Discuss EV Charger Installation - Cabling Query? in the Electric Vehicles Advice Forum area at ElectriciansForums.net
i fail to see any detriment in a PME system having a rod added as well. it's done as standard in some other countries, and round here a lot of older
TN-S systems also have a rod.
Its probably best to put all these points to the electrician who installed it, they can then hopefully answer some of the questions.So I assume the rod is installed outside, under the ground? I assume simply a connection from this rod is routed and connected to the charging unit inside (replacing the earth of this unit from the PME). Is that right?
I've never looked in any detail at the EV chargers regulations as ive never needed to yet. My thoughts are only based on my logic and what i've seen on the forum.
I assume the desire to connect the chargers to a TT earthing system relates to the car being connected to the installation earth whilst charging and thus becoming live during a PEN failure when connected to PME.
So if the car is inside then it becomes a big piece of exposed earthed metal whilst charging, so if it was connected to a TT system whilst the rest of the installation is connected to PME then the car would be an extraneous part to the installation introducing a dangerous earth potential.
If a rod does need to be installed it then needs to be connected at the right point in the installation (I.e. the small consumer unit housing the RCD and circuit breaker). The earth cable going into the small consumer unit would need to be removed otherwise you have 2 separate earthing systems
So I assume the rod is installed outside, under the ground? I assume simply a connection from this rod is routed and connected to the charging unit inside (replacing the earth of this unit from the PME). Is that right
Ok so the whole installation would have to be TT for this particular set up to comply?
No. The whole installation remains T-N-CS apart from the EV charging circuit. As the rod is connected to the EV charger only that one dedicated circuit becomes TT.
No! The rod is connected to the EV charger!! The CPC of the T&E would be insulated and parked at the charger end of the circuit, but connected to the MET at the supply side of the circuit. It's no different from the arrangement that would be used if you were installing a consumer unit in a garage via a TT system.
If an EV charger is to be installed on a T-N-CS system, not only is a rod(s) to be installed, but additional measures also need to be taken. For instance, any class I luminaires that are connected to the T-N-CS system and are located within simultaneous touching distance of the charger, the connection point and the vehicle under charge; would need to be replaced with class II fittings. Any extraneous conductive metalwork such a water or gas pipe would either need to be shielded in a non-conductive enclosure or converted to plastic piping. These arrangements are absolutely vital so to prevent simultaneous contact being made by a person between two different types of earthing systems. A risk-assessment needs to be undertaken. The written risk assessment document should be appended to the Electrical Installation Certificate. For clarity and reference, I have uploaded section 6.8 of the Code of Practice for Electric Vehicle Charging Equipment.
As long as the installer made you aware that the car must only be charged inside then it's all good. Maybe a sticker stating this on the charger itself as a reminder would have been a good idea too.
Completely agree. I feel they are a way of making the installer feel more comfortable with themselves even though they have potentially left a dangerous situation.Stickers are a pointless waste of time, they will not be read or taken notice of.
No, the circuit does not become TT, the circuit is connected to the PME. It is only the charger which would be connected to the earth electrode, this creates some interesting issues to my mind.
But the problem with this as I stated earlier is that you cannot have the charger which is inside connected to its own earth rod because that makes it and the car an extraneous part to the PME connected installation.
The charging point and car in the garage is within the equipotential zone of the installation.
These arrangements you suggest are laughable, changing lights to class 2? What happens when the light is replaced?
I was also taught as you describe, and that is what we have to do in installing ev systems, but I think Dave sparks is also right ( maybe I wouldn’t go as far as to say laughable).These are not my suggestions, they are what I was taught on the City & Guilds course in EV charging that I did. I dare say that anyone else who has completed the course would have been taught the same.
If these 'suggestions' amuse you, why not e-mail Bill Allan of NAPIT and laugh loudly at him while you tell him that you know more about EV charging than he does. Meanwhile, kindly desist from trying to me appear foolish. Fair enough?
https://professional-electrician.com/18th-edition/changes-introduce-shock-risk
Reply to EV Charger Installation - Cabling Query? in the Electric Vehicles Advice Forum area at ElectriciansForums.net
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