What is an RCBO on an EV charging circuit?
An RCBO is a residual current operated circuit-breaker with integral overcurrent protection: it combines leakage protection and protection against overloads and short circuits [S4]. For EV charging, the complete arrangement also needs appropriate DC fault protection. IET guidance describes 30 mA residual-current protection and suitable DC detection arrangements [S2]. Ask your designer to document the selection. Checked October 2026.
What does an RCBO mean for your site?
An RCBO is a residual current operated circuit-breaker with integral overcurrent protection. It combines the functions of a residual current device (RCD), which detects leakage, and a breaker for overloads and short circuits [S4].
For your site, it matters because a charger circuit needs a documented protective arrangement. A quotation saying only “breaker included” leaves the leakage protection unclear. Ask for the device schedule and the protection provided inside the charger as well as at the distribution board [S1].
Which protection does EV charging need?
Alternating current (AC) changes direction; direct current (DC) flows in one direction. EV charging electronics make the residual-current type important. The IET describes arrangements using 30 milliamp (mA) RCD protection with suitable DC detection [S2]. That is a design matter, rather than a reason to choose a device by appearance.
Read Type A versus Type B RCDs for the waveform distinction. Type A detects AC and pulsating DC residual currents; Type B additionally covers smooth DC [S3]. The RCBO label alone does not settle which of those characteristics the device has.
What should you check on the labels?
A breaker marked with a B tripping curve is not thereby a Type B RCD. The overcurrent characteristic and the residual-current type describe different functions [S3]. Ask the designer to identify both in writing.
Keep the schedule with your installation certificates. Use Section 722 explained for the wider installation questions. Use the charging cost tool separately when preparing your operating budget.
Next step
Start with the site check, then get matched with an installer that covers your area.
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Common questions
How does an RCBO differ from an RCCB?
An RCCB provides residual-current protection without integral overcurrent protection; an RCBO combines both [S4].
Can a miniature circuit-breaker replace residual-current protection?
A miniature circuit-breaker addresses overcurrent. Request the separate residual-current protection in the design, or a suitable combined device [S4].
Does every EV charger need Type B protection?
The IET also describes Type A or Type F arrangements with suitable DC detection. Selection depends on the complete equipment arrangement [S2].
Is a DC detector a complete RCD?
Not necessarily. Some detection modules signal a separate switching device. Ask for evidence of the complete protective arrangement [S2].
Does built-in charger protection remove the need for design checks?
No. Verify the integrated device's product standard and switching functions; the IET distinguishes product claims from installation requirements [S1].
Ask about your site
Sources
- RCDs for electric vehicle supply equipment, Institution of Engineering and Technology,Last checked 19 October 2026
- Protective, isolation and switching devices explained, Institution of Engineering and Technology,Last checked 19 October 2026
- Which RCD Type?, Institution of Engineering and Technology,Last checked 19 October 2026
- Automatic disconnection of supply for island mode prosumer electrical installations - definitions, Institution of Engineering and Technology,Last checked 19 October 2026