Within Zappi the PE check is an advanced feature in the zappi which is not provided by most other EV chargers.
It uses the impedance of the supply back to the primary transformer to confirm the continuity of the earth conductor so in some (very rare) cases where this impedance is too high for the PE check feature to work then this feature needs to be disabled.
To disable the PE Check, please select "IT Earthing" in the menu Settings -> Advanced -> Supply Grid -> Device -> Earthing
Please rest assured that, provided the installer has installed the zappi correctly and completed all the standard electrical checks, then zappi is completely safe to use to charge your electric vehicle.