Brand new. Granny charger trips RCD when charging. Replace how?

[RealEvil_UK]

Hi,

Got my M3 3 days ago. Tried granny charger at parents today and it trips the RCD as soon as charging is initiated.

Just got home. Same.

Question is - what's quickest way to get new one? Drive back to West Drayton delivery centre and complain? Anyone know if the delivery centre is open on Sundays? I know the service center isn't.


I need it for next weekend ideally as going somewhere with no destination charger.

 

[NorfolkMustard]

Hi. tried reducing the amps first?

What's your end-to-end setup? i.e. are you using an extension lead or is the 3pin tail of the tesla UMC plugged directly into a house socket that you know to be Ok (i.e. try plugging a kettle into it and see if it will boil)

Does it trip the RCD (i.e. does half the house go dark) or the MCB (just the downstairs sockets circuit goes off) ?

 

[RealEvil_UK]

Hi. tried reducing the amps first?

What's your end-to-end setup? i.e. are you using an extension lead or is the 3pin tail of the tesla UMC plugged directly into a house socket that you know to be Ok (i.e. try plugging a kettle into it and see if it will boil)

Does it trip the RCD (i.e. does half the house go dark) or the MCB (just the downstairs sockets circuit goes off) ?

Hi, no extension lead, it trips RCD not circuit breaker it's on so it's not an Amp draw issue.

Car has been charged on 2 different 7kw chargers so I assume it's not the car at this stage.

 

[Glan gluaisne]

Sounds like an earth leakage fault within the granny charger itself. One thing to check is whether the granny lead trips the RCD when plugged in to the mains outlet, but with the car lead disconnnected. If it still trips then that indicates a leakage fault on the incoming side of the granny lead box, and could be something related to the adapter lead that connects the box to a 13 A outlet. If it only trips with the car connected, then that suggests a leakage fault on the output side, which is almost certainly internal to the granny lead box.

Do you have access to a commando outlet, or even a 13 A plug to 16 A commando socket? If so, this may be a quick way to establish if there may be an fault in the plug in adapter lead, as you could swap the 13 A plug lead over for the supplied 16 A commando lead, just for a test (can't run it like this off a 13 A to 16 A commando lead as it will overload the 13 A plug).

 

[RealEvil_UK]

Sounds like an earth leakage fault within the granny charger itself. One thing to check is whether the granny lead trips the RCD when plugged in to the mains outlet, but with the car lead disconnnected. If it still trips then that indicates a leakage fault on the incoming side of the granny lead box, and could be something related to the adapter lead that connects the box to a 13 A outlet. If it only trips with the car connected, then that suggests a leakage fault on the output side, which is almost certainly internal to the granny lead box.

Do you have access to a commando outlet, or even a 13 A plug to 16 A commando socket? If so, this may be a quick way to establish if there may be an fault in the plug in adapter lead, as you could swap the 13 A plug lead over for the supplied 16 A commando lead, just for a test (can't run it like this off a 13 A to 16 A commando lead as it will overload the 13 A plug).

When plugged in it has green lights as normal and doesn't trip RCD. As soon as car initiates charge (i.e. after the blue light flashing dance for a few seconds) the RCD trips and the car reports that charging has stopped.

I don't have access to a commando lead or adpater and I suspect the issue is an earth issue inside the charger as you say.

I have no clue how to replace it other than just go back to the delivery centre?

 

[ewoodrick]

It sounds like a ground leak to me, a common issue.

 

[Glan gluaisne]

Definitely sounds like an earth leakage fault on the output side of the granny lead, either the box itself or the lead to the car. Should be easy enough to test for leakage between the line, neutral, and PE, at the car end connector (don't try this on the mains inlet side of the box), should be safe enough to do as the contactor inside the box will be open, so there's no risk of damage to the box when testing that side of things. Just need someone with an MFT and a few minutes spare to test it. Could be something like a wiring problem inside the connector that connects to the car, that may be fixable, as these come apart fairly easily, usually.

 

[MrBadger]

When it happens again, before resetting the RCD, turn off all other circuits at MCB for the side of the consumer unit that the tripped RCD controlled - but not the MCB for the circuit that the UMC is connected to. Reset the RCD.

Now retry the charge.

It will either work, so fault or leakage is probably in the house (other circuits or devices), or not, in which case it is probably the car or the UMC.

 

[ianto999]

I've had the same problem. Even using a 3 pin RCD from garden equip[emt in between to tesla plug and the garage socket, the RCD in the house trips, as soon as the car starts charging..

 

[NorfolkMustard]

Raise it as a service request in the app, so at least it gets recorded as an issue within your first few days of ownership - you may get a ranger drop one off or get one posted

 

[RealEvil_UK]

Raise it as a service request in the app, so at least it gets recorded as an issue within your first few days of ownership - you may get a ranger drop one off or get one posted

I already have an appointment booked for delivery paint issues. I don’t see how to create another appointment/request/thing?

 

[RealEvil_UK]

When it happens again, before resetting the RCD, turn off all other circuits at MCB for the side of the consumer unit that the tripped RCD controlled - but not the MCB for the circuit that the UMC is connected to. Reset the RCD.

Now retry the charge.

It will either work, so fault or leakage is probably in the house (other circuits or devices), or not, in which case it is probably the car or the UMC.

I have tried in 2 houses. It’s either the car or UMC

 

[NorfolkMustard]

I already have an appointment booked for delivery paint issues. I don’t see how to create another appointment/request/thing?

you can add/edit that existing one - that's what I did for my car and the next morning I got a text confirming the change and asking a few questions about it.

 

[MrBadger]

I have tried in 2 houses. It’s either the car or UMC

It could just as easily be something common plugged into both houses. I got ours working by turning off two white appliances, both made by the same manufacturer.

I do need to do some more tests though just to confirm this. I'm certainly not going to look forward to plugging the umc into someone else's house. I would love to be wrong, but having gone through every circuit in the house, the kitchen and these two appliances seem to be the common factor as to whether the RCD blows or not, although they may be the leak that broke the camels back.

Would be good to see if another car or UMC behaves the same.

Also, some say dial down the charge rate. Not sure how to do this prior to starting the charge. By time charge screen comes up, it looks like its going to be too late to dial down the amps before it trips although haven't paid too much attention to this.

 

[ianto999]

1) I tried umc on an old car park external 3 pin and it didn’t trip at the start of charge.
2) It does trip immediately car starts to charge, every time in house, so I think it is house//umc/car combo. I have PV. It doesn’t trip when plugged into car and socket, only when charge tries to start.
3) It also always immediately trips when I use a leaf Esve 3 pins and a type 2 adaptor.
4) It doesn’t trip immediately if I use the old leafs tethered rolec with the type 2 adaptor, but it does trip sometimes even with this setup during the Night charge, or when I turn on hearing remotely in the morning.
5) The house never trips otherwise.

I’m having zappi installed soon, so going to ask the electrician then, and will report back.

 

[MrBadger]

I’m having zappi installed soon, so going to ask the electrician then, and will report back.

Try and make sure its not connected to the consumer unit but via a separate unit. @arg says lots of little things can just mount up and the high current draw can tip the balance.

3 Pin Charger Tripping House

 

[WannabeOwner]

I have tried in 2 houses. It’s either the car or UMC

Too small a sample size IMO. I've only plugged the M3 13AMP into two houses. in laws tripped the whole house (tried garage separate "fuse box", and a couple of other "direct from consumer unit" circuits, all the same), but plugged into their neighbours on an extension cable was fine.

There have been a fair few posts on here about tripping whole house that turned out to be solved by unplugging a specific device, such as white goods. PITA to find, but all the hassle involved in getting/waiting for Tesla to replace your UMC and then finding that hasn't changed anything would equally be a PITA. I recommend doing the isolated-everything-else test.

 

[arg]

I fear there is something systematic going on here, as there's been a sudden flood of these UMC-trips-RCD reports from Model 3 owners (after hardly any over the years from Model S/X drivers).

Possibilities:

1. Some awful quality problems or design flaw in the version 2 UMC. Good news if true (replacement UMCs will sort it), but seems relatively unlikely.
2. Significant 'as-designed' leakage current in the Model 3 charger (eg. from EMC filtering components) that causes cumulative leakage to exceed the breaker's threshold in houses where existing leakage is close to the limit.
3. Neutral-related issues if the UMCv2 sequences the contactor differently from UMC1 (noting that UMC2 no longer cares which is L vs N).
   
4. High-frequency emissions from the Model 3 charger causing false tripping of some breakers, depending on the breaker design. This is a problem widely seen with the Renault Zoe, but not previously an issue with Tesla vehicles.
5. Other things I haven't thought of....

If people are definitely seeing the problem arise specifically when the car starts charging (rather than when the UMC contactor closes) that favours option 4 over the others. This can to some extent be tested by setting up timed charging and observing if the problem arises when hitting the 'start charge' button in the app to override the timer - though note that for Model S at least (and most likely Model 3 too), having the heater running while plugged in will still draw current through the charger even though it's not counted as "charging".

 

[Glan gluaisne]

Out of interest, are there a significant number of reports of Model 3's tripping RCDs/RCBOs when charging from a fixed charge point, or is this an issue related solely to using a UMC?

With the general increase in low level leakage current that seems to be a consequence of a larger number of appliances using switched mode power supplies, I wonder if it may just be a cumulative effect, with the car OBC having a high, but within limits, apparent leakage current, which is OK when it's running on a dedicated circuit, but which, when added to the cumulative leakage current from other appliances on a shared circuit causes the 30 mA trip threshold to be exceeded?

 

[arg]

With the general increase in low level leakage current that seems to be a consequence of a larger number of appliances using switched mode power supplies, I wonder if it may just be a cumulative effect, with the car OBC having a high, but within limits, apparent leakage current, which is OK when it's running on a dedicated circuit, but which, when added to the cumulative leakage current from other appliances on a shared circuit causes the 30 mA trip threshold to be exceeded?

That's my theory (2) above, and certainly a plausible one. The RCD-trip reports I have seen have almost all related to the UMC, though there have been some other charging issues with Model 3 that may muddy the waters (there are the persistent reports of charging at half speed, which seems like a software bug).