American wire gauge (AWG), also known as the Brown & Sharpe wire gauge, is a logarithmic stepped standardized wire gauge system used since 1857, predominantly in North America, for the diameters of round, solid, nonferrous, electrically conducting wire. Dimensions of the wires are given in ASTM standard B 258.The cross-sectional area of each gauge is an important factor for determining its current-carrying ampacity.
The United States of America (USA), commonly known as the United States or America, is a country comprising 50 states, a federal district, five major self-governing territories, and various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is slightly smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U.S. is the third most populous country. The capital is Washington, D.C., and the most populous city is New York City. Most of the country is located contiguously in North America between Canada and Mexico.
Brown & Sharpe is a division of Hexagon AB, a Swedish multinational corporation focused mainly on metrological tools and technology. During the 19th and 20th centuries, Brown & Sharpe was one of the best-known and most influential machine tool builders and was a leading manufacturer of instruments for machinists. Its reputation and influence were such that its name is often considered to be inseparably paired with certain industrial standards that it helped establish, including:
In mathematics, the logarithm is the inverse function to exponentiation. That means the logarithm of a given number x is the exponent to which another fixed number, the base b, must be raised, to produce that number x. In the simplest case, the logarithm counts the number of occurrences of the same factor in repeated multiplication; e.g., since 1000 = 10 × 10 × 10 = 103, the "logarithm to base 10" of 1000 is 3. The logarithm of x to baseb is denoted as logb (x), or without parentheses, logb x, or even without the explicit base, log x—if no confusion is possible.
Increasing gauge numbers denote decreasing wire diameters, which is similar to many other non-metric gauging systems such as British Standard Wire Gauge (SWG), but unlike IEC 60228, the metric wire-size standard used in most parts of the world. This gauge system originated in the number of drawing operations used to produce a given gauge of wire. Very fine wire (for example, 30 gauge) required more passes through the drawing dies than 0 gauge wire did. Manufacturers of wire formerly had proprietary wire gauge systems; the development of standardized wire gauges rationalized selection of wire for a particular purpose.
IEC 60228 is the International Electrotechnical Commission's international standard on conductors of insulated cables. The current version is Third Edition 2004-11 Among other things, it defines a set of standard wire cross-sectional areas:
The metric system is an internationally recognised decimalised system of measurement. It is in widespread use, and where it is adopted, it is the only or most common system of weights and measures. It is now known as the International System of Units (SI). It is used to measure everyday things such as the mass of a sack of flour, the height of a person, the speed of a car, and the volume of fuel in its tank. It is also used in science, industry and trade.
Wire drawing is a metalworking process used to reduce the cross-section of a wire by pulling the wire through a single, or series of, drawing die(s). There are many applications for wire drawing, including electrical wiring, cables, tension-loaded structural components, springs, paper clips, spokes for wheels, and stringed musical instruments. Although similar in process, drawing is different from extrusion, because in drawing the wire is pulled, rather than pushed, through the die. Drawing is usually performed at room temperature, thus classified as a cold working process, but it may be performed at elevated temperatures for large wires to reduce forces. It is a best drawing.
The AWG tables are for a single, solid, round conductor. The AWG of a stranded wire is determined by the cross-sectional area of the equivalent solid conductor. Because there are also small gaps between the strands, a stranded wire will always have a slightly larger overall diameter than a solid wire with the same AWG.
AWG is also commonly used to specify body piercing jewelry sizes (especially smaller sizes), even when the material is not metallic.
Body jewelry sizes express the thickness of an item of body jewelry, using one of several possible systems.
By definition, No. 36 AWG is 0.005 inches in diameter, and No. 0000 is 0.46 inches in diameter. The ratio of these diameters is 1:92, and there are 40 gauge sizes from No. 36 to No. 0000, or 39 steps. Because each successive gauge number increases cross sectional area by a constant multiple, diameters vary geometrically. Any two successive gauges (e.g., A & B ) have diameters in the ratio (dia. B ÷ dia. A) of (approximately 1.12293), while for gauges two steps apart (e.g., A, B, & C), the ratio of the C to A is about 1.122932 = 1.26098. The diameter of a No. n AWG wire is determined, for gauges smaller than 00 (36 to 0), according to the following formula:
(see below for gauges larger than No. 0 (i.e., No. 00, No. 000, No. 0000 ).)
The gauge can be calculated from the diameter using
and the cross-section area is
The standard ASTM B258 - 02(2008) Standard Specification for Standard Nominal Diameters and Cross-Sectional Areas of AWG Sizes of Solid Round Wires Used as Electrical Conductors defines the ratio between successive sizes to be the 39th root of 92, or approximately 1.1229322. inches (0.1 mils) for wires larger than No. 44 AWG, and 0.00001 inches (0.01 mils) for wires No. 45 AWG and smaller.ASTM B 258-02 also dictates that wire diameters should be tabulated with no more than 4 significant figures, with a resolution of no more than 0.0001
Sizes with multiple zeros are successively larger than No. 0 and can be denoted using "number of zeros/0", for example 4/0 for 0000. For an m/0 AWG wire, use n = −(m − 1) = 1 − m in the above formulas. For instance, for No. 0000 or 4/0, use n = −3.
The sixth power of 39√ is very close to 2, which leads to the following rules of thumb:
The table below shows various data including both the resistance of the various wire gauges and the allowable current (ampacity) based on a copper conductor with plastic insulation. The diameter information in the table applies to solid wires. Stranded wires are calculated by calculating the equivalent cross sectional copper area. Fusing current (melting wire) is estimated based on 25 °C (77 °F) ambient temperature. The table below assumes DC, or AC frequencies equal to or less than 60 Hz, and does not take skin effect into account. "Turns of wire per unit length" is the reciprocal of the conductor diameter; it is therefore an upper limit for wire wound in the form of a helix (see solenoid), based on uninsulated wire.
|AWG||Diameter||Turns of wire, without insulation||Area||Copper wire|
|Resistance/length|| Ampacity, at 20 °C insulation material temperature rating,|
or for single unbundled wires in equipment for 16 AWG and smaller
|60 °C||75 °C||90 °C||Preece||Onderdonk|
|(in)||(mm)||(per in)||(per cm)||(kcmil)||(mm2)||(mΩ/m )||(mΩ/ft )||(A)||~10 s||1 s||32 ms|
|0000 (4/0)||0.4600||11.684||2.17||0.856||212||107||0.1608||0.04901||195||230||260||3.2 kA||33 kA||182 kA|
|000 (3/0)||0.4096||10.405||2.44||0.961||168||85.0||0.2028||0.06180||165||200||225||2.7 kA||26 kA||144 kA|
|00 (2/0)||0.3648||9.266||2.74||1.08||133||67.4||0.2557||0.07793||145||175||195||2.3 kA||21 kA||115 kA|
|0 (1/0)||0.3249||8.251||3.08||1.21||106||53.5||0.3224||0.09827||125||150||170||1.9 kA||16 kA||91 kA|
|1||0.2893||7.348||3.46||1.36||83.7||42.4||0.4066||0.1239||110||130||145||1.6 kA||13 kA||72 kA|
|2||0.2576||6.544||3.88||1.53||66.4||33.6||0.5127||0.1563||95||115||130||1.3 kA||10.2 kA||57 kA|
|3||0.2294||5.827||4.36||1.72||52.6||26.7||0.6465||0.1970||85||100||115||1.1 kA||8.1 kA||45 kA|
|4||0.2043||5.189||4.89||1.93||41.7||21.2||0.8152||0.2485||70||85||95||946 A||6.4 kA||36 kA|
|5||0.1819||4.621||5.50||2.16||33.1||16.8||1.028||0.3133||795 A||5.1 kA||28 kA|
|6||0.1620||4.115||6.17||2.43||26.3||13.3||1.296||0.3951||55||65||75||668 A||4.0 kA||23 kA|
|7||0.1443||3.665||6.93||2.73||20.8||10.5||1.634||0.4982||561 A||3.2 kA||18 kA|
|8||0.1285||3.264||7.78||3.06||16.5||8.37||2.061||0.6282||40||50||55||472 A||2.5 kA||14 kA|
|9||0.1144||2.906||8.74||3.44||13.1||6.63||2.599||0.7921||396 A||2.0 kA||11 kA|
|10||0.1019||2.588||9.81||3.86||10.4||5.26||3.277||0.9989||30||35||40||333 A||1.6 kA||8.9 kA|
|11||0.0907||2.305||11.0||4.34||8.23||4.17||4.132||1.260||280 A||1.3 kA||7.1 kA|
|12||0.0808||2.053||12.4||4.87||6.53||3.31||5.211||1.588||20||25||30||235 A||1.0 kA||5.6 kA|
|13||0.0720||1.828||13.9||5.47||5.18||2.62||6.571||2.003||198 A||798 A||4.5 kA|
|14||0.0641||1.628||15.6||6.14||4.11||2.08||8.286||2.525||15||20||25||166 A||633 A||3.5 kA|
|15||0.0571||1.450||17.5||6.90||3.26||1.65||10.45||3.184||140 A||502 A||2.8 kA|
|16||0.0508||1.291||19.7||7.75||2.58||1.31||13.17||4.016||18||117 A||398 A||2.2 kA|
|17||0.0453||1.150||22.1||8.70||2.05||1.04||16.61||5.064||99 A||316 A||1.8 kA|
|18||0.0403||1.024||24.8||9.77||1.62||0.823||20.95||6.385||10||14||16||83 A||250 A||1.4 kA|
|19||0.0359||0.912||27.9||11.0||1.29||0.653||26.42||8.051||—||—||—||70 A||198 A||1.1 kA|
|20||0.0320||0.812||31.3||12.3||1.02||0.518||33.31||10.15||5||11||—||58.5 A||158 A||882 A|
|21||0.0285||0.723||35.1||13.8||0.810||0.410||42.00||12.80||—||—||—||49 A||125 A||700 A|
|22||0.0253||0.644||39.5||15.5||0.642||0.326||52.96||16.14||3||7||—||41 A||99 A||551 A|
|23||0.0226||0.573||44.3||17.4||0.509||0.258||66.79||20.36||—||—||—||35 A||79 A||440 A|
|24||0.0201||0.511||49.7||19.6||0.404||0.205||84.22||25.67||2.1||3.5||—||29 A||62 A||348 A|
|25||0.0179||0.455||55.9||22.0||0.320||0.162||106.2||32.37||—||—||—||24 A||49 A||276 A|
|26||0.0159||0.405||62.7||24.7||0.254||0.129||133.9||40.81||1.3||2.2||—||20 A||39 A||218 A|
|27||0.0142||0.361||70.4||27.7||0.202||0.102||168.9||51.47||—||—||—||17 A||31 A||174 A|
|28||0.0126||0.321||79.1||31.1||0.160||0.0810||212.9||64.90||0.83||1.4||—||14 A||24 A||137 A|
|29||0.0113||0.286||88.8||35.0||0.127||0.0642||268.5||81.84||—||—||—||12 A||20 A||110 A|
|30||0.0100||0.255||99.7||39.3||0.101||0.0509||338.6||103.2||0.52||0.86||—||10 A||15 A||86 A|
|31||0.00893||0.227||112||44.1||0.0797||0.0404||426.9||130.1||—||—||—||9 A||12 A||69 A|
|32||0.00795||0.202||126||49.5||0.0632||0.0320||538.3||164.1||0.32||0.53||—||7 A||10 A||54 A|
|33||0.00708||0.180||141||55.6||0.0501||0.0254||678.8||206.9||—||—||—||6 A||7.7 A||43 A|
|34||0.00630||0.160||159||62.4||0.0398||0.0201||856.0||260.9||0.18||0.3||—||5 A||6.1 A||34 A|
|35||0.00561||0.143||178||70.1||0.0315||0.0160||1079||329.0||—||—||—||4 A||4.8 A||27 A|
|36||0.00500||0.127||200||78.7||0.0250||0.0127||1361||414.8||—||—||—||4 A||3.9 A||22 A|
|37||0.00445||0.113||225||88.4||0.0198||0.0100||1716||523.1||—||—||—||3 A||3.1 A||17 A|
|38||0.00397||0.101||252||99.3||0.0157||0.00797||2164||659.6||—||—||—||3 A||2.4 A||14 A|
|39||0.00353||0.0897||283||111||0.0125||0.00632||2729||831.8||—||—||—||2 A||1.9 A||11 A|
|40||0.00314||0.0799||318||125||0.00989||0.00501||3441||1049||—||—||—||1 A||1.5 A||8.5 A|
In the North American electrical industry, conductors larger than 4/0 AWG are generally identified by the area in thousands of circular mils (kcmil), where 1 kcmil = 0.5067 mm2. The next wire size larger than 4/0 has a cross section of 250 kcmil. A circular mil is the area of a wire one mil in diameter. One million circular mils is the area of a circle with 1000 mil (1 inch) diameter. An older abbreviation for one thousand circular mils is MCM.
AWG gauges are also used to describe stranded wire. The AWG gauge of a stranded wire represents the sum of the cross-sectional areas of the individual strands; the gaps between strands are not counted. When made with circular strands, these gaps occupy about 25% of the wire area, thus requiring the overall bundle diameter to be about 13% larger than a solid wire of equal gauge.
Stranded wires are specified with three numbers, the overall AWG size, the number of strands, and the AWG size of a strand. The number of strands and the AWG of a strand are separated by a slash. For example, a 22 AWG 7/30 stranded wire is a 22 AWG wire made from seven strands of 30 AWG wire.
As indicated in the Formulas and Rules of Thumb sections above, differences in AWG translate directly into ratios of diameter or area. This property can be employed to easily find the AWG of a stranded bundle by measuring the diameter and count of its strands. (This only applies to bundles with circular strands of identical size.) To find the AWG of 7-strand wire with equal strands, subtract 8.4 from the AWG of a strand. Similarly, for 19-strand subtract 12.7, and for 37 subtract 15.6. See the Mathcad worksheet illustration of this straightforward application of the formula.
Measuring strand diameter is often easier and more accurate than attempting to measure bundle diameter and packing ratio. Such measurement can be done with a wire gauge go-no-go tool such as a Starrett 281 or Mitutoyo 950-202, or with a caliper or micrometer.
Alternative ways are commonly used in the electrical industry to specify wire sizes as AWG.
The industry also bundles common wire for use in mains electricity distribution in homes and businesses, identifying a bundle's wire size followed by the number of wires in the bundle.
14/3 and 12/3 cables are also available, used mainly between three-way (two-location) switches, and to have separate wall controls for ceiling fans and their attached light fixtures, or to have one half of a duplex outlet switched and the other always on.
12/2 and 14/2 can also be used for the rare 240-volt-only 15- or 20-amp plug by clearly marking the white wire red or black, since there is no neutral wire. Two conductor cable is available with black and red conductors only for this purpose; the outer sheath is likewise red.
277/480-volt cable is identical to 120/240, except that neutral is grey and hot is yellow (plus an optional orange, used as the red is). The higher voltage, used only in large non-residential buildings, allows more than twice as much electrical power (in watts) to be drawn through the same gauge of wire.
UF-B cable is “underground feeder” cable, which regardless of wire gauge has a solid waterproof grey sheath completely surrounding and filling the space between the conductors, which still have their individual colors. Other types of armored or metallic cable (types AC and MC) have an aluminum casing that may be used as a ground conductor, for which it is not necessary to calculate an equivalent wire gauge.
All new cables are marked as being “with ground” or “w/gnd”, since installation of ungrounded cables has been prohibited by electrical codes for decades. The ground wire is typically the same gauge as the others, despite not being intended to carry large amounts of current for more than a few seconds in the event of a short circuit.
AWG is colloquially referred to as gauge and the zeros in large wire sizes are referred to as aught // . Wire sized 1 AWG is referred to as "one gauge" or "No. 1" wire; similarly, smaller diameters are pronounced "x gauge" or "No. X" wire, where x is the positive integer AWG number. Consecutive AWG wire sizes larger than No. 1 wire are designated by the number of zeros:
and so on.
An electrical cable is an assembly of one or more wires running side by side or bundled, which is used to carry electric current.
Coaxial cable, or coax is a type of electrical cable that has an inner conductor surrounded by a tubular insulating layer, surrounded by a tubular conducting shield. Many coaxial cables also have an insulating outer sheath or jacket. The term coaxial comes from the inner conductor and the outer shield sharing a geometric axis. Coaxial cable was invented by English physicist, engineer, and mathematician Oliver Heaviside, who patented the design in 1880.
In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge in one or more directions. Materials made of metal are common electrical conductors. Electrical current is generated by the flow of negatively charged electrons, positively charged holes, and positive or negative ions in some cases.
Electrical wiring is an electrical installation of cabling and associated devices such as switches, distribution boards, sockets, and light fittings in a structure.
A power cable is an electrical cable, an assembly of one or more electrical conductors, usually held together with an overall sheath. The assembly is used for transmission of electrical power. Power cables may be installed as permanent wiring within buildings, buried in the ground, run overhead, or exposed.
Ampacity is a portmanteau for ampere capacity defined by National Electrical Codes, in some North American countries. Ampacity is defined as the maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Also described as current-carrying capacity.
Litz wire is a special type of multistrand wire or cable used in electronics to carry alternating current (AC) at radio frequencies. The wire is designed to reduce the skin effect and proximity effect losses in conductors used at frequencies up to about 1 MHz. It consists of many thin wire strands, individually insulated and twisted or woven together, following one of several carefully prescribed patterns often involving several levels. The result of these winding patterns is to equalize the proportion of the overall length over which each strand is at the outside of the conductor. This has the effect of distributing the current equally among the wire strands, reducing the resistance. Litz wire is used in high Q inductors for radio transmitters and receivers operating at low frequencies, induction heating equipment and switching power supplies.
Speaker wire is used to make the electrical connection between loudspeakers and audio amplifiers. Modern speaker wire consists of two or more electrical conductors individually insulated by plastic or, less commonly, rubber. The two wires are electrically identical, but are marked to identify the correct audio signal polarity. Most commonly, speaker wire comes in the form of zip cord.
Mineral-insulated copper-clad cable is a variety of electrical cable made from copper conductors inside a copper sheath, insulated by inorganic magnesium oxide powder. The name is often abbreviated to MICC or MI cable, and colloquially known as pyro. A similar product sheathed with metals other than copper is called mineral insulated metal sheathed (MIMS) cable.
Wire gauge is a measurement of wire diameter. This determines the amount of electric current a wire can safely carry, as well as its electrical resistance and weight.
A circular mil is a unit of area, equal to the area of a circle with a diameter of one mil. It corresponds to 5.067×10−4 mm2. It is a unit intended for referring to the area of a wire with a circular cross section. As the area in circular mils can be calculated without reference to π, the unit makes conversion between cross section and diameter of a wire considerably easier.
A thermoplastic-sheathed cable (TPS) consists of a toughened outer sheath of polyvinyl chloride (PVC) thermoplastic, covering one or more individual annealed copper conductors, themselves insulated with PVC. This type of wiring is commonly used for residential and light commercial construction in many countries. The flat version of the cable, with two insulated conductors and an uninsulated earth conductor, is referred to as twin and earth. In mainland Europe, a round equivalent is more common.
Magnet wire or enameled wire is a copper or aluminium wire coated with a very thin layer of insulation. It is used in the construction of transformers, inductors, motors, generators, speakers, hard disk head actuators, electromagnets, and other applications that require tight coils of insulated wire.
British Standard Wire Gauge is a set of wire sizes given by BS 3737:1964, and is generally abbreviated to SWG. It is also known as: Imperial Wire Gauge or British Standard Gauge. Use of SWG sizes has fallen greatly in popularity, but is still used as a measure of thickness in guitar strings and some electrical wire. Cross sectional area in square millimetres is now the more usual size measurement for wires used in electrical installation cables. The current British Standard for metallic materials such as wire and sheet is BS 6722:1986, which is a solely metric standard.
Telecommunications cables are a type of guided transmission mediums. Cables are usually known to transmit electric energy (AC/DC); however, cables in telecommunications fields are used to transmit electromagnetic waves; they are called electromagnetic wave guides.
Copper has been used in electrical wiring since the invention of the electromagnet and the telegraph in the 1820s. The invention of the telephone in 1876 created further demand for copper wire as an electrical conductor.
FASTON terminals are connectors, widely used in electronic and electrical equipment. These terminals are manufactured by many different vendors, commonly using the term "quick disconnect", "tab" terminals, or blade connectors. They are similar in size to some of the Packard terminals, such as Packard 56, and may have been derived from them.