Home charging point: circuit, protective devices, diagram

Book 1 of the RGIE devotes a whole chapter to charging points: chapter 7.22, on the supply of electric road vehicles. It supplements the general rules of the Book and sets out, among other things, the dedicated circuit, residual-current protection and overcurrent protection. Here is what the text provides, and how to reflect it in the electrical file.

One dedicated circuit per connection point

Book 1 (section 7.22.3) requires a dedicated circuit for each connection point, meaning each socket-outlet or vehicle connector that forms part of the charging point (section 7.22.2). The protective devices may sit in the fixed installation upstream, in the charging point, or in a combination of the two. Figures 7.17 to 7.20 illustrate some configurations, without being exhaustive.

The same section forbids connecting a charging point to the fixed installation by means of a plug and socket-outlet. Chapter 7.22 applies to charging points whose construction or replacement started on or after 1/11/2022. The fixed installation that supplies a vehicle connected without a specific fixed charging point falls under the general requirements of the other parts of the Book (section 7.22.1).

Sizing the circuit to the charging point

The starting point is the charging point’s data sheet: power, rated current, number of connection points, built-in protective devices or not. On the regulatory side, each dedicated circuit is individually protected against overcurrent by a device complying with chapter 4.4, placed upstream or in the charging point (subsection 7.22.4.2).

• Several connection points: if they are not used simultaneously, they may share a common overcurrent protective device, provided it gives each of them the required protection (for example, a rated current no higher than the lowest rated current of the connection points).
• Circuit length: section 5.2.5 requires voltage drops to be limited to the values described in good practice. A charging point far from the board should be checked from that angle too.
• Earthing system: applying a TN-C system to the dedicated circuit is forbidden (subsection 7.22.4.1).

Choosing the cable size follows the same principles as for any circuit, covered in our article on cable sizes and ratings. At inspection, the report certifies that the overcurrent protective devices match the cable sizes of the circuits they protect (subsection 6.4.6.4).

Residual-current protection

This is the most technical point of the job. Under subsection 7.22.4.1, where protection relies on automatic disconnection of supply, each dedicated AC circuit is individually protected by an RCD with a rated residual operating current of 30 mA at most.

The text also deals with insulation faults with a disturbing DC component. The connection point is protected either by an RCD built to keep working when such a component is present, or by an RCD used together and in coordination with a DC residual-current detection device that takes the charging point out of service. These devices may sit in the fixed installation upstream, in the charging point, or in both. The IT system is the subject of specific provisions in the same subsection. For a refresher on the role of the sensitivities in the installation, see our article on 300 mA and 30 mA RCDs.

Where and how to install the charging point

Section 7.22.5 adds rules on the equipment and its location:

• Outdoors, the equipment has a degree of protection of at least IP44 (subsection 7.22.5.1).
• In all cases, additional measures protect against mechanical stresses due to any reasonably foreseeable collision (subsection 7.22.5.1).
• The connection point is located as close as possible to the parking space, and is connected to only one vehicle at a time (subsection 7.22.5.3).
• If the charging point can feed energy back into the installation, the requirements for decentralised generating units apply, and a warning that energy may be fed back into the installation is placed on the charging point or points and on the switching and distribution board or boards supplied from them (subsection 7.22.5.4).
• Charging points and their parking spaces are not located in places characterised by the external influence BE3 (subsection 7.22.5.5).

The emergency switching provided for charging points installed in a building (subsection 7.22.5.2) does not apply to charging points that form part of the electrical installation of a dwelling unit.

Metering and load management

Two options can accompany the charging point:

• Dedicated metering: an energy meter on the charging point’s circuit, to track the vehicle’s own consumption.
• Load management: a module that takes the dwelling’s consumption into account to adjust the power delivered by the charging point.

Chapter 7.22 does not deal with these options. If they are planned, include them at wiring time and show them on the diagram, like the rest of the equipment.

The charging point must appear in the file

For a domestic installation, the single-line diagram shows, among other things, the type, cross-section and number of conductors of the wiring, the installation method, the RCDs and the overcurrent protective devices (subsection 3.1.2.2). The position plan shows the position of the equipment listed on the diagram (subsection 3.1.2.3). Table 2.23 provides a symbol for a charging point for electric road vehicles.

At inspection, the report also certifies that the installation has been carried out in accordance with the single-line diagrams and position plans (subsection 6.4.6.4). A charging point fitted at the end of the job and never carried over onto the documents therefore creates a discrepancy. Updating the diagram and the plan when it is fitted avoids that. In Amperio, what you draw or dictate on site is placed on the diagram and the plan, always in agreement. The course of the visit is covered in our inspection checklist.

One last point: adding a circuit to a domestic installation is one of the examples of a major modification (section 2.11.2). A major modification undergoes a conformity inspection before it is put into use, limited to the added or modified part (subsection 6.4.7.3). If the modification has an impact on the unmodified part, that part is inspected for the modified characteristics. The person responsible for the work draws up the single-line diagrams and position plans (subsection 3.1.2.1). Plan the visit into the job schedule.

This article is informative. It replaces neither the RGIE (Book 1) nor the advice of your inspection body.