Engineering Fundamentals: An Introduction to Engineering, 4th ed.c

The American Wire Gage (AWG)

Electrical wires are typically made of copper or aluminum. The actual size of wires is commonly

expressed in terms of gage number. The American Wire Gage (AWG) is based on successive gage

numbers having a constant ratio of approximately 1.12 between their diameters. For example, the

ratio of the diameter of No. 1 AWG wire to No. 2 is 1.12 (289 mils /258 mils1.12),

or, as another example, the ratio of diameter of No. 0000 to No. 000 is 1.12 (460 mils /

410 mils1.12). Moreover, the ratio of cross sections of successive gage numbers is approxi-

mately (1.12)

2

1.25. The ratio of the diameter of wires differing by 6 gage numbers is approx-

imately 2.0. For example, the ratio of diameters of wire No. 1 to No. 7 is 2 (289 mils / 144 mils

2.0), or the ratio of diameters of No. 30 to No. 36 is 2 (10.0 mils /5.0 mils2.0).

Table 12.2 shows the gage number, the diameter, and the resistance for copper wires. When

examining Table 12.2, note that the smaller the gage number, the bigger the wire diameter. Also

note from data given in Table 12.2 that the electric resistance of a wire is increased as its diam-

eter is decreased.

The National Electrical Code, published by the Fire Protection Association, contains

specific information on the type of wires used for general wiring. The code describes the wire

TABLE 12.2 Examples of American Wire Gage (AWG)

for Solid Copper Wire

American Wire

Gauge (AWG) Diameter Resistance per 1000 ft

Number (mils) (ohms) @ 77F

0000 460.0 0.0500

000 410.0 0.0630

00 365.0 0.0795

1 289.0 0.126

2 258.0 0.159

5 182.0 0.319

6 162.0 0.403

7 144.0 0.508

10 91.0 1.28

12 81.0 1.62

14 64.0 2.58

16 51.0 4.09

18 40.0 6.51

20 32.0 10.4

22 25.3 16.5

24 20.1 26.2

26 15.9 41.6

28 12.6 66.2

30 10.0 133

32 8.0 167

34 6.3 266

36 5.0 423

38 4.0 673

40 3.1 1070

12.4 Electrical Circuits and Components 355

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