Help with electrical question RE Installation of wall charger

[SimmieC]

Hi,
Are there any electricians out there who could help with my situation.
I live in France and the electrics over here are only slightly different to the systems in the UK.
First of all has anyone had a wall charger installed in a French property?
Secondly can anyone help with the specifics when it comes to the installation of the charger box.
To give a rough idea of my situation....
In my house I have a consumer box with a 6mm2 cable supply from the meter. I have space in the consumer box for another 4 trip switches.
I will need to run a cable to the barn opposite the house, which is a run of either 25m (through the house) or 35m (out of the back of the house and through an adjacent barn).
Now, can I use 6mm2 cable for a 7.3kw charger (looking at Zappi as I will have PV next year) or should I upgrade to 10mm2?
Also what trips/protection will I need?
Really sorry for the long text but wanted to make sure I put as much detail as possible!!!
Simon

 

[Coulomb]

In my house I have a consumer box with a 6mm2 cable supply from the meter. I have space in the consumer box for another 4 trip switches.
...
Now, can I use 6mm2 cable for a 7.3kw charger (looking at Zappi as I will have PV next year) or should I upgrade to 10mm2?

6 mm² is good for at least 35 A, which is fine for a single phase 7.2 A EVSE.

But usually, you would need a dedicated line from the EVSE right back to the main switch board. It sounds like that 6 mm² cable would or at least could be shared with other things. I don't know the European regulations, but that would not fly in Australia. Unless that board with the 4 spare slots IS the main switchboard.

At 35+ m, it's a fairly long run, but I think you will be fine with the voltage drop from 6 mm².

 

[Wookey]

Now, can I use 6mm2 cable for a 7.3kw charger (looking at Zappi as I will have PV next year) or should I upgrade to 10mm2?

This IET discussion points out that the loses with a 6mm2 cable, especially over a 35m run, are significant (around 200W whilst charging at 7kW), and after a few years you'd have saved money installing 10mm2 (which will approx halve those losses). Especially if you consider emissions too there is a lot to be said for just doing the better/more efficient job. It's not excessive, and will cost about an extra £50 (up front, not over the long term)

IET EngX® Wiring Regulations Discussions

Questions on electrical systems design, electrical installations and BS7671 Wiring Regulations.

communities.theiet.org

There are also earthing considerations if you have a PME installation (shared neutral and earth back to the substation - not sure if that's common in France - it is in the UK). The Zappi has built-in PME fault protection so it's simple. most other chargers don;t so you'll have to install an earth rod near the charger/car (or a separate PME fault detection box which is over £200).
This doc explains it all nicely. https://evcables.co.uk/d/global/EOC...l_Electrical_Guidelines_for_Installations.pdf
As someone else said it's much simpler if you can go straight from a supply with no RCD (again there is one in the Zappi). if not you need to worry about discrimination between two RCDs.

 

[Coulomb]

For those not familiar with the acronym PME (I had to look it up), it stands for Protective Multiple Earthing. In Australia, we'd call that (or something very similar) MEN: Multiple Earthed Neutral. It's MGN in North America (Multiple Grounded Neutral).

 

[SimmieC]

Thanks both of you for your input. I've decided to go with 2 x 102mm cable and install a separate Earth rod close to the unit (belt and braces).
Cheers.