Calculate cable cross-section for wallbox
The recommended cable cross-section for a wallbox depends on the maximum output in kW. For example, the supply cable for a wallbox 3-phase (400V) with 11 kW power should be designed with a cable cross-section of at least 2.5 mm², 6 mm² is recommended. For a single-phase (230V) charging station with 3.7 kW, the recommended cable cross-section is 6 mm².
| Voltage (V) | Current (A) | Mains max. power (kW) | Conductor cross-section recommended (mm²) | Minimum conductor cross-section (mm²) |
|---|---|---|---|---|
| 230 V | 10A | 1-phase | 2,3 | 6 |
| 230 V | 16A | 1-phase | 3,7 | 6 |
| 230 V | 32A | 1-phase | 7.4 | 10 |
| 400 V | 16A | 3-phase | 11 | 6 |
| 400 V | 32A | 3-phase | 22 | 10 |
Operating a charging station for an electrically powered car requires more than just the recommended cable cross-section of the supply line: when connecting a wallbox, e.g. with 22 kW power, you must comply with the correct cable cross-section and obtain approval from your grid operator. If the cable cross-section in a motorhome is too small, a charging booster can provide a remedy. It counteracts a voltage drop if a consumer with an output of 10 A is operated on a cable with only 2.5 mm².