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Discussion Starter · #1 ·
Hi so recently bought an EV and need to get 7k charger installed on garage wall, At present I have 10mm SWA connected to the main consumer unit in the house to with a 40amp mcb, that runs to a smaller garage consumer that has 63amp rcd, 32amp mcb unused , 16amp with plug sockets and 6amp with lights so it's possible to use the 32 with twin and earth through the wall and into the back of the charger? So there would be no outside cable running ?
 

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Possibly, but as a minimum you will need a charge point that has integrated open PEN fault protection, plus DC tolerant earth leakage protection, and you will need to ensure that the RCD feeding the charge point circuit is a Type A, and not a Type AC, and that there are not two RCDs in series without some form of selectivity.

The installer will do a survey as a part of the job, so will assess whether there is enough spare capacity on that supply, or whether another supply needs to be run to the charge point. In general it's better to run a separate supply from the meter tails, rather than take the supply from the main house CU, because charge points run for hours on end, and thus tend to heat up the MCB feeding them. There is also a possible selectivity issue with RCDs, as the feed from the CU (if using that approach) must come from a non-RCD protected way if there is another RCD downstream from it, or some other means must be used to provide RCD selectivity. Your installer should sort all this for you, just explain that you would prefer to have no outside cabling visible, if at all possible.
 

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Hi so recently bought an EV and need to get 7k charger installed on garage wall, At present I have 10mm SWA connected to the main consumer unit in the house to with a 40amp mcb, that runs to a smaller garage consumer that has 63amp rcd, 32amp mcb unused , 16amp with plug sockets and 6amp with lights so it's possible to use the 32 with twin and earth through the wall and into the back of the charger? So there would be no outside cable running ?
Sounds a good plan to me you may want to replace the RCD in the garage to a type A and check your earthing arrangements .


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Hi so recently bought an EV and need to get 7k charger installed on garage wall, At present I have 10mm SWA connected to the main consumer unit in the house to with a 40amp mcb, that runs to a smaller garage consumer that has 63amp rcd, 32amp mcb unused , 16amp with plug sockets and 6amp with lights so it's possible to use the 32 with twin and earth through the wall and into the back of the charger? So there would be no outside cable running ?
There are some very good words of advice in the JH post. If you ignore them you will have at best a very inconvenient installation: at worst an unsafe one.
 

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There is no option to run any cabling from the house or the meter
Installers are used to dealing with the most awkward arrangements, particularly the common arrangement of putting the meter and CU under the stairs in older houses. Daft place to put it, really, and probably the most awkward when it comes to adding additional circuits.

The key points are:

  • The supply cable to the charge point must be fed from a supply that can take an additional load of 32 A
  • The supply cable must be over current protected, and if not armoured cable must also be RCD protected.
  • The charge point must have DC tolerant earth leakage protection (either built in, or via a supply protected with a Type B, EV or F RCD)
  • If the installation is TN, and not TT, then the charge point must have open PEN fault protection (either built in, or via a PEN fault protection device in the supply)
  • The charge point must be protected by a manually resettable RCD or RCBO, with a Type A characteristic, unless protected by a separate Type B, EV or F RCD.
  • Any RCD protection must be arranged to ensure selectivity if there is more than one RCD in series. For example, if the garage 10mm² supply is fed from the main CU, then it must be supplied by a non-RCD protected MCB, if there is another RCD in the circuit. The alternative is to fit some other form of selectivity, by swapping out RCD types, but it's far easier to just avoid series RCDs if at all possible.
I would just discuss this all with your chosen installer. There are ways and means to supply charge points neatly in pretty much every situation, and any installer that's done a few will have a small arsenal of tricks and tips as to how best to make sure an installation is safe and neat.
 

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Discussion Starter · #7 · (Edited)
OK but when you say awkward I mean there is no possible means to connect another cable from the house to the garage at the end of the drive, no one wants to actually come out they just ask for pictures that is all well but like I've said you cannot run another cable and I don't want to be in a situation when he turns up and says he can't do it, it's also 20 meters away from the house
 

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OK but when you say awkward I mean there is no possible means to connect another cable from the house to the garage at the end of the drive, no one wants to actually come out they just ask for pictures that is all well but like I've said you cannot run another cable and I don't want to be in a situation when he turns up and says he can't do it, it's also 20 meters away from the house
I doubt you’ll get any installer wanting to visit to survey and quote unless you are happy to pay for a survey fee - they pretty much always ask for photos and details.

The issue with your existing arrangement is that it is all existing, and the installer will become responsible for sorting out any issues when reusing the connection from your consumer unit, the 10mm cable, and garage CU too. This is why most also insist on using a direct connection from the meter with a separate small stand-alone CU for the EVSE installation. That’s not to say there is anything wrong with your intended approach provided all aspects of the regs and any rectification/improvement works needed are taken care of.

In your case I would take lots of photos, and include plenty of detail about the existing arrangements, and send these to the installers you are wanting to quote and see what they say. I’d suggest you may be better choosing electrical contractors over the lines of manufacturers, as you are more likely to be able to discuss the installation details with someone who can look at the requirements objectively, rather than simply having a fixed installation method from which they will not deviate.
 

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OK but when you say awkward I mean there is no possible means to connect another cable from the house to the garage at the end of the drive, no one wants to actually come out they just ask for pictures that is all well but like I've said you cannot run another cable and I don't want to be in a situation when he turns up and says he can't do it, it's also 20 meters away from the house
No such thing as an impossible job. Difficult and awkward, perhaps, but there's always a way. I helped a friend run a duct under a drive a few years ago, took us about half a day, caused zero damage to the drive, and when we left there was virtually no sign any work had been done. That was power and control cables for an electric gate, where the customer had a super expensive drive that he didn't want damaged.

Try using a local electrican. The charge point installers are often trying to cut costs to the bone, so are reluctant to come out and price a job. Any decent electrician can install a charge point, and the majority will want to come out and price the job up personally, just so they don't get any nasty surprises when they come to do the work.
 

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Discussion Starter · #10 ·
So putting aside installers who don't want to install anything other than new due to becoming responsible for the entire equipment , a resinbond drive that is edge to edge with no means to get under it without damage is it possible to connect to what I have or not ?
 

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So putting aside installers who don't want to install anything other than new due to becoming responsible for the entire equipment , a resinbond drive that is edge to edge with no means to get under it without damage is it possible to connect to what I have or not ?

The drive we went under was resin bonded, as it happens.

No one here on an internet forum can sign off your installation as being compliant and safe, especially not when those of us trying to help are guessing as to what you may really have from your description. The requirements that need to be met are as I detailed earlier in this thread, and rather than deal with charge point installers my advice would be to try and find a good local electrician, and worth with them to come up with a solution. Any competent electrician can install a charge point, although if you are claiming the grant then they do have to register and do some paperwork. For a difficult installation you may well be better off using a trusted local electrician.

The charge point manufacturers that offer an installation service often sub-contract work out, but they are always taking a cut, so are acting as middle men, and often they try and cut costs by relying on the customer taking photos, rather than doing a proper survey. The majority of electricians will want to look at a job before giving a quote, so you get a chance to discuss your concerns and what you would prefer. In your case that seems to be your best option, and it may be worth considering not bothering with the grant, if that means using a local electrician that doesn't want the hassle of registering for it. Doing that means you have a greater choice in terms of charge points, to some extent, if you don't need the smart functionality that grant-funded charge points must have.

The challenge for you will be finding a good local electrician. Best bet is to ask around, as a personal recommendation is always better than just cold-calling someone.
 

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Discussion Starter · #12 ·
So how did you get under the drive without damage ? And why are you guessing into what I might have when I have told you ? Not worried about grant I am a data engineer and have trade accounts at majority of electrical factors
 

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If you want the advice of the experienced people on these forums, some of whom have put time and effort into answering your query, then it might help to be politer and less abrasive.

If you don't, then why are you here?
 

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So how did you get under the drive without damage ? And why are you guessing into what I might have when I have told you ? Not worried about grant I am a data engineer and have trade accounts at majority of electrical factors
With respect, you haven't told us at all. For example, what type of CU do you have? Is it compliant with current regs? Is the garage supply MCB before or after any RCD in the CU? If it's after, what type of RCD is it? What type of RCD is in the garage CU? What type of cable runs from the garage to the main CU? How is that cable run and protected? What terminations are being used at the ends of that cable? Is the supply TN-S, TN-C-S or TT? Is the garage supply connected as a TT supply or is it using the exported earth from a PME supply?

There are a dozen more things needed to give you a definitive answer, those were just examples as to why a look at the job is always a damned good idea.

We got under the drive with a mole, hired for the day from the local hire place. I've also gone under a drive with a hose and a bit of pipe before now, messier, but does the job OK in some soil types.
 

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Discussion Starter · #15 ·
I just asked if what I had was possible. Not how others have installed and how its not impossible, I have explained cable cannot be run from Meter or comsumer, the drive is edge to edge with no mean to get under it without damage only to be told that someone else got under one so I asked how ?
 

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I just asked if what I had was possible. Not how others have installed and how its not impossible, I have explained cable cannot be run from Meter or comsumer, the drive is edge to edge with no mean to get under it without damage only to be told that someone else got under one so I asked how ?

As above, "how" means knowing a lot more about your present installation. I listed some of the things that anyone needs to know to give you sound advice. If you start by trying to answer some of those questions, or, perhaps, post some photos of what exists at either end at the moment, then we may have some chance of giving advice that may be useful.

I told you how I've got under drives using a mole or a pipe and hose. The former is so common that most hire stores have moling rigs that can be hired by the day, the latter is an old school method that works in some soil types. We have no way of knowing whether either method could be used for your drive, as we don't have the benefit you have of knowing what it looks like, and whether either technique might work or not.

This is all about information. If you can provide a bit more information about your existing installation then it may be possible to give more focussed advice. For example, if it turns out that your garage supply is already TT, then there's no requirement to provide open PEN fault protection, as there is no PEN to develop a fault.
 

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If the existing cable meets the requirements one option might be to split the meter tails into a separate CU that feeds the garage, replace the termination in the garage if required, ensure appropriate earthing/PEN fault protection. I'm a big fan of keeping the 32A draw off the house CU. It avoids needlessly heating that up. There's one story of a pretty catastrophic electrical fire on this forum that was the result of an installation fault. As to whether the act of disconnecting the garage feed from the existing CU requires everything to be re-certified, @Jeremy Harris can comment on this.
 

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Discussion Starter · #18 ·
The main consumer is a hager, a year old, it has a 63amp AC cd 263 u RCD, it has 2 x 20amp trips mtn120 b20, 2 feeds to the garage 1 I from what I can see is standard twin and earth run though the cavity to a box on the outside wall from there its 2.5 armoured straight to inside of the garage to a standard internal isolation socket that runs the electric garage door and that is it its connected to a mtn116 - b16 MCB, then I have a 2nd feed that is connected to a mtn140 - b40 mcb , this is 10mm 3 core ( black,brown,grey) pva swa straight from the main consumer with an internal gland to the garage consumer again with an internal gland , this is an AXIOM, it had a 63amp rcd, rcd63br, then a 32amp cub32sp (not used) a 16 amp cub16sp ( 2 x double socket 1 x interernal 1 x external ) a 6 amp cub6sp ( 1 internal light 2 x external carriage lights on a pir ) both armoured cables are run underground, there is no earth spike/rod , in the meter box there is a 100amp fuse , one red 1 black out to the digital meter reader and an earth I guess going to the main consumer then 2 grey out of the meter to again I guess the main
 

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The main consumer is a hager, a year old, it has a 63amp AC cd 263 u RCD, it has 2 x 20amp trips mtn120 b20, 2 feeds to the garage 1 I from what I can see is standard twin and earth run though the cavity to a box on the outside wall from there its 2.5 armoured straight to inside of the garage to a standard internal isolation socket that runs the electric garage door and that is it its connected to a mtn116 - b16 MCB, then I have a 2nd feed that is connected to a mtn140 - b40 mcb , this is 10mm 3 core ( black,brown,grey) pva swa straight from the main consumer with an internal gland to the garage consumer again with an internal gland , this is an AXIOM, it had a 63amp rcd, rcd63br, then a 32amp cub32sp (not used) a 16 amp cub16sp ( 2 x double socket 1 x interernal 1 x external ) a 6 amp cub6sp ( 1 internal light 2 x external carriage lights on a pir ) both armoured cables are run underground, there is no earth spike/rod , in the meter box there is a 100amp fuse , one red 1 black out to the digital meter reader and an earth I guess going to the main consumer then 2 grey out of the meter to again I guess the main
Thanks, that helps a great deal.

Is there space by the main CU to do as suggested by @idiotzoo and reconfigure the 10mm² SWA so it can connect to a small connection box fed from the tails, via a couple of henleys? That would then separate out the charge point supply from the domestic supply, and remove the series RCD problem that I think you have at the moment. I'm assuming that the 40 MCB feeding the 10mm² SWA is RCD protected in the main CU, is that right?

Are you sure that the main fuse is 100 A, or is that just the marking on the fuse holder? All the fuse holders are marked 100A, as that's the fuse holder rating, but the fuse fitted maybe either a 60 A, 80 A or 100 A. As the Hager board was fitetd very recently, the main fuse type and rating will be on the EIC for that, and you should have a copy of that. With luck, the actual fuse fitted may be marked with an additional label, too (helps a lot when this is done, but it's not universal practice). If the fuse is either 80 A or 100 A it should be fine, but if it's 60 A then you may need to talk with the DNO about getting it uprated, if possible. Your installer needs to inform the DNO of the charge point installation anyway, as that's a requirement.

It sounds as if you may be able to re-jig some of the garage internal wiring so that you can re-use that 10mm² SWA feed as a dedicated charge point supply. Best bet would be to see if all the existing garage loads can be run from the 2.5mm² SWA radial. Depends on the loads you have there, but that could run a small CU with 16 A power and 6 A lighting circuits OK. That would then mean the 10mm² SWA could become a dedicated charge point supply cable, making things a fair bit neater.

I still think you would probably get more sense out of talking with a local electrician than one of the big installation companies, as from what you've written above it does seem as if there may be a way to re-jig what you have to re-use the existing cables. A local electrician may well be more flexible and open to doing the additional work needed to either end of the cables to make this option work well.
 

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Discussion Starter · #20 ·
Yes the 40amp is rcd protected, I wouldn't be able to add another CU near the main its built into a dedicated space, what is the problem with running out of the spare 32 as it is now ? What if I was to get another CU in the garage then and conecting that to the 2.5 with a 16 and 6 to run the sockets, lights and garage doors and just have the charger on the 32 in the existing? If it helps I was looking at the Project EV , due to the features
 
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