The i3's delivered in the UK (and the USA) are essentially one-phase devices. At least in the USA, some vehicles, often things like busses and delivery trucks, that can accept 3-phase power, and thus, quicker recharging (fast ac?). The i3's on-board ac-dc power supply is only capable of 7.4Kw maximum and is only wired for single-phase power. So, if the communications works, it still should charge at its maximum considering that it should be reporting more power is available. Depending on the design, the imbalance from hooking a 3-phase capable EVSE up to a vehicle only capable of single-phase might prevent it from working, but since it is just a fancy switch and the contacts aren't being overloaded, it probably would work. JUst like you can plug in a 15W florescent lamp into a circuit capable of 20A, it still will not draw more power than it is designed for, and in the case of the i3, that's 7400W.