EV Chargepoint - Wiring Options

[ChewChew]

I won't be ordering my EV car until mid 2018 so can't get the 32A chargepoint installed under the government grant scheme right now (rules!), but as I have the en-suite floor up now would be a good time to run some cable in readiness. A once never to be repeated opportunity because the floor will be tanked and tiled.

Distance from house consumer unit to chargepoint would be less than 10m if run underfloor. If fitted later and through loft, 15m.

The garage has a light and double power socket one of which is used for the garage door. Both these are spurs off the house lighting and mains rings.

The options I see are:

1. run a suitable cable @32A under floor to garage - simplest.

2. fit a consumer unit in garage and run a suitable cable @??A under floor to garage to supply lighting, power and chargepoint - a more elegant solution and provision could be made for another light and at least one more double power socket.

Option 2 seems the best to me, but there may be other/better options so any suggestions please?

What sort of cable would you suggest for each option? Is there anything I should consider so not to fall foul of building and P regs?

Thanks

 

[motorbiking]

4mm radial off a 32a MCB in your CU

more knowledgeable posters may have better ideas

 

[stillp]

Some EV chargers are very sensitive to voltage drop, so don't scrimp on the size of cable - I'd suggest 6mm².

 

[securespark]

Has the cable to go outside?

If so, use SWA.

The difference in price and OD is minimal, so I would go for 10milli.

 

[JohnW2]

Some EV chargers are very sensitive to voltage drop, so don't scrimp on the size of cable - I'd suggest 6mm².

That seems rather odd - if that's the case, do you have any idea of why?

How do they cope with supply voltages (at original of installation) of 216.2 volts (even if one wires the EV Charger from there in 25mm² cable)?

Kind Regards, John

 

[ban-all-sheds]

Are there any relevant changes proposed for the 18th?

 

[securespark]

The DPC says:

Section 722 Electric Vehicle Charging Installations

This section contains a significant change to Regulation 722.411.4.1 concerning the use of a PME supply. The exception concerning reasonably practicable has been deleted.

Changes have also been made to requirements for external influences, RCD's, socket-outlets and connectors.

 

[stillp]

do you have any idea of why?

Poor design.

How do they cope with supply voltages (at original of installation) of 216.2 volts (even if one wires the EV Charger from there in 25mm² cable)?

The ones in question don't cope, they just fail to charge.

 

[JohnW2]

Poor design.

I suppose that has to be the case, but it would be so relatively easy to design a charger that was tolerant to supply voltage variations that one has to wonder!

Are you perhaps implying that it's a matter of 'cost cutting', rather than suggesting that the designers were incapable of designing products which did not have this problem?

Kind Regards, John

 

[stillp]

Just found some old notes! Contrary to what I said above, one of the two makes of charger in question worked at low supply voltages (notes don't list the actual limit values, sorry) but could not cope with the drop in voltage due to the spikes of current into the battery. The other make had the same problem with impedance, but also failed at supply voltages below something quite foreseeable (again forgotten) or above, from my unreliable memory, around 245 volts.
Both these makes were associated with 'reputable' brands of EVs.

 

[JohnW2]

Just found some old notes! Contrary to what I said above, one of the two makes of charger in question worked at low supply voltages (notes don't list the actual limit values, sorry) but could not cope with the drop in voltage due to the spikes of current into the battery. The other make had the same problem with impedance, but also failed at supply voltages below something quite foreseeable (again forgotten) or above, from my unreliable memory, around 245 volts.

I think my latest comments still stand. One might have thought that they could have avoided those problems 'by first intent' during initial design but, even if they didn't achieve that, one would have thought that the issues would have been detected during development and testing, and hence subsequently 'designed out' before the products went into production!

Kind Regards, John

 

[stillp]

Blinded by their zealotry in saving the planet.

 

[ban-all-sheds]

... or above, from my unreliable memory, around 245 volts..

I hope your memory is unreliable - they aren't allowed to make a charger which fails above 245V.

 

[davelx]

4mm radial off a 32a MCB in your CU

more knowledgeable posters may have better ideas

Some EV chargers are very sensitive to voltage drop, so don't scrimp on the size of cable - I'd suggest 6mm².

If you are thinking of a Tesla Model 3 (I am), then I guess you are referring to installing a standard 32A industrial socket?

TESLA specify 6mm² in their guidance note and and the regs require an interlocked socket cf. 722.55.201.1 (ii) or (iii)

note also earthing requirements for PME installations referenced in a previous reply.

https://www.tesla.com/sites/default...nstall_guide_industrial_socket_blue_DEC16.pdf

 

[EFLImpudence]

4mm radial off a 32a MCB in your CU

Just to say, you are correct - for cable clipped or buried in masonry.

For the instructions to state "Minimum conductor cross section area 6 mm2, or higher depending on installation specifics and local regulations" is not exactly correct -

"Minimum conductor cross section area 4 mm2, or higher depending on installation specifics and local regulations" would be.