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"). The concrete implementation follows the project-specific risk assessment and manufacturer instructions.
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.
The diagram records the actual SPD, connection and protection data. Location, backup protection, conductor length, earthing system and coordination follow the risk assessment and manufacturer instructions; “typically 20 A” is not a general AREI rule.
Does this apply to existing installations?
There is no universal yes/no answer. Transitional rules, the date and scope of later alterations, and the specific risk assessment must be checked. Section 4.5.1 states protection objectives; it does not say “retrofit Type 2 in every dwelling”. A professional assesses lightning protection, supply, routes, equipment and the manufacturer concept.
SPD with photovoltaic (PV) systems
For PV, assess the AC and DC sides separately:
- 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.
Source and planning boundary
The primary source is FPS Economy AREI/RGIE Book 1 version 06, especially the protection objective in section 4.5.1. Cost depends on poles, discharge capacity, lightning protection, backup device, space and alterations, so use a current project quotation. PlanElec documents the selected design and offers a limited self-check; it does not guarantee design or compliance.