Installation of Electric Vehicle charging equipment
The increasing use of Electric Vehicles (EVs), and the demand for faster charging rates, will place higher loading demands on existing installations, especially domestic installations.
Equipment specifications
It is important to check the equipment’s specifications before installing an EV charging station or a socket outlet for an In Cord-Control and Protection Device (IC-CPD). Make sure the equipment is designed to operate from NZ supplies of 230 or 400 volts at 50 hz.
When installing an EV charging station, especially where the charging station requires more than 15 A, the installing Electrician must make sure that the incoming mains will not be overloaded. It is not acceptable for the loading of an installation to be controlled by the consumer turning the equipment on and off.
Maximum demand and maximum volt drop
Equally, it is necessary to double-check both the maximum demand, and the maximum volt drop of the installation. This will confirm that all parts of the installation, including all electrical appliances and fittings are supplied with electricity within their safe operating voltage.
Excessive volt drop may be a sign that the installation wiring will not tolerate a high load for prolonged periods. It may also result in fires, or cause the Residual Current Devices (RCDs) to fail. Many EV chargers contain safety function equipment such as a residual current monitoring function, which are different to RCDs.
You cannot rely only on the inbuilt function of the charging station to turn off the power if the voltage drops below a preset level. The supply mains should be upgraded first, when this is not practicable, “smart” technology will be needed to moderate the charging rate of the charging station.
Supplier declaration of conformity (SDoC)
It is recommended that any permanently connected EV charging station is supplied through a dedicated subcircuit from the installation’s main switchboard that is rated for the anticipated load. EV charging stations are declared medium-risk articles and they require the supplier to have completed a supplier declaration of conformity (SDoC).
It is good practice for installers to get a copy of the SDoC and attach this to their CoC for the installation, then you as the installer don’t take the responsibility for the compliance of the charging station. If you do attach the SDoC to your CoC, that responsibility is then placed with the SDoC issuer.