Bill01803
The issue isn’t conversion of the clients property to a TT system, if there is any class 1 light outside fittings or bonded pipes to gas or water within 10 metres of the charging point you have the risk of dangerous touch voltages under earth fault (possibly from neighbours property etc) it’s part of the risk assessment you have to carry out prior to installation.
EV installation not straight forward external influences play a big part of installation, if you change the property from a PME to TT there’s always a risk of another electrician who doesn’t know the legislation on EV installation puts the PME connection back.
Also some ground conditions you would struggle to get the earth potential acceptable for the EV installation, hence why in the installation it’s easier and straight forward to install an isolating transformer.
Lee