Charing query

[GarethWhyte]

Hi Everyone,

hope all is well, I’ve placed an order for a long range model 3 to replace my current lease car through Knowls (NHS) and was planning to get w charger fitted on the garage wall in front of the drive. The garage has electricity supplied (however just found out it’s only a 20amp connection) does anyone know if you can run a charge of 20amps?

My other option is straight out the front of the house (the fuse box is in the downstairs toilet) but I didn’t really want to park the car out the front.

last solution would be to fit a weather proof socket and just “trickle” charge?

To add complication looking to move around June next year (2021)

Any thoughts or suggestions welcome!

Gareth

 

[Dilly]

My fuse box is in the garage so no issue for the Zappi in the garage. My second Zappi is round the side of bungalow so they ran a big cable from the attached garage, through the loft and out of the wall.

you could set a device Limit to 20 amps but it will restrict your charging ability. It depends upon your circumstances and your future needs but I would have a proper supply run from the house to the garage. That will cover you for any eventuality.

 

[Radders]

Most chargers are 7kw which would require 32amp.

You could have a charger reduced down to 3.5kw, which would need about 16amp so may be possible depending on what other loading is on your garage

 

[GarethWhyte]

Thanks Both,

the upgrading the power isn’t really an option due to the location of the fuse board/Garage (the cost and disruption would be shocking)

I could “downgrade” the Charing to keep it around 16amp but how would that stack up against just plugging into a normal socket (charging time wise?)

thanks again!

 

[Roy W.]

Thanks Both,

the upgrading the power isn’t really an option due to the location of the fuse board/Garage (the cost and disruption would be shocking)

I could “downgrade” the Charing to keep it around 16amp but how would that stack up against just plugging into a normal socket (charging time wise?)

thanks again!

A standard 13A socket will only charge your car at 10A, so quite a bit slower than 16A.

 

[ACarneiro]

Also depends a bit on what mileage you’re doing.
16A would make it impossible for me to charge my car at E7 rates on my daily commute.
32A will give you approximately 10% charge per hour. 16A would obviously be approximately half that much.

 

[LongRanger]

Cheapest solution would be 16A commando (CEE) interlocked socket on the wall in the garage, the blue caravan hookup type connector, and buy the 16A Tesla UMC adaptor for Commando 16A.

You could get that installed really quickly and easily by an electrician and then see if you really wanted a bigger capacity charging option.

It would be 20-22 hours to fully charge your car from a low % with this option. So 50% overnight if you got home at 8 and needed to leave at 7AM. Probably enough for most folks daily routine ....

There are obviously loads of other charging options with proper EV wall connectors and type 2 sockets, but this would be cheapest on parts, install and get you a pretty decent (but not the best) setup.

You could get away with a 16A RCBO next to a 6A lighting circuit on the garage with this option, but if the garage already has power sockets you may have to sacrifice those (although you would then have a 16A blue connector that you could re-use with 13A 3-pin adaptor - for drill, saw, sander, whatever else you need to do in garage, knowing this was safe at 16/13A).

Commando is the way to go ! Lol.

 

[Glan gluaisne]

Perhaps worth noting that the law requires that any power outlet that is dedicated for charging an EV must be suitably protected, and just fitting an RCBO or RCD most probably will not provide the required level of protection. Given that some charge points now have this special level of required protection built-in, and given that the cost of providing separate protection to the required standard can be fairly high, it might be better to just get a charge point installed and have the maximum current set internally to ensure it cannot exceed the rating of the rest of the installation, especially as there is a grant available towards the cost of this.

The reason that additional protection is required (as detailed in Section 722 of BS7671, the wiring regs) for any circuit installed for the purpose of charging an electric vehicle, relates to the greater risk of electric shock that exists from having a large lump of easily touchable metal insulated from local earth by its tyres. There are fault conditions that can occur, that may have nothing to do with the car, its onboard charger, the connecting cable or the charge point outlet, that can result in the car body reaching a potentially lethal voltage if touched. No normal household protection device, be it an RCD or RCBO can guarantee protection against this type of fault condition, hence the reason for the additional safety requirements.

 

[FlyingHappily]

There are fault conditions that can occur, that may have nothing to do with the car, its onboard charger, the connecting cable or the charge point outlet, that can result in the car body reaching a potentially lethal voltage if touched.

Which component is it that causes such a fault, if not the car, onboard charger, cable, or outlet? (I am not debating the point And haven’t any knowledge here - just interested to learn which additional components / systems are involved here that I don’t know about.)

 

[Chrisgillett]

Is the move next year a certainty? Guess that determines how much effort you'll need to go to. Are there any options for charging at work? Also, how far is your commute? If only short you might get away with a low pace overnight charge, or just popping to the nearest supercharger once a week?
I have calculated that my 80 mile commute should *just* be covered by the overnight 4hr cheap rate.... I hope!

 

[MrBadger]

Which component is it that causes such a fault, if not the car, onboard charger, cable, or outlet? (I am not debating the point And haven’t any knowledge here - just interested to learn which additional components / systems are involved here that I don’t know about.)

Much of the recent regulation changes seem to concentrate on earthing faults on PME systems causing a large voltage difference between the wiring and standing outside on the ground. Hence earthing rods or Open PEN devices.

 

[Glan gluaisne]

Which component is it that causes such a fault, if not the car, onboard charger, cable, or outlet? (I am not debating the point And haven’t any knowledge here - just interested to learn which additional components / systems are involved here that I don’t know about.)

As above, the main concern is if there is a PEN fault on a TN-C-S system. If this happens, the PE (protective earth) that all the "earth" connections in the house are connected to, can float up to a dangerous (>70 V) relative to the local earth potential outside (i.e. standing on the ground, garage floor etc). If such a fault occurs, then the normal protective devices in the house may not detect it, which is usually OK, as there's little chance inside the house of someone being able to be in contact with the local earth outside and something conductive that's connected to the incoming PE.

This isn't the the case for a car, though, as the car bodywork will be electrically connected to the incoming PE and the ground the car is standing on will be at local earth potential, and this then gives the pretty dangerous condition where touching the car bodywork may lead to an electric shock, with the current flowing from the hands, through the body, to ground via the feet.

 

[AndrewGR]

So what protection is provided if you connect to a 13a socket, or 16a commando socket via the UMC? Seems to me that there is a load of protection required for a dedicated charging socket that is not required with the UMC. Why?

 

[Adopado]

So what protection is provided if you connect to a 13a socket, or 16a commando socket via the UMC? Seems to me that there is a load of protection required for a dedicated charging socket that is not required with the UMC. Why?

That's the question! As far as I can see the risks would be the same.

 

[Glan gluaisne]

So what protection is provided if you connect to a 13a socket, or 16a commando socket via the UMC? Seems to me that there is a load of protection required for a dedicated charging socket that is not required with the UMC. Why?

That's the question! As far as I can see the risks would be the same.

The risk is there using the UMC, but the regs don't apply to that, as it's a portable appliance. There's no way to prohibit the use of the UMC, even though it presents a risk of electric shock in the event of a PEN fault, simply because it's not covered by BS7671:2018 Amendment 1. The idea behind the protection requirements for all fixed electric vehicle charging outlets is that the vast majority of EVs will be charged using them, with only a small number being regularly charged using a portable charge point cable.

Risk mitigation is as much about the time exposed to a risk, in terms of total charging hours for all EVs, as anything else. By ensuring that the majority of EV charge points are safe, the safety of most people is better assured.

TBH, the risk of a PEN fault occurring isn't that high, it's the serious consequences that arise from it that has led to the protection requirement being added to the regs. It's not a new requirement, either, as it's been required for any charge point installed with government grant funding from long before it got shifted across into BS761 in 2018. My charge points both now comply with the regs, although for years I used a home made charge point that would not have complied, although I was confident it was OK, given that I'd installed that circuit as a separate TT installation. Doing this isn't enough to comply with the current regs, though, unless a protection device is fitted that cannot be blinded by the DC component that may exist under fault conditions (such as that from the CP, which flows via PE), or unless some other device is fitted that can detect a risky potential difference between local earth and the PE conductor potential.

Like wise, although I've upgraded my charge points here so they comply with the latest version of the regs, I was pretty confident that a PEN fault was very unlikely here, primarily because I saw one of the copper tape multiple earth electrodes being buried alongside the underground cable joint that's less than 5m from where I park the car. Having one of the earth electrodes so close, and being on clay soil (fairly conductive) significantly reduces the risk of an appreciable difference in potential between local ground adjacent to the car and any voltage that the electrical earth that the car body is connected to might reach.

 

[Adopado]

The idea behind the protection requirements for all fixed electric vehicle charging outlets is that the vast majority of EVs will be charged using them, with only a small number being regularly charged using a portable charge point cable.

I think if the number who regularly charge using the UMC or equivalent was added to the number of occasional UMC charges that any of us might do it would not be insignificant! I am also fortunate in having an earth rod within feet of the car that is in permanently damp earth so hopefully there was a degree of safety even before I had a professional installation of my dedicated charge point. I am curious to know if there have been any cases of people receiving an electrical shock that resulted from charging faults. Whenever I have Googled the topic in the past I have never come up with any instances (which is reassuring). My presumption is that the regulations are carefully formulated to take account of predicted scenarios rather than in response to previous tragic outcomes. I wonder how UK regulations compare with regulations in other countries ... I would speculate that the UK is not top of the international league for potentially unsafe charging arrangements!

 

[Glan gluaisne]

I've not ever heard of a car charging incident where the body has become live due to a PEN fault, but this has happened several times with some other, similar, installations in the past, like caravans and trailers with plug-in supplies. In those cases, just having the external outlet connected as a TT installation, with a local earth electrode and RCD or RCBO provides adequate protection. Caravan hook ups have been protected like this for years, usually with an RCD or RCBO in the hook up enclosure.

EVs throw a spanner in the works, though, as there is inherently a DC component (from the control pilot signal) returning to earth, so the RCD may be blinded by the small DC leakage current. The fix for this for EVs was originally to specify a Type B RCD, together with a local earth electrode. The snag with that was that Type B RCDs are very expensive, maybe ten times the price of a normal Type A RCD. The regs have been relaxed to allow alternative ways of sensing a PEN fault condition, so that now quite a few charge points have this feature built in.

 

[MrBadger]

iirc I read that there are around 400 PEN faults reported each year in the UK.

 

[MOBB]

We got our Model 3 and i3 about 2 months before we moved house so I just used 3 pin for that period as I didnt want to get chargers fitted til we moved.

It was fine, never an issue, in fact I dare say we could have made do with 3 pin in our new house!

Next June is some way off though, I would try it and see!

 

[Mr Miserable]

I have charged my car using a commando socket and not been electrocuted.
I also do the lottery and have never won the jackpot.
This is the same argument that went on for years about setbelts.
I went to Tesco this morning and didn't need the seatbelt, so why bother?