation used for continuous filament formation. It now makes up most of the fiberglass production in the world, and also is the single largest consumer of boron minerals globally. It is susceptible to chloride ion attack and is a poor choice for marine applications. S-glass ("S" for "stiff")
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