EV Charger Installation - Cabling Query?

[DT1991]

Why not the supplementary earth rod path?

When put into maths it requires a stupid low Ra value which cannot in reality be sustained.

That's my understanding?

 

[Midwest]

When put into maths it requires a stupid low Ra value which cannot in reality be sustained.

That's my understanding?

But isn't that the case for all earth rods with ev chargers (don't they do an efli test), whether TT or supplementary earth rod?

 

[DT1991]

I dont think the maths is the same.

When PME and using a supplementary earth rod it takes into account the max current of the installation and this is put into the equation which brings up a low Ra value.[/QUOTE]

 

[Deleted account]

When put into maths it requires a stupid low Ra value which cannot in reality be sustained.

That's my understanding?

Yes we did some calcs at college when we did the course. It was nigh on impossible. I think 3 earth rods 1 meter apart 2.4 meters deep might do it. Depending on resistivity of the earth.
So they have given us a solution to the problem that is pretty pointless.

 

[Deleted account]

I dont think the maths is the same.

When PME and using a supplementary earth rod it takes into account the max current of the installation and this is put into the equation which brings up a low Ra value.

[/QUOTE]
You don’t take the pme into account when doing the maths as the rods are there in case you loose the neutral, thus loose the pme.

 

[Deleted account]

duplicate post again ok

 

[DT1991]

Sorry pete what do you mean by that?

 

[Deleted account]

The major point of TT for ev is in case of dropped neutral on supplier side.

That in itself is pretty rubbish that we have to prepare for faults that are nothing to do with our regs and are in the control of the DNO’s.

So we need to know that the earth rods being put in at the origin are adequate without the pme if the neutral is lost by DNO

 

[davesparks]

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 don't claim to know more about EV charging than anyone. However is is obvious (hopefully) that introducing an extraneous earth potential into an installation then connecting it to a big piece of exposed metal (car) goes against the basic principles of protection against electric shock.

I am not trying to make you appear foolish, I have no need to do this. By suggesting that one can laugh loudly in an email you have achieved this appearance without my input.

 

[davesparks]

if the prohibition of PME for EV chargers is to eliminate risk if the supply N is lost (as with metalclad caravans) the I can't see any reason to differentiate between inside or outside. a fault occuring would have a similar result, in or out. then, i have not done any research on EV so my knowledge is limited.

If the vehicle is inside then it is, technically, within the equipotential zone and becomes no different to any other exposed, earthed, metal in the building. The car being charged in the garage presents the same hazard as the class 1 freezer in the garage.

 

[davesparks]

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.

So how do you ensure that the zone of influence of the earth electrode does not overlap the zone of influence of any metalwork connected to the PME earth?
Do you trace and map out every gas and water pipe, buried structural steel etc?
Do you get accurate maps from the DNO showing the extent of the zone of influence of every buried PME electrode in the street, street furniture, repurposed PILC cable etc?

 

[Midwest]

So how do you ensure that the zone of influence of the earth electrode does not overlap the zone of influence of any metalwork connected to the PME earth?
Do you trace and map out every gas and water pipe, buried structural steel etc?
Do you get accurate maps from the DNO showing the extent of the zone of influence of every buried PME electrode in the street, street furniture, repurposed PILC cable etc?

The link I posted from WPD, gives their views on such (for those who've not read it);
‘The earthing considerations for the connection of electric vehicle charge points are firstly the type of earthing arrangement (PME, SNE or TT) and secondly the required segregation between these different earthing types. The requirements of the Code of Practice for the installation of EV charging equipment makes the use of protective multiple earthing (PME) prohibitive and steers installations towards a TT setup. However the IET Wiring Regulations (Guidance note 7) requires segregation of a minimum of 10m between the PME and TT earthing systems. We understand that this requirement will restrict installations in the street and therefore we have recalculated the requirement using modelling specifically for a street side application. As a result we can reduce the distance so that a balanced three phase demand utilising a TT earthing system will require segregation from the WPD earthing system by a minimum of 0.3m and a single phase or unbalanced connection would require a segregation of 3.6m.’

 

[Midwest]

Yes we did some calcs at college when we did the course. It was nigh on impossible. I think 3 earth rods 1 meter apart 2.4 meters deep might do it. Depending on resistivity of the earth.
So they have given us a solution to the problem that is pretty pointless.

What formulae were used?

Seem crazy now, that the 18th draft was considering going earth rod mungus or is that something different?

 

[stevethesparks]

How many electricians install an earth rod for an outdoor socket on a pme system, supplementary or otherwise. Cant see much difference myself.

 

[Midwest]

How many electricians install an earth rod for an outdoor socket on a pme system, supplementary or otherwise. Cant see much difference myself.

You’re not plugging in a big metal box on rubber wheels into your outdoor socket. Must of the things I plug into my outdoor socket are Class II.

 

[stevethesparks]

just for instance, a trailing lead across a pavement for a booster charger, admittedly not as big a target, but there are many class I appliances that could be plugged in to such.
Surely similar considerations should be given to outdoor sockets, especially as there is no end to what some mugs will plug into them.

 

[hyeung]

Hi,

I got back in touch with the installer.....and sent the following email:

"There is something I was looking to clarify with you in relation to my recent charger installation.

As you know the charging unit is located internally in my garage, as my primary intensions will be to charge whilst the car is parked inside the garage overnight.

However, as the selected location of the charging unit is next to the garage door, I had also anticipated that the unit could be used for outside charging as the cabling could easily run under the garage door.

A friend of ours has a similar EO installation where their charger is also located internally next to the garage door like ours, therefore enabling him to charge either indoors or outdoors.

However, he had pointed out to me that in order to charge outside there are some safety regulations required on the earthing requirements of the install; such that their installer had advised that an Earthing rod would be required.

It appears within my installation, the charging unit is setup to use our domestic earthing system (i.e. T-N-CS (PME)) and not via an Earthing rod?

I had checked out the EO website regarding this requirement, and as per the latest 18th edition regulations (Section 722.411.4.1) it does appear to state that PME earthing systems should not be used for any outdoor charging, and that the primary mechanism should be an Earthing rod for the EO charging unit.

It looks like this regulation is primarily there as a protection against the risk of fatal shock hazards caused from faults within the supply network of earthing systems (i.e T-N-CS (PME))

So having come across the above information, I am naturally concerned particularly on the safety aspects if one was to charge outside?

As I’ve mentioned, the primary use will be charging indoors, but with the possibility of future and occasion-use for outdoor charging in mind – Hence the selected location of the charging unit is located next to the garage door; allowing cabling to reach the front of the driveway.

Prior and during the install, I was not made aware that there would be any issues based on my anticipated use-cases; and likewise there were no earthing requirements highlighted for consideration.

However, these latest regulations seem to suggest otherwise, and therefore I would want to obtain clarification that I am safe to use the charger as intended (i.e. both indoors and outdoors)

Or is it the case that the earthing setup will need to be changed to cater for outdoor use i.e. Earthing rod?

If an Earthing rod must be used, would I still be able to charge safely whilst parked inside the garage as per my primary intended use i.e. assessment of any extraneous conductive parts that are simultaneously touchable with the vehicle or charge point etc."

 

[HappyHippyDad]

Hi,

I got back in touch with the installer.....and sent the following email:

"There is something I was looking to clarify with you in relation to my recent charger installation.

As you know the charging unit is located internally in my garage, as my primary intensions will be to charge whilst the car is parked inside the garage overnight.

However, as the selected location of the charging unit is next to the garage door, I had also anticipated that the unit could be used for outside charging as the cabling could easily run under the garage door.

A friend of ours has a similar EO installation where their charger is also located internally next to the garage door like ours, therefore enabling him to charge either indoors or outdoors.

However, he had pointed out to me that in order to charge outside there are some safety regulations required on the earthing requirements of the install; such that their installer had advised that an Earthing rod would be required.

It appears within my installation, the charging unit is setup to use our domestic earthing system (i.e. T-N-CS (PME)) and not via an Earthing rod?

I had checked out the EO website regarding this requirement, and as per the latest 18th edition regulations (Section 722.411.4.1) it does appear to state that PME earthing systems should not be used for any outdoor charging, and that the primary mechanism should be an Earthing rod for the EO charging unit.

It looks like this regulation is primarily there as a protection against the risk of fatal shock hazards caused from faults within the supply network of earthing systems (i.e T-N-CS (PME))

So having come across the above information, I am naturally concerned particularly on the safety aspects if one was to charge outside?

As I’ve mentioned, the primary use will be charging indoors, but with the possibility of future and occasion-use for outdoor charging in mind – Hence the selected location of the charging unit is located next to the garage door; allowing cabling to reach the front of the driveway.

Prior and during the install, I was not made aware that there would be any issues based on my anticipated use-cases; and likewise there were no earthing requirements highlighted for consideration.

However, these latest regulations seem to suggest otherwise, and therefore I would want to obtain clarification that I am safe to use the charger as intended (i.e. both indoors and outdoors)

Or is it the case that the earthing setup will need to be changed to cater for outdoor use i.e. Earthing rod?

If an Earthing rod must be used, would I still be able to charge safely whilst parked inside the garage as per my primary intended use i.e. assessment of any extraneous conductive parts that are simultaneously touchable with the vehicle or charge point etc."

Ha ha, your electrician will be thinking "sxxx, he knows his stuff!"
I think that's well worded hyeung, however from the little I've seen of your posts you're not one to just accept a half answered question. I wonder what you will do if he just says says 'yes, it's fine for outside'!
Let us the know the response and then we can start the discussion all over again.

 

[hyeung]

Hi,

I got back in touch with the installer.....and sent the following email:

"There is something I was looking to clarify with you in relation to my recent charger installation.

As you know the charging unit is located internally in my garage, as my primary intensions will be to charge whilst the car is parked inside the garage overnight.

However, as the selected location of the charging unit is next to the garage door, I had also anticipated that the unit could be used for outside charging as the cabling could easily run under the garage door.

A friend of ours has a similar EO installation where their charger is also located internally next to the garage door like ours, therefore enabling him to charge either indoors or outdoors.

However, he had pointed out to me that in order to charge outside there are some safety regulations required on the earthing requirements of the install; such that their installer had advised that an Earthing rod would be required.

It appears within my installation, the charging unit is setup to use our domestic earthing system (i.e. T-N-CS (PME)) and not via an Earthing rod?

I had checked out the EO website regarding this requirement, and as per the latest 18th edition regulations (Section 722.411.4.1) it does appear to state that PME earthing systems should not be used for any outdoor charging, and that the primary mechanism should be an Earthing rod for the EO charging unit.

It looks like this regulation is primarily there as a protection against the risk of fatal shock hazards caused from faults within the supply network of earthing systems (i.e T-N-CS (PME))

So having come across the above information, I am naturally concerned particularly on the safety aspects if one was to charge outside?

As I’ve mentioned, the primary use will be charging indoors, but with the possibility of future and occasion-use for outdoor charging in mind – Hence the selected location of the charging unit is located next to the garage door; allowing cabling to reach the front of the driveway.

Prior and during the install, I was not made aware that there would be any issues based on my anticipated use-cases; and likewise there were no earthing requirements highlighted for consideration.

However, these latest regulations seem to suggest otherwise, and therefore I would want to obtain clarification that I am safe to use the charger as intended (i.e. both indoors and outdoors)

Or is it the case that the earthing setup will need to be changed to cater for outdoor use i.e. Earthing rod?

If an Earthing rod must be used, would I still be able to charge safely whilst parked inside the garage as per my primary intended use i.e. assessment of any extraneous conductive parts that are simultaneously touchable with the vehicle or charge point etc."

In response I got the following....

"Your understanding of the earthing requirements is correct, if you wish to use your charger to charge the car outside then regulations state the use of a TT earth is required, if the charge point is to be used inside then connection to your house earth is recommended.

Looking back at the information you provided, you requested that the charge point be installed inside the garage and we have assumed that this would be for the purpose of charging inside, we will look to clarify this to all customers going forward.

If the charge point is fitted outside and connected to a TT earth then it should not be used inside the garage as this is a different earthing zone(house earth)

Hope this clarifies matters.
Regards"

It seems from his response it suggest that I cannot have it both ways?

So when the charger is inside, its recommended that I use house earth and can only charge whilst inside.

If I want to charge outside, then the charger unit should ideally sit outside and an earth rod used (TT); and in this case I cannot use this for charging inside.

There is no both?
However, a friend of ours has the exact same EO installation (but his is tethered). It has been installed in his garage, and he uses this inside but has been installed with an earth rod for outside charging?
See attached photos.
The car forums that I've been on, have also shown similar folk using their charge in their garage for outside charging.

I've gone back to clarify with the installer that I can definitely not do it both ways?
Perhaps I should contact the manufacture of the unit and get their side of the story as well? If they say the same, then i'm happy to walk away and stick to the setup that I have - which is what i'd primarily use it for. It's just that I've seen others use it both ways, which either means it possible and fine, or perhaps in reality is genuinely isn't a safe approach?

What are your thoughts??

 

[hyeung]

Ha ha, your electrician will be thinking "sxxx, he knows his stuff!"
I think that's well worded hyeung, however from the little I've seen of your posts you're not one to just accept a half answered question. I wonder what you will do if he just says says 'yes, it's fine for outside'!
Let us the know the response and then we can start the discussion all over again.

I think more thanks to my sparky buddies on this forum...sounds like I know my stuff