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Common US Wire Gauges – AWG Gauges Vs Current Ratings

MS Chaudhry

The AWG – American Wire Gauge – is used as a standard method denoting wire diameter, measuring the diameter of the conductor (the bare wire) with the insulation removed. AWG is sometimes also known as Brown and Sharpe (B&S) Wire Gauge.

The AWG table below is for a single, solid, round conductor. Because of the small gaps between the strands in a stranded wire, a stranded wire with the same current-carrying capacity and electrical resistance as a solid wire, always have a slightly larger overall diameter.

The higher the number – the thinner the wire. Typical household wiring is AWG number 12 or 14. Telephone wire is typical AWG 22, 24, or 26.

The table below indicates the current ratings of PVC-insulated single and multicore wiring cables. Be aware that the current load depends on installation method – the enclosure – and how well the resistance heat is removed from the cable.

Operating temperature of the conductor, ambient temperature and type of conductor insulation is important. Always check the manufactures data before detailed engineering.

AWG Diameter
(mm)		 Diameter
(in)		 Square
(mm2)		 Resistance
Copper
(ohms/1000m)
(Ohms/1000 ft)
 Typical Max. Current Load Ratings – Copper (amps)1)
Single Core Multicore
up to 3 cores 4 – 6 cores 7 – 24 cores 25 – 42 cores 43 and above
40 0.08 . 0.0050 3420
39 0.09 . 0.0064 2700
38 0.10 0.0040 0.0078 2190
37 0.11 0.0045 0.0095 1810
36 0.13 0.0050 0.013 1300
35 0.14 0.0056 0.015 1120
34 0.16 0.0063 0.020 844
33 0.18 0.0071 0.026 676
32 0.20 0.0080 0.031 547
30 0.25 0.010 0.049 351
28 0.33 0.013 0.080 232
27 0.36 0.014 0.096 178
26 0.41 0.016 0.13 137
25 0.45 0.018 0.16 108
24 0.51 0.020 0.20 88 3.5 2 1.6 1.4 1.2 1.0
22 0.64 0.025 0.33 52 5.0 3 2.4 2.1 1.8 1.5
20 0.81 0.032 0.50 34 6.0 5 4.0 3.5 3.0 2.5
18 1.0 0.040 0.82 22 9.5 7 5.6 4.9 4.2 3.5
16 1.3 0.051 1.3 13 20 10 8.0 7.0 6.0 5.0
14 1.6 0.064 2.1 8.5 24 15 12 10 9.0 7.5
13 1.8 0.072 2.6 6.8
12 2.1 0.081 3.3 5.4 34 20 16 14 12 10
10 2.6 0.10 5.3 3.4 52 30 24 21 18 15
8 3.3 0.13 8.3 2.2 75 40 32 28 24 20
6 4.1 0.17 13.3 1.5 95 55 44 38 33 27
4 5.2 0.20 21.2 0.80 120 70 56 49 42 35
3 26.7 154 80 64 56 48 40
2 6.5 0.26 33.6 0.50 170 95 76 66 57 57
1 7.4 0.29 42.4 0.40 180 110 88 77 66 55
0 (1/0) 8.3 0.33 53.5 0.31 200
00 (2/0) 9.3 0.37 67.4 0.25 225
000 (3/0) 10.4 0.41 85.0 0.20 275
0000 (4/0) 11.7 0.46 107 0.16 325
250 127 345
300 152 390
400 178 415

1) Current ratings for up to 1000 V, PVC-insulated single and multicore wiring cables, ambient temperature up to 30oC

The higher the gauge number, the smaller the diameter, and the thinner the wire.

Because of less electrical resistance a thicker wire carries more current with less voltage drop than a thinner wire. For longer distances it may be necessary to increase wire diameter – reducing the gauge – to limit voltage drop.

Correction-factors at ambient temperature above 30oC

American Wire Gauge Conductor Size Table

American wire gauge (AWG) is a standardized wire gauge system for the diameters of round, solid, nonferrous, electrically conducting wire. The larger the AWG number or wire guage, the smaller the physical size of the wire. The smallest AWG size is 40 and the largest is 0000 (4/0). AWG general rules of thumb – for every 6 gauge decrease, the wire diameter doubles and for every 3 gauge decrease, the cross sectional area doubles. Note – W&M Wire Gauge, US Steel Wire Gauge and Music Wire Gauge are different systems.

American Wire Gauge (AWG) Sizes and Properties Chart / Table

Table 1 lists the AWG sizes for electrical cables / conductors. In addition to wire size, the table provides values load (current) carrying capacity, resistance and skin effects. The resistances and skin depth noted are for copper conductors. A detailed description of each conductor property is described below Table 1.

Table 1: American Wire Gauge (AWG) Cable / Conductor Sizes and Properties

AWG  Diameter 
[inches]		  Diameter 
[mm]		 Area
[mm2]		 Resistance
[Ohms / 1000 ft]		 Resistance
[Ohms / km]		  Max Current 
[Amperes]		 Max Frequency
for 100% skin depth
 0000 (4/0) 0.46 11.684 107 0.049 0.16072 302 125 Hz
000 (3/0) 0.4096 10.40384 85 0.0618 0.202704 239 160 Hz
00 (2/0) 0.3648 9.26592 67.4 0.0779 0.255512 190 200 Hz
0 (1/0) 0.3249 8.25246 53.5 0.0983 0.322424 150 250 Hz
1 0.2893 7.34822 42.4 0.1239 0.406392 119 325 Hz
2 0.2576 6.54304 33.6 0.1563 0.512664 94 410 Hz
3 0.2294 5.82676 26.7 0.197 0.64616 75 500 Hz
4 0.2043 5.18922 21.2 0.2485 0.81508 60 650 Hz
5 0.1819 4.62026 16.8 0.3133 1.027624 47 810 Hz
6 0.162 4.1148 13.3 0.3951 1.295928 37 1100 Hz
7 0.1443 3.66522 10.5 0.4982 1.634096 30 1300 Hz
8 0.1285 3.2639 8.37 0.6282 2.060496 24 1650 Hz
9 0.1144 2.90576 6.63 0.7921 2.598088 19 2050 Hz
10 0.1019 2.58826 5.26 0.9989 3.276392 15 2600 Hz
11 0.0907 2.30378 4.17 1.26 4.1328 12 3200 Hz
12 0.0808 2.05232 3.31 1.588 5.20864 9.3 4150 Hz
13 0.072 1.8288 2.62 2.003 6.56984 7.4 5300 Hz
14 0.0641 1.62814 2.08 2.525 8.282 5.9 6700 Hz
15 0.0571 1.45034 1.65 3.184 10.44352 4.7 8250 Hz
16 0.0508 1.29032 1.31 4.016 13.17248 3.7 11 k Hz
17 0.0453 1.15062 1.04 5.064 16.60992 2.9 13 k Hz
18 0.0403 1.02362 0.823 6.385 20.9428 2.3 17 kHz
19 0.0359 0.91186 0.653 8.051 26.40728 1.8 21 kHz
20 0.032 0.8128 0.518 10.15 33.292 1.5 27 kHz
21 0.0285 0.7239 0.41 12.8 41.984 1.2 33 kHz
22 0.0254 0.64516 0.326 16.14 52.9392 0.92 42 kHz
23 0.0226 0.57404 0.258 20.36 66.7808 0.729 53 kHz
24 0.0201 0.51054 0.205 25.67 84.1976 0.577 68 kHz
25 0.0179 0.45466 0.162 32.37 106.1736 0.457 85 kHz
26 0.0159 0.40386 0.129 40.81 133.8568 0.361 107 kHz
27 0.0142 0.36068 0.102 51.47 168.8216 0.288 130 kHz
28 0.0126 0.32004 0.081 64.9 212.872 0.226 170 kHz
29 0.0113 0.28702 0.0642 81.83 268.4024 0.182 210 kHz
30 0.01 0.254 0.0509 103.2 338.496 0.142 270 kHz
31 0.0089 0.22606 0.0404 130.1 426.728 0.113 340 kHz
32 0.008 0.2032 0.032 164.1 538.248 0.091 430 kHz
33 0.0071 0.18034 0.0254 206.9 678.632 0.072 540 kHz
34 0.0063 0.16002 0.0201 260.9 855.752 0.056 690 kHz
35 0.0056 0.14224 0.016 329 1079.12 0.044 870 kHz
36 0.005 0.127 0.0127 414.8 1360 0.035 1100 kHz
37 0.0045 0.1143 0.01 523.1 1715 0.0289 1350 kHz
38 0.004 0.1016 0.00797 659.6 2163 0.0228 1750 kHz
39 0.0035 0.0889 0.00632 831.8 2728 0.0175 2250 kHz
40 0.0031 0.07874  0.00501 1049 3440 0.0137 2900 kHz

AWG Notes: American Wire Gauge (AWG) is a standardized wire gauge system used predominantly in the United States to note the diameter of electrically conducting wire. The general rule of thumb is for every 6 gauge decrease the wire diameter doubles and every 3 gauge decrease doubles the cross sectional area.

Diameter Notes: A mil is a unit of length equal to 0.001 inch (a “milli-inch” or a “thousandth of one inch”) ie. 1 mil = 0.001″.

Resistance Notes: The resistance noted in the table above is for copper wire conductor. For a given current, you can use the noted resistance and apply Ohms Law to calculate the voltage drop across the conductor.

Current (ampacity) Notes: The current ratings shown in the table are for power transmission and have been determined using the rule of 1 amp per 700 circular mils, which is a very conservative rating. For reference, the National Electrical Code (NEC) notes the following ampacity for copper wire at 30 Celsius:
14 AWG – maximum of 20 Amps in free air, maximum of 15 Amps as part of a 3 conductor cable;
12 AWG – maximum of 25 Amps in free air, maximum of 20 Amps as part of a 3 conductor cable;
10 AWG – maximum of 40 Amps in free air, maximum of 30 Amps as part of a 3 conductor cable.

Check your local electrical code for the correct current capacity (ampacity) for mains and in wall wiring.

Skin Effect and Skin Depth Notes: Skin effect is the tendency of an alternating electric current (AC) to distribute itself within a conductor so that the current density near the surface of the conductor is greater than that at its core. That is, the electric current tends to flow at the “skin” of the conductor. The skin effect causes the effective resistance of the conductor to increase with the frequency of the current. The maximum frequency show is for 100% skin depth (ie. no skin effects).

American Wire Guage (AWG) Wire Sizes

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