The liitle black box with the black wire coming out that is connected th the live (brown) meter is a current clamp (CT), the piggy wire then connects to a small circuit board (see image). The current clamp monitors the load in amps going through you house. If it detects the load is close to exceeding the maximum the house is able to handle, then the charge rate on your charger will be reduced. It will protect your cutout fuse from blowing. Its a safety feature with some EV chargers but not all. (see image)
A CT clamp in solar PV systems is also useful with some charge points, as it will detect how much you are exporting back to the grid and instead transfer any spare solar to charge your EV.
Showing the CT clamp which connects to a mall circuit board, which you can see behind the earth wire.
