Resources
Conductor resistance tables
DC resistance of copper and aluminium conductors used by the GridCircuits voltage-drop calculator.
North American sizes (NEC)
Source: NEC (NFPA 70) Chapter 9, Table 8 — stranded, uncoated, 75 °C. Values in Ω/1000 ft.
| Size | Copper | Aluminium |
|---|---|---|
| 14 AWG | 3.14 | — |
| 12 AWG | 1.98 | 3.25 |
| 10 AWG | 1.24 | 2.04 |
| 8 AWG | 0.778 | 1.28 |
| 6 AWG | 0.491 | 0.808 |
| 4 AWG | 0.308 | 0.508 |
| 3 AWG | 0.245 | 0.403 |
| 2 AWG | 0.194 | 0.319 |
| 1 AWG | 0.154 | 0.253 |
| 1/0 AWG | 0.122 | 0.201 |
| 2/0 AWG | 0.0967 | 0.159 |
| 3/0 AWG | 0.0766 | 0.126 |
| 4/0 AWG | 0.0608 | 0.1 |
| 250 kcmil | 0.0515 | 0.0847 |
| 300 kcmil | 0.0429 | 0.0707 |
| 350 kcmil | 0.0367 | 0.0605 |
| 400 kcmil | 0.0321 | 0.0529 |
| 500 kcmil | 0.0258 | 0.0424 |
| 600 kcmil | 0.0214 | 0.0353 |
| 750 kcmil | 0.0171 | 0.0282 |
| 1000 kcmil | 0.0129 | 0.0212 |
Metric sizes (IEC)
Source: IEC 60228 — Class 2 stranded, maximum DC resistance at 20 °C. Values in Ω/km.
| Size | Copper | Aluminium |
|---|---|---|
| 1.5 mm² | 12.1 | — |
| 2.5 mm² | 7.41 | — |
| 4 mm² | 4.61 | — |
| 6 mm² | 3.08 | — |
| 10 mm² | 1.83 | — |
| 16 mm² | 1.15 | 1.91 |
| 25 mm² | 0.727 | 1.2 |
| 35 mm² | 0.524 | 0.868 |
| 50 mm² | 0.387 | 0.641 |
| 70 mm² | 0.268 | 0.443 |
| 95 mm² | 0.193 | 0.32 |
| 120 mm² | 0.153 | 0.253 |
| 150 mm² | 0.124 | 0.206 |
| 185 mm² | 0.0991 | 0.164 |
| 240 mm² | 0.0754 | 0.125 |
| 300 mm² | 0.0601 | 0.1 |
| 400 mm² | 0.047 | 0.0778 |
| 500 mm² | 0.0366 | 0.0605 |
| 630 mm² | 0.0283 | 0.0469 |
Temperature correction
RT = R20 · [1 + α (T − 20)], with α = 0.00393 /°C for copper and 0.00403 /°C for aluminium.