# Wire Gauge and Current Limits Including Skin Depth and Strength

April 30, 2018
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## AWG Wire Sizes (see chart below)

AWG: In the American Wire Gauge (AWG) system, diameters can be calculated by applying the formula D(AWG)=.005·92((36-AWG)/39) inch. For the 00, 000, 0000 etc. gauges you use -1, -2, -3, which makes more sense mathematically than "double nought." This means that in American wire gage every 6 gauge decrease gives a doubling of the wire diameter, and every 3 gauge decrease doubles the wire cross sectional area. Similar to dB in signal and power levels. An approximate but accurate enough form of this formula contributed by Mario Rodriguez is D = .460 * (57/64)(awg +3) or D = .460 * (0.890625)(awg +3).

## Metric Wire Gauges (see table below)

Metric Gauge: In the Metric Gauge scale, the gauge is 10 times the diameter in millimeters, so a 50 gauge metric wire would be 5 mm in diameter. Note that in AWG the diameter goes up as the gauge goes down, but for metric gauges it is the opposite. Probably because of this confusion, most of the time metric sized wire is specified in millimeters rather than metric gauges.

## Load Carrying Capacities (see table below)

Definition: ampacity is the current carrying capability of a wire. In other words, how many amps can it transmit? 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. NOTE: For installations that need to conform to the National Electrical Code, you must use their guidelines. Contact your local electrician to find out what is legal!

## Maximum Frequency for 100% Skin Depth Chart

This data is useful for high frequency AC engineering. When high frequency AC is conducted by a wire there is a tendency for the current to flow along the outside of the wire. This increases the effective resistance. The frequency listed in the table shows the frequency at which the calculated skin depth is equal to the radius of the wire, and is an indication that above this frequency you should start considering the skin effect when calculating the wire's resistance.

## Breaking Force for Copper Wire

This estimate is based on nick-free soft annealed Cu wire having a tensile strength of 37000 pounds per square inch.

 AWG gauge ConductorDiameter Inches ConductorDiameter mm Conductor cross section in mm2 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 Breaking force Soft Annealed Cu 37000 PSI 0000 0.46 11.684 107 0.049 0.16072 380 302 125 Hz 6120 lbs 000 0.4096 10.40384 84.9 0.0618 0.202704 328 239 160 Hz 4860 lbs 00 0.3648 9.26592 67.4 0.0779 0.255512 283 190 200 Hz 3860 lbs 0 0.3249 8.25246 53.5 0.0983 0.322424 245 150 250 Hz 3060 lbs 1 0.2893 7.34822 42.4 0.1239 0.406392 211 119 325 Hz 2430 lbs 2 0.2576 6.54304 33.6 0.1563 0.512664 181 94 410 Hz 1930 lbs 3 0.2294 5.82676 26.7 0.197 0.64616 158 75 500 Hz 1530 lbs 4 0.2043 5.18922 21.1 0.2485 0.81508 135 60 650 Hz 1210 lbs 5 0.1819 4.62026 16.8 0.3133 1.027624 118 47 810 Hz 960 lbs 6 0.162 4.1148 13.3 0.3951 1.295928 101 37 1100 Hz 760 lbs 7 0.1443 3.66522 10.6 0.4982 1.634096 89 30 1300 Hz 605 lbs 8 0.1285 3.2639 8.37 0.6282 2.060496 73 24 1650 Hz 480 lbs 9 0.1144 2.90576 6.63 0.7921 2.598088 64 19 2050 Hz 380 lbs 10 0.1019 2.58826 5.26 0.9989 3.276392 55 15 2600 Hz 314 lbs 11 0.0907 2.30378 4.17 1.26 4.1328 47 12 3200 Hz 249 lbs 12 0.0808 2.05232 3.31 1.588 5.20864 41 9.3 4150 Hz 197 lbs 13 0.072 1.8288 2.63 2.003 6.56984 35 7.4 5300 Hz 150 lbs 14 0.0641 1.62814 2.08 2.525 8.282 32 5.9 6700 Hz 119 lbs 15 0.0571 1.45034 1.65 3.184 10.44352 28 4.7 8250 Hz 94 lbs 16 0.0508 1.29032 1.31 4.016 13.17248 22 3.7 11 k Hz 75 lbs 17 0.0453 1.15062 1.04 5.064 16.60992 19 2.9 13 k Hz 59 lbs 18 0.0403 1.02362 0.823 6.385 20.9428 16 2.3 17 kHz 47 lbs 19 0.0359 0.91186 0.653 8.051 26.40728 14 1.8 21 kHz 37 lbs 20 0.032 0.8128 0.519 10.15 33.292 11 1.5 27 kHz 29 lbs 21 0.0285 0.7239 0.412 12.8 41.984 9 1.2 33 kHz 23 lbs 22 0.0253 0.64516 0.327 16.14 52.9392 7 0.92 42 kHz 18 lbs 23 0.0226 0.57404 0.259 20.36 66.7808 4.7 0.729 53 kHz 14.5 lbs 24 0.0201 0.51054 0.205 25.67 84.1976 3.5 0.577 68 kHz 11.5 lbs 25 0.0179 0.45466 0.162 32.37 106.1736 2.7 0.457 85 kHz 9 lbs 26 0.0159 0.40386 0.128 40.81 133.8568 2.2 0.361 107 kHz 7.2 lbs 27 0.0142 0.36068 0.102 51.47 168.8216 1.7 0.288 130 kHz 5.5 lbs 28 0.0126 0.32004 0.080 64.9 212.872 1.4 0.226 170 kHz 4.5 lbs 29 0.0113 0.28702 0.0647 81.83 268.4024 1.2 0.182 210 kHz 3.6 lbs 30 0.01 0.254 0.0507 103.2 338.496 0.86 0.142 270 kHz 2.75 lbs 31 0.0089 0.22606 0.0401 130.1 426.728 0.7 0.113 340 kHz 2.25 lbs 32 0.008 0.2032 0.0324 164.1 538.248 0.53 0.091 430 kHz 1.8 lbs Metric 2.0 0.00787 0.200 0.0314 169.39 555.61 0.51 0.088 440 kHz 33 0.0071 0.18034 0.0255 206.9 678.632 0.43 0.072 540 kHz 1.3 lbs Metric 1.8 0.00709 0.180 0.0254 207.5 680.55 0.43 0.072 540 kHz 34 0.0063 0.16002 0.0201 260.9 855.752 0.33 0.056 690 kHz 1.1 lbs Metric 1.6 0.0063 0.16002 0.0201 260.9 855.752 0.33 0.056 690 kHz 35 0.0056 0.14224 0.0159 329 1079.12 0.27 0.044 870 kHz 0.92 lbs Metric 1.4 .00551 .140 0.0154 339 1114 0.26 0.043 900 kHz 36 0.005 0.127 0.0127 414.8 1360 0.21 0.035 1100 kHz 0.72 lbs Metric 1.25 .00492 0.125 0.0123 428.2 1404 0.20 0.034 1150 kHz 37 0.0045 0.1143 0.0103 523.1 1715 0.17 0.0289 1350 kHz 0.57 lbs Metric 1.12 .00441 0.112 0.00985 533.8 1750 0.163 0.0277 1400 kHz 38 0.004 0.1016 0.00811 659.6 2163 0.13 0.0228 1750 kHz 0.45 lbs Metric 1 .00394 0.1000 0.00785 670.2 2198 0.126 0.0225 1750 kHz 39 0.0035 0.0889 0.00621 831.8 2728 0.11 0.0175 2250 kHz 0.36 lbs 40 0.0031 0.07874 0.00487 1049 3440 0.09 0.0137 2900 kHz 0.29 lbs
Voltage Drop Calculator by Gerald Newton http://www.electrician2.com

The following calculator calculates the voltage drop, and voltage at the end of the wire for American Wire Gauge from 4/0 AWG to 30 AWG, aluminum or copper wire. (Note: It just calculates the voltage drop, consult the above table for rules-of-thumb, or your local or national electrical code or your electrician to decide what is legal!) Note that the voltage drop does not depend on the input voltage, just on the resistance of the wire and the load in amps.
 Select Copper or Aluminum Copper Aluminum Select American Wire Gauge (AWG) Size 30 AWG 28 AWG 26 AWG 24 AWG 22 AWG 20 AWG 18 AWG 16 AWG 14 AWG 12 AWG 10 AWG 8 AWG 6 AWG 4 AWG 3 AWG 2 AWG 1 AWG 1/0 AWG 2/0 AWG 3/0 AWG 4/0 AWG 250 kcmil 300 kcmil 350 kcmil 400 kcmil 500 kcmil 600 kcmil 700 kcmil 750 kcmil 800 kcmil 900 kcmil 1000 kcmil 1250 kcmil 1500 kcmil 1750 kcmil 2000 kcmil Select Voltage 120 Volts 1-phase 240 Volts 1-phase 208 Volts 3-phase 3-wire 120/208 Volts 3-phase 4-wire 277 Volts 1-phase 480 Volts 3-phase 277/480 3-phase 4-wire 48 VDC or 1-phase AC 24 VDC or 1-phase AC 12 VDC or 1-phase AC 6 VDC or 1-phase AC 3 VDC or 1-phase AC Enter 1-way circuit length in feet (the calculation is for the round trip distance) Enter Load in amps Voltage drop Voltage at load end of circuit Per Cent voltage drop Wire cross section in circular mils

This chart of American Wire Gauge (AWG) wire sizes and rated ampacities is data intended for the pleasure of our readers only. Typographical errors, etc. are probable, since the typist is not a professional (our CEO). Please point out errors. The data listed are incomplete and should be used as a guideline only. Please contact manufacturers for the latest data.

We hope that this information is helpful. Now go out and design something that needs a charger, power supply, or battery pack!

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