What's the difference between "If an EV cannot be charged inside the building, then the building's PME earth should not be used" and "No external sockets should be installed with PME supplies"?
Because I don't think I've ever seen the latter stated.
I had to read a few times before it registered but yes there is a problem in that we have to provide an earth connection even when it is to supply a class II item.
Outside sockets are in the main used for Class II stuff but the question has be asked before what if the home owner wants to plug in his motor home or caravan to maintain the batteries over long time storage?
The point was raised that although a caravan or motor home it is not a caravan site and as such section 708 does not apply. Also often they are parked closer to the house than fire regulations would allow on a caravan site so there could be a connection between extraneous-conductive-parts like cast iron drain pipes and the vehicle at the same time.
Where houses are close or even joined again one can have extraneous-conductive-parts of one house touchable at the same time as an extraneous-conductive-part of a neighbours house which is why the DNO select the earthing system not the electrician or home owner.
For the electrician to do a risk assessment and use his expertise to decide if to export house earth or to use TT is fair enough, but to recommend that TN-C-S is never exported will with some properties it may not be appropriate.
The IET paper on supplies to vehicles is to me trying to create a standard where really it should be left to the electrician to select. However it makes it hard not to TT a charger point with a TN-C-S supply as 10 years or less down the line when the next EICR is done your work may be rejected as non compliant.
Although the song may say we all live in little boxes and we all turn out the same in real terms this is not the case. My house has plastic external pipework and all external electric devices are above hands reach but my mother has metal pipe work which is a problem with a narrow drive way between the houses were one would naturally park a car and not to use the TN-C-S would present a danger.
To my mind there are just too many rules. Common sense should prevail but while the rules are there we have no real option but follow them.