In order to charge your electric vehicle quickly and safely, there are some basic requirements that must be met. We have compiled a list to prepare you perfectly for the upcoming installation.
1. Power connection
The Wallbox or charging station must be connected via its own power line, so make sure that no other power consumers, such as sockets, washing machines, lights, etc., are connected. It is important to take the diversity factor into account. The diversity factor refers to the load on the power line and is a maximum of 1 or 100%. It takes into account the fact that not all system devices are always operated simultaneously and at full power. If a device requires 10% of the power, the simultaneity factor is 0.1. For a charging station, the simultaneity factor is 1.0. Therefore, the connected load of the charging station must be 100%.
2. Dimensioning of the power line
The power line must be adapted to the desired charging power. Therefore, for example, with a charging current of 16 amps and higher, use of a cable with a power cross-section of at least 2.5mm² is recommended to avoid a cable fire. To be able to charge an electric car with a charging power of 11-22kW (three-phase), the supply cable must be 5-core. It is best to have the cable cross-section determined by competent electricians, because it depends on factors such as voltage drop, ambient temperature, cable length and type of installation. Since electric cars will have higher charging capacities and battery capacities in the future, it is advisable to prepare a three-phase connection now in order to be equipped accordingly.
3. Installing a residual current device (FI / RCD)
When installing your charging station, you will need a residual current device to protect against electric shock. It must have the same charging capacity as your electric car.
How does a residual current device work?
The FI circuit breakers compares the outgoing and return currents to/from the electric car. If the currents no longer match, the FI trips and breaks the circuit. Sometimes such RCDs are already included in the charging station – if this is not the case, the FI circuit breaker must be connected. A diversity factor of 1.0 applies here, so the circuit is individually protected.
Which residual current circuit breakers are available?
Every charging station must have a type A residual current circuit breaker. This type of switch is a standard circuit breaker and is part of an electrician’s everyday equipment. It only detects certain fault currents. Sometimes smooth DC fault currents occur during charging. If the normal standard circuit breaker is not able to exclude these, DC residual current protection must be installed. There are various options for this:
DC residual current sensor / DC residual current detection:
To be safe from DC residual currents, more and more charging station manufacturers are deciding to install DC residual current sensors. In addition, a type A RCD is required. Even though charging stations with built-in residual current sensors are somewhat more expensive, the overall price is significantly lower – you save on installation.
FI type A EV is the best option if DC residual current protection is not already installed in the charging station. This switch is the cheaper alternative to the RCD type B and was specially developed for eMobility requirements, i.e. it also reacts to smooth DC residual currents.
FI type B detects all types of AC and DC residual currents and is therefore perfectly suited for installing charging stations.
4. The line circuit breaker (LS/CB)
This circuit breaker, also called LS/CB, protects the line from overload due to excessive currents and must match the electric car’s charging power. The only drawback is that the FI type B is very expensive.
Why do I need a circuit breaker?
If too much current flows through the line, the miniature circuit breaker (MCB), also called an “overcurrent protection device”, ensures that the circuit is interrupted. This can cause damage to the power lines due to heating. As with the FI, an extra circuit breaker is required for the charging station circuit.
Which is the right circuit breaker?
- Tripping characteristic C is recommended by most manufacturers.
- The circuit breaker must be matched to the rated current, in this case the desired charging power. It is imperative for the installation to be carried out by a competent electrician, as it is a source of danger. Only an expert knows which existing standards and installation regulations must be observed.
- The rated current is the current absorbed by the electrical equipment. The rated current of the selected circuit breaker must not under any circumstances be lower than the specifications on the charging station’s rating plate.
5. Approval from the grid operator
If you wish to purchase a charging station with a charging capacity of more than 12kW, it is necessary to obtain approval from your grid operator – either personally or through your electrician(s).
Since an electric car with a charging capacity of 12kW draws an extremely large amount of electricity from the grid at once, the grid operator must be informed, so that power cuts do not occur. The approval process varies from grid operator to grid operator.