A Stobie pole is a power line pole made of two steel I-beams, joined by tie-bolts, and held apart by a slab of concrete. It was invented by Adelaide Electric Supply Company engineer James Cyril Stobie, who suggested the use of readily available materials due to the shortage of suitably long, strong, straight and termite-resistant timber in South Australia.
They have continued to be used in the state capital, Adelaide, and around South Australia ever since, and there are some in other places in Australia as well. Since the 1980s, many Stobie poles have been decorated with artworks or surrounded with plants to beautify them.
In July 1924 engineer James Cyril Stobie (1895–1953) [1] submitted the patent application for his pole design in both English and French. It was accepted in November 1925. Stobie described his invention as
...an improved pole adopted to be used for very many purposes, but particularly for carrying electric cables, telegraph wires... [it] consists of two flanged beams of iron or steel, preferably rolled steel joist of 'H' or of channel sections, placed one beside the other with their flanges inward and preferably at a very slight angle one with the other and held together by means of tie bolts, the space between them being filled with cement concrete. [2]
A second patent was granted to Stobie and Frederick William Herbert Weadon in 1946. With John Ragless Brookman they formed The Stobie Pole Syndicate [3] for the purpose of patenting the design and then selling the patent or manufacturing rights. The Hume Pipe Company became their first agents and, while there were numerous international enquiries, as of the mid-1990s South Australia remained the only place where they are widely used. [2]
The first poles were erected in South Terrace, Adelaide city centre, in 1924, and were then used extensively in building the electricity transmission and distribution infrastructure throughout the state. The Stobie pole was central to the speedy expansion of Adelaide Electricity Supply Company's supply. It was cheap and simple to produce, had a uniform appearance, saved an enormous amount of timber from being harvested, had a long life expectancy and, at the time, was seen as more environmentally sensitive. [2]
Stobie poles are also common in Broken Hill, as well as the Darwin CBD, and there are a few thousand installed across Tasmania.[ citation needed ] A few also exist in Canberra [4] and isolated settlements in the Goldfields-Esperance region of Western Australia such as Eucla and Rawlinna.[ citation needed ]
SA Power Networks review alternative pole designs available on the market from time to time and has yet to find one with the benefits offered by the Stobie pole, which include long life, low cost and ease of maintenance, and resilience in bushfire and flooding events. One disadvantage is greater susceptibility to lightning strikes. [5]
SAPN sister company, Powercor, also has a number of stobie poles installed on its network.
Each year SA Power Networks manufactures around 4,500 Stobie poles at a plant in Angle Park, South Australia. [5]
The poles carry supply voltages from 240 to 275,000 volts and come in various sizes from 9–26 m (30–85 ft) in length, though studies indicate heights to 36 m (118 ft) are feasible. [6] The service life of a Stobie pole is predicted to be in excess of 80 years. It is now commonly regarded as a South Australian icon. [5] [7]
Its modern construction is a composite of two steel I-beams connected intermittently by bolts to manage compressive buckling, with the gap between the beams filled with concrete. The bolts transfer the shear, with an equal number of bolts above and below ground. The poles are tapered from ground level to the top and the toe. This construction uses the tensile properties of the steel, giving the poles excellent properties in bending. Stobie pole strength in the strong direction may be up to 4.5 times the weak direction strength. [8] Small holes through the concrete enable attachment of modular cross-arms, insulators and other hardware. The poles are fireproof, rotproof, and termiteproof. Stobie poles are widely regarded in Australia to be dangerous to vehicles, with collisions sometimes "almost cutting the vehicle in half". [9] [10] [11]
Stobie pole designs are calculated to ensure the installation uses a suitably sized pole. Factors such as physical mass (static load) of transformers, cross beams, voltage regulators, protection devices, conductors (including tension), etc. are considered, and the wind loading (dynamic load) of this equipment must also be calculated. In some cases the wind loading factors far exceed the static load values. [8]
Stobie poles were first used for art in the 1980s by pioneering artist Ann Newmarch, who lived and worked in Prospect. [12]
Artist Clifton Pugh painted Adam and Eve in the Garden of Eden on a Stobie pole in 1984, but was subsequently asked to "cover up" the genitals on his painting. [13]
Since then, various attempts have been made to beautify their appearance through Stobie pole gardens [14] [15] and Stobie pole art projects. [16] [17]
SA Power Networks has an application process for submitting designs for Stobie pole art, used by community groups, artists, and primary and high schools, which have painted murals or installed mosaics on Stobie poles located outside their premises. [5]
Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines that facilitate this movement form a transmission network. This is distinct from the local wiring between high-voltage substations and customers, which is typically referred to as electric power distribution. The combined transmission and distribution network is part of electricity delivery, known as the electrical grid.
A flange is a protruded ridge, lip or rim, either external or internal, that serves to increase strength ; for easy attachment/transfer of contact force with another object ; or for stabilizing and guiding the movements of a machine or its parts. Flanges are often attached using bolts in the pattern of a bolt circle.
Electric power distribution is the final stage in the delivery of electricity. Electricity is carried from the transmission system to individual consumers. Distribution substations connect to the transmission system and lower the transmission voltage to medium voltage ranging between 2 kV and 33 kV with the use of transformers. Primary distribution lines carry this medium voltage power to distribution transformers located near the customer's premises. Distribution transformers again lower the voltage to the utilization voltage used by lighting, industrial equipment and household appliances. Often several customers are supplied from one transformer through secondary distribution lines. Commercial and residential customers are connected to the secondary distribution lines through service drops. Customers demanding a much larger amount of power may be connected directly to the primary distribution level or the subtransmission level.
Single-wire earth return (SWER) or single-wire ground return is a single-wire transmission line which supplies single-phase electric power from an electrical grid to remote areas at lowest cost. The earth is used as the return path for the current, to avoid the need for a second wire to act as a return path.
A transmission tower is a tall structure, usually a lattice tower made of steel that is used to support an overhead power line. In electrical grids, transmission towers carry high-voltage transmission lines that transport bulk electric power from generating stations to electrical substations, from which electricity is delivered to end consumers; moreover, utility poles are used to support lower-voltage sub-transmission and distribution lines that transport electricity from substations to electricity customers.
A utility pole 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. It can be referred to as a transmission pole, telephone pole, telecommunication pole, power pole, hydro pole, telegraph pole, or telegraph post, 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.
An I-beam is any of various structural members with an Ɪ- or H-shaped cross-section. Technical terms for similar items include H-beam, I-profile, universal column (UC), w-beam, universal beam (UB), rolled steel joist (RSJ), or double-T. I-beams are typically made of structural steel and serve a wide variety of construction uses.
A girder is a beam used in construction. It is the main horizontal support of a structure which supports smaller beams. Girders often have an I-beam cross section composed of two load-bearing flanges separated by a stabilizing web, but may also have a box shape, Z shape, or other forms. Girders are commonly used to build bridges.
The Electricity Trust of South Australia (ETSA) was the South Australian Government-owned monopoly vertically integrated electricity provider from 1946 until its privatisation in 1999.
A girder bridge is a bridge that uses girders as the means of supporting its deck. The two most common types of modern steel girder bridges are plate and box.
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The Adelaide Desalination plant (ADP), formerly known as the Port Stanvac Desalination Plant, is a sea water reverse osmosis desalination plant located in Lonsdale, South Australia which has the capacity to provide the city of Adelaide with up to 50% of its drinking water needs.
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The provision of electricity in Queensland required a considerable degree of pioneering, innovation, and commitment. Queensland proved to be a pioneer in the supply of electricity in Australia, with the first public demonstration in Australia, the first recorded use for public purposes in the country, the first Parliament House in Australia and the first commercial operations in Australia all occurring in Brisbane.
Mobile cell sites are infrastructures transportable on trucks, allowing fast and easy installation in restricted spaces. Their use is strategic for the rapid expansion of cellular networks putting into service point-to-point radio connections as well as supporting sudden increases in mobile traffic in the case of extraordinary events. Mobile cell sites are also used by law enforcement organizations to gather intelligence. Mobile cell sites require neither civil works nor foundations, just minimal requirements like commercial power and grounding. The mobile units have been designed to be a temporary solution, but if requested, they can be transformed into permanent stations.
South Australia is a leader in utility-scale renewable energy generation, and also produces gas and uranium for electricity generation. Gas production is mostly concentrated in the Cooper Basin in the state's north-east. Gas is delivered from these fields by pipeline to users interstate and to Port Adelaide where it fuels three separate gas-fired power plants. Uranium is also mined in South Australia, though nuclear power generation is prohibited nationally. The Olympic Dam mine is the world's single largest known deposit of uranium and represents 30% of the world's total uranium resource. Many utility-scale wind farms and solar farms have been commissioned during the 21st century and geology with potential for geothermal energy has also been identified but is yet to be developed.
Sir George Brookman KBE was a South Australian businessman who made a fortune from a gold discovery in Western Australia, and is remembered as a generous benefactor of the South Australian School of Mines and Industries and the University of Adelaide.
Stobie the Disco Cuttlefish was the mascot of the 2014 Adelaide Fringe in South Australia. Its design was inspired by the cephalopod species the Australian giant cuttlefish. Stobie was a 13 metre long mechanised parade float which featured blinking eyes, waving tentacles and an elaborate sound, light and dance show. It made appearances each Saturday night during the festival, accompanied by a professional dance troupe which performed a set routine. This was followed by an original dance called 'The Cuttlefish' during which crowd participation was invited. Stobie also played a pre-recorded soundtrack of disco hits including a megamix of "Stayin' Alive", "Billie Jean", "You Should Be Dancing" and "Le Freak". The opening set routine was performed to the theme-song from the 1980 dance movie, Fame.
Ann Foster Newmarch, known as "Annie", was a South Australian painter, printmaker, sculptor and academic, with an international reputation, known for her community service to art, social activism and feminism. She co-founded the Progressive Art Movement and the Women's Art Movement (WAM) in Adelaide, and is especially known for her iconic 1978 colour screenprint piece titled Women Hold Up Half the Sky!.
The South Australian blackout of 2016 was a widespread power outage in South Australia that occurred as a result of storm damage to electricity transmission infrastructure on 28 September 2016. The cascading failure of the electricity transmission network resulted in almost the entire state losing its electricity supply, affecting 850,000 SA customers. Kangaroo Island did not lose its supply, as the Kangaroo Island power station had been built to supply the island for the contingency of a failure in the power cable under the Backstairs Passage.
Media related to Stobie poles at Wikimedia Commons