Renovation and AREI: When Do You Need New Electrical Plans?

When does a renovation lead to new plans and an inspection?

The electrical scope decides, not the word “renovation”. A substantial alteration or extension needs an updated single-line diagram and situation plan and undergoes a conformity inspection before it is put into use. That inspection is limited to the added or modified parts; an unchanged part is only included for the characteristics the alteration affects (AREI/RGIE Book 1 V06, Subsection 6.4.7.3). A non-substantial alteration does not need a new single-line diagram: a short dated and signed description is enough, and the situation plan still shows the change (Subsection 3.1.2.1 a).

The AREI contains no list that automatically classifies every moved socket as “substantial” or “non-substantial”. Agree the classification with your electrician before work starts and, when in doubt, with the inspection body.

Which work triggers what?

A practical decision path

1. Is the work purely non-electrical? Painting or new flooring does not change the electrical installation.
2. Is only one device replaced like for like? Document the replacement and check that characteristics and protection concept stay the same.
3. Are new cables, circuits, sources or a new board added? Treat the project as a possible substantial alteration or extension until the electrician has classified it.
4. Do voltage, supply type, earthing or the protection chain change? Then the effect reaches beyond the new component.
5. Which existing sections are affected? Delimit them by circuit, board and real cable route.

A new sub-board, an extra circuit for an EV charger or heat pump, a board replacement or a change of supply therefore goes to your electrician early. A cover plate, luminaire or switch replaced like for like, without changing the electrical characteristics, is closer to maintenance.

Is there a “contamination rule”?

No. The popular term claims that any small change makes the whole house subject to inspection under current rules. Book 1 does not say that. The inspection of a substantial alteration covers the modified and added parts; an unchanged part is only inspected for the characteristics that the alteration shifts (Subsection 6.4.7.3).

There is, however, one rule that reaches the whole installation, and it concerns old installations: when an old domestic installation as referred to in Part 8 undergoes a substantial alteration or extension, at least one RCD of at most 300 mA at the origin protects the entire installation (Subsection 4.2.4.3 b). Plan this RCD into any larger renovation of a house with an old installation.

Delimit the work clearly: record which circuits, cable sections, protective devices and rooms are touched. Mark the existing installation, the new part and shared protection or supply points. This documentation makes the inspection scope understandable; what the approved body inspects, it decides itself.

What Part 8 really does

Part 8 contains specific derogations for existing parts, depending on when they were installed. Section 8.2.1 covers old domestic installations whose construction began before 1 October 1981; Section 8.2.2 covers installations inspected under the former AREI. Every derogation has a precise scope and often conditions. New or substantially altered parts are designed to current requirements.

Important for the documents: for existing parts of old installations, Section 8.2.1 No. 7 allows a simplified single-line diagram with address, nominal voltage, cross-section of the main board’s supply cable, type and cross-section of the outgoing ways and the residual current and other protective devices with their characteristics, and a simplified situation plan with sockets, switches, lighting points and fixed appliances.

For each existing section, record the installation period, existing inspection reports, cable and protection data and later changes. A house from the 1960s often contains components from several decades. The year the building was constructed therefore does not prove which derogation applies to a given circuit.

House with existing plans

If a current single-line diagram and situation plan exist:

1. Update the plans: draw new circuits and changed positions.
2. Distinguish old and new: make modified and unchanged parts recognisable.
3. Raise the version: adjust number, version and version date, then present the updated plans to the approved body.

House without plans

Many older houses have no documents at all. Then:

1. New and substantially altered parts get a complete single-line diagram and situation plan (Subsection 3.1.2.1 a).
2. Existing parts from before 1981 that appear on the diagram are marked “older part”; for them, the simplified set under Section 8.2.1 No. 7 is sufficient.
3. The installation file under Section 9.1.2 contains the diagrams and plans of the installation. If they are missing at the inspection visit on sale, the approved body records this as an infringement; its brief description and rough sketch do not replace a single-line diagram (Subsection 8.4.2.2 d).

If you are renovating anyway, survey the existing installation at the same time. That survey belongs in the quotation as a separate item.

Documentation during a renovation

Survey without dangerous assumptions

Start with existing inspection reports, plans, invoices and labels and compare them with the real board. For the survey, a professional switches circuits off in a controlled way and records which points actually go dead; work on live parts and inside the board belongs in qualified hands. A presumed cable route stays marked as a presumption, not drawn as fact.

Make a list per circuit: reference, rooms supplied, visible cable type and cross-section, protective device, RCD, known boxes and permanently connected appliances. Keep unknown values separate from confirmed ones. Photos record labels and condition; they replace neither measurement nor diagram.

Split the renovation into work packages

Separate safety defects, adjustments needed for the new scope and desired comfort extensions. You then see what must be settled before commissioning and what can follow later. Look at shared points first: main board, earthing, supply and shared RCDs connect several rooms. A new kitchen circuit is local in space but touches the board and its protection chain electrically.

For each package, document the initial state, the planned change, the affected existing characteristics and the final state. Settle the substantial or non-substantial classification before plastering. Inspection scope, measurements and accessible test points determine the schedule and the appointment.

Produce the as-built state

Do not copy planned positions into the final version without checking. Compare sockets, switches, lighting points, boxes and fixed appliances room by room, then match each circuit with its protective device, cable data and board position. Older parts whose construction began before 1 October 1981 carry the note “older part” on the single-line diagram when they are shown.

Diagrams and plans carry number, version and version date. A short change note names the rooms or circuits worked on. Keep earlier approved versions; they show when each existing section was created. The current plans stay available on site for supervision, inspection, maintenance, repair and alteration (Subsection 3.1.2.1 d).

Handle the inspection report

Give the approved body the requested plans and documents in readable form. A finding does not disappear with a nicer drawing: a measured value, wrong execution or unsuitable equipment is fixed technically. Then the installation and the documents are brought back to the same state. Inspection report, signed plans, measurements and manufacturer documents go into the installation file.

Three examples of scope

The bathroom is completely renewed

New cables, sockets, lighting and protective measures are recorded as the new scope of work. Also document which supply and which board branch feed the bathroom. The electrician checks bathroom zones, protection, cables and bonding against the real execution. Other rooms are not inspected by default; shared or affected characteristics are part of the scope, though.

An existing circuit is repaired

Replace the faulty device like for like, record type and characteristics and have the safe restoration checked. As soon as location, cable, protection or function changes, the electrician reclassifies the work. The word “repair” does not hide a real extension.

The board is replaced

A new board touches many shared protection and assignment data. Before removal, all outgoing ways are recorded unambiguously. After the work, labels, RCD groups, phases, cables and diagrams match the installed layout. Unknown old circuits are identified before connection, not carried forward under generic names.

Questions for the first meeting

• Which parts will be new, moved, replaced or left unchanged?
• Which existing data are proven, and which must be measured or opened up?
• Which shared protection or supply points are affected?
• Is the work a substantial alteration or extension, and who confirms that?
• Is it an old installation that needs an RCD at the origin after the work?
• Which plans, descriptions, measurements and manufacturer documents are needed?
• When do the inspection and the document release take place in the schedule?

In occupied homes, also plan safe intermediate states. Unfinished circuits stay clearly out of service and labelled. Temporary supplies are installed properly and documented separately. After each phase, record which parts already match the as-built plan and which are still a working state.

Planning effort and cost

Cost depends on the survey, missing documentation, number of circuits, measurements, the scope of the works and the inspection body. Price ranges found online are no substitute for a quotation. Ask for separate items for survey, design, execution, first inspection and possible rework; how to compare such quotations is explained in What does an electrical plan cost?.

During early access PlanElec costs EUR 0. For the period after the paid plans start, which we will announce well in advance, the prices are published: Free stays free, single property costs EUR 15 per property and Pro EUR 29 per month, excluding VAT.

What PlanElec contributes to renovations

PlanElec links floor plan, topology, board, single-line diagram and situation plan in one project. With it you can:

• survey and document the existing installation;
• add new circuits and test them with the indicative AREI/RGIE self-check against the supported rules;
• keep old and new traceable in the same model;
• export the single-line diagram and situation plan as PDF with consistent references.

The material list and the working dossier are available as pilot features with stated limits. The roles are clear: PlanElec provides the structured documentation, the electrician designs and installs, and the approved body gives the official assessment.

Checklist for renovators

Before you start:

• Is the work a substantial alteration or extension?
• Existing electrical plans and inspection reports located?
• Old installation? Then plan the RCD at the origin.
• Budget for survey, documentation and inspection planned?
• Electrician involved early?

After the renovation:

• Single-line diagram and situation plan match the installed state?
• All new circuits on the single-line diagram?
• Inspection body booked?
• Report and any findings handled with the electrician?

Official source

• FPS Economy: RGIE/AREI Book 1, Version 06
• Especially relevant: Section 3.1.2, Subsection 4.2.4.3 b, Subsection 6.4.7.3, Sections 8.2.1 and 8.4.2 and Section 9.1.2.

Related articles

• Old wiring in Belgium: AREI Part 8 explained
• What does an electrical plan cost? Cost factors 2026
• What does the inspector check during the inspection?
• Electrical dossier for property sales

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