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.

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.