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EO Mini Pro 2

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HI,

I've been looking at getting an EO Mini Pro 2 installed but unfortunately I'm not having the easiest time to decipher some of the installation requirements.

AFAIK, the installer is telling me that there will need to be an external RCD protection "box" between my consumer unit and the charger. I've watched a few YouTube videos and read the content from EO's website and only found this:

"A dedicated 30mA Type A RCD must be used on the supply circuit Integral 6mA DC leakage detection - no Type B RCD required"

Mentioned on a data sheet: https://static1.squarespace.com/sta...4/EO+Mini+Pro+2+Data+Sheet+[UK+&+Ireland].pdf

Has anyone had a charger from EO and could comment?
 
The usual method for connecting a charge point, as much because of the relatively high continuous demand as anything else, would be to tap into the tails that supply the consumer unit with Henley blocks, and install a small CU that contains double pole protection against overload and residual current. Several ways to do this, but small metal enclosures that have a 4 module DIN rail are probably most common. These allow the cable that supplies the charge point to be mechanically terminated with a gland, be it SWA (needs a metal cable gland) or NYY-J (can used a nylon cable gland). 4 modules is wide enough for two double pole devices, a DP isolation switch plus a 40 A RCBO usually (if the charge point has integral DC leakage current detection). Using spare positions in an existing CU isn't easy, due to the space needed for the protection device(s) needed (few CUs will easily accept double pole protection devices without a bit of faffing around),

The EO Mini has integral DC leakage current protection, hence the statement that a Type A RCD is all that's required. In practice, rather than use a Type A RCD plus a 40 A MCB, it's cheaper and easier to use an RCBO, that combines both functions into a single two module wide package. The cable from this small CU to the charge point will be 6mm² SWA or, perhaps, NYY-J, depending on the mechanical protection requirements needed for the location.

What's not clear from that data sheet is whether the EO Mini includes some form of open PEN protection system or not. It it does not, then it will require either an earth electrode located near the charge point location, or the fitment of an alternative device, like the O-PEN from matt-e. The latter is around £100, but includes an RCBO, IIRC, so can replace the small additional enclosure with the RCBO. Perhaps check with EO as to whether or not the protection in the newer units complies in full with Section 722 in BS7671:2018, Amndt 1.
 
The usual method for connecting a charge point, as much because of the relatively high continuous demand as anything else, would be to tap into the tails that supply the consumer unit with Henley blocks, and install a small CU that contains double pole protection against overload and residual current. Several ways to do this, but small metal enclosures that have a 4 module DIN rail are probably most common. These allow the cable that supplies the charge point to be mechanically terminated with a gland, be it SWA (needs a metal cable gland) or NYY-J (can used a nylon cable gland). 4 modules is wide enough for two double pole devices, a DP isolation switch plus a 40 A RCBO usually (if the charge point has integral DC leakage current detection). Using spare positions in an existing CU isn't easy, due to the space needed for the protection device(s) needed (few CUs will easily accept double pole protection devices without a bit of faffing around),

The EO Mini has integral DC leakage current protection, hence the statement that a Type A RCD is all that's required. In practice, rather than use a Type A RCD plus a 40 A MCB, it's cheaper and easier to use an RCBO, that combines both functions into a single two module wide package. The cable from this small CU to the charge point will be 6mm² SWA or, perhaps, NYY-J, depending on the mechanical protection requirements needed for the location.

What's not clear from that data sheet is whether the EO Mini includes some form of open PEN protection system or not. It it does not, then it will require either an earth electrode located near the charge point location, or the fitment of an alternative device, like the O-PEN from matt-e. The latter is around £100, but includes an RCBO, IIRC, so can replace the small additional enclosure with the RCBO. Perhaps check with EO as to whether or not the protection in the newer units complies in full with Section 722 in BS7671:2018, Amndt 1.

From my research the EO doesn't need an earth rod. My main consumer unit is in need of replacement - it is currently full and has no RCD protection. EO's default installer didn't want anything to do with replacing the main unit, but, I'd like to have the new consumer unit be capable of supporting the house and the charger if possible. It seems having enough space for a 40A RCBO should be enough?

I'll also try to speak to some other installers, I'd much prefer to kill two birds with one stone.
 
Thanks Jeeves, that is helpful. Was your main consumer unit "full" ?

Because my charge point included some of the protection requirements (Zappi) it was possible to use a couple of available spaces for the RCBO in the existing garage located consumer unit. It's not quite a standard slotting in because the box has to be altered inside to bypass the main CU RCD so that the charge point has its own distinct supply (despite being physically in the same CU).

"Glan" has helpfully given you chapter and verse on the requirements and issues so, in theory, you now have all the info!
 
From my research the EO doesn't need an earth rod. My main consumer unit is in need of replacement - it is currently full and has no RCD protection. EO's default installer didn't want anything to do with replacing the main unit, but, I'd like to have the new consumer unit be capable of supporting the house and the charger if possible. It seems having enough space for a 40A RCBO should be enough?

I'll also try to speak to some other installers, I'd much prefer to kill two birds with one stone.

I've just read the MIs for it. They clearly state that "The installer must select the RCD and earthing configuration in accordance with local regulations and best practice". In the UK, that means that if the supply to the house is TN (any flavour, inc PME) then it must adhere to BS7671:2018, Amndt 1, Section 722, which in turns means either connecting the installation as TT, with a local earth electrode close to where the vehicle will be when charging, or fitting some alternative form of open PEN protection. Note that this is not related to the RCD protection requirement, it's needed in case the incoming PEN conductor develops a fault such that the local PE conductor may float up to the same potential as the line conductor (up to 253 VAC theoretically). In turn this would make the car body live, hence the reason for the requirement for open PEN protection.

Personally I really try and avoid packing RCDs/RCBOs in a CU, as they do run warm, and with several close together in a CU, especially with high current circuits, things can get a bit toasty. I installed an all-RCBO CU in our house, and I'm very glad that we have no high current, long duration, loads, as the RCBOs do tend to get warm. If separated out so that high current, long duration, circuits, like car charging, are in a standalone box then there's more room for air circulation and less chance of heat build up. I am known to be fussy, though, and prefer things not to look warm when I point a thermal camera at them when doing safety checks!
 
I've just read the MIs for it. They clearly state that "The installer must select the RCD and earthing configuration in accordance with local regulations and best practice". In the UK, that means that if the supply to the house is TN (any flavour, inc PME) then it must adhere to BS7671:2018, Amndt 1, Section 722, which in turns means either connecting the installation as TT, with a local earth electrode close to where the vehicle will be when charging, or fitting some alternative form of open PEN protection. Note that this is not related to the RCD protection requirement, it's needed in case the incoming PEN conductor develops a fault such that the local PE conductor may float up to the same potential as the line conductor (up to 253 VAC theoretically). In turn this would make the car body live, hence the reason for the requirement for open PEN protection.

Personally I really try and avoid packing RCDs/RCBOs in a CU, as they do run warm, and with several close together in a CU, especially with high current circuits, things can get a bit toasty. I installed an all-RCBO CU in our house, and I'm very glad that we have no high current, long duration, loads, as the RCBOs do tend to get warm. If separated out so that high current, long duration, circuits, like car charging, are in a standalone box then there's more room for air circulation and less chance of heat build up. I am known to be fussy, though, and prefer things not to look warm when I point a thermal camera at them when doing safety checks!

You are to the electrical world what Mr Miserable is to the shipping forum (they are both compliments by the way - an unusual lapse in sarcasm for once!)
 
I've just read the MIs for it. They clearly state that "The installer must select the RCD and earthing configuration in accordance with local regulations and best practice". In the UK, that means that if the supply to the house is TN (any flavour, inc PME) then it must adhere to BS7671:2018, Amndt 1, Section 722, which in turns means either connecting the installation as TT, with a local earth electrode close to where the vehicle will be when charging, or fitting some alternative form of open PEN protection. Note that this is not related to the RCD protection requirement, it's needed in case the incoming PEN conductor develops a fault such that the local PE conductor may float up to the same potential as the line conductor (up to 253 VAC theoretically). In turn this would make the car body live, hence the reason for the requirement for open PEN protection.

Personally I really try and avoid packing RCDs/RCBOs in a CU, as they do run warm, and with several close together in a CU, especially with high current circuits, things can get a bit toasty. I installed an all-RCBO CU in our house, and I'm very glad that we have no high current, long duration, loads, as the RCBOs do tend to get warm. If separated out so that high current, long duration, circuits, like car charging, are in a standalone box then there's more room for air circulation and less chance of heat build up. I am known to be fussy, though, and prefer things not to look warm when I point a thermal camera at them when doing safety checks!

Thank you, I am still googling and reading to understand most of the reply but I can see that having a second CN for the EV charger seems to be a normal thing.

FYI, the EO Mini Pro 2 installation includes a "Garo earthing device" which they say mitigates the need for earth rods. The EO Mini Pro 2 was only officially released on their website last week.
 
Thank you, I am still googling and reading to understand most of the reply but I can see that having a second CN for the EV charger seems to be a normal thing.

FYI, the EO Mini Pro 2 installation includes a "Garo earthing device" which they say mitigates the need for earth rods. The EO Mini Pro 2 was only officially released on their website last week.

Every installation tends to be a bit different, depending on the easiest and safest way to make the connection from the incoming supply to the charge point location (and, BTW, the bit on the wall isn't a charger, the charger and it's associated control circuitry is all built in to the car). Connecting to the tails (the heavy cables that run from the meter to the consumer unit) is often the safest and most convenient way to connect a charge point, because the charge point will draw a high current for several hours, so will probably be far and away the highest load within the whole installation, because the charge point has specific protection requirements that exceed those for the rest of a domestic installation and because it's easier to terminate the hefty cable that a charge point needs in a separate metal enclosure.

The protection requirements fall into three categories. First, there is the normal overcurrent protection required to protect the cable that supplies the charge point. This can be by a fuse or circuit breaker. Secondly, there is a requirement to protect the installation from the risk of electric shock in the event of insulation damage or similar, something that's provided by residual current protection, and finally there is the slightly unusual requirement, that applies to any electrical installation that includes extraneous conductive parts located where someone may touch them whilst in contact with the local earth. This latter requirement applies to supplies feeding caravans, metal framed greenhouses, metal sheds, as well as electric vehicle charge points.

The over current and earth leakage protection is fairly straightforward, although the latter needs to be DC tolerant, because there is a DC component in the signalling protocol between the charge point and the charger, hence the statement from EO that they include this. The protection from electric shock from the extraneous conductive parts, i.e. the metal car body, that's insulated from local earth by the tyres, comes about because most houses have the protective earth (PE) provided by the incoming cable from the local grid, often with the neutral being the protective earth, what's called a Protective Earth and Neutral, or PEN, conductor. The protective earth conductors that are connected to the earth pins on all the outlets are, in reality, connected to the neutral terminal at the incoming supply. This means that there is often no local earth, as such. If the neutral conductor in the cable supplying the installation was to go open circuit, say from storm damage, or someone working carelessly in the road, then what can happen is that the line conductor will supply current through the appliances in the house that are connected and so raise the voltage of the neutral, and protective earth, conductors in the house to line potential, typically around 240 VAC.

Inside the house this doesn't matter, as the metalwork or the taps etc will be bonded to the same potential (which is why those bonding wires to pipes etc are called equipotential bonding), and the floor of the house will probably be a reasonable insulator, so there's little risk of shock. Outside, it's very different, as any "earthed" metalwork, like the car body, may now be sitting at a lethal voltage. It would be easy for someone to have their feet on the ground and also touch the car metalwork, with possibly lethal consequences. This is why there is a need to either connect the charge point, and hence car bodywork, to local earth potential, with an earth electrode, and suitable RCD to kill the power if there is any earth leakage, or have some device that can sense an open PEN fault and disconnect not just the live conductors, line and neutral, but also the PE conductor, so that there is no chance that the car bodywork could be at a lethal touch voltage.

There are one or two devices that can provide this open PEN protection, the matt-e O-PEN is perhaps the best known. I'm not familiar with a Garo product that does this, but Garo make some decent protective devices so this may be a new product I've not yet seen. Also, some newer charge points have built in open PEN protection, I believe. The cheapest solution is an earth electrode, though, if one can be positioned close to where the car will be when charging. An earth electrode, cable clamp, and ground termination box is about £20, so a lot cheaper than an O-PEN box.

If the above isn't clear, feel free to come back with questions.