A dedicated circuit
A charging station draws a lot of current for hours. That's why it gets its own circuit: a dedicated cable from the fuse box with its own breaker. How thick that cable needs to be depends on your charging station's power and the distance to your fuse box. If the charging station is outside, an underground cable often runs to it.
Also check whether there's room in your fuse box for an extra circuit, and whether your supply has enough capacity. If it's tight, load balancing can help.
Why DC leakage current matters
A standard RCD (type A) trips on AC leakage current. While charging, a car can also cause a small DC leakage current. If that gets too large, a type A RCD can no longer do its job properly. So a charge point must also be protected against DC leakage current. There are two ways to do that:
- With a type B RCD in the fuse box. It also detects DC leakage current.
- With a type A RCD combined with a charging station that detects DC leakage current from 6 mA itself and then switches off. Many modern charging stations have this detection built in.
Which route goes with your charging station is in its manual and listed on its page. Your electrician checks it when connecting it.
B curve is not the same as type B
On an RCBO you often see a B or C, for example B16. That's the trip curve: when the breaker switches off on overload or short circuit. It says nothing about which leakage currents it detects. An RCBO with a B curve is therefore not the same as a type B RCD.
Single or three-phase in the fuse box
With a three-phase charging station, the circuit runs over all three phases and you need three-pole (3P+N) protection; on a single phase, single-pole (1P+N). The current rating depends on your charging station and the cable to it. Read more about phases in Single or three-phase: how fast does your car charge?
Have it connected
Have the circuit and charging station connected by a qualified electrician. They choose the right protection, cable and current rating, and check that your fuse box can handle it. The rules that apply in your country are listed below.