EV charger circuits are one of the most common places where installers get tied in knots over RCD/RCBO selection. Between Type A, Type B, high-immunity options, and different charger manufacturer requirements, the rules can feel muddy. But once you understand the leakage behaviour of EV chargers, the choice becomes straightforward.
Quick Answer: Most domestic EV chargers require a Type A RCBO - ideally a high-immunity variant to avoid nuisance tripping from inverter noise. Type B RCBOs are only needed for chargers that can produce smooth DC leakage and don’t include 6mA DC detection internally.
Start with the full range here: RCBOs for EV Chargers.
This guide breaks down the exact RCBO types you should use depending on the charger design, leakage behaviour and manufacturer requirements.
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Why EV Chargers Need Specific RCBO Types
EV chargers use inverter technology that can generate DC leakage, harmonics and high-frequency noise. This behaviour affects how an RCD or RCBO responds - and whether it trips correctly, too slowly, or unnecessarily.
EV chargers typically create:
- Pulsating DC leakage during charging cycles
- Harmonic distortion from the inverter
- High-frequency noise during ramp-up
- Leakage spikes during vehicle plug-in
That’s why charger manufacturers specify minimum RCD types - and why Type AC devices are not permitted.
Which RCBO Type You Need
Here’s the straightforward breakdown for EV installers.
1. Type A RCBO - the standard for most domestic EV chargers
This is the most common requirement. Nearly all mainstream EV charger brands include 6mA DC fault detection internally, meaning a Type A device is fully compliant.
- Handles AC + pulsating DC leakage
- Works with single-phase inverter chargers
- Approved by most EV manufacturers
2. High-Immunity Type A RCBO - best option for avoiding nuisance trips
EV chargers generate harmonic noise that can cause false trips. High-immunity RCBOs smooth this out and significantly reduce nuisance tripping.
- Ideal for garages, outbuildings and long cable runs
- Excellent for chargers with fluctuating leakage
- Recommended for heat-pump + EV dual installs
3. Type B RCBO - for chargers without 6mA DC detection
If the manufacturer explicitly states the charger does not include 6mA DC protection, you must fit a Type B RCBO.
- Detects smooth DC leakage
- Required for older or commercial EV chargers
- Common for fast/rapid charging points
4. 4-Pole RCBO (Three-Phase EV Chargers)
For commercial or three-phase EV chargers, a 4-pole (L1-L2-L3-N) RCBO is required to disconnect all live conductors simultaneously.
- Protects three-phase charging stations
- Handles complex leakage patterns
- Best for fleet charging and commercial installs
RCBO Size & Curve for EV Chargers
Most domestic EV chargers run on a 32A circuit, so the RCBO is typically 32A with either a B- or C-curve depending on the inrush behaviour of the charger.
B Curve
Used when inrush currents are low (many modern domestic chargers).
C Curve
Better for chargers with higher inrush, long cable runs or mini-distribution setups.
You can also use 40A RCBOs when the charger or manufacturer specifies it - especially on installs with thicker tails or longer external runs.
Installer-Favourite RCBOs for EV Charger Circuits
Reliable Type A, Type B, high-immunity and 4-pole options for all EV installations.
- 32A High-Immunity Type A RCBO – C Curve
- 20A High-Immunity Type A RCBO – B Curve
- 32A High-Immunity Type A RCBO – B Curve
- 32A Type A RCBO + SPD – B Curve
- 40A High-Immunity Mini RCBO – B Curve
- EV Kit – 2-Way A-Type RCBO Board (6A)
- 4-Pole High-Immunity A-Type RCBO
- 4-Pole High-Immunity A-Type RCBO – ADR440C
Browse the full EV RCBO range: View All EV RCBOs.
FAQs
Installers ask these all the time when wiring EV chargers.
Do all EV chargers need a Type A RCBO?
Yes - Type AC is not allowed. Type A is the minimum unless the unit requires Type B or includes its own DC detection.
How do I know if the charger has 6mA DC protection?
The manufacturer manual will state this clearly. If it doesn’t, assume you need Type B leakage protection.
What curve RCBO is best for an EV charger?
B curve for most domestic chargers. C curve for units with higher inrush or long cable runs.
Do I need a 4-pole RCBO for EV chargers?
Only for three-phase chargers. Most domestic chargers are single-phase and use 1-pole + N RCBOs.
👉 Need the correct RCBO for your EV install? Browse all EV-ready RCBOs