Wire gauge

Figure 1. A diagram showing the different gauges of wire and their corresponding number based on its cross section.[1]

Wire gauge measures how large a wire's cross sectional area is. Knowing the gauge is important because it determines how much electric current a wire can carry without being damaged—this quantity is called ampacity.

American Wire Gauge System

The American Wire Gauge system or AWG standardizes the cross sectional area of a wires by assigning them an AWG number. As seen in Figure 1, a lower numbered gauge wire has a larger diameter and thus is able to carry higher currents. There are a total of 40 different gauge sizes with cross sectional areas ranging from 0.013 mm2 to 107.22 mm2 with their diameters changing incrementally between each gauge number.

Wire Gauge Values

AWG number Cross sectional area (mm2) Ohms/km (/km) Ampacity (A) Usage example
18 0.82 20.95 14 Low voltage lighting
16 1.31 13.18 18 Extension cords
14 2.08 8.28 25 Lighting fixtures
12 3.31 5.21 30 Kitchen appliances
10 5.26 3.28 40 Electric dryers
8 8.37 2.06 55 Electric ovens
6 13.30 1.30 75 Large electric heaters
4 21.15 0.81 85 Large furnaces
3 26.67 0.65 115 Large commercial wiring
2 33.63 0.51 130 Car battery cable
1 42.41 0.41 145 Power distribution
1/0 53.47 0.32 170 Power distribution
2/0 67.43 0.26 195 Power distribution
3/0 85.03 0.20 225 Power distribution
4/0 107.22 0.16 260 Power distribution
250 126.68 0.13 290 Power distribution
350 177.35 0.10 350 Power distribution
400 202.68 0.08 380 Power distribution

The figures above are taken from Table 310.15(B)(16) in the 2014 National Electrical Code (USA) and assume a temperature rating of 90°C.[2] Also, Table 3.1 on page 69 in Introduction to Electricity was used as a template and reference.[3]

For a more complete list, please see Dr. Rowlett's unit page.

For Further Reading

For further information please see the related pages below:

References

  1. Wikimedia Commons. (October 3, 2015). Wire Gauge [Online]. Available: https://upload.wikimedia.org/wikipedia/commons/2/23/Wire_gauge_(PSF).png
  2. "2014 National Electrical Code" Table 310.15(B)(16)
  3. R. Paynter and B. Boydell, Introduction to electricity. Upper Saddle River, N.J.: Pearson Prentice Hall, 2011.

Authors and Editors

Bethel Afework, Braden Heffernan, Kailyn Stenhouse, Jason Donev
Last updated: May 18, 2018
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