Is Surge Protection (SPD) Mandatory Under AREI?
AREI requires protection against overvoltages (section 4.5.1) but prescribes no specific SPD type. What that means for your distribution board, existing installations and PV.
AuthorStephan BehmShort answer: a protection goal yes, a mandatory SPD type no
AREI requires persons and property to be protected, according to good practice, against the harmful effects of overvoltages – for example from atmospheric phenomena or switching surges (AREI Book 1, section 4.5.1). Book 1 does not prescribe a specific device such as "Type 2 SPD in the main board" for homes. Whether to fit a surge protective device (SPD), and which one, is decided with the project's risk assessment and the manufacturer's data.
Chapter 4.5 explicitly regulates only two things: surge protective devices are designed and installed so that their operation poses no danger to persons and property (4.5.1). And in IT systems, an overvoltage limiter is connected where necessary at the origin of the installation between the earth electrode and the neutral or a line conductor (4.5.3).
What an SPD does
An SPD diverts short voltage spikes to earth before they reach equipment. Such spikes come from nearby lightning strikes, switching operations on the grid or other disturbances, and mainly hit sensitive electronics: computers, televisions, heat pumps and inverters.
| SPD type | Protects against | Usual location |
|---|---|---|
| Type 1 | Partial lightning currents | At the origin, typically with an external lightning protection system |
| Type 2 | Indirect overvoltages | In the main board – the usual choice in homes |
| Type 3 | Residual overvoltages | Close to the equipment, as fine protection behind a Type 2 |
These types come from product standards, not from AREI.
Where the SPD sits in the board
A Type 2 sits in the distribution board. Two arrangements are common:
Grid → main switch → main RCD (300 mA) → Type 2 SPD → group RCDs → circuit breakers
Grid → main switch → Type 2 SPD with its own back-up fuse → main RCD (300 mA) → …
Which arrangement fits depends on the manufacturer's instructions, the earthing system and the installation concept. Back-up protection, connecting-lead lengths and coordination with other SPDs follow the datasheet; "typically 20 A" is not an AREI rule. In the single-line diagram you document the SPD actually installed with its type, connection method and protection data.
Does this apply to existing installations?
AREI has no general retrofit obligation along the lines of "every home gets a Type 2". Section 4.5.1 sets a protection goal. For an existing installation the electrician assesses lightning protection, supply, cable routing, sensitive loads and the manufacturer's concept – and documents the decision. For renovations, the modified part follows the rules applicable at the time of the work.
SPD and photovoltaics
For PV, assess the AC and DC sides separately:
- AC side: surge protection in the distribution board as described above.
- DC side: Chapter 7.112 does not explicitly require a DC SPD for domestic PV installations. A DC SPD at the inverter is still common practice, especially with long DC runs across the roof; good practice and the manufacturer's data decide.
Tip: Many inverters already include a DC SPD. A look at the datasheet can save you an extra device.
Documenting the SPD in PlanElec
In PlanElec you place the SPD as a protective device in its own right in the single-line diagram and in the board; its data appear in the PDF. The AREI/RGIE self-check assesses whether surge protection is present and reports the result as information – in line with the regulation, since there is no general SPD obligation. The full scope is in What the self-check verifies. Sizing, discharge capacity and coordination are set according to the risk assessment and datasheet; costs come from a current project quotation.
Related articles
- A 30 mA RCD for every socket?
- Inspection checklist: what the inspector verifies
- PV system in the single-line diagram
Legal basis: AREI/RGIE Book 1, version 06, Chapter 4.5 (sections 4.5.1 and 4.5.3) and Chapter 7.112. The official text published by the FPS Economy prevails.