EV charging point

[Stinsy]

With the imminent (only a few months to go...) arrival of my iD4 I've been checking out charging facilities along routes and at destinations where I do or might travel. I was interested to see the accommodation I stayed at this weekend boasted EV charging facilities:




I'm unsure what to make of a single 13A socket and a 16A commando. I assumed 7.4kW Type 2 at least. I noticed the property was supplied by 3-phase so 22kW wouldn't have been too much trouble.

[nowty]

Installing a charger is expensive, especially a tethered one. Just sticking a 13A socket and a 32A socket (I am presuming that commando socket is 32A but yes could be 16A) is cheap and simple and allows the user to use whatever granny charging cable they have.

Even if they have a 3 phase supply, not many vehicles (yet) can charge faster than about 11kW or 12kW on an AC supply. Your ID4 will only charge at a max of 11kW even if connected to a 22kW 3 phase AC charger.

[John_S]

Whilst it might be tempting to install a 16A or 32A 'Commando' socket and then to use it to charge an EV, it is not at all clear if such an installation would comply with the 18th edition wiring regulations for EVSE, in particular earthing regulations, unless expressly installed to do so. Earthing requirements are complex and I do not pretend to fully understand them, particularly earthing rods in dry soil and PEN fault detection.

I am not prepared to take the risk of my home insurance being invalidated by such an arrangement and shall only install a fully compliant arrangement.

I am presently in the process of commissioning an EICR to see what I need to upgrade my home installation, rewired in 1999, to meet all the subsequent changes and to form the basis of supplying a 32A EVSE via a detached garage.

Frankly it is confusing, especially as the OZEV appears to wash it hands of installations funded by itself or its predecessors which do not meet current (no pun intended) wiring regulations.

[Oldgreybeard]

The requirements of the wiring regs, and the law in England and Wales, do indeed mandate that a charge point, or any outlet installed for EV charging, have additional safety protection over that needed for an outlet to run, say, a lawn mower or hedge trimmer.

The reasons are two fold. Firstly, there is a risk of DC earth leakage when charging an EV, and DC can "blind" a conventional earth leakage circuit breaker, as they use a sensitive AC current transformer. Any DC earth leakage can bias the core of this transformer to saturation, so it no longer responds to earth leakage, making the connected circuit potentially unsafe. The second problem is that, unlike mowers and hedge trimmers, EVs are not double insulated appliances. There is a failure mode on the low voltage network that can lead to the protective earth provided by that network to rise to a high voltage relative to the local earth around a plugged in car. As that protective earth will be connected to the car body, and as the tyres are insulators, if such a fault occurs on the local network then there could be a serious electric shock risk from the voltage on the car body.

The regulations require that any power outlet installed to charge an EV be provided with Type B, EV or F earth leakage protection (or the equivalent built in to a permanently wired and fixed charge point) together with open PEN fault protection, to remove the risk of electric shock should there be a break in the PEN conductor in the local supply. There are connection units available that include all the required protection, and these can be used to supply the outlet for charging.

Finally, installing an outlet for charging an EV is notifiable work under Part P of the building regulations, so must not only comply with the wiring regs, but must also be approved by building control, or notified by a person that's a member of an approved Part P scheme. There is also a legal requirement to notify the DNO that an EV charging outlet has been installed, together with it's current rating.