Steel is typically used in housing, enclosure and support systems struts and cable trays. Overhead conductor installation guide general cable. I am really confused as to why a power release is being held up because the inspector had a question as to wheather anti oxidant was used on the aluminum conductors of a residential service. An acsr conductor can in part be denoted by its stranding, for example, an acsr conductor with 72 aluminium strands with a core of 7 steel strands will be called 727 acsr conductor.
It degrades the conductivity of the aluminum and makes contacting difficult. The language has remained relatively unchanged since then. It would have been far cheaper to go with aluminum wiring, with the price of. Oxidation of conductors electrical engineering portal. Conductaclean from afl agitates a specialized solution to remove oxidation and grime from conductor strands, and can be adjusted for one, three or six minute cycles depending on the condition of the conductor.
For example, it is necessary if an aluminium ring conductor is located in an industrial area, but the adjacent plants are supplied via copper conductors. Start studying splicing and terminating low voltage. In my opinion there is nothing wrong with aluminum conductors. Aluminum and aluminum alloys have many outstanding attributes that lead to a wide range of applications, including good corrosion and oxidation resistance, high electrical and thermal conductivities, low density, high reflectivity, high ductility and reasonably high strength, and.
The oxide layer should be removed, and an oxideinhibiting compound applied to reduce oxidation. It exhibits the highest state of oxidation, allowing hydrodynamic stability no ageing, chemical inertness and a resistance to corrosion. Both materials can be fabricated into various types of flexible or rigid conductors. Aluminum oxide is a fast forming, hard, nonconductive coating that develops on the surface of aluminum conductors exposed to air. Minimize corrosion of electrodes and grounding conductors in irrigation systems irrigation professionals have been using various grounding grids for electronic equipment for over 30 years. Many electricians recommend changing out aluminum wires in favor copper wiring. Bare aluminum conductors are built with a righthand lay on the outside layer, so the bullwheel tensioner, regardless of the type, must be a righthand lay design. The primary reason for choosing aluminum windings is.
This means an increase in heat that possibly results in fire. These compounds retard oxidation at the connector conductor interface, and they do not have. Use of anti oxident on aluminum wire mike holts forum. The areas of application of copper and aluminium as electrical conductors are relatively distinct, and mainly depend on material properties other than con ductivity density is the main example. This compound is quite stable and does not experience the problems of the older compound. The nec recognized aluminum alloy conductor materials in 1981 and expanded their use in 1987. The aluminum association use to publish a book on proper installation of aluminum conductors, basics were wire brush conductors, coat with noox and wire brush again, set in connector and torque connection to the recommenced value.
Aluminum is an excellent conductor of heat and electricity. Book for wire connectors zmvv, oxide inhibitor for aluminum or copper wire. To attribute to an aluminium conductor the same resistance as a copper conductor, the crosssectional area of the aluminium conductor must become larger to compensate for aluminium s higher electrical resistivity. The 8000 series aluminum conductor alloys appear to have corrected many problems that originally occurred with aluminum wire, such as creep failure and excessive thermal expansion. Ultrathin aluminum oxide as a thermal oxidation barrier. The reactivity of aluminum powders is determined using the following parameters. The issues included a large coefficient of thermal expansion, a susceptibility to bending and creep failures, a high rate of oxidation and a. Ul in their white book general information for electrical equipment, 2002 edition has the following information. Aluminum wire is more easily oxidized than copper wire, and the compound formed by this process aluminum oxide is less. Unlike copper oxides, aluminum oxide is not visually obvious and should be assumed to exist in all cases of bare aluminum. Corrosion behaviour of aluminium in marine environnements. The trend in substation construction is toward use of mostly aluminum conductors. Aluminium oxide is not an electrical conductor, but rather an electrical insulator.
In some corrosive locations, aluminum performs better and in others copper performs better, but you have to do the research when the question arises. I am familiar with chromate conversion coatings on aluminum per milc5541 link is to free spec at defense logistics agency, dla. Design considerations when terminating aluminum wire. Reducing the risk of aluminum wiring hazards, part 1. Connector sample assembly with equalizers and conductor copper conductor with aluminum connector samples shown. Their diameters are controllable within the range 5 100 nm as a linear function of anodisation voltage. The resulting oxidation causes extra resistance to the electric current. Anodic oxidation of aluminium and its alloys focuses on the basic principles of anodic oxidation, choice of materials, pretreatment, design, properties of the anodic film, testing, and maintenance. In most other areas of the world, copper is the predominant winding material. It crystallizes in the facecentred cubic structure. Astms electrical and magnetic conductor standards are instrumental in specifying, evaluating, and testing the electrical, magnetic, and physical properties of conducting materials used primarily in electrical and magnetic devices and related equipments. Correctly connecting al and cu klauke professional tools.
We use and prefer class 3 for electrical conductivity. Steel, aluminum and copper are the three main metals used in electrical applications. However, particularly when preparing joints on aluminium conductors, attention must be paid to the connector in regard to the phenomenon of oxidation. Earlier aluminum conductors were susceptible to failure several issues were encountered with the use of aluminum alloy 50 for conductors. To understand the aluminum wiring fiasco, it pays to keep in mind not only the. However, with the compact conductors normally used for aluminum alloy building wire, conduit sizing is generally the same for equal ampacity copper and aluminum. In north america, aluminum is the predominant choice of winding material for lowvoltage, drytype transformers larger than 15 kilovoltampereskva. We have investigated the role of aluminum oxide films as barriers to thermal oxidation of co, ni, fe, ni fe, mn, ta, cu 80 20 and cr in air. Some rare corrosion occurrences have been reported to bare copper grounding conductors recently. Aluminum building wire installation and terminations.
Aluminum building wire installation and terminations iaei magazine. Aluminum wire terminations, oversize distribution panels and more. For the vast majority of locations, either copper or aluminum alloy conductors are equally acceptable, and in certain circumstances, even utility grade aluminum is acceptable per the nec. Anodic oxidation of aluminium and its alloys sciencedirect. And aluminum can be found most oft en in conductors, conduits, armor. Mesoporous alumina membranes anodic aluminium oxide, or aao are prepared by anodic oxidation of aluminium metal 1,2. Once the oxides are stabilized, they prevent further oxidation of the parent metal. For several code cycles now the nec has specified aa8000 aluminum compound for conductors. All natural aluminum is the stable isotope aluminum 27. The oxidation of the film is monitored by measuring the electrical resistance following a brief anneal in air. Aluminum oxide must be removed from a conductor s surface prior to making a connection. Copper connectors are available for use with copper conductor, and aluminum connectors are available for use with copper and aluminum conductors. Aluminum terminations are evaluated by ul and the evaluations are done without the use of oxide inhibitor.
If you are unsure about whether your home may be affected, call westridge electric to book a home inspection. The thin, protective layer of oxide on aluminum conductors contributes to the. Electrical standards and magnetic conductor standards. Corrosion of aluminium and copper in cable conductors. Highresistance oxides form very quickly on aluminum and copper conductors expose to air.
This protection can be seen on copper roofs and gutter work as well as on outdoor sculptures and statuary, namely the statue of liberty. Excess heat caused home fires and thats why people got so scared of aluminum wiring. Equipment manufactured under these standards whether the conductor is al or cu must meet the prescribed criteria for short circuit withstand testing. The nec does not require oxide inhibitor for either aluminum or copper, but it does. These consisted of 1 m lengths of copper and aluminum bare conductor with no connector attached. Oxidation results from a chemical reaction between oxygen and aluminum, yielding an oxide layer on the conductor. Grillini, in biotribocorrosion in biomaterials and medical implants, 20. This difference is highly relevant for power cables. Several issues were encountered with the use of aluminum alloy 50 for conductors.
Oxidation adds a verdigris color bluegreen to copper or copper carbonates like brass or bronze. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The cylindrical pores, perpendicular to the membrane surface, form hexagonal arrays of straight nonintersecting channels with pore densities up to 10 11 cm 2. The issues included a large coefficient of thermal expansion, a susceptibility to bending and creep failures, a high rate of oxidation and a vulnerability to galvanic corrosion. The aluminum wires in a round wire stranded conductor leave approximately 25% of an air gap between the aluminum strands. Connecting aluminium and copper is required more often than you might think. Oxidation occurs as a result of coppers exposure to air, though water especially salt water heat and acidic compounds can also induce corrosion. The protection of copper is unnecessary, even in salty offshore environments, whereas oxidation is a particular problem with aluminium conductors. Anodic oxidation of aluminum and its alloys the pergamon materials engineering practice series henley, v. I do use it as a personal preference, and this guy must be legally blind, but is there some require. Why use copper rather than aluminium as the conductor in. If an oxidized conductor is connected without any pretreatment to. While it is normal for oxidation to form, necessary steps should be taken to clean. Its thermal conductivity is about onehalf that of copper.
Copper has a significantly lower specific electrical resistivity than aluminium. The oxidized aluminum is aluminum oxide which has a pretty high. Connector sizing must match the awg or kcmil size of the conductor. Earlier aluminum conductors were susceptible to failure.
It is the most commonly occurring of several aluminium oxides, and specifically identified as aluminium iii oxide. Aluminium oxide, also called alumina al 2 o 3, consists of a polycrystalline monophasic structure. Minimize corrosion of electrodes and grounding conductors. At the same time, steel screws became more common than brass screws on receptacles. Nec for the use of an oxide inhibitor on aluminum conductor terminations. Aluminum wire terminations, oversize distribution panels. Splicing and terminating low voltage flashcards quizlet. Some lugs are provided with an antioxidant paste supplied by the manufacturer and some are not. The nec contains tables to size either copper or aluminum conductors with a variety of insulations. Aluminum building wiring is a type of electrical wiring for residential construction or houses that. Effects of oxidation on copper one positive effect of copper oxidation includes the formation of a protective outer layer that prevents further corrosion. Comparative corrosion and current burst testing of copper. Although rarely used, there are some conductors that have more steel strands than aluminum strands.
The chapters in this book describe other processes re. Anodic oxidation of aluminum and its alloys the pergamon materials engineering practice series. When the connection points of aluminum conductors are exposed to a wide range of temperatures. Conductor oxidation exposure of conductor to air will cause oxidation to form on the conductor. Anodic oxidation of aluminum and its alloys the pergamon. Aluminum electrical wire information the aluminum association. Conductor materials copper and aluminum are the two major conductor materials used for substation buses and equipment connections. In the end however, the insulating material used with the wire plays a crucial role in performance and an aluminium wire can possess the same current carrying capacity as an h07rnf copper wire.
Copper as used in electrical equipment engineers ieee publish the leading industry standards for the design and testing of electrical equipment. The oxide layer should be removed, and often an oxideinhibiting compound can be applied to reduce oxidation. Test standards for power connectors include the csa c57 or ansi c119. If aluminium is used as a conductor material, its lower conductivity requires a wire size that is approximately a third larger than that of a copper wire. Copper conductors may allow the use of a smaller conduit size. Aluminium oxide iupac name or aluminum oxide american english is a chemical compound of aluminium and oxygen with the chemical formula al 2 o 3. Below ive listed some of the issues with aluminum for use in electrical applications. Aluminiumconductor steelreinforced cable wikipedia. Oxides form an insulating layer aluminum forms a dense and very hard oxide layer on the wire surface. Even in transformer stations, aluminium conductors need to be connected to copper bars.
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