Guide

Single-phase or three-phase? Belgian networks and building connections

1×230 V, 3×230 V or 3N~400/230 V: understand the street network, neutral conductor and connection phase count in Belgium.

Published on 27 July 2026 Updated on 29 August 2026 12 min

Short answer: there are more than two cases

Two separate questions matter in Belgium:

The low-voltage street network: 230 V without neutral, or 400/230 V with neutral.
Your individual building connection: single-phase or three-phase.

“Single-phase = 1×230 V” is a valid connection description, but not a separate street-network form. A single-phase 230 V connection can be line-to-neutral from a 400/230 V network or line-to-line from a 3×230 V network. ORES explicitly says that a single-phase connection does not necessarily include a neutral conductor.

The four combinations

Street network	Building connection	Conductors at the connection	Technical notation
400/230 V with N	Single-phase	L + N	1×230 V, L–N
400/230 V with N	Three-phase	L1 + L2 + L3 + N	3N~400/230 V
230 V without N	Single-phase	Two line conductors	1×230 V, L–L
230 V without N	Three-phase	Three line conductors	3×230 V without N

The 3×230 V network is not merely theoretical. Fluvius reported 18,101 km of 230 V low-voltage network at the end of 2024, concentrated especially in urban and western areas. Sibelga says about 80% of Brussels is covered by 230 V. That does not mean every home there has three phases: Sibelga describes 9.2 kVA, single-phase 230 V at 40 A, as its standard household connection.

Power with the same current rating

ORES publishes these values at 40 A:

Connection	Apparent power at 40 A
Single-phase 230 V	9.2 kVA
Three-phase 3×230 V	15.9 kVA
Three-phase 3N~400/230 V	27.7 kVA

Your actual contracted capacity still depends on the connection breaker and the grid operator's records.

EV chargers, heat pumps and solar

EV charger: 3.7 or 7.4 kW may be possible on single phase. 11 or 22 kW normally needs a suitable three-phase connection. Not every device works on 3×230 V; Sibelga lists restrictions for 11/22 kW charging.
Heat pump and cooker: Check the nameplate. Equipment designed for 3N~400 V cannot automatically run on 3×230 V without neutral.
Solar: Permitted inverter power and phase distribution depend on the grid operator and the actual connection. A blanket Belgian 5 kWp rule would be misleading.

Before buying a large load, check both single/three-phase and 230 V without N/400/230 V with N.

RCDs on a 3×230 V network

An RCD does not need a neutral conductor as a “reference”. It compares the currents in all active conductors routed through it. On a 3×230 V network, the participating line conductors must therefore be monitored and switched together. The previous blanket claim that RCD protection is reduced merely because no neutral is present was incorrect.

Phase balancing

Sensible load distribution is good design practice on a three-phase connection. The AREI/RGIE does not, however, prescribe a universal exact 30% limit. Such a threshold may be used as a planning warning, but should not be presented as a verbatim statutory rule. A single-phase connection has no three phases to balance.

Identifying your connection

Check the meter, connection breaker and incoming conductors without opening sealed areas. ORES provides examples of single-phase 230 V, 3×230 V and 3×400 V + N. When in doubt, the grid operator or an electrician can confirm the connection. Counting visible wires alone can be misleading because of PE, internal wiring and legacy installations.

Upgrading or changing the connection

There is no single Belgian price or timeline. It depends on the grid operator, requested capacity, available street infrastructure, meter position and work required inside the building. Ask the relevant grid operator for a specific quotation first. Significant changes may also require updated diagrams and a new inspection.

Turn equipment data into a connection decision

Build a load schedule before requesting more capacity. Separate continuous loads, short coincident peaks and controllable consumers. A cooker, heat pump, instantaneous water heater, EV charger and inverter have different operating profiles. Adding every nameplate is not automatically the required connection capacity, but dismissing large loads without a calculation is equally unsafe. Load management can reduce peaks only when it is compatible with the actual equipment, meter and grid-operator process.

For each item, record four basics: permitted supply voltage, whether neutral is required, phase count and maximum current per phase. Add starting current, power factor and manufacturer conditions where relevant. “Three-phase” is insufficient: equipment designed for 3N~400 V may require a neutral or internal connection unlike equipment intended for 3×230 V. The electrician must also resolve protection, conductor sizing, disconnection and possibly phase sequence.

Reading the kVA figures correctly

For single-phase 230 V, apparent power is approximately voltage multiplied by current. For a balanced three-phase load, use voltage multiplied by current and √3, with the relevant line voltage. ORES therefore lists about 9.2 kVA for 40 A single phase, 15.9 kVA for 3×230 V and 27.7 kVA for 3×400 V + N. These are technical magnitudes, not automatically the usable real power of every appliance, diversity allowance, contract value or network approval.

With an unbalanced installation, each line conductor matters. A generous total capacity does not prevent one phase being overloaded by many single-phase loads. Document assignments in the board and revisit them after changes. Software may use planning alerts, but an arbitrary percentage cannot replace connection conditions and electrical calculation.

Representing the supply in the single-line diagram

Record voltage, current type and connection configuration at the supply point. Show main protection and every active conductor without ambiguity. Do not invent a neutral on a 3×230 V network; on 3N~400/230 V, show it where it is actually distributed. After a conversion, review the board population, protective devices, conductors and final circuits, then update the diagrams to the as-built state.

PlanElec can document network form, building connection, phase allocation and circuits as separate structured data. It cannot know the binding street-network availability, all appliance characteristics or grid approval. Its output therefore does not replace a grid-operator request, professional execution design or official inspection.

Frequent decision errors

Reading only the meter: its display alone may not establish the full conductor configuration.
Treating 3×230 V and 3N~400/230 V as equivalent: both are three-phase, but provide different voltages and conductors.
Equating kVA and kW: real power also depends on the load and power factor.
Using charger power as total connection demand: other coincident loads and management are omitted.
Keeping old drawings after conversion: supply, protection chain and phase allocation no longer describe reality.
Opening sealed equipment: rely on safe visible records, the operator or a qualified person.

Three planning scenarios

Existing 1×230 V: first confirm the actual breaker rating and neutral situation. A charger at limited single-phase power with load management may be possible, but vehicle, charger, house demand and operator conditions decide. A higher number in a brochure does not create available capacity.

Existing 3×230 V: distribute single-phase consumers across line-conductor pairs and check every three-phase appliance explicitly for operation without neutral. The RCD monitors all participating active conductors together. Equipment is not compatible merely because its brochure says “three phase” if its controls require 230 V to neutral.

Existing 3N~400/230 V: single-phase loads normally use line to neutral and three-phase equipment follows its manufacturer's connection. A generous calculated capacity removes neither the per-phase current limit nor the need for protection and conductor sizing.

Before requesting a quotation

Collect the EAN or connection reference, current breaker setting, requested capacity, equipment data and target commissioning date. Ask explicitly which voltage, phases and neutral are available at the address. Have the electrician identify work to the meter position, connecting cable, main board, RCD arrangement and phase distribution. Only then can the network quotation and internal work be compared meaningfully.

After conversion, do more than update one project field. Review every dependent conductor, protective chain and appliance assignment. Preserve the previous drawing and issue a new dated as-built revision.

Measurement and commissioning

Do not establish the final configuration from paperwork alone. A qualified person verifies actual voltages with suitable methods without unauthorised access to operator equipment. Phase sequence, neutral routing and protective conductors are checked separately where relevant. Following alteration, the required tests and measurements cover the affected work.

For controlled high-power loads, observe behaviour in operation. Load management needs a safe documented response to communication loss or bad measurements. Its limit must agree with connection protection and consider per-phase peaks, not only an average. Treat setting changes as design-relevant records.

Use a decision matrix

Consider confirmed network form, equipment voltages, peaks per phase, planned additions and operator costs together. Three-phase is not automatically necessary or economical; single-phase is not automatically sufficient. The sound option satisfies verified requirements and is accepted by both network process and professional electrical design.

Sources

Document the network and building connection separately in PlanElec →

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