Diagrams and inspection

What single-line and situation diagrams show, when you need them and why they may receive inspection remarks.

A Belgian household electrical installation must be understandable on paper. Not only for the owner, but also for the inspector, the next electrician and anyone who later works on the installation.

The single-line diagram and situation diagram are therefore more than paperwork added afterwards. They connect the actual distribution board, the cables in the building and the symbols on the plan.

What is the difference between the two diagrams?

  • A single-line diagram shows the electrical structure, connections and properties of all components.
  • A situation diagram shows where the components are physically located on a floor plan.

Single-line diagram

  • Supply, distribution boards and protective devices.
  • Cables, their cross-sections and installation methods.
  • Circuits and points or appliances.
  • Codes such as A1, A2, B1.
  • Detailed properties.

Situation diagram

  • Locations of sockets, lights and switches.
  • Locations of fixed appliances and building services.
  • Placement does not need to be accurate to the centimetre.
  • Codes must be identical on both diagrams.

Single-line diagram or situation diagram?

The two diagrams complement each other. Each serves a different purpose and contains a different kind of information.

The single-line diagram is the most important and complex. It provides an overview of every individual component of your electrical installation and how they are connected. It also shows critical properties so that compliance with the technical and legal requirements can be assessed.

The situation diagram is simpler. It contains a floor plan of the building, but its dimensions do not need to be exact. A rough outline is sufficient as long as the rooms and floors clearly correspond to the actual building. Every symbol from the single-line diagram must appear with a relevant designation, except for components permanently mounted in a distribution board, such as protective devices and home automation modules.

Useful with Condui

Condui helps keep the single-line diagram and situation diagram synchronized. This keeps each relevant symbol on both diagrams.

When do you need diagrams?

Diagrams are needed for:

  • a new installation;
  • a major extension or modification;
  • the sale of a home;
  • a reinspection following remarks;
  • the addition of solar panels, an EV charger, a battery, a sub-board or a large appliance;
  • documenting an old installation.

When selling a home, a non-compliant inspection report does not automatically prevent the sale. However, the buyer receives an installation with remarks. If the diagrams are missing, this is the first issue to resolve.

Single-line diagrams and situation plans must be prepared for a new household installation or a major modification or extension of an existing household installation. A new single-line diagram is not required for a minor modification, but a brief description must be included in the installation file and the situation plan must continue to show the actual installation.

What must the single-line diagram show?

A useful diagram shows at least the logical chain:

  1. the supply or connection;
  2. the main distribution board and any sub-boards;
  3. residual-current devices and other protective devices;
  4. circuit breakers or fuses for each circuit;
  5. cable type, conductor cross-section and, where relevant, the number of conductors;
  6. points and appliances such as sockets, lighting points, fixed appliances, solar panels, an EV charger or other sources;
  7. the codes that match the situation diagram.

The aim is simple: someone should be able to trace a socket or appliance back through its circuit, circuit breaker and residual-current device.

The complete list of diagram contents, technical properties and installation documents is available under Documentation, inspection and responsibility.

Which technical properties?

Each component of an installation has properties that are critical for an inspector to assess. These requirements differ somewhat between household and industrial installations.

Household diagrams mainly concern the supply, protective devices, residual-current devices, circuits, cables, sources, codes, installation address and responsible installer. The complete table is available under Which technical properties belong on the diagrams?.

Frequently asked questions

Can you draw a diagram yourself?

Yes. An electrician does not necessarily have to draw the diagram. It must be correct, complete and consistent with the actual installation.

Does it have to be drawn digitally?

Not necessarily. A hand-drawn diagram can work in principle. In practice, it is often slower and more prone to mistakes than using a dedicated drawing program such as Condui.

Is a diagram enough to make the installation compliant?

No. A diagram describes the installation. If the installation itself is unsafe or does not comply with AREI, a good-looking diagram does not fix that. Conversely, a technically sound installation can still receive remarks if the diagrams are missing or do not match.

Condui helps

Condui makes drawing diagrams easier and faster with a simple interface and built-in validation checks.