Sometimes, yes — but no general rule names a bidirectional RCBO as the device every two-way charger must have. What the rules require is protection that still works when power and fault current can flow in both directions. A bidirectional charger is both a load and a power source, so its protective device has to be chosen for that duty. The charger’s manual and your local rules name the device; the installer fits what they specify.
Key Takeaways
- No general rule names a bidirectional RCBO; the rules require protection that works with power flowing both ways.
- A two-way charger is both load and source, so fault current can come from the car’s battery as well as the grid.
- Direction (bidirectional rating) and waveform (Type B) are separate questions; the charger manual, local rules and your installer decide the device.
Why Two-Way Power Flow Changes the Protection Question
On an ordinary charging circuit, current flows one way: from the supply, through the protective device, to the car, and the device is selected around that direction. A bidirectional unit — the kind used for vehicle-to-home and vehicle-to-grid work, as our overview of bidirectional charging: V2L, V2H and V2G explains — reverses the flow on purpose. When the car discharges, its battery becomes the source.
That reversal raises the question. A fault on a two-way circuit can be fed from either side: the grid, or the car’s battery. A device chosen only for one-way duty may not sense or interrupt a fault fed from the other direction as its design assumes.
What “Bidirectional” on the Device Actually Means
A bidirectional RCBO is an RCBO — overcurrent plus residual-current (earth fault) protection in one device — that the manufacturer rates for reverse feed: fault current arriving from the load side as well as the supply side. Three separate questions are easy to confuse:
| Question | What it is about | Who settles it |
|---|---|---|
| Direction: can fault current come from either side? | Whether the device is rated for reverse feed | The charger manual’s specified upstream protection |
| Waveform: can the fault current be smooth DC? | Type A versus Type B protection and 6 mA DC detection | The manual plus local rules, as our guide to RCD protection for EV chargers explains |
| Isolation: does the circuit disconnect completely? | Single-pole versus double-pole switching | The installer, from your supply and earthing |
A two-way design may have to satisfy more than one row at once — which is why quotes for the same charger can list different devices.
Where the Answer for Your Installation Comes From
Three sources decide the device, in this order:
- The charger’s installation manual. Bidirectional units are listed as systems, and their manuals state the upstream protection the listing depends on. If the manual calls for a bidirectional RCBO, a Type B device, or built-in protection with a named external device, that is not optional.
- Your local wiring rules and inspector. Requirements for two-way equipment are still developing and differ between regions. The honest answer for a specific address is the one your installer designs to local rules — not a product name from a forum.
- The unit’s built-in protection. Many two-way units carry specified protection inside the enclosure. It complements board-level protection; it does not automatically replace it.
What This Means When You Buy a Charger Today
EVDANCE’s current range is built for charging — one-way power flow — so this question does not arise on our units; the same principle applies: fit the protection the manual states. The EVDANCE EV-ACT5006T 48A Level 2 wall charger is ETL, FCC and CE listed, and its documentation sets out the circuit protection its installation requires. See the full range on our products page. When two-way models reach your market, that manual-first habit is what protects you.
Frequently Asked Questions
Is a bidirectional RCBO the same thing as a Type B RCD?
No. They answer different questions. Type B is about waveform — it can still trip on smooth DC fault currents. Bidirectional is about direction — the device is rated for fault current fed from either side. A two-way installation may need both answered.
My bidirectional charger has built-in protection. Do I still need a device in the panel?
Quite possibly, yes. Built-in protection handles the faults the manufacturer designed it for; the circuit still needs overcurrent and residual-current protection at the board unless the manual and local rules say the built-in provision covers it. Your installer settles the combination.
Can I fit a standard RCBO now and change it when I buy a two-way charger?
Protection selection is design work, not trial and error. A device not rated for reverse feed should not protect a two-way circuit. If you are preparing a circuit today for a bidirectional unit later, tell the electrician now — the device choice belongs in that conversation.
Related Reading
- RCD Protection for EV Chargers: Type A, Type B and 6 mA DC Detection Explained
- Bidirectional Charging Explained: V2L, V2H and V2G
- When Will Vehicle-to-Home Be Available?
