3-Phase EV Charger RCBO & SPD Requirements UK | Guide
3-Phase and Multi-Charger EV Installs
Three-phase and multi-charger sites multiply the protection decisions: per-charger devices, shared upstream protection and a board to hold it all.
Quick answer
Each charger needs its own correctly rated protection (a 4-pole RCBO or MCB plus RCD arrangement suited to the charger), with surge protection and PEN fault detection upstream. Use a TPN distribution board to hold it, and load management where the supply cannot support every charger at full power.
Protection per charger
| Charger | Current per phase | Protection basis |
|---|---|---|
| 11kW three-phase | 16A × 3 | Three-phase protection suited to the charger, 4-pole where RCD protection applies |
| 22kW three-phase | 32A × 3 | As above, 32A-rated |
| 7kW single-phase | 32A on one phase | 2-pole RCBO, spread chargers across phases |
Whether a Type B device is needed depends on the charger’s own DC leakage detection. See What is a Type B RCD? and 4-pole vs 2-pole RCDs.
Shared upstream protection
On a PME supply, a single correctly rated three-phase PEN fault unit fitted upstream can protect several chargers, and combined units with RCBO and surge protection reduce the number of components to wire and certify. See PME protection devices.
Supply capacity and load management
Several chargers rarely all run at full power at once, and the supply may not support it if they did. Dynamic load management caps total demand and shares it across chargers. Confirm the available supply capacity with your DNO before specifying, and balance single-phase chargers evenly across L1, L2 and L3.
Frequently asked questions
Can one PEN fault unit protect several chargers?
Yes, where the unit is correctly rated for the combined arrangement and the manufacturer documents the multi-charger configuration. Check the datasheet for the number and type of chargers supported.
Do I need a separate RCBO for each charger?
Each charger circuit needs protection suited to it, so each is normally protected individually. This also keeps a fault on one charger from taking out the others.
How do I stop a multi-charger site overloading the supply?
Use dynamic load management to cap total demand, and confirm the available capacity with your DNO.
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