Load curtailment for EV charging allows the entire load of an installation to be monitored and as it approaches a pre-set limit it curtails the amount of load available to the EV charger accordingly to balance the load.
Having load curtailment prevents a situation where the entire installation is overloaded and thus protects the main intake fuse from operating.
It measures the load by using a small CT device. A CT (current transformer) is a small device clamped around the Line conductor on the incoming supply (after the metre), and provided it is installed correctly (in the right direction and correct location) then it will measure the load and be in constant communication with the EV charger.
It communicates with the EV charger by sending data along a data cable, this can either be from a twisted data cable integrated within the power cable using a specialist EV cable such as EV-Ultra, or it can involve the use of a separate data cable run independently – this will depend on the run and where the mains intake is in relation to the consumer unit and where the EV charger is powered from.
Possibly, but even if/when it does then it’ll likely be for very brief periods of time.
Scenarios where this might happen could be if there is an intake fuse of 60 amps which cannot be upgraded by the DNO and for example there is an electric shower running – the shower and EV charger would both pull in excess of 60 amps combined so the EV will be curtailed while the shower is in use, increasing when the shower is switched off.
The same could be the case if you have a 100-amp supply and have air source heat pumps running and are using the oven and induction hub there could be moments when the peak demand is close to or above the intake rating of 100 amps and the load curtailment will work its magic.
As most EV charging is carried out in the off-peak hours when most of us are asleep, the typical demand in most installations is at its lowest so load curtailment isn’t going to be too restrictive. Possibly houses with lots of electrical heating and cooking may experience curtailment at times during the day, but daytime charging is not common due to the increased costs.
Most EV chargers at present have a load curtailment facility.
