We can't generally assume they are the same earthing arrangements, because one installation may be, either already, or at some time in the future be

• Changed to a different earthing arrangement (TT)
• Supplied from a different transformer or distribution main

More importantly, regarding the PME issue, what if the broken PEN happens between the two properties?

Hi Graham,

Thank you for responding.

So if neighbouring properties park their cars on their drives which are within the simultaneous contact distance, then only one can have an EV charging socket installed?

Would some form of barrier be satisfactory such as a wooden fence?

With regards to the broken PEN, the supplies are SP&N and the chargers would have internal PEN fault protection as detailed in indent (iv).

Mark Fleming said:

So if neighbouring properties park their cars on their drives which are within the simultaneous contact distance, then only one can have an EV charging socket installed?

That is one conclusion - although that doesn't mean nothing can be done about it.

Mark Fleming said:

Would some form of barrier be satisfactory such as a wooden fence?

Yes, the clue is 'simultaneously-accessible'. Preventing 'simultaneous contact' with both vehicles is the best (perhaps only) approach here. Trying to do things with the electrical installation to join the two installations is frought with difficulties - not least because the two installations have different owners, who may not always agree on how the installations are to be maintained going forward (or as I said above, one wants a change to their installation, for which the DNO might insist on going TT - I know of someone whose connection agreement for PV upgrade including battery storage who was required to go TT by their DNO very recently).

Mark Fleming said:

With regards to the broken PEN, the supplies are SP&N and the chargers would have internal PEN fault protection as detailed in indent (iv).

Whilst this is covered by 722.411.4.1, and helps minimise the risk if someone is touching both vehicles with the PEN fault in between the premises, it's got nothing to do directly with 411.3.1.1.

411.3.1.1 is really to do with control of touch-voltage in a fault to PE (an exposed-conductive-part), helping limit the effects.The fault in this case doesn't have to be at the vehicle, but could be transferred from a fault elsewhere in the installation - for example, one for which a 5 s disconnection time is permissible.

I think that this is a really interesting question. It isn't at all uncommon for adjacent pairs of houses to have side-by-side drives with no boundary fence. If they are each about 8 feet wide, there is no difficulty installing EVCPs sufficiently far apart for them not to be simultaneously accessible. However, when the cars are plugged in, they (the cars, not the EVCPs) will be about 2 feet apart.

I am afraid I don't have an answer to that one.

Chris Pearson said:

I am afraid I don't have an answer to that one.

Wireless charging is another possibility that's not too far away for domestic (not sure on costs in the UK yet, though).

At some point there's going to be a push back against requirements that are impossible to achieve.

You can plonk a caravan on your driveway and hook it up to a Commando socket.  So long as the socket is fed by an RCD, nobody bats an eyelid.

But the rules for EV chargers seem to become more onerous with every amendment to BS7671.  You have to have the right sort of RCD.  And PEN fault detection.  If someone says you can't buy an EV because your neighbour has one, then people will just say "sod it".  They will buy a bootleg "granny lead" off Aliexpress, and plug it into the power socket they normally use for their lawnmower.

And nobody will stop them, because it's nobody's job to stop them.

At some point there's going to be a push back against requirements that are impossible to achieve.

I guess some folk buy these sort of things off amazon and dob them into a spare MCB or fuseway already and maybe fail to tell anyone...

In some parts of the planet regulations are not followed that well already. And because its not a problem, after all cars kill far more people mechanically than electrically, and that is not such a problem that society stops,  the situation will continue.

If you want  less controversial UK examples, look at the drive by flat EICR thing, or folk who put PAT stickers on everything willy nilly - scarcely worth it in terms of lives saved, so not worth chasing the irregularities too strongly. Or perhaps some aspects of part P ;-)

M.

Hi Mike,

'look at the drive by flat EICR thing' 

Unfortunately this is extremely common and even more so by some of the biggest in the industry who due to paying per additional circuit, have guys reportedly fully testing and inspecting an impossible amount circuits every day and no one thinks to question it as long as the boxes are ticked.

Simon Barker said:

You can plonk a caravan on your driveway and hook it up to a Commando socket.  So long as the socket is fed by an RCD, nobody bats an eyelid.

But the DNO is not really supposed to permit that in installations where PME conditions apply. The RCD will not protect against touch-voltage in the event of an open-PEN event.

Does 722.413.1.2 solve the problem?