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ITGlossary · EV charging
Type A vs Type B RCD (6 mA DC Leakage Detection)
The residual current protection of an EV charger must also cover DC leakage, using either a Type B RCD or a Type A RCD plus 6 mA DC detection.
Technical level:Advanced
In the event of a fault, an electric vehicle can produce smooth DC leakage current. Ordinary Type AC RCDs cannot detect it, and a Type A RCD can be "blinded" by it and fail to trip during a dangerous leak.
That is why the installation standard for charging points requires either a 30 mA Type B RCD or a 30 mA Type A RCD together with a 6 mA DC leakage detection device. Many wallboxes have this detection built in, in which case a Type A RCD in the panel is enough.
A common mistake is fitting a Type AC RCD on the charger circuit, or assuming the built-in detection is there. Check the datasheet and, if it does not explicitly mention 6 mA DC detection, install a Type B.
Related terms
- DC ChargingFast charging in which the station converts power to direct current and feeds it straight into the battery, typically at 50 to 350 kW.
- EV Connector Type 2The standard AC charging connector for electric vehicles in Europe, also known as Mennekes.
- AC ChargingCharging with alternating current, where the vehicle's on-board charger converts it to direct current to fill the battery.
- CCS2 (Combined Charging System)The European connector standard that adds two DC pins below a Type 2 plug, allowing fast DC charging through the same vehicle inlet.
- Charging Power (kW)How much energy flows into the battery per hour, which in AC charging depends on voltage, current and the number of phases.
- Smart ChargingCharging that adapts current and voltage to battery condition and temperature, or an EV charger’s power to the site’s available capacity.