I am aware that electrocution risk is already mitigated.
Missed that, how is it mitigated? The problem I will admit is not limited to EV's, any items used outside the equipotential bonded area i.e. outside where it is earthed i.e. not class II there is a problem with
loss of PEN there are a list of methods to reduce or remove the risk, however back in the 70's I well remember a problem with portable traffic lights, and although in the main the human can cope with 50 volt to earth, 25 volt can kill a cow, as to dogs and cats and other small animals it was not raised at the time, so don't know, but to raise what is considered as a safe touch voltage to get around the problems with TN-C-S supplies (PME) to 70 volt is not the answer.
We have three basic methods, 1) Don't use a PME supply. 2) Have a sample earth rod to switch off the supply if the supply earth voltage exceeds a limit. 3) Measure the voltage.
In reverse order our voltage is 230 volt +10%-5% so 253 to 218.5 so there has to be a 34.5 volt allowance, but although this works with a three phase system, with a single phase taken from a three phase system the PEN to true earth voltage can exceed the 50 volt while the PEN to line is still within the 34.5 volt limit.
Lost of PEN was rare, but with the extra loading on the system due to EV charging and heat pumps, the recorded incandesces is increasing, what we would hope is at the time of the PEN failure that no one is touching the EV and that before anyone does touch it the supply (this includes the earth) is isolated.
The other two methods have problems as to where earth rods are located, if it happens to be near some metal services they may not work, but too complex to go into here.
But the big problem is the granny charger, I like many others have an outside socket so I can use class II gardening equipment, and if some one was to visit with an EV as a one off I would be willing to allow them to charge their car. However where the problem lies, is if I bought an EV, now my mileage is very low, so I do not really need a 7 kW charger, in the main 2 kW would be fine, so it would be tempting not to bother with an EV charge point and use the existing 13 amp outdoor socket.
Since in my drive, milkman, postman, and my family only walk the drive, so risk is low, but if I used on street parking, and one of those cable protectors to remove the trip hazard, then people walking past the car increases, and so does the chance with loss of PEN some one touching the car.
Now the question is does the granny charger detect loss of PEN, well some do, and some don't, if using the charger in other countries where the voltage is not so steady, then to have loss of PEN detection could cause problems.
However it does not need to be a EV charger which causes the problem, hot tubs, and patio heaters may also have the earth connected, there are some which are class II but not all, so the question is should PME supplies ever have been permitted?
I see no reason why the built in EV charger of the car needs to be class I, it would be easy to make it class II, I know we did the same with a narrow boat, the shore supply went to the isolation transformer of the battery charger only so boat hull was not connected to shore supply earth, OK more of an issue was galvanic corrosion protection. However there is no reason why the car body needs to be earthed, and if it was not earthed there would be no problem with loss of PEN.
However as it stands there is still a problem so how is it "now is it mitigated"?
