V2L Earthing - how?

[Coulomb]

b) measuring L to E voltage I get 186v
c) measuring N to E voltage I get 28v (seems like a centre tapped transformer output)

Interesting that these aren't more similar, as I would expect if it's a fully floating system. There won't be a 50 z transformer in there; too heavy at this power level. Also, 186+28 = 214, 12 V short of the 226 you get line to neutral, so this suggests that there are small capacitors to "earth", as is very common with any switching power converter.

d) the earth is not connected to the chassis of the car (no continuity)

I'm surprised at that. What does earth on the outlets connect to then?

Is the MG vehicles V2L system safe to be used or not.?

I'd say yes. It seems to be essentially a floating system, and there's nothing wrong with that.

 

[deanhalllincoln]

I assume that you mean earth and neutral. Shorting live and neutral is definitely a fault.

Yes sorry corrected

Hi Coulomb the output is almost certainly an inverter but it provides a centre tapped output “like a centre tapped transformer” the mid point is where the earth is connected.
i came to the conclusion (rightly or wrongly) the V2L output is similar to a small inverter that uses IT earth arrangement like this video describes

So safe to use when using one item only unless type 2 (double insulated). I am surprised the official V2L lead has two sockets thus suggesting can be used with more than one item of equipment.

 

[1Pawn]

What if you ignore the earth of the car? Just take line and neutral from the car. Connect neutral of the car to the ground of the house. This happens before the transfer switch and the RCD.

.
k) I have tried connecting earth and neutral together at the output of the V2L connector to simulate a TN-C-S system and the car shuts down the discharge as it sees the connection as a fault.

So I can power my house from the V2L connector but not safely with the right level of protection I would want. The car prevents me creating a safe system as it shuts down the discharge if earth is connected to neutral.

I got this far if anyone else can come up with a safe way of doing this I’m all ears.

Dean

Hi Dean, did you figure a way to safety use the car to power the house?
Did you try ignoring the ground from the car, and bonding the neutral of the car to the ground of the house?
This would need to be before the RCDs of the loads in the house.
Thanks for updating, this is important for me to decide to buy the car or not...

 

[Tim Green]

Deanhalllincoln shows some interesting information on test.
If the question "is it safe to use V2L to power the house" is applied, one could answer:
1. A floating supply is inherently safe.
2. However RCD's will not work in the house due to no relation to earth.
3. That is only a problem if a leak occurs in a load or wiring during the period on V2L, how likely is that?
4. BUT, Deanhalllincoln finds that there is a system in the car that detects leakage to earth, and the car shuts down, so acts like an RCD. But at what leakage current?
5 Another BUT - how fast does it react to shut-down? RCD's are very fast, apparently usually fast enough to save life. (Not that I would rely on it!!)
So I think my answer would be, its up to the user to decide on what level of risk they are happy to take.....

 

[Les burrows]

Yes sorry corrected

Hi Coulomb the output is almost certainly an inverter but it provides a centre tapped output “like a centre tapped transformer” the mid point is where the earth is connected.
i came to the conclusion (rightly or wrongly) the V2L output is similar to a small inverter that uses IT earth arrangement like this video describes

So safe to use when using one item only unless type 2 (double insulated). I am surprised the official V2L lead has two sockets thus suggesting can be used with more than one item of equipment.

Well reading this thread again to night it appears we still have not really got an answer but to say you can’t power to things at once is totally wrong I have done this many times with my double 3 pin scoket on the end of my V2L cable
Les

 

[Coulomb]

4. BUT, Deanhalllincoln finds that there is a system in the car that detects leakage to earth, and the car shuts down, so acts like an RCD. But at what leakage current?

That would detect leakage from the main battery to chassis. So that's not the V2L output and it's not earth.

The current would be quite low, low enough so that an accidental touch to one side of the battery would not be fatal in most circumstances. But this has little to nothing to do with V2L.

V2L is not designed to run a whole house. It would certainly be possible to safely do it in an emergency, with the appropriate wiring (a changeover switch and "generator" input). You would not run the whole house (e.g. oven, water heater, large air conditioning), but lighting, refrigerators, and washing machine can be used with a little care (not running too many large loads at once).

Also be aware that V2L is quietly removed from some models, check carefully. In particular, new ZS EVs. Since they advertised V2L, they will replace a unit and make it work under warranty if you complain enough, but there could be a long delay.

It's a real shame that they are no longer providing V2L. I suspect that they switched manufacturers of the Charge Control Unit, which are now failing and causing charging problems. I'm guessing that the CCU they switched to doesn't provide V2L functionality, and they got caught out.

 

[Staffex]

PE on my MG5 is certainly not a centre tap, but neither is it firmly bonded to the car's chassis. However, the car does have internal RCD protection and any leakage current from live or neutral to PE (as caused by a faulty appliance) will immediately stop the discharge. There was a discussion about this here: V2L adapters

 

[Coulomb]

PE on my MG5 is certainly not a centre tap,

Yes, the centre tap is a North American thing.

However, the car does have internal RCD protection and any leakage current from live or neutral to PE (as caused by a faulty appliance) will immediately stop the discharge.

How can it do that if there is no connection to earth apart from my feet standing in this puddle of water? It can detect a fault where I touch both the live wire and the metalwork (if any) of the appliance, but that's not going to be particularly common.

That doesn't make V2L particularly unsafe, just that RCDs won't provide much protection. [ Edit: I should have said, the in-built RCD won't provide much protection. An RCD in a house or other situation where there is a real earth connection would protect as normal. ]

 

[Tim Green]

But dealhalllincoln states in his item "k" that if he connects earth and neutral together the system shuts down. Thus if the car is joined to the house by all three earth, Live and Neutral but all separated, if there were an earth leakage fault the V2L would shut down. However, I accept there may by leakage current and speed of cut-off limitations.

Obviously one could not run the whole house as normal, but under limited load conditions it could keep essential items running.

 

[Gadget Geek]

Last year we had a planned power outage for a cable connector repair in the street. V2L powered the fridge-freezer, internet and computers, TV, (and not all at the same time) - kettle, microwave and air fryer without any issues.

 

[Staffex]

Yes, the centre tap is a North American thing.


How can it do that if there is no connection to earth apart from my feet standing in this puddle of water? It can detect a fault where I touch both the live wire and the metalwork (if any) of the appliance, but that's not going to be particularly common.

That doesn't make V2L particularly unsafe, just that RCDs won't provide much protection.

Think of the PE connection as a current sensor. Consider an electric kettle with a tired heating element whose insulation is deteriorating. Any leakage current flowing to the kettle's earthed metal casing will be sensed as a residual current by the PE connection and the discharge will be halted immediately.

The PE connection sits at quite a high potential compared either L or N. And that's why If the Earth is carried through to your domestic supply (where E and N are bonded locally or at the sub-station) the leakage current will trip the car's internal 'RCD'. (You can confirm easily confirm this for yourself by plugging a lamp into the V2L's 13A socket. The lamp will work just fine but if you momentarily bridge the E and N terminals in the 13A plug the car will stop discharging.)

 

[1Pawn]

Think of the PE connection as a current sensor. Consider an electric kettle with a tired heating element whose insulation is deteriorating. Any leakage current flowing to the kettle's earthed metal casing will be sensed as a residual current by the PE connection and the discharge will be halted immediately.

The PE connection sits at quite a high potential compared either L or N. And that's why If the Earth is carried through to your domestic supply (where E and N are bonded locally or at the sub-station) the leakage current will trip the car's internal 'RCD'. (You can confirm easily confirm this for yourself by plugging a lamp into the V2L's 13A socket. The lamp will work just fine but if you momentarily bridge the E and N terminals in the 13A plug the car will stop discharging.)

So what's the best way to safely wire the house, and make sure the RCDs are still working?
Do we connect the ground of the car to the earth of the house or not?
I understand we can't bond the neutral of the car with the ground of the car, otherwise the RCD of the car trips.
Can we bond the neutral of the car with the ground of the house, and ignore the ground of the car?
What happens if instead we don't connect the ground of the car with the ground of the house, and we don't bond the neutral with the ground? Basically the equipment in the house would still be grounded to earth, but there would be no return path to the neutral of the car: I guess the RCDs inside the house wouldn't work, but maybe the one inside the car would still defect a fault?

 

[Staffex]

So what's the best way to safely wire the house, and make sure the RCDs are still working?
Do we connect the ground of the car to the earth of the house or not?
I understand we can't bond the neutral of the car with the ground of the car, otherwise the RCD of the car trips.
Can we bond the neutral of the car with the ground of the house, and ignore the ground of the car?
What happens if instead we don't connect the ground of the car with the ground of the house, and we don't bond the neutral with the ground? Basically the equipment in the house would still be grounded to earth, but there would be no return path to the neutral of the car: I guess the RCDs inside the house wouldn't work, but maybe the one inside the car would still defect a fault?

Of course only a qualified electrician should attempt this but speaking hypothetically... To 'safely wire the house' would require a break-before-make changeover switch to isolate the live feed to the consumer unit from the incoming mains supply, feeding it instead from the car. The V2L live would be connected to the c/o switch and CU with a 3-core cable but the earth would NOT be connected at the consumer unit. (The earth wire would serve only to trip the car's RCD if the cable between the CU and was to be damaged.). The V2L neutral would be connected to neutral bar of the CU. All of the RCDs or RCBOs in the consumer unit would then continue to function as normal, protecting the domestic wiring and appliances.

Personally I wouldn't go to these lengths as my MG5 is incapable of meeting the normal energy demands of my home. I only needed to run the fridge, freezer, TV and possibly the gas boiler and CH pump in the event of a power cut. The 'Death Lead' I described elsewhere does this admirably. It's a simple matter to run it from the garage and plug it into my ground floor ring - after first remembering to switch off the g/f 32A RCBO in the consumer unit!

 

[Tim Green]

Interesting thoughts Staffex, and I assume you are not connecting the car ground to the house ground because the house Neutral would be already related to the house ground.
I have a petrol generator which I have tested as a substitute supply in case of power outage. Under test conditions it works fine but I have not tested an earth leak response. Next time I test it I will!

 

[Les burrows]

Can I just say I know very little about electronics but this idea of running the house off A V2L cable is stupid it is not and never was designed to do that kind of thing I have written earlier in this tread I have powered 2 items off it from the dual socket on the end of the cable without a problem but together they where below 2.5 kW which I believe is the recommended maximum I know others have gone beyond this but it was never intended to be like that also there is some voltage loss when using items via V2L example of this was a 2kW heater which on the house ring circuit it draws around 2060 watts on my meter, but only around 1830 on the car V2L and then when I plugged something else in the other outlet about 300 watts a hand held vacuum the heat current on the heater went a little below 1800w
Les

 

[1Pawn]

Can I just say I know very little about electronics but this idea of running the house off A V2L cable is stupid it is not and never was designed to do that kind of thing I written earlier in this tread I have powered to items of it from the dual socket on the end of the cable without a problem but together they where below 2.5 kw which I believe is the recommended maximum I know others have gone beyond this but it was never intended to be like that also the is some voltage loss when using item ms via V2L example of this was a 2kw heater which on the house ring circuit it draws around 2060 watts on my meter, but only around 1830 on the car and then when I plugged something else in the other outlet about 300 watts a hand held vacuum the heat currant went a little below 1800w

I would be fine with a 2000W load. However, instead of being it one single 2000W heater, I want to power 50 different loads spread around the house, for a total power load of 1500W.
I'm talking fridge, gas boiler, lights, TV computer and so on.
At the same time, I want the system to be safe, so grounding and working RCDs.
I understand if you find this stupid, but it makes sense to me and I'm pretty sure it's technically possible.

Take a portable petrol generator. Some people fire it up and connect it to 2 lights and call it a day. Some other wire it up to a transfer switch to power (most of) a house.
I don't get how the V2L power is different than a petrol generator

 

[Staffex]

Interesting thoughts Staffex, and I assume you are not connecting the car ground to the house ground because the house Neutral would be already related to the house ground.
I have a petrol generator which I have tested as a substitute supply in case of power outage. Under test conditions it works fine but I have not tested an earth leak response. Next time I test it I will!

PE on the car isn't an earth in the accepted sense: it isn't bonded to neutral (mine sits 83V above it), nor is it bonded to the car's chassis (I measured 11.9 Ohms) to the 12V battery negative which is strapped to chassis. In a premises the earth and neutral are always bonded together, either locally or at the substation, so a very low impedance exists between them. This means that if the car's PE (carried on the green/yellow wire) is connected at the house end it will place a short between PE and N, a current will flow and the car's RCD will trip - even though no fault exists.

I don't know why MG use this arrangement. It's satisfactory in that if there's any leakage current between PE ("E") and L or N (as would occur with a faulty appliance) the car's RCD will trip. But it's certainly not compliant with the IET 18th Edition Wiring Regulations as applying to portable generators (section 515.4.4). I would expect your portable generator to have floating outputs with regard to the E connection which will be bonded to chassis, so it will behave like a building site isolating transformer. Alternatively, your generator will have a designated live output, and a neutral output which will be bonded to chassis, so a very low impedance will exist between E and N.

 

[kiwi]

While cumbersome, an isolating transformer is the obvious answer to the V2H predicament. Floating towards the EV V2L cable and MEN bonded at the house via the approved manual transfer switch.

 

[Nicko]

Of course only a qualified electrician should attempt this but speaking hypothetically... To 'safely wire the house' would require a break-before-make changeover switch to isolate the live feed to the consumer unit from the incoming mains supply, feeding it instead from the car. The V2L live would be connected to the c/o switch and CU with a 3-core cable but the earth would NOT be connected at the consumer unit. (The earth wire would serve only to trip the car's RCD if the cable between the CU and was to be damaged.). The V2L neutral would be connected to neutral bar of the CU. All of the RCDs or RCBOs in the consumer unit would then continue to function as normal, protecting the domestic wiring and appliances.

Personally I wouldn't go to these lengths as my MG5 is incapable of meeting the normal energy demands of my home. I only needed to run the fridge, freezer, TV and possibly the gas boiler and CH pump in the event of a power cut. The 'Death Lead' I described elsewhere does this admirably. It's a simple matter to run it from the garage and plug it into my ground floor ring - after first remembering to switch off the g/f 32A RCBO in the consumer unit!

I advise no one attempts the death lead as it is stupidity at its best. The pins on the 13A plug are live and if anyone switched the RCBO back whilst it was plugged into the ring main there would be a serious fire risk.

 

[Gadget Geek]

The clue is in the name; V2L, Vehicle to Load, not V2H nor V2G.