Wire ampacity

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Latest revision as of 03:53, 22 July 2013

Accessed from: http://wiki.xtronics.com/index.php/Wire-Gauge_Ampacity


Load Carrying Capacities or Ampacities

In part from Reference Data for Engineers: Radio, Electronics, Computer and Communications 7th Ed

  • De-rate with +0.00393 per °C - wire carrying current capacity sitting in the insulation and conduit will not be at 20 °C You will want to derate to at least the temperature rating of your insulation. Resistance listed here are not trade maxima - most wire that is soft or annealed will be slightly higher. Resistance of hard-drawn copper is slightly greater - 2 - 3%. Stranded wire may also be higher.
AWG Dia Inch Cir Mil Dia mm Area Inch2 lb/kft ohms
/kft
Ohms
/km
CU Max
free-air Amps
CU Max
enclosed Amps
32 0.008 63.2 0.20 4.964E-05 0.19 164.1 538.4 .53 0.32
30 0.010 100.5 0.25 7.894E-05 0.30 103.2 338.6 .86 0.52
28 0.013 159.8 0.32 1.255E-04 0.48 64.9 212.9 1.4 0.83
26 0.016 254.1 0.40 1.996E-04 0.77 40.81 133.9 2.2 1.3
24 0.020 404.0 0.51 3.173E-04 1.22 25.67 84.22 3.5 2.1
22 0.025 642.4 0.64 5.046E-04 1.94 16.14 52.95 7.0 5.0
20 0.032 1,021.5 0.81 8.023E-04 3.09 10.15 33.30 11.0 7.5
18 0.040 1,624.3 1.02 1.276E-03 4.92 6.385 20.95 16 10
16 0.051 2,582.7 1.29 2.028E-03 7.82 4.016 13.18 22 13
14 0.064 4,106.7 1.63 3.225E-03 12.43 2.525 8.284 32 17
12 0.081 6,529.9 2.05 5.129E-03 19.77 1.588 5.210 41 23
10 0.102 10,383.0 2.59 8.155E-03 31.43 1.215 3.985 55 33
8 0.128 16,509.7 3.26 1.297E-02 49.98 0.998 3.274 73 46
6 0.162 26,251.4 4.12 2.062E-02 79.46 0.395 1.296 101 60
4 0.204 41,741.3 5.19 3.278E-02 126.35 0.248 0.8136 135 80
2 0.258 66,371.3 6.54 5.213E-02 200.91 0.156 0.5118 181 100
1 0.289 83,692.7 7.35 6.573E-02 253.34 0.123 0.4035 211 125
0 0.325 105,534.5 8.25 8.289E-02 319.46 0.0983 0.3225 245 150
00 0.365 133,076.5 9.27 1.045E-01 402.83 0.0779 0.2556 283 175
000 0.410 167,806.4 10.40 1.318E-01 507.96 0.0618 0.2028 328 200
0000 0.460 211,600.0 11.68 1.662E-01 640.53 0.04901 0.1608 380 225


  • A second version of the above table with 60°C trade derating - (affects ohms/kft and ohms/km.)

Max ambient 60°C

AWG Dia Inch Cir Mil Dia cm Area Inch2 lb/kft ohms
/kft
Ohms
/km
CU Max
free-air Amps
CU Max
enclosed Amps
32 0.008 63.2 0.020 4.964E-05 0.19 199.587 654.613 .53 0.32
30 0.010 100.5 0.025 7.894E-05 0.30 125.521 411.690 .86 0.52
28 0.013 159.8 0.032 1.255E-04 0.48 78.941 258.915 1.4 0.83
26 0.016 254.1 0.040 1.996E-04 0.77 49.647 162.833 2.2 1.3
24 0.020 404.0 0.051 3.173E-04 1.22 31.223 102.407 3.5 2.1
22 0.025 642.4 0.064 5.046E-04 1.94 19.636 64.404 7.0 5.0
20 0.032 1,021.5 0.081 8.023E-04 3.09 12.349 40.504 11.0 7.5
18 0.040 1,624.3 0.102 1.276E-03 4.92 7.767 25.473 16 10
16 0.051 2,582.7 0.129 2.028E-03 7.82 4.884 16.020 22 13
14 0.064 4,106.7 0.163 3.225E-03 12.43 3.072 10.075 32 17
12 0.081 6,529.9 0.205 5.129E-03 19.77 1.932 6.336 41 23
10 0.102 10,383.0 0.259 8.155E-03 31.43 1.215 3.985 55 33
8 0.128 16,509.7 0.326 1.297E-02 49.98 0.764 2.506 73 46
6 0.162 26,251.4 0.412 2.062E-02 79.46 0.481 1.576 101 60
4 0.204 41,741.3 0.519 3.278E-02 126.35 0.302 0.991 135 80
2 0.258 66,371.3 0.654 5.213E-02 200.91 0.190 0.623 181 100
1 0.289 83,692.7 0.735 6.573E-02 253.34 0.151 0.494 211 125
0 0.325 105,534.5 0.825 8.289E-02 319.46 0.120 0.392 245 150
00 0.365 133,076.5 0.927 1.045E-01 402.83 0.095 0.311 283 175
000 0.410 167,806.4 1.040 1.318E-01 507.96 0.075 0.247 328 200
0000 0.460 211,600.0 1.168 1.662E-01 640.53 0.060 0.196 380 225


PCB Trace Width vs Current

PCB current.png

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