Creating a Single-Line Diagram — Step by Step
Learn how to prepare a reviewable single-line diagram with circuits, conductor data, protective devices and unambiguous references.
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.
For a new domestic installation and a substantial modification or extension, AREI/RGIE requires this document together with the position plan. Existing installations and non-substantial changes have their own bounded rules. The approved control body assesses the actual dossier and installed work.
Why is it Important?
The single-line diagram serves multiple critical purposes:
- Required documentation — For new domestic installations and substantial changes or extensions
- 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 records must describe the current state. A dated short description can suffice for a non-substantial change, while the position plan still remains updated.
Understanding AREI Symbols
AREI/RGIE Table 2.23 provides the starting symbols. If none is listed for an item, another unambiguous symbol may be used when the legend defines it. Important groups include:
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:
- Open PlanElec and create a new project
- Define the rooms in your building (living room, kitchen, bedrooms, etc.)
- 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 can suggest protective devices as a reviewable starting point:
- General residual-current protection — At most 300 mA at the supply point (Art. 4.2.4.3b); type, rating and coordination are checked for the actual protection chain
- 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 (for example 16 A or 20 A; table values are ceilings and do not replace complete conductor sizing)
- 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
Check the required information systematically
For a domestic installation, Book 1 V06 lists at least the conductor type, cross-section and number of conductors, installation method, type and properties of residual-current and overcurrent protection, switches, connection and junction boxes, sockets, lighting points, fixed machines and appliances, and sources such as an inverter or battery. Diagrams and documents also carry a number, revision and revision date. Supply voltage, current type and unambiguous elementary-circuit identification complete the context.
An uppercase letter identifies each elementary circuit. Lighting points, sockets and control devices receive sequential numbers from the upstream overcurrent device. The position plan reuses those references. A switch is identified through the circuit and the light or device it controls. This shared key is what lets an inspector read the two drawings together.
A practical circuit walk
Start at the supply and follow each branch to its last consumer. At every transition, ask whether the real device exists, its purpose is clear, the conductor is fully described, and its position-plan reference agrees. Pay special attention to junction boxes and shared branches; a flat row of symbols is not a truthful substitute for a physical branch.
Where there are several sources, the grid, PV inverter and any other explicitly modelled supplies must remain understandable as separate paths. A battery icon or bidirectional charger must not be presented as a complete published PlanElec workflow merely because an internal type exists. For PV, PlanElec can represent structured DC strings and recorded protection or cable sections; unknown and unassigned data remain visible as gaps.
Existing work and later changes
Substantial changes or extensions to a domestic installation require the single-line diagram and position plan to be prepared or updated. For a non-substantial change, a dated and signed short description may replace a new single-line diagram, while the change still appears on the position plan. Parts installed before 1 October 1981 are marked as an “older part” when shown. Part 8 contains narrow derogations for existing parts, not a general exemption from documentation or safety.
Prefer electrical truth to visual polish
Clear routing improves readability but proves no conductor sizing. Do not check cross-section and protection against one table alone: installation method, current capacity, grouping, temperature, voltage drop, fault conditions and disconnection all matter. The same applies to RCD type, selectivity, surge protection and appliance-specific instructions. A custom symbol is useful only when unambiguous and explained in the legend; Table 2.23 is the official starting point.
Example of a complete circuit record
Do not label a branch merely “Kitchen”. A usable record might identify circuit B, upstream protective device, RCD assignment, cable type, conductor count, cross-section, installation method and numbered consumers B1 through B6. A fixed cooker is named as a specific appliance, not hidden among general sockets. A real junction box appears at its actual topological position.
That structure makes discrepancies searchable. If B4 is absent from the position plan, either the spatial record is incomplete or the diagram contains an extra item. If the cable changes after a junction, describe the segment separately. Applying one default conductor to an entire branch would misrepresent reality.
Release check for every sheet
Read the PDF at its intended output size. Check title block, sheet number, revision, date, address, responsible parties, voltage and current type. Then inspect clipped labels, overlaps and legend coverage. For multiple sheets, continuation points must remain understandable.
Trace a sample from board to consumer and back. Include a lighting branch with switching, one fixed high-load appliance and one source such as PV. Keep unsupported, unknown and unassigned information visible. Do not delete a warning solely to create a cleaner-looking page.
The document author aligns the release with the as-built state. The electrician checks sizing, protection and installation. The approved control body performs the official assessment. Software does not silently assume any of these roles.
Archive the released files with their revision and supporting evidence. After a later alteration, compare against that release instead of editing history. This lets the owner and inspector distinguish the previously assessed installation, the new design and the final modified state.
Official source and boundary
- FPS Economy: RGIE/AREI Book 1, Version 06
- Section 3.1.2 and Table 2.23 are central to diagram content.
PlanElec creates a traceable project output and offers an advisory self-check. It does not issue a certificate of conformity. Only the approved control body officially assesses the installed work and complete dossier.
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/RGIE self-check for supported rules that can be decided from project data
- PDF export of the single-line diagram and situation plan
Create your single-line diagram now — it's free →