Knowledge

9 October 2026

Load management for EV charging in an apartment building: what it controls, what the grid operator requires and what belongs in the quote

Load management shares the available capacity of the building connection between the charging stations instead of upgrading the connection. What the VSE information sheet and the Swiss eMobility guide say about it — and what an electrical contractor should settle before quoting.


Load management for EV charging shares the available capacity of the building connection between the connected charging stations, so that several vehicles can charge without overloading the connection. In many cases it saves an expensive upgrade of the building connection. For the electrical contractor this means: as soon as more than one charging station is planned in an apartment building, load management belongs in the quote — and so does a conversation with the grid operator beforehand.

What load management is

Load management is a control system that shares the available capacity of the building connection between the connected charging stations. The guide «Ladeinfrastruktur in Mietobjekten» (Swiss eMobility with EnergieSchweiz, version 2, October 2024) gives the reason: in Switzerland a car covers less than 30 kilometres a day on average, so it stands on its parking space far longer than charging takes. Charging can therefore be spread over time, and in many cases an expensive upgrade of the building connection can be avoided even though more charging stations are operated.

Without control that only goes so far. According to the same guide a single charging station can be supplied by a direct feeder from the building's main distribution board to the parking space, without intelligent control — but such a solution can hardly be extended: several charging stations installed that way would overload the building connection.

What the VSE information sheet says

The information sheet «Elektromobilität — Infoblatt Ladestationen» from the Association of Swiss Electricity Companies (VSE) names two points for installations with several charging stations that matter directly to the installer:

  • Load on the connection. Several charging stations at the same connection point, for instance in apartment buildings, can place a heavy load on the service line and the grid. According to the sheet, a local load management system can prevent this.
  • Symmetrical distribution. The load on the outer conductors at the connection point must never show an imbalance (power difference) above 3.7 kVA; otherwise the charging stations have to be connected so that the load is spread as evenly as possible. This is achieved with an integrated dynamic phase-balancing system or with a rotating phase connection, in which single-phase charging vehicles sit on alternating phases.

Controllability is a further requirement: charging stations above 3.7 kVA must give the distribution grid operator a way to reduce the power temporarily when the safe operation of the grid is directly at risk (Art. 12.3 Werkvorschriften CH). On request, conformity is shown by the device's CE declaration of conformity. The sheet names a second advantage of controllable chargers: they help save the fees for an increase of the connection capacity.

What must be reported before installation

The sheet requires the distribution grid operator to know the locations and technical specifications of all charging stations in its area. Installing plug-in and permanently connected charging stations is therefore subject to notification: the installer submits a technical connection request (TAG) and an installation notice early, that is before work begins (see Art. 2.2 and 2.3 Werkvorschriften CH). For installations with several charging stations the sheet recommends contacting the grid operator as early as possible. The details are in the article «Installation notice: which jobs must be reported to the grid operator».

How the installation is sized

The Swiss eMobility guide recommends dimensioning the basic installation and the control for the final stage of expansion from the start. The deciding factors are the available capacity of the building connection, the structural conditions and the forecast demand for charging stations. The charging power actually available per parking space also depends on how many vehicles charge at the same time, on the charging power of the vehicles and on the configuration of the load management. The guide notes that electric cars can have standard consumption up to 30 per cent higher in winter.

For a car park in an underground garage the same guide gives rough costs per parking space: CHF 500 to 1,500 for the one-off basic installation (service life 20 years) and CHF 2,000 to 3,500 for the charging station including installation from the basic installation (service life 8 years), plus CHF 0 to 15 a month for billing, control and operation. These are guide values, not prices: missing space in the main distribution board, a new sub-distribution or long feeder routes can raise them. A quote follows the site visit.

What belongs in the quote

For every installation with more than one charging station at the same building connection:

  • Ask the distribution grid operator for the connection capacity and record it before the price is fixed.
  • Show load management as a position of its own, stating which capacity it shares between how many charging stations.
  • Settle the phase distribution (dynamic phase balancing or rotating phase connection) and stay within the 3.7 kVA limit for imbalance.
  • Choose charging stations above 3.7 kVA with controllability and a CE declaration of conformity.
  • Plan the TAG and the installation notice before work starts.
  • Size the basic installation for the final stage, so that further charging stations can follow later without new feeders.

Inspection is the same as for any installation; the article «Initial verification, final inspection, acceptance inspection» tells the three apart. Which inspection period applies in a given case is shown by the calculator for inspection periods.

Load management, condominium ownership and ZEV

Who decides whether to build at all in a condominium community is covered in «Wallbox in condominium ownership»; for a rented flat see «Wallbox in a rented flat». If a self-consumption community (ZEV) hangs on the same building connection, load management keeps the connection capacity unchanged — and with it the reference value of the 10 per cent threshold, as «Wallbox and ZEV on the same building connection» shows.

Common questions

What is load management for EV charging stations? A control system that shares the available capacity of the building connection between the connected charging stations, so that the connection is not overloaded.

Does every wallbox need load management? A single charging station can be connected without control. For several charging stations at the same connection point, such as in an apartment building, the VSE sheet names a local load management system as the means against overloading the service line and the grid; according to the Swiss eMobility guide, several charging stations without control would overload the building connection.

How large may the imbalance be? At the connection point the power difference between the outer conductors must never exceed 3.7 kVA (VSE information sheet). Otherwise the load has to be spread as evenly as possible over the phases.

Must the grid operator be able to control the charging station? For charging stations above 3.7 kVA, yes: they must offer a way for the distribution grid operator to control them (Art. 12.3 Werkvorschriften CH).

Does a wallbox have to be reported? Yes. Before work begins the installer submits the technical connection request and the installation notice to the distribution grid operator.


Sources: Verband Schweizerischer Elektrizitätsunternehmen (VSE/AES), information sheet «Elektromobilität — Ladestationen», strom.ch, for the load on the connection, phase distribution, controllability, CE conformity and the duty to notify. Swiss eMobility with the support of EnergieSchweiz, «Ladeinfrastruktur in Mietobjekten — Ein Leitfaden für Eigentümerschaften und Verwaltungen», version 2, October 2024, laden-punkt.ch, for how load management works, sizing and rough costs. The Werkvorschriften CH are only cited there, not read; the grid operator's own version governs the wording. This article is not a substitute for professional planning; in each case the distribution grid operator sets the requirements.

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