Single-Phase or Three-Phase? The Belgian Homeowner's Guide

What's the difference between single-phase and three-phase?

Most Belgian households have a single-phase connection (1×230V). For higher power needs, there's the three-phase connection (3×400V+N). But when is the upgrade worth it — and what's the Belgian delta network?

Single-phase vs. three-phase at a glance

The Belgian delta network — a local peculiarity

In some older Belgian neighbourhoods, the delta network (driehoeksnet / réseau triangle) still exists: 3×230V without a neutral conductor. This means:

• Between any two phases there's 230V (instead of 400V in a star network)
• There is no neutral conductor — every device connects between two phases
• Modern three-phase devices (EV charger, heat pump) don't work without modification

Important: If your house is still on the delta network and you want to install an EV charger or heat pump, the grid operator may need to convert to a star network (3×400V+N). Clarify this early.

When do you need three-phase?

An upgrade to three-phase makes sense or is necessary when:

EV charger (wallbox)

• Single-phase: Maximum 7.4 kW (32A) — approx. 35 km range per hour of charging
• Three-phase: Up to 22 kW (3×32A) — approx. 100 km per hour
• Recommendation: From 11 kW, a three-phase connection is practically required (3×16A). This is not an AREI requirement, but may be mandated by the grid operator

Heat pump

• Small heat pumps (up to 5 kW) run on single-phase
• Above 5 kW: Three-phase connection recommended or required
• At startup, the heat pump draws high currents briefly — three-phase distributes this better

Photovoltaics (PV)

• Up to 5 kWp: Single-phase inverter possible
• Above 5 kWp: Three-phase inverter recommended (better feed-in balance)
• For systems over 5 kWp, some grid operators require three-phase feed-in

Multiple heavy loads simultaneously

If you want to run EV charger + heat pump + electric cooker + instantaneous water heater simultaneously, ~9.2 kW single-phase (40A) won't suffice. Note: 32A is the maximum rating for a single branch circuit, not for the connection itself.

The upgrade process with Fluvius / ORES / Sibelga

Total timeline: Plan for 4 to 12 weeks, depending on grid operator and region.

Tip: In Flanders (Fluvius), the process is usually faster than in Wallonia (ORES). Brussels (Sibelga) falls in between.

Phase balancing — What the AREI requires

For three-phase installations, as even a load distribution as possible across the three phases is good installation practice. The AREI requires in Art. 5.3.5.3d that the load be distributed across circuits such that no unintended tripping of residual current devices occurs. A specific numerical limit is not stated; in practice, an imbalance of max. approx. 30% is considered acceptable.

Practical example

In this example, L3 is significantly more loaded. Better: connect the EV charger three-phase or redistribute consumers.

What this means for your single-line diagram

With three-phase, the single-line diagram must show:

• All circuits assigned to a phase (L1, L2, L3)
• 4-pole RCDs for multi-phase circuits and as main RCD. For single-phase branch circuits, 2-pole RCDs are also permitted (Art. 5.3.5.3 c)
• The phase balancing visibly

PlanElec supports phase assignment directly in the editor — you can immediately see whether the load is evenly distributed.

Cost overview

The total includes no PlanElec fee because Early Access is currently free. If you have the diagram drawn up by an electrician instead (€300 – €600), the range is €1,425 – €4,270.

Conclusion: When is it worth it?

Related articles

• Installing an EV charger in Belgium — What does the AREI say?
• Registering & documenting a PV system (Belgium)
• What does an electrical plan cost? Price comparison 2026
• Surge protection mandatory since AREI 2020

Plan your three-phase installation with PlanElec — including phase assignment →