UK domestic socket charging

[Fluffykins]

I've used my granny charger a few times when away from home. Mostly when visiting my son. I bung him a few quid for the 'leccy. I use a short high current extension lead that has a single 13A socket on it, which fits thru his letterbox, and I monitor juice used with a small kWh meter mounted in a box that's hardwired into the extension lead.

The granny and the outdoor end of the extension lead mount in a very handy box from Lidl that's sold for use in gardens. The box intended to have enough space for a 4-way mains power strip and a bunch of plugs / chargers / wallwart power supplies etc. leads enter the box via a multi way rubber sealed gland. Conveniently, when not in use the granny coils up and fits inside, complete with it's mains plug and car connector.

This is the box, but I couldn't find a Lidl page with it on.: Cable Protection Box With 5 Cable Openings
It looks very similar to this:

Electraline 300180 Waterproof Protective Box for Outdoor Electrical Connections Weatherproof IP54 with 5 Cable Outlets (from 7.5 mm to 12.4 mm), Dimensions 390 x 228 x 138 mm, Green, Empty X-Large : Amazon.co.uk: DIY & Tools

Free delivery and returns on all eligible orders. Shop Electraline 300180 Waterproof Protective Box for Outdoor Electrical Connections Weatherproof IP54 with 5 Cable Outlets (from 7.5 mm to 12.4 mm), Dimensions 390 x 228 x 138 mm, Green, Empty X-Large.

www.amazon.co.uk

 

[mikgle]

Thanks for the clarifications. It took a few re-reads for me to be happy I understood correctly, but that was due to the time of night and not your description.

As to the need for extra PEN protection when granny charging, the small extra risk of a PEN fault causing injury for us is almost 0 as we don't charge often and would rarely touch the car.

By chance I came across some stats on the myenergi Ireland website which said only about 400 PEN faults were reported each year and only about 10 caused injury. It didn't mention if any of them were via an EV.

It is a very small risk.. I can only assume the PEN fault scenario has come to the Fore with ev charging due to the amount of time the car is connected and charging.. every metal class 1 appliance would be affected in a TNCS installation.. cooker, kettle, toaster, microwave, metallic light switch etc. Yet none of these were ever required to have pen fault protection, unless the powers that be hadn't thought of it when they introduced tncs earthing? BTW tncs stands for terra (earth), neutral, connected, separated.. its the connected bit that causes the potential problem, the clues is in the name!

 

[Buster72]

Do you have a an EV certified plug socket or a dedicated circuit, or do you just plug it in a regular plug socket?

Just the regular wall socket. The very most it pulls is just under 2 amps as part of the power ring main. So not a problem.

 

[fnegroni]

Just the regular wall socket. The very most it pulls is just under 2 amps as part of the power ring main. So not a problem.

2 amps? 500W?

 

[Buster72]

From the replies, it looks like the majority of people who charge with their granny chargers don't have problems.. this is what you would expect really as if a granny charging lead (called mode 2) were problematic they would never be approved to be used as such.
The problems will mainly occur within the domestic installation, at the plug, socket, cabling etc because any weakness will be found out by the longer load time, hence more stress. This is why it would be prudent to have a professional check done (Condition Report) of the circuit being contemplated for granny lead charging, or else have a dedicated circuit installed

But the granny charger pulls just under 2 amps. Compare that with a domestic cooker or even a tumble dryer.

 

[fnegroni]

But the granny charger pulls just under 2 amps. Compare that with a domestic cooker or even a tumble dryer.

Are you sure it only pulls 2 amps? Is that your granny charger specifically?
Because mine pulls 10 amps

But the granny charger pulls just under 2 amps. Compare that with a domestic cooker or even a tumble dryer.

A tumble drier will pull, at peak, maybe 13amps, but for very brief periods of time. Most times it will pull between nothing and maybe 6 amps.
Plus the car is an object that is out there in the open. Potentially with someone going past it. I doubt your tumble dryer is in the middle of the living room

 

[decrep]

my Granny charger pumps 1.4kW into the car, so must be drawing almost 6A from the 240V mains. I plan to do a 10% to 100% charge soon, which will take around 20hrs so will be overnight.
Should I be worried?

 

[Buster72]

Are you sure it only pulls 2 amps? Is that your granny charger specifically?
Because mine pulls 10 amps

That is interesting.
While I only charge the car at night on the off peak EV tariff, when I used to charge during the day, I thought I was seeing 1.9 amps on the MG app. But I am probably wrong and that was the kW value. My apologies for the mistake.

 

[siteguru]

No - that was 1.9kW. (Which equates to nominally 8.26A). The app doesn't report current, it reports charge rate.

 

[Buster72]

A tumble drier will pull, at peak, maybe 13amps, but for very brief periods of time. Most times it will pull between nothing and maybe 6 amps.
Plus the car is an object that is out there in the open. Potentially with someone going past it. I doubt your tumble dryer is in the middle of the living room

Fair point.

No - that was 1.9kW. (Which equates to nominally 8.26A). The app doesn't report current, it reports charge rate.

Thanks for the correction.

 

[mikgle]

Are you sure it only pulls 2 amps? Is that your granny charger specifically?
Because mine pulls 10 amps

Probably means 2kW..

 

[siteguru]

You just needed to read a few more posts and you'd have found that this was already resolved.

 

[M44LCY]

I can see no absolute reason why using a granny charger is inherently dangerous. If there was, they wouldn't be approved for sale or use. BUT, because domestic wiring systems can be as variable as the patterns of snowflakes, it can't be assumed that the conditions under which they are used is safe.

I use my granny charger (which, by the way is an EVSE as are 7kw home chargers) almost universally. Thus far, I have had absolutely no problems. BUT I run mine from a "proper" EV-rated socket outlet (BS 1363-2 EV compliant) that has been designed and tested for continuous high loads. The socket is connected to my consumer unit (sometimes called a fuse box) by a dedicated circuit with an RCD (ideally, it would use an RCBO, which is an RCD protecting a single circuit breaker). Because the MG EVSE has quite a short cable, I use a high quality (H07RN-F) extension cable with a fully-weatherproof (IP66) socket enclosure. Plus, using the belt & braces principle, I have this inside a plastic box with clip-on lid, which doubles for storage between charges.

MY home system has a 100 amp fuse, which means EV charging shouldn't overload the system It has an earth conductor provided by the distribution company (more modern systems DO NOT have a separate earth, which is the system which gives rise to most of the concerns about potential electric shocks). Still, it's technically possible that the earth could be broken somewhere outside my home, and a PEN fault detection device can be fitted to the circuit. (PEN refers to "Protective Earth & Neutral", meaning the earthing is done by the neutral conductor - there is no separate earth. "PEN Faults" arise where the earthing capability is compromised.) I don't have such a device at present, which doesn't overly concern me ... the fault is definitely POSSIBLE, but it's highly IMPROBABLE. Nonetheless, I am planning to have one installed as soon as my supply company can fit a block after my meter which will let me have a separate consumer unit fitted specifically for EV charging, and which has built-in PEN fault detection. [NOTE - I am NOT an electrician. The subject is complex and my description is not comprehensive. I have investigated the topic in some depth, but you should do your own research and - in any case - speak to a qualified person before coming to your own conclusion.]

Because much of the above relates specifically to my home wiring system, here's a link to information about "Safely Charging Your Electric Vehicle Using A Granny Charger". It doesn't cover PEN Faults, but does include an outline of "Section 722 Electrical Vehicle Charging Installations of the IET Wiring Regulations - additional requirements for socket outlets which are installed specifically to supply an EV". It is very sound, and easy to understand.

Safely Charging your Electric Vehicle

The definitive beginners guide to safely charging your electric vehicle including types of connectors, granny chargers, extension leads, timers for off peak tariffs, meters to log energy used and adaptors to enable charging abroad. Also covers using a European or Scandinavian granny charger in...

toughleads.co.uk

 

[Rolfe]

my Granny charger pumps 1.4kW into the car, so must be drawing almost 6A from the 240V mains. I plan to do a 10% to 100% charge soon, which will take around 20hrs so will be overnight.
Should I be worried?

I did this twice or three times before I got my Zappi and it took about 26 hours for the 51 kWh battery. No issues at all. As others have said, it's all down to the quality of your house wiring.

 

[decrep]

Should be OK, it's only about 15 years old and well protected with fuses and RCDs. But it may have me getting up in the night to check on it.

 

[Rolfe]

My plug was still stone cold at the end of the 26 hours, so it's entirely possible you'll have no problems.

 

[decrep]

Thanks Rolfe

 

[DixieTGS]

If time's not an issue you can reduce the current in the car's settings. For the UK SE LR model you can choose between 6, 8, 16 and max. Hopefully the 6A setting would reduce it a bit on your 8A charger.

The other thing you could do is get an infrared thermometer as they're less than £20 now and often sold for use with pizza ovens I think. The cheap ones may not be accurate in absolute terms but are probably good enough for checking differences over time or distance.

 

[Deleted member 11291]

In hindsight I would not have invested in a wall charger back in 2022 and used the granny charger.

At the time the govt grant was in place, plus a contribution from Kia, so cost less than £500 fully installed.
It’s a BP Pulse which is no longer available and has already been replaced once. If it fails again after the guarantee period expires next January, I will revert to using a granny charger.

My weekly mileage is low these days and I would be easily able to keep on top of charging. If 100% is required I would build up over a few charges.
The house was fully rewired 4 years ago and there is a dedicated circuit for the garage, so in theory should not see any issues!

 

[decrep]

Good thinking Dixie.
I'll be able to monitor it through the day, so that should give me an idea of what's going on. If as Rolfe says it's stone cold I won't worry