Wire 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