Old Buildings and AREI Part 8: Special Rules for Existing Installations
What applies to older electrical installations in Belgium: part 8 of the AREI/RGIE with the key derogations, the duties without exception, control visits and step-by-step modernisation.
AuthorStephan BehmAn older electrical installation in Belgium does not have to match today's AREI/RGIE in every detail. Part 8 of AREI/RGIE Book 1 lists specific derogations for existing installations: for example thinner cables from 1 mm², socket and lighting circuits without a 30 mA RCD, or simplified plans. Anything part 8 does not expressly allow must comply with Book 1, and new or significantly modified parts are assessed under today's rules. This article shows you which installations part 8 covers, what it allows, what stays mandatory in every case and how to modernise sensibly.
Editing and review: PlanElec team, 5 October 2026, checked against AREI/RGIE Book 1, version 06, applicable since 1 April 2026.
What is part 8?
Part 8 contains the "special provisions relating to existing electrical installations". An installation is existing when its construction on site began before the current Book 1 entered into force on 1 June 2020 and it has not undergone a conformity inspection under chapter 6.4 of the current Book (section 8.1.1). For domestic installations, part 8 distinguishes two groups, each with its own list of derogations:
| Group | Characteristic | Derogations |
|---|---|---|
| Old domestic installation | Construction started before 1 October 1981, with or without a visit under the former AREI | 8.2.1 |
| Domestic installation under the former AREI | Construction from 1 October 1981, conformity inspection under the former AREI | 8.2.2 |
For installations built from 1 June 2020 under the current Book 1, the derogations for existing parts are in subsection 6.5.8.1.
Part 8 is a closed list, not a general grandfather clause. Even under part 8, equipment may only stay in service if, when correctly installed, maintained and used, it does not endanger people's safety and is suited to the external influences (8.2.1 no. 1).
When is an old installation assessed under today's rules?
As soon as you carry out a significant modification or extension. A modification is significant when it has an additional impact on the safety of people or property that no conformity inspection has covered yet (definition in part 2). A new circuit in the board is typically significant; swapping a socket for an equivalent model is not. If in doubt, clarify the classification with your electrician and the inspection body before work starts.
For a significant modification:
- The new or modified part is inspected under the current Book 1 before it is put into use (6.4.7.3).
- If the modification affects an unchanged part, that part is inspected with regard to the modified characteristics (6.4.7.3).
- For a significant modification of an old domestic installation, the entire installation must be protected by at least one RCD of at most 300 mA at the origin (4.2.4.3 b).
- The remaining unchanged parts keep their part 8 derogations.
Non-significant changes to socket and lighting circuits without a 30 mA RCD remain expressly covered by the derogation (8.2.1 no. 16, 8.2.2 no. 10). They still go into the installation file as a short description (9.1.2 no. 7).
What part 8 allows
The table lists the most important derogations for domestic installations. "8.2.1" applies to installations from before 1981, "8.2.2" to installations under the former AREI; several derogations in 8.2.2 also depend on the construction date.
| Topic | Current rule | Part 8 derogation | Reference |
|---|---|---|---|
| Cross-section | At least 2.5 mm², 1.5 mm² without sockets (5.2.1.2) | Cables from 1 mm² may stay; 1 mm² protected by a fuse of at most 6 A or a circuit breaker of at most 10 A | 8.2.1 no. 5 |
| Marking thin circuits | – | Circuits below 1.5 mm²: red sign of at least 8 × 5 cm on the board door | 8.2.1 no. 3 |
| Fire behaviour of cables | Specified fire behaviour (4.3.3) | Cables without predetermined fire behaviour may stay | 8.2.1 no. 5, 8.2.2 no. 5 |
| 30 mA RCD | For sockets and lighting (4.2.4.3 b) | Socket and lighting circuits without a high-sensitivity RCD; more than eight circuits per RCD | 8.2.1 no. 16, 8.2.2 no. 10 |
| RCD at the origin | At least 40 A, own isolating function | Devices below 40 A may stay; isolation via an upstream general switch | 8.2.1 no. 2, 8.2.2 no. 2 |
| Overcurrent protection | Energy limitation class 3 (5.3.5.5) | Devices without this marking may stay (8.2.2: construction before 31.12.2007) | 8.2.1 no. 3, 8.2.2 no. 3 |
| Main switch-disconnector | At least 40 A (5.3.5.1 b) | At least 25 A (8.2.2: construction before 16.9.1991) | 8.2.1 no. 4, 8.2.2 no. 4 |
| Sockets without earth contact | Earth contact mandatory (5.3.5.2 b) | Allowed if the cable has no protective conductor and an RCD of at most 30 mA protects it | 8.2.1 no. 6 b |
| Sockets per circuit | At most eight (5.3.5.2 b) | More than eight, if the permitted power of the cable is not exceeded | 8.2.1 no. 6 b, 8.2.2 no. 6 |
| Lighting circuits | Two separate circuits above two rooms (5.3.5.2 b) | A single lighting circuit | 8.2.1 no. 14 |
| Protective conductor | In every cable (5.2.1.3) | Cables without protective conductor may stay if they do not supply fixed class I appliances | 8.2.1 no. 12 |
| Main equipotential bonding | Required (4.2.3.4) | May be missing | 8.2.1 no. 13 |
| Earthing conductor | According to 5.4.2.2 | Copper from 6 mm² may stay | 8.2.1 no. 11 |
| Conductor colours | Green-yellow only for protective conductors (5.1.6.2) | Protective conductors in another colour may stay; green-yellow live conductors are forbidden | 8.2.1 no. 10 |
| Single-line diagram and situation plan | Full content (3.1.2) | Simplified plans with minimum content (8.2.1); missing signature, VAT number or protective device type tolerated (8.2.2) | 8.2.1 no. 7, 8.2.2 no. 7 |
| Conformity inspection report | Belongs in the file (9.1.2) | Its absence is tolerated at the control visit | 8.2.1 no. 9, 8.2.2 no. 9 |
For installations from before 1981, the simplified single-line diagram contains at least the address, nominal voltage, cross-section of the main board's supply cable, type and cross-section of the outgoing circuits, and the RCDs and protective devices with their characteristics; the simplified situation plan shows sockets, switches, light points and fixed appliances. The two plans do not need to match each other (8.2.1 no. 7).
What remains mandatory even under part 8
Part 8 contains no derogation for the following points. They are therefore checked in an old installation too:
| Duty | Reference |
|---|---|
| RCD of at most 300 mA at the origin of the installation | 4.2.4.3 b |
| RCD of at most 30 mA for rooms with a bath or shower | 4.2.4.3 b no. 3 |
| RCD of at most 30 mA for washing machine, tumble dryer and dishwasher | 4.2.4.3 b no. 4 |
| Exposed parts of class I appliances connected to the protective conductor | 4.2.4.3 a |
| Socket with earth pin only with a real connection to the earth electrode | 8.2.1 no. 6 |
| Single-line diagram and situation plan, at least in simplified form | 8.2.1 no. 7, 8.4.2.2 d |
| Equipment that does not endanger safety in normal use | 8.2.1 no. 1 |
On top of that come conditions that no derogation covers because they are immediately dangerous: bare or damaged cables, accessible live parts, junction boxes without covers, overheated or loose connections, bridged fuses, a protective device rated higher than the conductor permits, and low-voltage sockets in zone 0 or 1 of the bathroom.
Existing bathrooms have their own rule: rooms whose construction started before 1 March 2025 may use the former zone layout (6.5.8.1 no. 3). For installations from before 1981, part 8 also allows certain cables, underfloor heating and the absence of supplementary bonding to remain if zone 2 is extended to 1 m (8.2.1 no. 15.2).
Control visits for existing installations
Which deadline applies?
For an installation inspected under the former AREI, the first control visit takes place within the deadline stated in the last report under the former AREI (8.1.2); after that, a domestic installation is visited at the latest every 25 years (6.5.2). For old installations without a conformity inspection, chapter 8.4 sets its own triggers: before an increase in connection capacity (8.4.1), when a dwelling is sold (8.4.2) and in other cases (8.4.3). So always check the last report and the specific trigger.
When selling
When selling a dwelling with an old installation that has not been significantly modified since 1 October 1981, or whose old part has not yet been visited, the seller arranges a control visit and records the report date in the deed of sale (8.4.2).
18-month deadline (8.4.2.2 a): if the report is negative, the buyer has it checked within 18 months from the day of the deed of sale that the infringements have been corrected. The buyer chooses the approved body freely.
These 18 months are not interchangeable with the re-visit after a periodic control visit, which the same body carries out within one year (6.5.7.2 b.7). The FPS Economy FAQ on Book 1 explains the sale procedure.
What the control visit checks
| Check | Assessment |
|---|---|
| Visual check of cables and connections | Damage, overheating, fixing |
| Earth resistance | Below 100 Ω (4.2.3.2); above 30 Ω a stricter RCD layout (4.2.4.3 b, with the part 8 derogations) |
| Insulation resistance | At least 500 kΩ per circuit at a 500 V test voltage (6.4.5.1, table 6.1) |
| RCDs | Presence, assignment and operation |
| Overcurrent protection | Protective device matched to the cross-section (4.4.1.4, table 4.11) |
| Protection against direct contact | Covers, boxes, boards |
| Documentation | Single-line diagram and situation plan present |
The report expressly lists infringements, remarks and the part 8 derogations that apply to the installation (6.5.7.2 b.5). If the plans are missing at a sale visit, the inspector draws up a short description and a rough sketch so that it remains traceable what was inspected; the missing plans are still recorded as an infringement (8.4.2.2 d).
Partial renovation: what the so-called contamination rule really means
In the trade, people often speak of a "contamination rule": new work would force the whole installation up to today's standard. Book 1 does not know this concept. The actual rules are more precise:
- New and significantly modified parts follow the current Book 1 (6.4.7.3).
- Unchanged parts are inspected to the extent the modification affects their characteristics (6.4.7.3).
- After a significant modification of an old domestic installation, at least one 300 mA RCD at the origin protects the whole installation (4.2.4.3 b).
- All other part 8 derogations remain in place for the unchanged parts.
In practice
- Plan new circuits so that old and new parts are clearly separated, for example via a dedicated sub-distribution board.
- Mark on the single-line diagram what is old and what is new.
- Clarify contentious boundaries with the inspection body before work starts.
Modernising step by step
Priority 1: duties and hazards
- Add an RCD of at most 300 mA at the origin if it is missing
- 30 mA RCD for the bathroom and for washing machine, tumble dryer and dishwasher
- Replace damaged cables, fix loose connections, close boxes
- Have the earthing measured and improved if needed
Priority 2: clearly more safety
- 30 mA RCD for socket and lighting circuits too
- Install sockets with earth contact and a protective conductor
- Replace old fuses with circuit breakers
- Have surge protection assessed professionally (4.5.1)
Priority 3: comfort and future
- Modernise the board with spare capacity and clear labelling
- Prepare for an EV charger or PV – the new circuit for it is a significant extension that requires a conformity inspection
Define the work before asking for prices
Have the existing installation surveyed, separate duties from voluntary improvements and get a dated quote for the specific building. Cable routes, finishes, accessibility, board condition and renovation scope drive the effort far more than any online price range.
Clarify the installation history before relying on a derogation
The year of construction alone is not enough. Build a timeline from earlier inspection reports, board labels, invoices, permits and the visible workmanship. Determine which parts existed before 1 October 1981, what was significantly modified or extended later, and whether that work was inspected. For each derogation you rely on, record the exact reference, the affected circuit, the evidence of age and the remaining safety conditions. Without evidence, the field stays open; cable colour or appearance is not a reliable date. The inspection body decides on applicability based on the actual installation.
Survey on site
Photograph and label the board, fuses, RCDs, earth connections, visible cables and junction boxes without removing covers from live parts. Record each identified circuit first as the existing state. Unknown origin, unknown cross-section or illegible ratings stay explicitly open. The electrician then separates urgent measures, changes requiring inspection and voluntary modernisation. That way your diagram shows the existing installation as it is – not as a new build.
Summary
| Question | Answer |
|---|---|
| Must my old installation comply with today's AREI? | Yes, apart from the part 8 derogations; new and significantly modified parts in full |
| Do I need a 300 mA RCD at the origin? | Yes. Part 8 only allows devices below 40 A and upstream isolation, not omitting it |
| Do I need 30 mA RCDs? | Yes for the bathroom and washing machine, tumble dryer and dishwasher; recommended for sockets and lighting |
| Are sockets without earth contact allowed? | In installations from before 1981, if the cable has no protective conductor and a 30 mA RCD protects it |
| How often is it inspected? | By the deadline in the last report, then every 25 years; for old installations depending on the trigger |
| What about a partial renovation? | New part under the current Book 1, unchanged part keeps the part 8 derogations |
Related articles
- Electrical Inspection in Belgium: The Complete Guide
- AREI/RGIE Regulations 2026: The Key Changes
- Preflex vs. Open Wiring
- Distribution Board Planning
Even in an old building, you build the single-line diagram and situation plan from one project with PlanElec and mark old and new parts cleanly. The self-check shows you findings in the supported rules; whether a part 8 derogation applies to your installation is decided on site by the approved inspection body. Start for free →