## IEC 60228 DC Resistance

Last updated on 2022-06-02 3 mins. to read

The international standard for conductors is IEC 60287.  The standard classifies conductors according to four classes:

- Class 1: solid conductors

- Class 2: stranded conductors

- Class 5: flexible conductors

- Class 6: flexible conductors (more flexible than class 5)

For each class of conductor, the standard defines the maximum allowable resistance at 20 oC:

Maximum Resistance of Conductors in mΩ/m
CSA mm² Copper (plain) Copper (tinned) Aluminium
class 1 & 2 class 5 & 6 class 5 & 6 class 1 & 2
0.5 36.0 39.0 40.1 -
0.75 24.5 26.0 26.7 -
1 18.1 19.5 20.0 -
1.5 12.1 13.3 13.7 -
2.5 7.41 7.98 8.21 -
4 4.61 4.95 5.09 -
6 3.08 3.30 3.39 -
10 1.83 1.91 1.95 3.08
16 1.15 1.21 1.24 1.91
25 0.727 0.78 0.795 1.20
35 0.524 0.554 0.565 0.868
50 0.387 0.386 0.393 0.641
70 0.268 0.272 0.277 0.443
95 0.193 0.206 0.210 0.320
120 0.153 0.161 0.164 0.253
150 0.124 0.129 0.132 0.206
185 0.0991 0.106 0.108 0.164
240 0.0754 0.0801 0.0817 0.125
300 0.0601 0.0641 0.0654 0.100
400 0.0470 0.0486 0.0495 0.0778
500 0.0366 0.0384 0.0391 0.0605
630 0.0283 0.0287 0.0292 0.0469
800 - - - 0.0367
1000 - - - 0.0291
1200 - - - 0.0247

David Mullins May 15, 2019 9:41 PM
Is this IEC 60228 or 60287?
Steven McFadyen May 15, 2019 9:47 PM
IEC 60228 : Conductors of Insulated Cables
Leandro Freire Jun 02, 2022 12:51 PM
This tables refers to the "Minimum Resistance of Conductors in mΩ/m" or the Maximum?
Steven McFadyen Jun 02, 2022 2:29 PM
Thanks for pointing out the confusion.  The values are maximum.
VINOD P Apr 23, 2024 9:07 AM
Where i can find the cable reactance and which IEC Standard is applicable here ?
Steven McFadyen Apr 23, 2024 9:38 AM
The reactance depends on the cable spacing, so you must calculate it for each arrangement you want. Manufacturers sometimes provide reactance on their datasheets for a few arrangements, which may be helpful.
VINOD P Apr 23, 2024 10:53 AM
Thank you for the quick response. Can you please provide the formula with necessary details. Thank You in Advance.
Steven McFadyen Apr 23, 2024 11:48 AM
You will need to look them up yourself.  We have some in the Knowledge Base. Otherwise, if you search with Google, you will be able to find many papers discussing cable reactance.
VINOD P Apr 24, 2024 8:28 AM
So what my first question was about which IEC standard is applied. It is better to refer the IEC standard than search in google. Anyway thanks for the reply.
VINOD P Jul 30, 2024 5:24 AM
The resistance in the table are ZERO Resistance values ?
Steven McFadyen Jul 30, 2024 10:22 AM
There are no zero values.  The values given are those in the standard.  The standard does not give values for some CSA; in this case, you must calculate.