Install your own e-car charging station – guidebook

The current K subsidy for charging stations for electric cars (residential buildings) for the purchase and connection of 900 euros per charging point, at privately used parking spaces in residential buildings, has created a real boom. Wherever possible, everyone who has the means should take advantage of this promotion and install their own wallbox at home.

Wallbox installation: who is handy and for example does the installation work himself or. The lines to the wallbox laid by yourself, only need to hire a specialist company for the connection work of the wallbox. Thus, in the best case, the costs may be covered by the K subsidy.

In this article, you will learn all the details you need to pay attention to in order to get your own wallbox at home as inexpensively as possible.

why should you install a wallbox?

Many are certainly of the opinion that you can charge the electric car at a normal power or Schuko sockets..?

That’s true, but there are some disadvantages, which is why the installation of a wallbox quickly pays for itself and safety also plays a major role. The three most important arguments for installing a wallbox at home are:

1. The loading efficiency

Charging at a normal household socket is possible, but the cost of charging (according to a study by the ADAC) here up to 30% more than with a wallbox. When charging at a normal schuko socket, enormous charging losses occur, which are wasted and therefore cannot be used. Surely you save the costs for the purchase and the installation of the wallbox in the beginning, but if you charge the e-car regularly at a schuko socket, there are so much more costs so that an installation of a wallbox pays off quickly. In addition, you currently still receive a lucrative K subsidy.

Charging at a normal schuko socket, which is fused with 16A, would result in a charging capacity of ca. 3.680 watt gives (voltage 230 volt x current 16 ampere = charging power 3.680 watts). This would be maximum possible. However, this is not realistic, since heat losses occur and it is very questionable whether the existing electrical installation can withstand a charge of 3.7 KW for several hours. Charging at a Schuko socket is possible for a short time, but is not recommended in the long term.

Moreover, charging would take too long. If in the ideal case 3.7 KW charge the electric car 4 hours, would be charged just 14.8 KW. With a 11 KW wallbox it is usually 3 times as fast.

Using an existing earthed socket for charging is not only disadvantageous because of the charging efficiency and the charging speed, but also because of the reliability and the safety. When charging an electric car, the electrical installation is subjected to extreme stress over several hours. This is certainly not good in the long run. In the worst case, a fire could occur.

If someone nevertheless charges his electric car permanently at a shockproof socket, he should have the existing electrical installation checked by an electrician (cables and fuse protection). A residual current circuit breaker should definitely also be installed.

The advantages of a wallbox (e-car charging station)

  • Charging the electric car is usually quite fast with a wallbox
  • The own wallbox at home can be used at any time, in contrast to public charging stations
  • Ideally, the homeowner has installed a photovoltaic system + electricity storage ⇒ so there are almost no costs and you drive with your own electricity
  • With a wallbox the charging power is automatically regulated. The e-car communicates with the wallbox via the max. Available power, so the maximum possible power is always charged
  • Maximum safety and reliability during charging
  • The vehicle is not supplied with power until a safe connection has been made
  • Charging plug is locked in the vehicle during charging and cannot be disconnected
  • Many charging stations have an integrated RCD-TYPE-A (30ma) circuit breaker

Wallbox installation⇒ what is the best location?

A wallbox can be used as a free-standing charging station, for example above a charging station, but can also be mounted on a wall. However, there are several important details to consider beforehand:

1. Protection against external influences

Since many wallboxes are installed outdoors, they have an IP rating of at least IP54. This means protection against dust deposits (5) and protection against splash water from all sides (4). However, it is advisable to protect the wallbox from external weather conditions. Solar radiation, rain and frost over the years will eventually have a negative impact on the installation. If possible, the wallbox should be roofed over or placed inside a garage, under a carport or in a covered parking area.

2. Installation specific conditions

Is it possible to subsequently lay cables from the distributor to the wallbox?? Is the house connection (public power supply) large enough?? Since most of the wallboxes have a charging capacity of 11 or more, a. 22 amps, the electrical installation should be designed accordingly. Important in advance:

For the connection is accordingly also a strong current connection required and in the distributor a 3-pole fuse with a circuit breaker and a FI circuit breaker. It should therefore be checked in advance whether there is still space in the distributor for the connection or the wallbox. For the protection is available. Also should a feasible cable routing should be checked and accordingly the ideal place for the wallbox should be selected.

If, for example, a charging station with 22 KW is desired, a cable cross-section of 6mm² is required for a maximum cable length of 25 meters and a 3-pole fuse with 32 amperes (calculate cable cross-section).

If the grid operator has no objections to the installation of a wallbox, or if it is not possible, we will be able to supply you with a wallbox in the near future. Even the electrical distributor meets all the conditions to realize the protection of the connection, according to the wallbox, the cable length and the cable cross-section must be selected so that the desired charging power is also achieved.

3. Avoiding stumbling blocks

The charging cable should in no case become a tripping hazard. Accordingly, the charging socket on the e-car should also be on the same side of the wallbox. The correct length of the charging cable should also be taken into account when buying the vehicle. Better a little longer than too short.

Wallbox components

  • Housing
  • Connection unit
  • Installation protection by upstream circuit breaker and RCD-TYP-A (30ma)
  • Ground fault sensor 6 ma DC
  • Controller EVCC (electric vehicle charge controller)
  • Energy meter (optional)
  • Installation contactor
  • Charging plug (TYPE 2 plug)

Wallbox installation⇒ planning, subsidy, material, connection conditions

After clarifying which location is most suitable for the installation (taking into account installation-specific requirements), and which charging capacity the wallbox should have according to the circumstances, the K grant can now be applied for.

Important to know: not all wallboxes are eligible for subsidies. Check beforehand which ones are eligible for a grant. the federal government has made the wrong decision with a subsidy program for private charging stations (wallbox subsidy) for cars with e-drives or. Plug-in hybrids launched for private individuals. 11 KW charging stations at parking spaces, garages or carports are being subsidized. The grant amounts to 900 euro. However, there are some conditions to be met. The subsidy relates not only to the purchase of the wallbox, but also to its installation. The subsidy is also available for 22 KW wallboxes, but these must currently be throttled to 11 KW. Further requirements can be read on the K page.

If you don’t apply for a grant, you can of course start the installation immediately.

& important is: before starting the work the grant must be applied for. Only when the grant is approved, only then can the installation begin.

(the K subsidy for charging stations for electric cars (residential buildings) 440 only runs for a limited time. )

The approval from KWF looks like this:

Once a wallbox has been purchased according to the criteria explained, it can be installed in the most suitable place. After that, the connection cable can be laid from the electrical distributor to the wallbox. According to the connected load of the wallbox and the cable length, the circuit breaker can be procured for fusing in the distribution board.

DIN VDE 0100-722 stipulates that a separate circuit is required for charging stations for electric cars. So do not connect it to an existing circuit, but fuse it separately.

In addition, a residual current circuit breaker/RCD (type-A, type-B or type A-EV) must also be used, which has a max. rated differential current of 30 ma.

Furthermore, protection against DC fault currents must be provided, but often these are already integrated in the wallbox.

Optionally, a wallbox can also be connected to the internet via WLAN or network cable. This means that it can be accessed from anywhere, for example by smartphone. Monitor. Furthermore, it can also make sense to install a camera monitoring system.

  • &check local requirements (approval from the grid operator, space in the electrical distribution board for earth leakage circuit breaker, line circuit breaker)
  • &apply for K subsidy for charging stations (residential buildings) 440 (subsidy is limited). installation may only be started after approval has been granted
  • &get the ideal wallbox, according to the respective installation-specific requirements, the desired charging power and technical equipment
  • &Determine the connection cable (cross-section and cable type) for the wallbox according to the power and cable length
  • &determine the ideal route of the connection cable from the electrical distributor to the wallbox according to the local conditions (empty pipes, cable duct, pipes in the ground)?)
  • &Check the appropriate fuse protection and determine which circuit breakers and RCDs must be provided
  • &install the wallbox at the specified location
  • &laying the connection cable
  • &determine whether additional installations such as network cables (internet) or camera monitoring are possible
  • &hire specialist company for connection work and acceptance
  • & (K-subsidy) proof of commissioning of the specialist company resp. Submit invoices of wallbox, material to K (must be over 900 euro, otherwise no subsidy)

Best Seller wallbox:

For more information about the actuality of the displayed prices click here.

Wallbox installation⇒ determine cable type and cross-section⇒ lay cable yourself

If you want to save additional costs for the installation, you can lay the cables from the electric distributor to the wallbox yourself. Since the connection work should be done by a specialist company anyway, it is advisable to talk to the specialist company in advance and to agree on the laying work for the connection cable.

Often there are empty conduits left in electrical distribution boxes. Therefore, it should be checked in advance with a tension spiral* whether empty pipes can be used for the connection cable. If this is not the case, a surface installation, for example with a white cable duct or installation pipes, can be considered for the cable laying. In any case, the dimension of the duct should rather be chosen somewhat larger, so that possibly additional cables (network cables*) can be laid later as well.

If the charging station is accessible only through the ground, a ground cable (NYY-J) must be used. Otherwise, an installation cable NYM-J* is sufficient in the most frequent cases. In extreme conditions, such as damp rooms, outdoors, in agricultural areas, in areas subject to fire hazards, a high-grade rubber cable H07RN-F* is recommended for the connection. It is durable and suitable for extreme temperatures from -25°C to +60°C. however, this cable must not be laid in the ground.

What cable cross-section should be laid to the charging station ⇒ fuse protection of the cable

the dimension of the supply cable depends mainly on the charging power (power consumption) of the wallbox and the distance (cable length) from the electrical distribution board to the wallbox. The thicker the cross-section, the higher the power. On many charging stations the maximum power consumption can be additionally adjusted.

Examples for a 3 phase power connection. Since in private apartments an 11 KW wallbox is usually sufficient, the following cable cross-section would be sufficient here.

  • 11 KW wallbox ⇒ cable length up to 20 meters: cable cross-section 5 x 2.5 mm² ⇒ fuse protection in the distributor with a circuit breaker B16A
  • 11 KW wallbox ⇒ cable length up to 40 meters: cable cross-section 5 x 4 mm² ⇒ fuse protection in the distributor with a circuit breaker B25A
  • 11 KW wallbox ⇒ cable length up to 70 meters: cable cross-section 5 x 6 mm² ⇒ fuse protection in the distributor with a circuit breaker B32A

For more information on the actuality of the displayed prices, click here.

If a 22 KW charging station were to be installed, the following cable cross-sections would have to be laid:

  • 22 KW wallbox ⇒ cable length up to 25 meters: cable cross-section 5 x 6 mm² ⇒ fuse protection in the distributor with a circuit breaker B32A
  • 22 KW wallbox ⇒ cable length up to 50 meters: cable cross-section 5 x 10 mm² ⇒ fuse protection in the distributor with a circuit breaker B40A

For more information about the actuality of the displayed prices, click here.

For more information about the actuality of the displayed prices click here.

& the fuse protection with a circuit breaker (LS-switch) serves to protect the cable, regardless of how the charging station is protected internally. The circuit breaker is located in the sub-distribution board. From there, the supply line is laid to the charging station. The main purpose of the circuit breaker is to protect the supply cable from overcurrent, short circuit and overheating. A circuit breaker has the task of protecting the line or the power supply. to protect the building when cables overheat. The size or. The dimensioning of the correct circuit breaker for our wallbox is mainly based on the cable cross-section. Important for the dimensioning are also the cable route, how the cable is laid and the ambient temperature.

The RCD for the wallbox

Each charging station must also be protected by a residual current circuit breaker (RCD) be fused. An electric car runs on direct current, and direct current faults can occur in the process. The residual current circuit breaker prevents these dangerous fault currents. This prevents these currents from occurring, before which the RCD trips and disconnects the wallbox from the mains.

It should be noted: Basically, there are two types of RCDs: type A and type B. Many charging stations have their own internal built-in DC fault monitoring. If this should be integrated, the substantially more favorable FI circuit breaker type A is sufficient. If this is not the case, the considerably more expensive RCD type B must be installed in the sub-distribution board. It could also be that the RCD is already installed in the wallbox. This must be checked beforehand. Important: if the right or wrong RCD is not installed, safe charging cannot take place!

A residual current circuit breaker with a rated residual current of 30 ma must be installed. It is installed in the sub-distributor or. Meter cabinet installed. It is usually installed before the circuit breaker for the wallbox.

& to protect the wallbox, install a residual current circuit breaker (RCD) in addition to the line circuit breaker. It is necessary to check in advance whether the wallbox to be installed has an already integrated DC-DC fault monitoring, is installed as a protective device. If yes, then a type A earth leakage circuit breaker is sufficient, if not, a much more expensive type B earth leakage circuit breaker must be installed in the sub-distributor for protection.

Useful additions that could possibly be considered for the wallbox installation

Energy meter

The consumption resp. To have the power data of the wallbox always in view is a useful extension which makes sense. Some devices already have an integrated energy meter. You can access it for example via an app. If no energy meter is integrated, you could install such a meter in the sub-distributor (in the supply line to the wallbox). In the trade these devices are not so expensive.

Lighting

Lighting that turns on the light in the dark with an automatic motion detector is often useful. This will certainly make it easier to attach the plug-in device to the electric car or to the charging station. For general safety.

Network connection

Optionally, a wallbox can also be connected to the internet via WLAN or network cable. This means that you can access them from anywhere, for example by using a smartphone. Monitor.

Camera monitoring

Also a monitoring of the charging station by means of a camera that is controlled independently via WLAN or network, for example, often makes sense. The camera can be set to record and store all movements around the charging station. So you can also check the monitoring material afterwards.

Wallbox installation in practice

Practical example of how the wallbox installation can look like.

Starting point:

Installation of a wallbox from "VW elli charger pro" in the garage. Sub-distribution board in the garage with its own FI circuit breaker available. supply line to the sub-distributor 5 x 6 mm² fused with 35 A.

Since there is still enough space in the 3-row sub-distributor in the garage for the fuse protection of the wallbox, the wallbox can be fused there without any problems. The wiring path is very simple and can be done through a white 20 x 30 mm cable duct. the cable length of the power connection to the wallbox is only approx. 10 meters.

Since the wallbox is limited to a maximum of 11 KW, a NYM-J 5 x 2.5 mm² is completely sufficient in my case here. the cable is fused with a circuit breaker B-32 A 3-pole in the sub-distribution board. The FI switch in the sub-distribution is a 40/0,03 A TYPE-A. It is also sufficient because my wallbox from VW elli charger pro has an integrated dc-fault monitoring and is therefore well protected.

In addition, a network cable CAT 6 or CAT7* is laid from the wallbox to the communication distributor in the basement, in order to integrate the wallbox into the house network.

Wallbox installation example. List of materials:

The first step is to drill a hole through a 12 cm thick brick wall in the garage for the cable feed-through.

The wallbox is then installed in the ideal location in the garage. Open wallbox, mark drill holes for mounting. 4 mounting points with 8 mm holes are needed.

Now mount the cable duct vertically above the wallbox to the ceiling and from there horizontally, underneath the ceiling to the sub-distributor.

After the cable duct has been installed, the connection cable can be laid from the subdistributor to the wallbox. At the same time, network cable is also being laid in the cable duct. However, this does not end in the sub-distributor, but is pulled into an empty installation pipe that ends in the communication distributor in the basement.

Now insert the connection cable and the network cable into the wallbox according to the detailed instructions in the installation manual, cutting and stripping the cable to the correct length beforehand. Before connecting, follow the 5 safety rules.

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