3.0 Aligning Cable Voltage Rating with System Requirements
The critical first step in practical cable selection is matching the cable’s rated voltage to the system’s nominal and highest operating voltages. This section provides the definitive reference table from IEC 183 (Amendment 1) for ensuring system compatibility, thereby preventing the risks associated with under-specification or the unnecessary costs of over-specification.
Table 1: Relationship between Rated Cable Voltage (U₀/U) and Highest System Voltage (Um)
| Rated Voltage of Cables and Accessories (U₀ kV) | Nominal System Voltage (U kV) | Highest Voltage for Equipment (Um kV) |
| 1.8 | 3 | 3.6 |
| 3.6 | 6 | 7.2 |
| 6 | 10 | 12 |
| 8.7 | 15 | 17.5 |
| 12 | 20 | 24 |
| 18 | 30, 33 | 36 |
| 26 | 45, 47 | 52 |
| 36 | 60, 66, 69 | 72.5 |
| 64 | 110, 115 | 123 |
| 76 | 132, 138 | 145 |
| 87 | 150, 161 | 170 |
| 127 | 220, 230 | 245 |
| 160 | 275, 287 | 300 |
| 190 | 330, 345 | 362 |
| 220 | 380, 400 | 420 |
| 290 | 500 | 525 |
| 430 | 700, 750 | 765 |
With the correct voltage rating identified, the focus must shift to a detailed analysis of the project’s unique service and installation conditions, which will further refine the cable specification.