EV Charger Installation - Cabling Query?

[JK-Electrical]

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.

Spot on Dave.

 

[JK-Electrical]

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

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.

 

[JK-Electrical]

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

Correct!

 

[JK-Electrical]

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.

 

[JK-Electrical]

https://professional-electrician.com/features/are-you-installing-earth-electrodes-correctly-for-electric-vehicle-charging-points

 

[davesparks]

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 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.

 

[davesparks]

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.

It is very different to installing a supply to an outbuilding, this unit is within the equipotential zone of the installation, not seperate from it.

 

[davesparks]

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.

These arrangements you suggest are laughable, changing lights to class 2? What happens when the light is replaced?
Shielding pipes in non-conductive material? How do you test this site applied insulation? Who will maintain it and ensure it remains in good order?

Let me guess, the solution to the problems is going to be some sort of label telling people what to do or not do? Again, pointless, nobody reads these labels.

 

[davesparks]

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.

Stickers are a pointless waste of time, they will not be read or taken notice of.

 

[HappyHippyDad]

Stickers are a pointless waste of time, they will not be read or taken notice of.

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.
I have just seen a garage CU fed by 1.5mm SWA. It has as 32A MCB in it to feed 3 double sockets on a radial. It has a sticker on each socket saying '6A only'!

 

[JK-Electrical]

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.

Source:

https://professional-electrician.com/18th-edition/18th-edition-ev-charging

What do the Wiring Regulations say?

When opened to public comment, the draft revisions for section 722 came under intense scrutiny from the industry. In the final published document, the option to use a protective multiple earthing (PME) facility was reduced. PME is the most common form of earthing provided in new electrical installations.

There are ways that PME can be used, but these are often difficult to achieve. Therefore, most installations will rely on separation of the earthing system and making the EV a TT system (using an electrode in the ground).

 

[DT1991]

I see your point davesparks.

The fact on this particular job then is

1 - Either make the whole system TT
2 - Install a charging unit suitable for PME
3 - Remove the garage

I do not agree with the sticker idea as this is a step backwards, if we cannot label a socket in the loft 'TV booster only' then a EV charger is out of the question.

 

[JK-Electrical]

The attached scan is from section 5.3.3.3.1, page 32 of the Code of Practice for Electric Vehicle Charging Equipment Installation. The section heading is: Providing a TT earthing system for the charging equipment.

 

[JK-Electrical]

These arrangements you suggest are laughable, changing lights to class 2? What happens when the light is replaced?

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

 

[Deleted account]

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

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).

For these reasons I won’t fit EV charging points until the code of practice is sorted and an appropriate voltage potential device is invented and fitted in all ev chargers.