Summary:
Surge protection is now a requirement under BS 7671 Amendment 2, but choosing the right type for an EV installation can be confusing. This post breaks down the difference between single and three-phase surge protection and shows installers how to stay compliant without overcomplicating installs.
What Is Surge Protection and Why It Matters
Surge Protection Devices (SPDs) are designed to protect electrical systems from transient overvoltages — sudden spikes that can damage sensitive electronics, including EV chargers. These surges often come from nearby lightning strikes, grid switching, or large inductive loads.
For EV installations, surge protection isn’t just a “nice to have” — it’s a compliance requirement under BS 7671:2018 (A2:2022). Without SPD, an installation could fail inspection, void insurance, or worse — damage a charger.
Single vs Three Phase – What’s the Difference?
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Single-phase SPDs protect homes and smaller installations (230 V).
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Three-phase SPDs are used in commercial or multi-charger setups (400 V).
If you’re wiring multiple Tesla Wall Connectors or a mixed charger array, you’ll almost always need Type 2 three-phase protection.
SPD Types Explained
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Type 1: Protects against direct lightning strikes (rare in EV installs).
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Type 2: Protects against indirect surges and switching transients — the most common choice for EV chargers.
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Type 3: Used for point-of-use devices — not for distribution boards.
Eco Harmony’s 3-Phase PME RCBO + SPD Unit and TPN Distribution Board with SPD are both Type 2 solutions, ideal for compliant EV charger installs.
Why Surge Protection Should Be Installed Upstream
Always install the SPD at the origin of the installation or within the distribution board feeding the charger. This protects not only the charger but also cables and connected devices downstream.
If your charger includes DC components or solar integration, consider DC surge protection — like the WCED Standalone DC SPD Modules — for additional coverage.
Installation Tips
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Keep cable runs as short as possible.
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Always connect SPDs to earth using the shortest route.
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Replace SPDs after surge events (many feature visible indicators).
Recommended Products
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Single Phase: RCBO + SPD Consumer Unit (IP65)
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Three Phase: TPN Distribution Board with SPD
Conclusion
Surge protection is no longer optional for EV installations — it’s a key safety and compliance requirement. By fitting Type 2 SPDs in either single or three-phase setups, installers can prevent costly damage and ensure installations pass inspection every time.
👉 Explore SPDs and PME Solutions: https://ecoharmony.co.uk/collections/surge-protection-pme