Standard DC resistance of conductor

From standard IEC 60228 Ed.3.0 and UL 1581 (up to 2000 kcmil) and ASTM B8-11/B231-04 and ICEA S-94-649-2000 (2500 kcmil and above).

Please note that we have added the values for 3000, 3200, and 3500 mm² as published in the IEC 60228 edition 4 committee draft, published 2021-11-12. In this draft, the value for aluminium with 2500 mm² was changed from 0.0127 to 0.0119. The new value is in fact more reasonable and so we decided to use this value even though the edition 4 is only draft. If you want to use the value from the currently still valid edition 3, you can set it manually in the cable editor.

The fact that triplex or three core cables are twisted together leads to the possible need of a correction factor, the lay length factor $F_{lay}$, to take into account the longer length of the cores, considering the length of lay $L_{lay}$. If the manufacturer provides an electrical resistance value, the electrical resistance value must be valid for the cable, meaning that the $F_{lay}$ should already be included. This holds for any type of power cable, including three-core constructions and cables that are delivered as triplex constructions. Correction factors for lay length are not required where conductors comply with IEC 60228 but they are required for AWG/kcmil conductors to IEC TR 62602 and are given in that publication.
If the electrical resistance of a power cable is not provided by the manufacturer, the lay lengths must be taken into account manually. Then, the electrical resistance calculated on the basis of the conductor cross section must be multiplied by the $F_{lay}$ to take the effect of the twisting into account, refer to Cigre TB 880 Guidance Point 23.

The tabulated standard DC resistance values for cable conductors at 20°C are in $\Omega$/km. For calculation, values in in $\Omega$/m are used.

Symbol

$R_{co}$

Unit

$\Omega$/km

Formulae

${10}^9\frac{\rho_c}{A_c}$	at 20°C IEC 60287
${10}^9F_{lay,c} \frac{\rho_c}{n_{cw} \left(\frac{d_{cw}}{2}\right)^2 \pi}$	at 20°C Cigre TB 880 GP 20

Related

$A_c$

Cross-sectional area of conductor [mm$^2$]

$c_{type}$

Construction of conductor

$d_{cw}$

Average diameter of conductor wire strand [mm]

$F_{lay,c}$

Effective length per unit lay length of conductor strands

$M_c$

Material of conductor

$n_{cw}$

Number of wires in conductor

$\pi$

Archimedes' constant $\pi$

$\rho_c$

Electrical resistivity of conductor material [$\Omega$.m]

Choices

Size	Area mm²	solid copper plain	solid copper coated	solid alu	stranded copper plain	stranded copper coated	stranded alu	flexible class 5/C copper plain	flexible class 5/C copper coated	flexible class 6/D copper plain	flexible class 6/D copper coated
26 AWG	0.128	138	143	225	140	150	230
24 AWG	0.205	85.9	89.3	141	87.6	94.2	144
22 AWG	0.324	54.3	56.4	88.9	55.4	59.4	90.9
0.5 mm$^2$	0.5	36.0	36.7	57.47	36.0	36.7	57.47	39.0	40.1	39.0	40.1
20 AWG	0.519	33.9	35.2	55.4	34.6	36.7	57.1
0.75 mm$^2$	0.75	24.5	24.8	38.31	24.5	24.8	38.31	26.0	26.7	26.0	26.7
18 AWG	0.823	21.4	22.2	35.1	21.8	23.2	35.8
1.0 mm$^2$	1.0	18.1	18.2	28.74	18.1	18.2	28.74	19.5	20.0	19.5	20.0
16 AWG	1.31	13.5	14.0	22.0	13.7	14.6	22.5
1.5 mm$^2$	1.5	12.1	12.2	19.16	12.1	12.2	19.16	13.3	13.7	13.3	13.7
14 AWG	2.08	8.45	8.78	13.8	8.62	8.96	14.1	8.7	9.24	8.61	9.25
2.5 mm$^2$	2.5	7.41	7.56	11.49	7.41	7.56	11.49	7.98	8.21	7.98	8.21
12 AWG	3.31	5.31	5.53	8.71	5.43	5.64	8.88	5.48	5.81	5.53	5.94
4 mm$^2$	4.0	4.61	4.7	7.18	4.61	4.7	7.18	4.95	5.09	4.95	5.09
10 AWG	5.261	3.343	3.476	5.479	3.409	3.546	5.589	3.45	3.66	3.48	3.73
6 mm$^2$	6.0	3.08	3.11	4.79	3.08	3.11	4.79	3.3	3.39	3.3	3.39
8 AWG	8.367	2.102	2.163	3.446	2.144	2.23	3.515	2.18	2.33	2.18	2.35
10 mm$^2$	10.0	1.83	1.84	3.08	1.83	1.84	3.08	1.91	1.95	1.91	1.95
6 AWG	13.3	1.323	1.363	2.168	1.348	1.403	2.211	1.38	1.46	1.39	1.49
16 mm$^2$	16.0	1.15	1.16	1.91	1.15	0.16	1.91	1.21	1.24	1.21	1.24
4 AWG	21.15	0.8315	0.8559	1.363	0.8481	0.882	1.39	0.865	0.918	0.873	0.937
25 mm$^2$	25.0	0.727		1.2	0.727	0.734	1.2	0.78	0.795	0.78	0.795
3 AWG	26.67	0.6595	0.6788	1.081	0.6727	0.6996	1.103	0.686	0.728	0.699	0.744
2 AWG	33.62	0.5231	0.5384	0.8574	0.5335	0.5548	0.8745	0.547	0.58	0.554	0.595
35 mm$^2$	35.0	0.524		0.868	0.524	0.529	0.868	0.554	0.565	0.554	0.565
1 AWG	42.41	0.4146	0.4268	0.6798	0.423	0.4398	0.6934	0.434	0.46	0.44	0.472
50 mm$^2$	50.0	0.387		0.641	0.387	0.391	0.641	0.386	0.393	0.386	0.393
1/0 AWG	53.49	0.3287	0.3367	0.539	0.3354	0.3487	0.5498	0.344	0.357	0.349	0.374
2/0 AWG	67.43	0.2608	0.267	0.4275	0.266	0.2766	0.4361	0.272	0.284	0.276	0.3
70 mm$^2$	70.0	0.268		0.443	0.268	0.27	0.443	0.272	0.277	0.272	0.277
3/0 AWG	85.01	0.2069	0.2119	0.3392	0.211	0.2194	0.3459	0.216	0.224	0.221	0.238
95 mm$^2$	95.0	0.193		0.32	0.193	0.195	0.32	0.206	0.21	0.206	0.21
4/0 AWG	107.2	0.164	0.168	0.2689	0.1673	0.1722	0.2743	0.172	0.18	0.175	0.189
120 mm$^2$	120.0	0.153		0.253	0.153	0.154	0.253	0.161	0.164	0.161	0.164
250 kcmil	127.0				0.1416	0.1473	0.2322	0.146	0.125	0.149	0.159
150 mm$^2$	150.0	0.124		0.206	0.124	0.126	0.206	0.129	0.132	0.129	0.132
300 kcmil	152.0				0.118	0.1227	0.1935	0.121	0.126	0.123	0.133
350 kcmil	177.0				0.1011	0.1052	0.1659	0.104	0.108	0.106	0.114
185 mm$^2$	185.0	0.101		0.164	0.0991	0.1	0.164	0.106	0.108	0.106	0.108
400 kcmil	203.0				0.08851	0.09109	0.145	0.0911	0.0948	0.0928	0.0997
240 mm$^2$	240.0	0.0775		0.125	0.0754	0.0762	0.125	0.0801	0.0817	0.0801	0.0817
500 kcmil	253.0				0.0708	0.07287	0.1161	0.0729	0.0758	0.0743	0.0798
300 mm$^2$	300.0	0.062		0.1	0.0601	0.0607	0.1	0.0641	0.0654	0.0641	0.0654
600 kcmil	304.0				0.059	0.06135	0.09673	0.0613	0.0638	0.0619	0.0664
700 kcmil	355.0				0.05057	0.05205	0.08291	0.0525	0.0547	0.053	0.0569
750 kcmil	380.0				0.04721	0.04858	0.07738	0.0491	0.051	0.0495	0.0531
400 mm$^2$	400.0	0.0465		0.0778	0.047	0.0475	0.0778	0.0486	0.0495
800 kcmil	405.0				0.04425	0.04554	0.07251	0.046	0.0478	0.0464	0.0499
900 kcmil	456.0				0.03933	0.04048	0.06448	0.0409	0.0425	0.0413	0.0443
500 mm$^2$	500.0			0.0605	0.0366	0.0369	0.0605	0.0384	0.0391
1000 kcmil	507.0				0.0354	0.03643	0.05804	0.0368	0.0382	0.0371	0.0399
630 mm$^2$	630.0			0.0469	0.0283	0.0286	0.0469	0.0287	0.0292
1250 kcmil	633.0				0.02833	0.02915	0.04643	0.0295	0.0306
1500 kcmil	760.0				0.0236	0.02429	0.03869	0.0245	0.0255
800 mm$^2$	800.0			0.0367	0.0221	0.0224	0.0367
1750 kcmil	887.0				0.02023	0.02082	0.03316	0.021	0.0218
1000 mm$^2$	1000.0			0.0291	0.0176	0.0177	0.0291
2000 kcmil	1013.0				0.0177	0.01822	0.02902	0.0184	0.0192
2250 kcmil	1140.0				0.0156	0.0156	0.0255
1200 mm$^2$	1200.0			0.0247	0.0151	0.0151	0.0247
2500 kcmil	1270.0				0.014	0.0144	0.0229
1400 mm$^2$	1400.0				0.0129	0.0129	0.0212
2750 kcmil	1393.0				0.0126	0.0126	0.0209
3000 kcmil	1520.0				0.0117	0.012	0.0192
1600 mm$^2$	1600.0				0.0113	0.0113	0.0186
3500 kcmil	1770.0				0.0101	0.0104	0.0166
1800 mm$^2$	1800.0				0.0101	0.0101	0.0165
2000 mm$^2$	2000.0				0.009	0.009	0.0149
4000 kcmil	2030.0				0.0088	0.0091	0.0145
4500 kcmil	2280.0				0.0079	0.0082	0.013
2500 mm$^2$	2500.0				0.0072	0.0072	0.0127
5000 kcmil	2530.0				0.00715	0.0074	0.0117
3000 mm$^2$	3000.0				0.006	0.006	0.0099
3200 mm$^2$	3200.0				0.0056	0.0056	0.0093
3500 mm$^2$	3500.0				0.0051	0.0051	0.0085