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A residual current device (GFCI) is an important part of a building's electrical safety system. It protects people from electric shock by interrupting the circuit in the event of a fault current caused by a defect in the electrical system. The wallbox residual current circuit breaker or FI switch is a special residual current circuit breaker that is installed near wallboxes or other electrical charging stations. It is used to ensure the safety of electric vehicles during the charging process. If the RCD detects a malfunction or leakage current, the power supply to the Wallbox will be automatically cut off to prevent possible electric shock. It is important that the Wallbox RCD is regularly serviced and tested to ensure it is working properly. If you have any questions or concerns about installing or operating a wallbox RCD, you should consult a professional.
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It is important to ensure that the Wallboxes are fitted with an appropriate RCD to avoid electrical hazards. There are different types of RCDs that can be used for wallboxes including Type A, Type B or Type F. Type A is the most commonly used RCD and protects against residual currents caused by DC or AC power. Type B is specifically designed for protection against pulsating DC residual currents present in electric vehicles. Type F is suitable for use in high frequency areas such as in medical equipment.
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The following FI switches are suitable for wall boxes:
  • Residual current circuit breaker / FI switch type B
  • Residual current circuit breaker / FI switch type A-EV
  • earth leakage circuit breakerter / FI switch type A in conjunction with a suitable device for switching off the supply in the event of residual DC currents > 6 mA
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There are different types of residual current devices (GFCI) in Europe, including:
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  1. Type A: This RCD detects AC fault currents and pulsating DC fault currents. It is usually used in residential buildings.
  2. Type B: This RCD detects all types of fault currents, including smooth DC fault currents. It is typically used in industrial buildings and medical facilities.
  3. Type F: This RCD detects high-frequency fault currents and is typically used in buildings where many electronic devices are used, such as offices.
  4. Type H: This RCD detects pulsating DC fault currents and is typically used in buildings where photovoltaic systems are installed.
It is important to choose the correct RCD type for your specific application to ensure safe and reliable power supply.
 
RCD type A
The FI switch type A is a residual current device (also referred to as RCD = residual current device) with a tripping characteristic of 30 mA. It is used to protect people from dangerous body currents that can be caused by a fault current in the circuit.  Type A RCDs monitor the current flow in a circuit and automatically shut off the current if a deviation from normal current flow occurs. Type A is sensitive to AC fault currents and is therefore particularly suitable for protecting households and apartments with standard electrical installations. It is important to note that Type A RCDs are not intended as a substitute for overload or short circuit protection and must be used in combination with these to provide full protection.
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RCD type A-EV
An RCD type A-EV is a special RCD designed for electric vehicles (EV) and detects leakage currents caused by direct current (DC). It can usually detect fault currents from a frequency of 6 kHz and thus offers a particularly high level of protection against electric shocks and fires when using electric vehicles. It is important that a Type A-EV RCD is installed by a professional and is regularly serviced to ensure proper function and reliable protection. Another difference to conventional RCDs is that the Type A-EV RCD will trip even at high impedances. This means that it will switch off even if the fault current is very low due to a high impedance.
Overall, the Type A-EV residual current circuit breaker offers a higher degree of protection for electric vehicle charging devices and thus ensures more safety when charging electric vehicles.
 
RCD type B
The Type B residual current circuit breaker is an electrical circuit breaker that provides protection against residual currents caused by residual currents with DC components or pulsating DC components. Type B residual current circuit breakers have been specially developed for the protection of applications in which electronic devices or power converters with frequency-controlled drives are used, which can generate DC components in the event of a fault. In contrast to a conventional residual current circuit breaker, which normally only detects and trips AC residual currents, a type B residual current circuit breaker is able to detect and switch off residual currents with a DC component of more than 6 mA. For example, such switch types are often used in photovoltaic systems or electric vehicle charging devices. Type B RCDs have higher sensitivity than Type A or Type F RCDs and can detect and switch off fault currents with a frequency of up to 1 kHz. In Germany, type B RCCBs must be installed in some special applications according to DIN VDE 0100-410 to ensure greater safety. 
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Many wall boxes already have a DC residual current sensor integrated as standard. This is mandatory for the multi-phase charging of electric vehicles. Before you buy the charging station, pay attention to the integrated DC residual current detection. As a result, during the electrical installation of the wall box, next to dem Circuit breaker, only a simple RCD type A required.
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