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Discussion Starter · #1 ·
Hey

Hope you can help

First off I'm not an electrician however I'm trying to make sense of our setup

I want a charger installed in our Garage consumer unit, we have been assured all cabling to the unit etc is sufficient for a EV charger.
The CU is inside the garage and the charger will eventually be installed on the same wall, but the other side, fully sheltered in a car port.


My confusion comes with RCD Protection, our garage consumer unit is connected to our main consumer unit and is protected by a Type AC RCD
It's my understanding that EV chargers need Type A (or B depending on the unit) protection, and that you cannot have a Type AC RCD upstream of a Type A/B

Is this correct?

Our house is a new build, and we were assured when we purchased that the garage CU could simply have an EV charger connected and away we go, now it seems this is not the case, so looking to complain to those guys if need be, and hopefully get them to cover the cost of any additional works needed to be able to install the charger.



The garage consumer unit also has sockets connected to a 16a MCB and lights to a 6a MCB. The garage CU has no rcd, presumably because its protected by the main CU
There is two free slots on the garage CU

The main CU in the house only has one spare slot
 

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If there is a spare slot as you say, the RCDs in the CU can usually be shuffled along to create a non-RCD slot for your chargepoint connection.
The chargepoint installer you use will be able to advise you on this.
 

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Discussion Starter · #3 ·
If there is a spare slot as you say, the RCDs in the CU can usually be shuffled along to create a non-RCD slot for your chargepoint connection.
The chargepoint installer you use will be able to advise you on this.
For sure but where the garage is located it would have to be connected to the garage CU and not the main one
 

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ID3 Life
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First things first, you need to confirm the size of the cable feeding that sub board. I’d be amazed if the builder would use a more substantial cable than needed for a couple of garage sockets and lights.

Did they specifically say you‘d be able to run a 7kW point from it? or did they think you meant a 3pin charger.
 

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Discussion Starter · #5 ·
First things first, you need to confirm the size of the cable feeding that sub board. I’d be amazed if the builder would use a more substantial cable than needed for a couple of garage sockets and lights.

Did they specifically say you‘d be able to run a 7kW point from it? or did they think you meant a 3pin charger.
The cabling we are pretty sure is fine. I’ll attach a photo in case it’s obvious either way

143275
 

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ID3 Life
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yeah you need to know the size of the conductors, it’ll probably be embossed on the outer sheathing somewhere. Distance from the main board comes into play also, but it should be 6mm2 if you’re planning on a 7kW point alongside the existing garage stuff.

RCD, yes you should avoid doubling up and as far as I’m aware* the RCDrequired will be a dual pole jobby so will take two slots. That’s fine for the physical location on the garage board but you then have the issue of the RCD further upstream.

*I’m not a qualified spark, just going on stuff I’ve found out having a point fitted recently.
 

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Discussion Starter · #7 ·
yeah you need to know the size of the conductors, it’ll probably be embossed on the outer sheathing somewhere. Distance from the main board comes into play also, but it should be 6mm2 if you’re planning on a 7kW point alongside the existing garage stuff.
That run is all I can see. Only marking I can make out it 600/1000 v

assuming it is sufficient how about the rest of my questions? Any ideas?
 

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VW ID.3 1st Edition Manganese Grey - called Heidi Flowerpot
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One way forward might be to choose an EV chargepoint with built-in protection. I have a Myenergi Zappi, which is one of the more expensive chargepoints on the market but it integrates well with solar panel systems. It also has its own RCD proctection, and also PEN fault protection, and thus doesn't need a ground spike earth rod installed. This is important - your car is made of metal and it is important that when you approach the car there is no potential difference between the car body and the ground you're standing on.

I believe there are other brands of EV chargepoint that similarly have their own protection device built-in, if you chose one of these you wouldn't need to worry about the RCD type currently installed in your house.

A type A/C RCD, I believe, can be 'fooled' if there is a DC offset on the circuit it is protecting, and it can fail to trigger under those circumstances. This DC offset can occur when there is a DC/AC conversion, such as in computer power supplies - and vehicle chargers.

I'm not a qualified electrician, I do think you should rely on a specialist qualified installer. They will know what you need.
 

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Hey

Hope you can help

First off I'm not an electrician however I'm trying to make sense of our setup

I want a charger installed in our Garage consumer unit, we have been assured all cabling to the unit etc is sufficient for a EV charger.
The CU is inside the garage and the charger will eventually be installed on the same wall, but the other side, fully sheltered in a car port.


My confusion comes with RCD Protection, our garage consumer unit is connected to our main consumer unit and is protected by a Type AC RCD
It's my understanding that EV chargers need Type A (or B depending on the unit) protection, and that you cannot have a Type AC RCD upstream of a Type A/B

Is this correct?

Our house is a new build, and we were assured when we purchased that the garage CU could simply have an EV charger connected and away we go, now it seems this is not the case, so looking to complain to those guys if need be, and hopefully get them to cover the cost of any additional works needed to be able to install the charger.



The garage consumer unit also has sockets connected to a 16a MCB and lights to a 6a MCB. The garage CU has no rcd, presumably because its protected by the main CU
There is two free slots on the garage CU

The main CU in the house only has one spare slot
What year was the house erected?
The regulations changed a lot on 2019.
 

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Hyundai Ioniq 2021 38.3kWh
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Discussion Starter · #10 ·

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Discussion Starter · #11 ·
One way forward might be to choose an EV chargepoint with built-in protection. I have a Myenergi Zappi, which is one of the more expensive chargepoints on the market but it integrates well with solar panel systems. It also has its own RCD proctection, and also PEN fault protection, and thus doesn't need a ground spike earth rod installed. This is important - your car is made of metal and it is important that when you approach the car there is no potential difference between the car body and the ground you're standing on.

I believe there are other brands of EV chargepoint that similarly have their own protection device built-in, if you chose one of these you wouldn't need to worry about the RCD type currently installed in your house.

A type A/C RCD, I believe, can be 'fooled' if there is a DC offset on the circuit it is protecting, and it can fail to trigger under those circumstances. This DC offset can occur when there is a DC/AC conversion, such as in computer power supplies - and vehicle chargers.

I'm not a qualified electrician, I do think you should rely on a specialist qualified installer. They will know what you need.
Yup looking at Rolec with their dedicated earthing box I think, but that you mean type a rcd on the role and type ac upstream, think I might need to switch the garage CU to non RCD, and then replace the MCBs for the lights/sockets in the garage to RCBOs...
 

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Can you upload a picture of the main consumer unit in the house? (With the lid up so you can see the breakers).

The RCD in the main consumer unit may be able to be swapped for a Type A one depending on the manufacturer.

Do you have an Electrical Installation Certificate for the property? That will (should) detail the cable size supplying the garage. It will also detail the installation method, buried in the ground for example.

With these details we can determine the available capacity in the garage and advise on what best to do.
 

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Yup looking at Rolec with their dedicated earthing box I think, but that you mean type a rcd on the role and type ac upstream, think I might need to switch the garage CU to non RCD, and then replace the MCBs for the lights/sockets in the garage to RCBOs...
Note, the cable feeding the garage may well.need to .be protected by an RCD. It depends on the routing of the cable and depth from surfaces such as walls, ceilings, floors ( think nails and screws). You cant just go willy nilly removing protection without getting this reassessed.
 

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Yup looking at Rolec with their dedicated earthing box I think, but that you mean type a rcd on the role and type ac upstream, think I might need to switch the garage CU to non RCD, and then replace the MCBs for the lights/sockets in the garage to RCBOs...
Yes that's what I thought prior to having my system installed. However I checked with both the intallers and Myenergi manufacturers and both reassured me that the presence of the RCD device upstream of the chargepoint would not matter. So that's what I have. My CU is all RCBO. In the end my chargepoint is fed from a power take-off inside my Tesla Powerwall Gateway unit, so my system might not be directly comparable to yours, but the advice I got from installer and manufacturer is nevertheless probably relevant.
 

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Discussion Starter · #16 ·
Can you upload a picture of the main consumer unit in the house? (With the lid up so you can see the breakers).

The RCD in the main consumer unit may be able to be swapped for a Type A one depending on the manufacturer.

Do you have an Electrical Installation Certificate for the property? That will (should) detail the cable size supplying the garage. It will also detail the installation method, buried in the ground for example.

With these details we can determine the available capacity in the garage and advise on what best to do.
I have all that!
143291

The eic lists next to garage supply type a wiring, reference method c, number of pints served 1, live (mm2) 10 and cpc (mm2) 4
 

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Discussion Starter · #17 ·
Note, the cable feeding the garage may well.need to .be protected by an RCD. It depends on the routing of the cable and depth from surfaces such as walls, ceilings, floors ( think nails and screws). You cant just go willy nilly removing protection without getting this reassessed.
Oh I know I’m not doing any of this myself

I just want to be able to assess what the electrician does when they come to do it
 

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Discussion Starter · #18 ·
I have all that!
View attachment 143291
The eic lists next to garage supply type a wiring, reference method c, number of pints served 1, live (mm2) 10 and cpc (mm2) 4
Doesn’t list anything about installation method tho?
Any particular line or section to check?
 

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Doesn’t list anything about installation method tho?
Any particular line or section to check?
Reference method c implies surface run or buried in plaster etc, this governs thermal/ amperage rating of the cable which appears more than adequate to support 7kW charging plus garage.

Key is to trace cable routing.
 

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Discussion Starter · #20 ·
Reference method c implies surface run or buried in plaster etc, this governs thermal/ amperage rating of the cable which appears more than adequate to support 7kW charging plus garage.

Key is to trace cable routing.
The cable comes through the garage wall, outside the garage wall it goes directly into the ground. The only run I can see is the part in the photo above. Rest is underground from the property as far as I know

good to know the cable is at least sufficient.!
 
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