Creating a Single-Line Diagram — Step by Step

What is a Single-Line Diagram?

A single-line diagram (Dutch: eendraadschema, French: schéma unifilaire, German: Eindrahtschema) is a simplified electrical schematic that shows the structure of your entire installation using standardized symbols. Unlike a wiring diagram that shows every individual conductor, a single-line diagram uses a single line to represent each circuit.

This document is mandatory in Belgium for every electrical inspection according to the AREI/RGIE regulations. Without a correct and up-to-date single-line diagram, you cannot pass your inspection.

Why is it Important?

The single-line diagram serves multiple critical purposes:

• Legal requirement — Mandatory for every electrical inspection in Belgium
• Safety overview — Shows all protection devices and their coordination
• Maintenance reference — Helps electricians quickly identify circuits and components
• Modification planning — Essential for planning future changes to the installation
• Property documentation — Required when selling a property

Important: The single-line diagram must accurately reflect the current state of the installation. Any modification to the installation requires an update to the schema.

Understanding AREI Symbols

The AREI/RGIE prescribes specific symbols based on the IEC 60617 standard. Here are the most important ones:

Protection Devices

• Circuit breaker (automaat / disjoncteur) — Protects against overcurrent
• Differential switch (differentieelschakelaar / différentiel) — Protects against earth leakage
• Fuse (zekering / fusible) — Traditional overcurrent protection
• Main switch (hoofdschakelaar / interrupteur principal) — Disconnects the entire installation

Consumers

• Socket outlet — Represented by a semicircle symbol
• Lighting point — Circle with rays or cross
• Fixed appliance — Rectangle with device designation
• Motor — Circle with M designation

Special Symbols

• Earth connection — Three horizontal lines of decreasing length
• Equipotential bonding — Connecting line with earth symbol
• Surge protector — Zigzag line with arrow

Step-by-Step Guide with PlanElec

Step 1: Define Your Installation

Start by mapping out your electrical installation:

1. Open PlanElec and create a new project
2. Define the rooms in your building (living room, kitchen, bedrooms, etc.)
3. For each room, specify the electrical components:
   • Number and type of socket outlets (single, double, with earth pin)
   • Lighting points (ceiling, wall, switched)
   • Fixed appliances (oven, hob, boiler, etc.)
   • Special circuits (EV charger, heat pump, solar panels)

Step 2: Configure Protection Devices

PlanElec automatically suggests appropriate protection:

• Main differential switch — At most 300 mA at the supply point (Art. 4.2.4.3b), preferably selective (Type S/time-delayed) to achieve selectivity with the downstream 30 mA RCDs (state of the art)
• Additional 30 mA differentials — For socket circuits (not for fixed appliances), lighting, bathrooms, washing machine/dryer/dishwasher (Art. 4.2.4.3b); max. 8 final circuits per 30 mA RCD
• Circuit breakers — Sized according to cable cross-section and circuit type
• Surge protection — If required by your installation type

You can adjust these suggestions based on your specific requirements or your electrician's recommendations.

Step 3: Review the Topology

PlanElec generates the circuit topology automatically:

• Circuits are grouped logically (lighting, sockets, dedicated circuits)
• Each circuit gets a unique identifier (e.g., A1, A2, B1, B2)
• The hierarchy from main switch to end consumer is clearly visible
• Cable cross-sections are indicated for each circuit

Step 4: Generate and Export

With a single click, PlanElec generates your single-line diagram:

• Structured layout — Horizontal main bus with vertical branch circuits
• Symbol catalog — Electrical symbols for the Belgian planning context
• Automatic labeling — Circuit references, cable types, and protection ratings
• PDF export — Central document output for further professional review

Common Mistakes to Avoid

1. Incomplete Circuits

Every consumer must be traceable back to the main switch through a clear chain of protection devices. Don't leave any "floating" connections.

2. Wrong Symbol Usage

Use the symbols prescribed for your application. Common mistakes include old DIN symbols or custom notation. The PlanElec catalog supports a consistent representation; professional responsibility remains with the author.

3. Missing Information

Every circuit must show:

• Circuit reference number
• Cable type and cross-section (e.g., XVB 3G2.5)
• Protection device rating (e.g., 16A or 20A; typical breaker for 2.5 mm²: 20A — 16A is permissible but not the standard pairing)
• Number and type of consumers

4. Outdated Schema

If you've made changes to your installation, the single-line diagram must be updated accordingly. An outdated schema will be rejected during inspection.

Tips for a Perfect Schema

• Keep it clean — Avoid unnecessary crossings and overlapping labels
• Be consistent — Use the same notation style throughout the document
• Include all circuits — Even small additions like a doorbell or garden lighting
• Date your document — Always include the creation/modification date
• Add your details — Include the address of the installation and the name of the creator

Let PlanElec Do the Heavy Lifting

PlanElec brings the floor plan, electrical topology, and distribution board together in one project and derives the single-line diagram from them.

• No CAD software needed
• Central project data without duplicate transfer
• Advisory AREI self-check with a 31 March 2025 rules baseline
• PDF export of the single-line diagram and situation plan

Create your single-line diagram now — it's free →