Feasibility of installing 7kw charger in powered garage (and granny charging fall back if not)

[Gallo]

Hello all,

I'm thinking of getting an EV, as I drive quite infrequently and it's mostly town/local runs. I've seen a pretty cheap Renault Zoe that ticks all my boxes.

My garage has power and I've recently had a new consumer unit fitted to main house. The garage power is taken overhead from my CU as my garage is adjacent to my house. The armoured cable which takes power to the garage was replaced when I had the CU updated.

I've included pictures as I am not sure how best to describe the setup. My questions are:

1. Would it be relatively easy for a professional to install a 7kw wall charger inside the garage with my current setup or would it be more involved that just using the existing feed?

2. If a wall charger was prohibitively expensive, would an inline charger be able to be used? Renault don't seem to recommend this but many people use them, I understand they are not as efficient as a dedicated wall box and pose their own safety concerns if not used properly. I imagine I would only need to charge once a month if that, but rather than 30 hours at 3Kw I'd probably top up every couple of days for an hour or so. Although I don't know what would be the most optimum given this less than ideal setup.

If going this route I was planning on upgrading a socket in the garage using the one below:

https://www.screwfix.com/p/masterplug-ip66-13a-1-gang-weatherproof-outdoor-unswitched-active-plug-socket-with-rcbo/889rg

Coupled with this in line charger:

https://www.screwfix.com/p/masterplug-10a-2300w-mode-2-type-2-plug-electric-vehicle-charging-cable-5m/934ka

Many thanks for any advice. If it's all a big no no then I'll stay away from the whole idea but thought I'd try and get some informed answers before going any further.

 

[SUNRAY]

How recent?

I'd get the electrician back in to correct his errors 16A RCBO feeding a consumer unit with RCD and 20A MCB is bad design, shoddy.
Why did he run that conduit then convert to Armoured?

What details has he put on the EIC (Electrical Installation Certificate)? A photo of the circuits section will assist our advice.

As it is, you will not be able to fit a charging point in the garage but I'll assume a granny charger is okay.

 

[ericmark]

Screwfix needs their web site fixing, it will only open in private window, so to help others and are the links, you can get

which use the commando sockets so can charge at a series of rates 6A, 8A, 10A, 16A, 20A, 24A, 32A and has Built-in Type B RCD protection: Type A + 6mA DC so the only thing it does not have is the link to a CT coil on main incomer to house so it can reduce output if the house is using too much, and connection to the provider so they can reduce charge if there is a high demand on the system.
But:-
1) You only have a 16 amp feed to garage.
2) Garage CU has a type AC RCD.

So 13 amp plug, (10 amp charging) costs approx £150 and 32 amp approx £280, but the 13 amp plug type does not have Built-in Type B RCD protection: Type A + 6mA DC so would need it adding, the 13 amp outlet instructions state,

1) Type A RCD with DC leakage current sensing up to 6mA plus DC detection device inside in cable charger that limits leakage to 6mA

so why the bother fitting a RCBO to the outlet is any ones guess, seems totally pointless.

I have hunted of a unit to monitor and disconnect if DC leakage exceeds 6 mA, only ones found are built into the lead or charge point.

So to charge an EV we want either it charging within the equipotential bonding which a garage is, or have loss of PEN detection, it needs either a type B RCD (not seen any type B RCD's built into RCBO's) or a type A and a 6 mA DC detection and disconnection device.

It is better if the RCD only feeds the EV, so best option is new SWA cable (which does not need RCD protection) to garage rated at over 32 amp, with a MCB in the house and two RCBO's type A in the garage one for EV and one for rest of garage.

But the cost is climbing, and very soon you reach the cost of a dedicated EV charging point. And with the dedicated point it will have loss of PEN detection so you could charge outside, and also total house current detection so it will lower charge rate if other things used in the house.

Also you will have a serial number etc, so you can use the super cheap electric supply to charge car, firms offering 6p per kWh overnight charging want the details of the charging point, those not asking for that are only offering around 8.95p per kWh and only for 5 hours, where the ones asking for charge point details give 7 or more hours charge. i.e. Octopus need charge point details and British Gas don't.

 

[SUNRAY]

What problems are you having with SF site?

 

[Gallo]

How recent?

I'd get the electrician back in to correct his errors 16A RCBO feeding a consumer unit with RCD and 20A MCB is bad design, shoddy.
Why did he run that conduit then convert to Armoured?

What details has he put on the EIC (Electrical Installation Certificate)? A photo of the circuits section will assist our advice.

As it is, you will not be able to fit a charging point in the garage but I'll assume a granny charger is okay.

The CU was updated in November 2023 after some fault finding on one of the ring mains. I don't think I got an EIC, just the notification of works thing with the council.

The electrician didn't suggest any other changes in the garage apart from the feed cable as it was not apparently rated for outdoor use. That was replaced but nothing else inside the garage was.

 

[Gallo]

Screwfix needs their web site fixing, it will only open in private window, so to help others View attachment 357163 and View attachment 357164are the links, you can get View attachment 357165which use the commando sockets so can charge at a series of rates 6A, 8A, 10A, 16A, 20A, 24A, 32A and has Built-in Type B RCD protection: Type A + 6mA DC so the only thing it does not have is the link to a CT coil on main incomer to house so it can reduce output if the house is using too much, and connection to the provider so they can reduce charge if there is a high demand on the system.
But:-
1) You only have a 16 amp feed to garage.
2) Garage CU has a type AC RCD.

So 13 amp plug, (10 amp charging) costs approx £150 and 32 amp approx £280, but the 13 amp plug type does not have Built-in Type B RCD protection: Type A + 6mA DC so would need it adding, the 13 amp outlet instructions state, so why the bother fitting a RCBO to the outlet is any ones guess, seems totally pointless.

I have hunted of a unit to monitor and disconnect if DC leakage exceeds 6 mA, only ones found are built into the lead or charge point.

So to charge an EV we want either it charging within the equipotential bonding which a garage is, or have loss of PEN detection, it needs either a type B RCD (not seen any type B RCD's built into RCBO's) or a type A and a 6 mA DC detection and disconnection device.

It is better if the RCD only feeds the EV, so best option is new SWA cable (which does not need RCD protection) to garage rated at over 32 amp, with a MCB in the house and two RCBO's type A in the garage one for EV and one for rest of garage.

But the cost is climbing, and very soon you reach the cost of a dedicated EV charging point. And with the dedicated point it will have loss of PEN detection so you could charge outside, and also total house current detection so it will lower charge rate if other things used in the house.

Also you will have a serial number etc, so you can use the super cheap electric supply to charge car, firms offering 6p per kWh overnight charging want the details of the charging point, those not asking for that are only offering around 8.95p per kWh and only for 5 hours, where the ones asking for charge point details give 7 or more hours charge. i.e. Octopus need charge point details and British Gas don't.

Thank you. I don't really understand much of the terminology but if I were to summarise would this be accurate?
1. In line charging would require some wiring changes to make it safe and unlikely to get super cheap tariff for EV charging. This will be expensive and approach the cost of a dedicated charger install.
2. A dedicated charger is likely to require a completely new feed to the garage, replacement of current garage wiring and will be more expensive than a standard install.

Either is not great and the potential benefits of having an EV are rapidly disappearing. Glad I asked here first. I am definitely not in for throwing thousands of pounds on top of the car into the garage infrastructure. I have no problem slow charging, if that were easy and cost a few hundred to be safe I would go for it, but if it means the whole supply to the garage needs redesigning and renewing then I'm out.

 

[ericmark]

Wait for other replies, I started a thread EV are they worth it? now 163 pages of replies, it is a massive question, and clearly no easy answer.

At 73 retired I do not really need an electric car, careful not to say EV, as I do have two e-bikes and a mobility scooter. electric costs me 8.95p per kWh midnight to 5 am (problem is don't know if BST or UTC so only use it for 4 hours) and 31.31p per kWh peak, my solar panels waist electric as not paid for export (yet) but with a 3.2 kWh battery I use the off peak and solar until between 4 pm and all night depending on time of year, I export around an average of 7 kWh per day, want to fit a second battery to reduce that, as also import around 9.5 kWh per day of which around 4 kWh at off peak rate. Note averages based on whole year.

If I could use an EV car as a battery store as well as a car, then would save a £1000 on second battery. Some cars it seems can be used that way. I at the moment heat my DHW in summer using an iboost+ so uses spare solar only, if and I have not seen a system to do this, I could put excess solar into charging the car, possibly the car running costs could with storage as well go into negative figures.

But the major problem is governments get involved. We are told fit heat pumps as we have globule warming, if that is true then the idea of a heat pump which and heat and cool makes a lot of sense, as summers will be getting warmer, but government will not give grants to convert to a bi-directional heat pump, and mono-directional cost more to run than gas or oil, so the whole idea does not work. Due to government interference.

Around Wrexham we have a 50 MPH speed limit to get better air quality, but the EV is not exempt from the speed limit. Main reason for EV for me, was the VIP parking space really close to the shops, but I have a disabled badge now so don't need it.

 

[ericmark]

What problems are you having with SF site?

Have to use private window to view or I get

and to use

each time is a pain, so simply don't use Screwfix shop web site any more, just too much hassle. Been like that for weeks.

 

[EFLImpudence]

Around Wrexham we have a 50 MPH speed limit to get better air quality, but the EV is not exempt from the speed limit. Main reason for EV for me, was the VIP parking space really close to the shops, but I have a disabled badge now so don't need it.

 

[SUNRAY]

The CU was updated in November 2023 after some fault finding on one of the ring mains. I don't think I got an EIC, just the notification of works thing with the council.

The electrician didn't suggest any other changes in the garage apart from the feed cable as it was not apparently rated for outdoor use. That was replaced but nothing else inside the garage was.

For a CU change the documentation should have included something akin to this:

 

[Gallo]

For a CU change the documentation should have included something akin to this:View attachment 357211

I didn't get one of those - but the work was notified as I can see it on the register. I've just emailed the installer to see if I can get a copy.

 

[Gallo]

Why did he run that conduit then convert to Armoured?

Sorry that's my fault - that picture is the garage not the house. The conduit was already there. The armoured runs from the house to the garage then enters the conduit. It was only the external cable that was replaced.

 

[ericmark]

Theroy the installer sends the installation certificate to scheme provider or LABC and they send compliance or completion certificate to you.

Practice often an email with link, and you have to down load and print. Both installation certificate and compliance certificate.

You need to get them, as went selling mothers house, could not at start find them, asked LABC for replacements, and told will take 4 months, and will cost however long it takes the council worker to find them.

Lucky then found them, seems can take out an insurance, but that also costs.

 

[EFLImpudence]

error.

 

[Gallo]

Theroy the installer sends the installation certificate to scheme provider or LABC and they send compliance or completion certificate to you.

Practice often an email with link, and you have to down load and print. Both installation certificate and compliance certificate.

You need to get them, as went selling mothers house, could not at start find them, asked LABC for replacements, and told will take 4 months, and will cost however long it takes the council worker to find them.

Lucky then found them, seems can take out an insurance, but that also costs.

Thanks for the advice. The works were definitely notified. They are on the NICEIC register and my local authority register. I knew that had to happen so I remember checking it had. It's just the EIC I don't think I was ever sent and didn't know I needed that as well. Unless I've put it somewhere safe and now can't remember, but I'm generally pretty good with important stuff like this.