Surge Protection Under AREI — What You Need to Know
The AREI requires general surge protection (Art. 4.5.1) without mandating a specific SPD type. Learn what the AREI actually regulates.
Surge Protection Under the AREI
The AREI prescribes in Art. 4.5.1 as a general principle that persons and property must be protected against the harmful effects of overvoltages — including those caused by atmospheric phenomena and switching surges. However, the AREI does not contain an explicit obligation for a specific SPD device (e.g., "Type 2"). In practice, a surge protection device is expected and recommended by inspection bodies for new installations.
What is a surge protection device?
An SPD protects your electrical equipment from voltage spikes caused by lightning strikes, switching operations in the grid, or other disturbances. These spikes can destroy sensitive electronics like computers, TVs, heat pumps, and inverters.
| SPD Type | Protects against | Installation location |
|---|---|---|
| Type 1 | Direct lightning strike | At the main connection (only with external lightning protection) |
| Type 2 | Indirect surges | At the main distribution board — recommended |
| Type 3 | Residual surges | At the socket (fine protection, optional) |
Where is the SPD installed?
The SPD Type 2 is installed in the distribution board. A common installation variant is after the main RCD (residual-current device) and before the outgoing circuits:
Grid → Main switch → Main RCD (300mA) → SPD Type 2 → Group RCDs → MCBs
The SPD can also be installed directly after the main switch, before the main RCD, with its own upstream fuse — depending on the manufacturer's specifications and the installation concept.
In the single-line diagram, the SPD is shown as a dedicated branch, protected by a dedicated circuit breaker (typically 20A). Important: The maximum upstream fuse rating is specified by the SPD manufacturer and is not freely selectable. Some SPDs require a cartridge fuse (gL/gG) instead of an MCB.
Does this apply to existing installations?
No — for existing installations inspected before the 2020 AREI revision, there is no retrofitting obligation (Part 8). At the next periodic inspection, the absence of an SPD is not considered a defect.
Still recommended: The cost of an SPD module (€50–150) is minimal compared to the damage a surge can cause to your electronics (TV, router, heat pump — easily several thousand euros).
SPD with photovoltaic (PV) systems
If you have a PV system, you need surge protection on both sides:
- AC side: SPD Type 2 in the main distribution board — as described above
- DC side: SPD Type 2 at the inverter — protects modules and inverter from lightning damage. The AREI (Chapter 7.112) does not explicitly require a DC-side SPD for domestic PV systems; however, a DC SPD at the inverter is strongly recommended by good engineering practice and manufacturer guidance, especially with long DC cables or cabling routed across the roof (increased lightning strike risk)
Important: Many inverters already have a built-in DC SPD. Check your inverter's datasheet.
How much does surge protection cost?
| Component | Cost |
|---|---|
| SPD Type 2 module (single-phase) | €50 – €80 |
| SPD Type 2 module (three-phase) | €80 – €150 |
| Installation by electrician | €50 – €100 |
| Protection: household electronics | €5,000 – €20,000+ |
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