The Quick Answer

• Use a Type A RCD/RCBO when the charger provides integrated 6 mA DC fault protection (RDC‑DD per BS IEC 62955). That’s the most common domestic case and keeps costs down.
• Use a Type B RCD when the charger does not provide 6 mA DC detection, or the manufacturer explicitly requires Type B (typical for some early or commercial EVSE and certain three‑phase units).
• In all cases, the EV point must be individually protected by a ≤30 mA device that disconnects all live conductors (i.e. 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 (6–40A)
  • Outdoor/IP jobs: IP65 A‑Type RCBO EV Kit
• Use a Type 2 SPD on the EV circuit or in the EV board:
  • Neat tails upgrade: Meter Isolator with SPD
  • Space‑tight boards: WSPDT2 compact SPD
• On PME earthing, add PEN/PME fault protection to avoid rods:
  • PME Load‑Balancing Board (with kWh)
  • IP65 PEN Fault Detection Unit

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 (63A RCD + 40A MCB)
• Still include a Type 2 SPD. For 3‑phase hubs:
  • WSPD440 3‑Phase SPD
  • 3‑Phase SPD Unit (Metal, pre‑wired)

Planning multiple charge points on PME? See 3‑Phase PME Fault Unit — Multi EV.

How to Check the Charger for 6 mA DC Detection (RDC‑DD)

1. Read the EVSE datasheet - look for “integrated 6 mA DC detection”, “RDC‑DD (BS IEC 62955)” or similar.
2. If present → a Type A RCBO is acceptable (per manufacturer’s instructions).
3. If absent / unclear → specify a Type B RCD to be safe and compliant.

Related: How to Install an EV Consumer Unit

RCBO Sizing for 7 kW & 22 kW

• 7 kW single‑phase - typically a 40 A Type A RCBO (check EVSE spec and cable calc). Try:
  • A‑Type RCBO – WRT Range (10 kA)
  • High‑Immunity Type A Mini RCBO
• 22 kW three‑phase — use a 4‑pole device sized per design current:
  • 4‑Pole A‑Type RCBO (6–40A)
  • 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. 4P 100 mA A‑Type Time‑Delay).
• Always give the EV circuit its own 30 mA device (no shared RCD with house circuits).

Common Mistakes to Avoid

• Using Type AC on EV circuits - not acceptable under A2.
• Single‑pole RCBO on a charger - EV point protection must disconnect all live conductors (line + neutral).
• No SPD on a new EV circuit - A2 expects SPDs (fit a Type 2 as standard).
• PME with no PEN protection - add a PEN/PME device and skip the rod.

Deeper dive: Do You Still Need an Earth Rod with PME Protection?

FAQs

Here are some of the most common questions installers ask about RCDs and RCBOs for EV charger installations. Always confirm final choices against the charger manufacturer’s datasheet and BS 7671 requirements.

Do EV chargers need a Type B RCD?

Only if the EVSE doesn’t provide 6 mA DC detection (RDC-DD) or the manufacturer specifies Type B. Otherwise, a Type A RCBO is acceptable in most domestic installs. For specialist setups, see our full range of Type B RCDs.

What RCBO should I use for a 7 kW charger?

Typically a 40 A Type A double-pole RCBO (always confirm against the datasheet and cable calculations). Options include our A-Type RCBO – WRT and High-Immunity Mini RCBO.

Is surge protection mandatory on EV circuits?

Under Amendment 2 of the 18th Edition, SPDs are required on new circuits unless a documented risk assessment justifies omission. For EV installs, best practice is to fit a Type 2 SPD. Browse our Surge Protection Devices.

Do Tesla or modern chargers still need an RCD?

Yes - the charging point must have RCD protection. If the EVSE has integrated RDC-DD, you can use a Type A RCBO; otherwise a Type B RCD is required per the manufacturer’s instructions.

What size breaker do I need for a 22 kW three-phase charger?

It depends on design current and cable sizing. Many installs use a 32–40 A 4-pole device with balanced phases. Consider our 4P A-Type RCBO or a 4P Type B RCD paired with MCBs.