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Discussion Starter · #1 ·
I depend on the 7KW wall box at work to charge my I Pace and have had no issues for six months, then my local JLR garage changed a module on the vehicle as the solenoid pin on the charge flap wouldn't lock. Following this work, the RCD inside the wall box would occasionally trip randomly during charging, and I would have to reset it. The frequency of this tripping fault increased to several times a day, so I called Project EV, who changed the wall box for a brand new one and we connected the I Pace with a brand new cable. This new box also tripped its RCD after two minutes charging. The car charges ok elsewhere, but I have no idea why the problem has become acute with the Project EV box. What is at fault?
 

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Only way to pin it down will be to measure the earth leakage current and find where it's coming from. RCDs can vary very slightly in terms of sensitivity, especially if there is a DC component to the leakage that may be de-sensitising an RCD that doesn't have very good DC tolerance.

My suspicion would be that there is something within the charger that is creating a leak to earth, given that parts on the car have been replaced, and the fault only occurred after this. Could be coincidence, but the charger has to be much more likely to cause an earth leakage fault than the charge point, as there's nothing much in the charge point that could create such a fault.

Measuring the earth leakage current isn't difficult, but it does mean using a sensitive earth leakage clamp meter (ordinary current clamp meters aren't usually sensitive enough) and also means exposing the CPC to the charger, easiest way is to take the cover off the charge point and access it where it connects in there. Really needs an electrician to do this, given that there may be live parts exposed with the charge point cover off.

This testing could be done on any charge point if it's the charger that is suspected to be the cause, as if there is leakage it should be easy enough to check. If you are anywhere near Salisbury I'll happily come out and do the checks for you, for free (I'm retired so now just do stuff like this to keep busy!).
 

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Discussion Starter · #3 ·
Thanks Jeremy. I'm going to have to digest your reply in bitesize pieces and I'm sure to have done questions. Sadly too far away (Dudley) for even someone as helpful as you. Aidan
 

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Discussion Starter · #4 ·
Thanks Jeremy. I'm going to have to digest your reply in bitesize pieces and I'm sure to have done questions. Sadly too far away (Dudley) for even someone as helpful as you. Aidan
I agree that the most likely cause of the earth leakage is the car charger. The car does not trip other 7KW chargers, but maybe the Project EV wall box, which has no earthing requirement, has a more sensitive RCD? The workaround I have found is to drop the supplied current to 20A, using the App, and so far the car has not tripped the wall box. At 32A it does.
 

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I agree that the most likely cause of the earth leakage is the car charger. The car does not trip other 7KW chargers, but maybe the Project EV wall box, which has no earthing requirement, has a more sensitive RCD? The workaround I have found is to drop the supplied current to 20A, using the App, and so far the car has not tripped the wall box. At 32A it does.

I sincerely hope that the Project EV does have normal earthing, i.e the CPC in the cable MUST be connected by a low impedance path to the supply PE when in use. If it doesn't have such a connection then it is very unsafe.

The earth leakage protection will be in two parts, a DC tolerant earth leakage sensing system within the charge point, plus a normal double pole Type A RCD/RCBO on the supply. The way in which the built-in earth leakage works may well vary from one charge point manufacturer to another, but most just seem to open the charge point live conductor contactor/relay if they detect a current imbalance. Some may also deliberately cause the supply RCD/RCBO to trip, to ensure that any fault is known about by the user (because doing this requires a manual reset of the RCD/RCBO), some may just display an error/fault indication on the unit. Technically I think it's safer to cause the supply RCD/RCBO to trip, simply because that avoids automatic resetting after an intermittent fault, and makes the user aware that there may be a developing fault somewhere.

Odd that the leakage seems charge current dependent, but does hint that it may be related to an insulation breakdown within the charger that is, perhaps, temperature dependent. In all probability this may get worse with time, as insulation resistance related problems only tend to fix themselves if they are caused by water ingress somewhere. The fact that the charge port has been taken apart to replace the locking pin, and that this fault only started to show itself after that work, suggests that something may have been disturbed or damaged when that work was done. One way to prove this would be to do whatever insulation resistance testing Jaguar allow. It "should" be safe to do an insulation resistance test (using a normal MFT) on the vehicle charge connector if the two single phase live terminals (L1 and N) are connected together and the insulation resistance between them and protective earth (the vehicle body) is measured. Easy to do, but as the car is under warranty it's something that really needs to be handled by Jaguar.
 

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The ProjectEV units all have Earthing requirements, but the newer units in common with the market have moved to open-PEN protection and dispensed with any need for a separate Earth. I suspect that this may be what the OP is referring to.

@Abmaybe you comment that
The car does not trip other 7KW chargers
Are these commercial or Home units? It appears that commercial units have higher trip thresholds than domestic ones so that may be relevant.

In the units that I have seen the trip has been a CHINT unit which seem to generally be of reasonable quality, although I didn't check closely that they were "genuine" CHINT.

Edited to add - there's a similar thread regarding a Zoe
 

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This reminds me of the Zoe thread recently where a car would trip a domestic charge point but not public - a difference in RCD trip current was suggested as the culprit there, i.e the car is faulty and happens to hit the 30ma trip current of the domestic unit but not the 100ma (iirc) of the commercial unit.
 

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Discussion Starter · #8 · (Edited)
I Pace is booked in with Jardine Jaguar in two weeks. This thread has reminded me that the 'charger' is in the car and the wall box is only a connector, albeit with some communication to the car. Also the wall box has PEN (Protective Earth & Neutral) open circuit protection using electronics, that replaces the need of an earthing rod on the unit.
 
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