Wire Gauge and Current Limits

Jun 21, 2011 at 3:09 pm in Reference by admin


Wire Gauge and Current Limits

The following chart is a guideline of ampacity or copper wire current carrying capacity following the Handbook of Electronic Tables and Formulas for American Wire Gauge. As you might guess, the rated ampacities are just a rule of thumb. In careful engineering the voltage drop, insulation temperature limit, thickness, thermal conductivity, and air convection and temperature should all be taken into account. The Maximum Amps for Power Transmission uses the 700 circular mils per amp rule, which is very very conservative. The Maximum Amps for Chassis Wiring is also a conservative rating, but is meant for wiring in air, and not in a bundle. For short lengths of wire, such as is used in battery packs you should trade off the resistance and load with size, weight, and flexibility.

AWG gauge Conductor
Diameter Inches		 Conductor
Diameter mm		 Ohms per 1000 ft. Ohms per km Maximum amps for chassis wiring Maximum amps for
power transmission		 Maximum frequency for
100% skin depth for solid conductor copper
OOOO 0.46 11.684 0.049 0.16072 380 302 125 Hz
OOO 0.4096 10.40384 0.0618 0.202704 328 239 160 Hz
OO 0.3648 9.26592 0.0779 0.255512 283 190 200 Hz
0 0.3249 8.25246 0.0983 0.322424 245 150 250 Hz
1 0.2893 7.34822 0.1239 0.406392 211 119 325 Hz
2 0.2576 6.54304 0.1563 0.512664 181 94 410 Hz
3 0.2294 5.82676 0.197 0.64616 158 75 500 Hz
4 0.2043 5.18922 0.2485 0.81508 135 60 650 Hz
5 0.1819 4.62026 0.3133 1.027624 118 47 810 Hz
6 0.162 4.1148 0.3951 1.295928 101 37 1100 Hz
7 0.1443 3.66522 0.4982 1.634096 89 30 1300 Hz
8 0.1285 3.2639 0.6282 2.060496 73 24 1650 Hz
9 0.1144 2.90576 0.7921 2.598088 64 19 2050 Hz
10 0.1019 2.58826 0.9989 3.276392 55 15 2600 Hz
11 0.0907 2.30378 1.26 4.1328 47 12 3200 Hz
12 0.0808 2.05232 1.588 5.20864 41 9.3 4150 Hz
13 0.072 1.8288 2.003 6.56984 35 7.4 5300 Hz
14 0.0641 1.62814 2.525 8.282 32 5.9 6700 Hz
15 0.0571 1.45034 3.184 10.44352 28 4.7 8250 Hz
16 0.0508 1.29032 4.016 13.17248 22 3.7 11 k Hz
17 0.0453 1.15062 5.064 16.60992 19 2.9 13 k Hz
18 0.0403 1.02362 6.385 20.9428 16 2.3 17 kHz
19 0.0359 0.91186 8.051 26.40728 14 1.8 21 kHz
20 0.032 0.8128 10.15 33.292 11 1.5 27 kHz
21 0.0285 0.7239 12.8 41.984 9 1.2 33 kHz
22 0.0254 0.64516 16.14 52.9392 7 0.92 42 kHz
23 0.0226 0.57404 20.36 66.7808 4.7 0.729 53 kHz
24 0.0201 0.51054 25.67 84.1976 3.5 0.577 68 kHz
25 0.0179 0.45466 32.37 106.1736 2.7 0.457 85 kHz
26 0.0159 0.40386 40.81 133.8568 2.2 0.361 107 kH
27 0.0142 0.36068 51.47 168.8216 1.7 0.288 130 kHz
28 0.0126 0.32004 64.9 212.872 1.4 0.226 170 kHz
29 0.0113 0.28702 81.83 268.4024 1.2 0.182 210 kHz
30 0.01 0.254 103.2 338.496 0.86 0.142 270 kHz
31 0.0089 0.22606 130.1 426.728 0.7 0.113 340 kHz
32 0.008 0.2032 164.1 538.248 0.53 0.091 430 kHz
Metric 2.0 0.00787 0.200 169.39 555.61 0.51 0.088 440 kHz
33 0.0071 0.18034 206.9 678.632 0.43 0.072 540 kHz
Metric 1.8 0.00709 0.180 207.5 680.55 0.43 0.072 540 kHz
34 0.0063 0.16002 260.9 855.752 0.33 0.056 690 kHz
Metric 1.6 0.0063 0.16002 260.9 855.752 0.33 0.056 690 kHz
35 0.0056 0.14224 329 1079.12 0.27 0.044 870 kHz
Metric 1.4 .00551 .140 339 1114 0.26 0.043 900 kHz
36 0.005 0.127 414.8 1360 0.21 0.035 1100 kHz
Metric 1.25 .00492 0.125 428.2 1404 0.20 0.034 1150 kHz
37 0.0045 0.1143 523.1 1715 0.17 0.0289 1350 kHz
Metric 1.12 .00441 0.112 533.8 1750 0.163 0.0277 1400 kHz
38 0.004 0.1016 659.6 2163 0.13 0.0228 1750 kHz
Metric 1 .00394 0.1000 670.2 2198 0.126 0.0225 1750 kHz
39 0.0035 0.0889 831.8 2728 0.11 0.0175 2250 kHz
40 0.0031 0.07874 1049 3440 0.09 0.0137 2900 kHz