For a Qualified and Licensed Electrician to perform an installation, that complies with the applicable regulations, they will need to:
All RCD types continuously monitor the line and neutral AC currents which under normal conditions should be equal and opposite in direction of flow i.e. flowing from the line supply conductor through the load and returning via the neutral conductor. In the event of a fault causing current to flow via the earth then this creates an imbalance of currents between the line and neutral conductor currents causing the RCD to trip and isolate the supply from both line and neutral conductors.
RCDs with a Tripping point of 30mA and an operating time of 40ms when the earth current equals 150mA, are defined in the Standards as a means of ‘additional protection’ in the event of a person coming into contact with a live conductor.
In Australia and New Zealand, it is a requirement to install an RCD upstream from the EV charger (at the main supply or distribution board), even if the EV charger has an RCD built in. Part of the reason for this is that it will protect a person in the case that the supply is broken between the distribution board and the EV charger (for example a person cuts the supply cable with a power tool).
Different Types of RCD protection:
Residual current devices are classified as Type A and Type B and operate as follows:
Smooth DC Currents:
The charging circuitry in the power electronics of a modern EV has the potential to introduce harmonics or ‘smooth DC residual currents’ while charging. This DC residual current could potentially ‘blind’ a standard Type A RCD, rendering it incapable of responding to a situation in which there is a genuine electric shock risk.
The latest IEC standard for Mode 3 electric vehicle charging stations (IEC 61851-1:2017) section 8.5 refers to EV supply equipment requiring either:
BusinessLine G 4 and Iqon: