Main Switch Mandatory: What Does the AREI Require?
Why a main switch is mandatory in Belgium and what requirements AREI Art. 5.3.5.1b imposes.
Main Switch Mandatory: What Does the AREI Require?
Yes, a main switch is mandatory in Belgium. According to AREI Art. 5.3.5.1b, every main distribution and switchgear assembly must have an all-pole main load-break switch capable of simultaneously disconnecting all line conductors and, where applicable, the neutral conductor. For domestic installations, the AREI requires a rated current of at least 40 A (Art. 5.3.5.1b); the general minimum is 25 A. In practice, a load-break switch (interrupteur-sectionneur) is used as the main switch. Unlike a plain isolator, it may be switched under load.
Requirements for the Main Switch
The main switch must meet the following conditions:
- All-pole: For single-phase connections, 2-pole (phase + neutral); for three-phase connections, 4-pole (3 phases + neutral)
- Rated current at least 40 A for domestic installations (Art. 5.3.5.1b), matched to the specific installation
- Disconnect the entire installation: A single operation must separate all active conductors
- Easily accessible: Max. 1.80 m operating height (practical guideline from inspection bodies — the AREI requires 'easily accessible and reachable from the living area' but does not specify an exact height)
- At the entrance of the installation: Before the distribution board, as the first switching device after the meter
AREI Articles
| AREI Article | Requirement |
|---|---|
| Art. 5.3.5.1b | Main load-break switch is mandatory, all-pole, at the main distribution and switchgear assembly |
| Art. 5.3.5.1b | Rated current at least 40 A for domestic installations, matched to the specific installation |
| Art. 5.3.5.1c | Distribution and switchgear assemblies must be easily accessible and operable |
Why Is the Main Switch So Important?
The main switch fulfils two central functions:
- Emergency disconnection: In an emergency (fire, flooding, electric shock), any occupant must be able to disconnect the entire installation with a single action — even without electrical expertise.
- Maintenance: For work on the electrical installation, the entire system must be safely disconnectable.
Common Inspection Deficiency
A missing or incorrectly rated main switch is one of the most common deficiencies found during electrical inspection (keuring) in Belgium. Especially in older installations, it is often entirely absent, or only a single-pole switch is installed that does not disconnect the neutral.
Typical deficiencies:
- No main switch present
- Single-pole instead of all-pole
- Rated current below 40 A in a domestic installation
- Mounted too high (not easily accessible)
- Not easily accessible (behind furniture, in a locked room)
Main Switch vs. Main Circuit Breaker
The main switch is not a circuit breaker — it has no overcurrent protection function. It serves exclusively as a disconnector. Overcurrent protection is provided by the grid operator (fuse before the meter) and the downstream circuit breakers in the distribution board.
However, a main circuit breaker (e.g., 40 A) can combine both functions: disconnection and overcurrent protection.
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