EV charging question

[leebut]

Sorry they’re not in order

If there’s a class 1 light or bonded pipe within 10 metres of the charging point the charging point cannot be on a separate earthing system to the property or the neighbours property

 

[Lucien Nunes]

I've never installed a charging point and unfamiliar with accepted practice, but I can say with certainty that no 7kVA wirewound transformer ever mounted on a DIN rail. It will be in the order of 50-60kg and the size of a case of wine unenclosed. This is due to physical limitations of the copper and steel, and until someone invents a revolutionary material with better properties, it won't change much. It is possible to make a smaller, lighter switched mode converter, although not for a few hundred pounds.

But, surely the sensible approach is a device that disconnects the supply in the event of the PME earth exceeeding 70V to local mass of earth, as detailed in 722.411.4.1 option (iii). Put in two small spikes nearby (resistance need not be very low, and the two would allow for automatic monitoring of resistance), see the green light come on and the job is done. It's basically an improved version of a VOELCB used for a more suitable purpose, obviously with a bit of engineering to make it reliable enough to switch the PE as well as the live conductors.

I have to wonder why the charging point makers don't offer an integral solution. 722.411.4.1 option (iii) even suggests the voltage detection device could be included in the charging equipment. The convenience of being able to install one product to any supply without further complications would surely be attractive in spite of increased cost.

 

[mattg4321]

Can't see how its possible to fit an EV charger in most cases then. Back to petrol we go!

Sorry LeeBut a 7kw isolating transformer will be around £1000 and pretty large. Not an option.

Is your book saying a EV charger electrode can't be within 10m of a buried metallic bonded pipe, outside light, outside socket etc etc. Doesn't sound like this is possible in most cases where the charger would be mounted to an outside wall of a dwelling.

Anyone else that's done the course? Thinking of doing it soon, but if this is the case!

 

[leebut]

Well the instructors at the training centres must be talking through their Ar**s then

 

[leebut]

Can't see how its possible to fit an EV charger in most cases then. Back to petrol we go!

Sorry LeeBut a 7kw isolating transformer will be around £1000 and pretty large. Not an option.

Is your book saying a EV charger electrode can't be within 10m of a buried metallic bonded pipe, outside light, outside socket etc etc. Doesn't sound like this is possible in most cases where the charger would be mounted to an outside wall of a dwelling.

Anyone else that's done the course? Thinking of doing it soon, but if this is the case!

Yes it does, this is the reason why they say you should go down the isolating transformer route because if you live in a new estate house close together you cannot guarantee safe earthing if you convert property to TT. system

 

[leebut]

I've never installed a charging point and unfamiliar with accepted practice, but I can say with certainty that no 7kVA wirewound transformer ever mounted on a DIN rail. It will be in the order of 50-60kg and the size of a case of wine unenclosed. This is due to physical limitations of the copper and steel, and until someone invents a revolutionary material with better properties, it won't change much. It is possible to make a smaller, lighter switched mode converter, although not for a few hundred pounds.

But, surely the sensible approach is a device that disconnects the supply in the event of the PME earth exceeeding 70V to local mass of earth, as detailed in 722.411.4.1 option (iii). Put in two small spikes nearby (resistance need not be very low, and the two would allow for automatic monitoring of resistance), see the green light come on and the job is done. It's basically an improved version of a VOELCB used for a more suitable purpose, obviously with a bit of engineering to make it reliable enough to switch the PE as well as the live conductors.

I have to wonder why the charging point makers don't offer an integral solution. 722.411.4.1 option (iii) even suggests the voltage detection device could be included in the charging equipment. The convenience of being able to install one product to any supply without further complications would surely be attractive in spite of increased cost.

We asked the same questions as to why the manufacturers such as Rolec dont install them, I’ve heard another manufacturer does include the device but I cant find who does it

 

[Sparkingmad]

The guidance I received on acceptable TT Ra test results where the charge point was 32A and supplementary earth rod was to be installed on the MET of a TNS or TN-C-S was an RA less than 5Ω was considered stable where as it’s less than 200Ω for whole house TT rod. The other issue is this 10 meter zone. When charging leads can be 7.5Mtrs in length and the charging ports on the cars are not all in 1 standard location. So it is possible for the vehicle to be charged in different locations on the drive plus add the vehicle length, difference in plug location you could have an earthed metallic pipe or fitting that is not reachable with say a Nissan Leaf but you chuck a Tesla on the drive it suddenly becomes very touchable.

 

[Deleted account]

Good news leebut the voltage potential difference device that wasn’t invented when the ev charge code came out is now in production.

There was a recent threat on this issue and more information is on there.

I will try to locate the thread.
[automerge]1568446857[/automerge]
Have a look at the thread “Updates to 722”.

Not the thread I was looking for but it’s relevant
[automerge]1568447034[/automerge]
“EV Charger Installation - Cabling Query?” This was the thread I was originally looking for.

 

[Simon47]

So you install an isolating transformer, the trailing cable gets damaged and the "L" gets earthed. The car is now at 240V until someone touches it and the ONLY protection is the load-side RCD. Or put another way, the only protection against shock in that case is a device that's known to fail from time to time - I think we've all, or at least a lot of us, come across RCDs that don't trip when tested.
You also need active monitoring to ensure that (eg) insulation breakdown in the transformer or wiring doesn't make the vehicle "hard" to 240V (or some subset of it) with zero protection other than any upstream RCD.
Might as well save the cost (and bulk) of the transformer and just have active monitoring of CPC vs local ground voltage as already mentioned.

 

[davesparks]

So you install an isolating transformer, the trailing cable gets damaged and the "L" gets earthed. The car is now at 240V until someone touches it and the ONLY protection is the load-side RCD.

The car is only at 240V relative to the other pole of the transformer output, it will not present a shock hazard unless the person is in contact with the other pole of the output at the time they touch the car.

 

[Gavin John Hyde]

I will post a link later you can get a bit of kit to use pme for not much.
Otherwise fit a podpoint solo. Can use pme

 

[Fork Handles]

Most residential EV chargers are converted to TT. However a new generation of chargers are being introduced which monitor the PME supply and disconnect. Do EV chargers need earth rods - https://www.efixx.co.uk/Articles/next-generation-ev-charge-points-don-t-need-earth-rods

 

[Midwest]

Here's an articule, previously posted;

Do EV chargers need earth rods

Electric vehicle charge point manufacturers are adding intelligent electronics to remove the need for earth rods.

www.efixx.co.uk

 

[Gavin John Hyde]

There is a good source of devices to allow you to use chargers on a pme system. Cost around £130 per unit pdfs below.
Havent used one yet as i opt for the pod point solo or go down a tt set up.

 

[Amp David]

After completing this very course, it made my mind up for me, not to bother getting involved with EV. Its not a good business decision for a one man band like myself.

More regs, more paper work and less time to spend away from working!