If you’re wiring an EV charge circuit, RCD selection isn’t a guess: it’s defined by BS 7671:2018+A2:2022 and the charger’s own DC fault protection. This guide makes the call simple, shows when Type A is sufficient, when Type B is mandatory, and points you to compliant boards and devices that pass inspection first time.
EV protection devices form part of our wider Consumer Units range, including EV-ready boards, heat-pump boards, PME units and surge-protected enclosures.
Quick Answer: For EV charger installs, use a Type A RCBO if the charger includes 6 mA DC detection (RDC-DD). If not, or if the datasheet specifies it, install a Type B RCD. Always protect the EV point with a ≤30 mA double-pole device and add surge protection per Amendment 2.
🧭 Jump to:
The Quick Answer
- Use a Type A RCD/RCBO when the charger provides integrated 6 mA DC fault detection (RDC-DD per BS IEC 62955).
- Use a Type B RCD when the charger does not provide 6 mA DC detection, or the manufacturer explicitly requires Type B.
- In all cases, the EV point must be individually protected by a ≤30 mA device that disconnects all live conductors (double-pole on single-phase). Pair with surge protection per A2.
Related reads: What Is an EV Consumer Unit? · What Surge Protection Does an EV Charger Install Need?
When a Type A Is Enough
Most modern Mode 3 chargers ship with an internal 6 mA DC detection module (RDC-DD). In that case, BS 7671 allows a Type A device for additional protection.
- Pick a Type A RCBO that disconnects line and neutral.
- Installer favourite: High-Immunity Type A Mini RCBO (6–40 A)
- Outdoor/IP jobs: IP65 A-Type RCBO EV Kit
- Use a Type 2 SPD on the EV circuit or in the EV board.
- On PME earthing, add PEN/PME fault protection to avoid rods.
Installer’s Pick: Our IP65 A-Type RCBO EV Kit is ready for outdoor installs, fully compliant, and UK-stocked for next-day delivery.
When a Type B Is Required
Fit a Type B when no 6 mA DC detection is provided inside the charger, or when the EVSE datasheet calls for it. Type B detects AC, pulsed DC and smooth DC.
- Single-phase & three-phase options:
- 2-Pole Type B RCD (domestic / single EV)
- 4-Pole Type B RCD (3-phase / commercial)
- B-Type EV Kit (63 A RCD + 40 A MCB)
- Still include a Type 2 SPD for surge compliance.
Installer’s Pick: The B-Type EV Kit (63 A RCD + 40 A MCB) is ideal when the charger lacks RDC-DD. Fully 18th Edition compliant and in stock.
How to Check the Charger for 6 mA DC Detection (RDC-DD)
- Read the EVSE datasheet — look for “integrated 6 mA DC detection”, “RDC-DD (BS IEC 62955)” or similar.
- If present → a Type A RCBO is acceptable.
- If absent / unclear → specify a Type B RCD to stay compliant.
RCBO Sizing for 7 kW & 22 kW
- 7 kW single-phase — typically a 40 A Type A RCBO. Options:
-
22 kW three-phase — use a 4-pole device sized per design current:
- 4-Pole A-Type RCBO
- Or a 4-Pole Type B RCD if no RDC-DD in EVSE
Upstream Devices & Selectivity
A downstream Type A can be blinded by DC if there’s an upstream Type AC on the same path. Keep the RCD hierarchy clean:
- Do not place a Type AC upstream of a Type A EV device.
- For series RCDs, use time-delay/selective types upstream where discrimination is needed (e.g. 100 mA A-Type Time-Delay).
- Always give the EV circuit its own 30 mA device.
Regulation Reminder: BS 7671:2018+A2:2022 expects Type A or B on EV circuits; do not use Type AC where DC residual currents may occur. Confirm with the EVSE datasheet before final spec.
Common Mistakes to Avoid
- Using Type AC on EV circuits — not acceptable for modern EVSE.
- Single-pole RCBO — EV protection must disconnect line + neutral.
- No SPD — Amendment 2 expects a Type 2 SPD.
- PME with no PEN protection — add a PEN/PME device instead of rods.
FAQs
Do EV chargers need a Type B RCD?
Only if the EVSE doesn’t provide 6 mA DC detection or the datasheet specifies Type B. Otherwise, a Type A RCBO is acceptable in most domestic installs.
What RCBO should I use for a 7 kW charger?
Typically a 40 A Type A double-pole RCBO. Options: A-Type RCBO — WRT or High-Immunity Mini RCBO.
Is surge protection mandatory on EV circuits?
Yes — under Amendment 2, SPDs are required unless a risk assessment says otherwise. For EV installs, fit a Type 2 SPD.
Do Tesla or modern chargers still need an RCD?
Yes — all EVSE must have RCD protection. If RDC-DD is built in, use a Type A RCBO; otherwise a Type B RCD is required.
What size breaker for a 22 kW three-phase charger?
Depends on design current/cable. Commonly a 32–40 A 4-pole device. Options: 4P A-Type RCBO or 4P Type B RCD.
Products & Kits That Deliver
- Type A RCBOs: Mini High-Immunity RCBO · A-Type RCBO — WRT · IP65 A-Type RCBO EV Kit
- Type B RCDs: 2P Type B RCD · 4P Type B RCD · B-Type EV Kit
- EV Boards & PME: 4-Way EV Unit (A-Type + SPD) · PME Load-Balancing Board · IP65 PEN Unit
- Surge Protection: Surge-Protected Enclosures · 3-Phase SPD
Browse collections: Type A RCBOs · Type B RCDs · PME Units · SPDs · EV-Ready Consumer Units
Final Word
Match the RCD to the charger’s DC protection: Type A with RDC-DD, Type B otherwise. Add a Type 2 SPD, ensure double-pole disconnection, and include PME protection on TN-C-S supplies. Do this and your EV installs pass inspection first time.
👉 Ready to spec? Compare our EV-ready consumer units, stock up on A-Type RCBOs, or secure compliance with Type B RCDs for installs without RDC-DD.