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UMC/3-Pin charger tripping fuse board...

JS77

Member
Nov 24, 2019
141
88
England
Just collected my SR+ (Separate post about that experience incoming!) - however, just got home and tried to charge using the UMC/3-Pin charger. As soon as the light turns blue and about to start drawing power, my house fuse board trips. Have tried this using a Tough Leads extension lead and also directly into a socket without an extension lead.

Any sparkies on this forum please advise? (I have messaged my electrician but maybe I'm missing something obvious?)

Thanks in advance.
 

Tonyf

Member
Sep 24, 2020
31
28
Warrington
Just collected my SR+ (Separate post about that experience incoming!) - however, just got home and tried to charge using the UMC/3-Pin charger. As soon as the light turns blue and about to start drawing power, my house fuse board trips. Have tried this using a Tough Leads extension lead and also directly into a socket without an extension lead.
Any sparkies on this forum please advise? (I have messaged my electrician but maybe I'm missing something obvious?)

Thanks in advance.
I had exactly the same problem and on the electricians advice I replaced the fuse board. Still no luck.

I logged a service request on the Tesla App, a few days later the Ranger called with a replacement UMC. We kept swapping the new and old just to confirm the lead was at fault. New one still works fine.
 
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VanillaAir_UK

Well-Known Member
Jun 17, 2019
8,249
5,772
Surrey, UK
What fuse tripped? The RCD or a overcurrent device?

If an RCD, normally identified by having a test button, its most likely to be that the earth leak on the house is close to the limit on the RCD (typically 30mA) and putting the car on charge takes it over the limit. Things like modern power supplies normally have quite a bit of leakage and the cumulative effect just mounts up.

Its a pain to test, but if you disable a decent number of circuits with sockets on them, you may be able to get the car charging. Its very likely that you can then reintroduce the other circuits and everything will be fine, until you try and charge the car again. The UMC seems to have a large but transient effect. If that is the case, its not a fault of anything in particular, just the straw that broke the camels back. The solution is for an electrician to confirm then come up with a way of reducing the effects of cumulative earth leak. Best solution is to have a dedicated RCD/RCBO for the circuit that the UMC is on so it doesn't contribute to the whole house leakage.
 
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JS77

Member
Nov 24, 2019
141
88
England
What fuse tripped? The RCD or a overcurrent device?

If an RCD, normally identified by having a test button, its most likely to be that the earth leak on the house is close to the limit on the RCD (typically 30mA) and putting the car on charge takes it over the limit. Things like modern power supplies normally have quite a bit of leakage and the cumulative effect just mounts up.

Its a pain to test, but if you disable a decent number of circuits with sockets on them, you may be able to get the car charging. Its very likely that you can then reintroduce the other circuits and everything will be fine, until you try and charge the car again. The UMC seems to have a large but transient effect. If that is the case, its not a fault of anything in particular, just the straw that broke the camels back. The solution is for an electrician to confirm then come up with a way of reducing the effects of cumulative earth leak. Best solution is to have a dedicated RCD/RCBO for the circuit that the UMC is on so it doesn't contribute to the whole house leakage.

Thanks, very informative - the extension leads I purchased from Tough Leads has an inline RCD, so wouldn't that have prevented the main house board from tripping? (Sorry, I'm useless with stuff like this)

I had exactly the same problem and on the electricians advice I replaced the fuse board. Still no luck.

I logged a service request on the Tesla App, a few days later the Ranger called with a replacement UMC. We kept swapping the new and old just to confirm the lead was at fault. New one still works fine.

Thanks - I tried the UMC on 3 different plugs and it tripped every time... so I guess I should log an issue on the App. My neighbour has kindly offered to let me try the UMC from their socket tonight so I'll do that just to see if I can rule out a defective UMC.
 

Adopado

Active Member
Aug 19, 2019
4,177
3,142
Scotland
My neighbour has kindly offered to let me try the UMC from their socket tonight so I'll do that just to see if I can rule out a defective UMC.

... I was just going to suggest that course of action. That should rule out or confirm defective UMC.
 

VanillaAir_UK

Well-Known Member
Jun 17, 2019
8,249
5,772
Surrey, UK
Thanks, very informative - the extension leads I purchased from Tough Leads has an inline RCD, so wouldn't that have prevented the main house board from tripping? (Sorry, I'm useless with stuff like this)

Not if its a cumulative earth leak on the house RCD. If its a fault with the UMC/cable, then its a lottery as to which, or both will trip.

Watch out if testing things - you don't want to go tripping circuits unnecessarily if you have sensitive kit in - its a pita that the sensitive kit may be contributing to the cumulative leak.

These earth leaks are perfectly normal and safe - iirc there is a 3mA limit on a device, so you don't need many devices to potentially push the cumulative leak close to the 30mA limit. In addition, an RCD may age, so the 30mA limit may be less in reality.
 
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Dooo

Member
May 23, 2021
19
5
Uk
I had similar issue yesterday when I tried to charge with a socket in meter cupboard. Rcd kept tripping. Used a different socket and no issues so far.
 

JS77

Member
Nov 24, 2019
141
88
England
Quick update - tried the UMC at my neighbours and it worked fine, so it looks like I need an electrician out to check my fuse board etc Will update once I manage to book an appointment.

Until then, public chargers and supercharging it is...
 

AndrewGR

Member
Oct 18, 2019
421
206
Oxfordshire, UK
Quick update - tried the UMC at my neighbours and it worked fine, so it looks like I need an electrician out to check my fuse board etc Will update once I manage to book an appointment.

Until then, public chargers and supercharging it is...

You can unplug all your electronic equipment and see if the UMC works without tripping and then plug stuff back in one item at a time and see if the RCD trips. Quite likely the problem is with a piece of plugged in equipment rather than your house wiring.
 
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JS77

Member
Nov 24, 2019
141
88
England
Have tried the UMC at a few different plugs at my house, and switched off as many other appliances as I can, but it's still tripping the fuse board. Works fine tested at both my neighbours.... ☹️

Trying to get hold of an electrician not going well either. SIgh....
 

Adopado

Active Member
Aug 19, 2019
4,177
3,142
Scotland
Have tried the UMC at a few different plugs at my house, and switched off as many other appliances as I can, but it's still tripping the fuse board. Works fine tested at both my neighbours.... ☹️

Trying to get hold of an electrician not going well either. SIgh....

From what I read and from my own experiences (though not with respect to car charging) these RCD trips can be a pain to track down. If everything has been unplugged then you would think it has to be either something that is permanently wired or a faulty RCD itself. Do you have any electrical sockets with built in USB chargers ... I've heard these can be poor quality and can cause issues. Definitely going to need a good electrician by the sound of things. ( @arg on this forum sometimes comments with authority on these topics but tracking this problem down is most likely going to need someone on the ground ... no pun intended!)
 

Fursty Ferret

Member
Jun 13, 2021
85
52
Leeds
The first thing I'd do is switch off every circuit breaker except for the one that the UMC is plugged into and see if that fixes the problem.

If it does, turn each one back on in turn until the RCD trips, and you've gone some way towards isolating the problem.

If it doesn't then the fault lies with the circuit that the UMC is connected to or the RCD itself. You could do some provisional troubleshooting by taking each socket off the wall (with the power off at the consumer unit) and check for loose connections or insulation damage, but realistically it needs an electrician with suitable insulation test equipment.

I notice that you've been asked several times already whether it's the RCD (which looks bigger than the others with a test button on it) or the circuit breaker for the individual circuit, which implies an overload fault. Until you answer that then no one can really help.
 

Jason71

Active Member
May 8, 2019
2,985
2,934
Shropshire
I notice that you've been asked several times already whether it's the RCD (which looks bigger than the others with a test button on it) or the circuit breaker for the individual circuit, which implies an overload fault. Until you answer that then no one can really help.
new houses now have combined RCD and MCB in one so you can't always tell but assuming not then you are right we really need to know what is tripping.
A photo of the board would be good. showing any numbers + details of which device it is. sockets are normally on a 30 amp breaker so no way that should be tripping unless its faulty.
I would try plugging your kettle into the same extension lead/socket. That is more amps than the car draws. if that works OK I would say it has to be a faulty UMC? though since it works at your neighbours an over sensitive device in the board seems more likely
 

Cloggie

Member
Nov 18, 2020
184
98
West Midlands, UK
Having moved into a 1930s house with more recent, but very 'interesting wiring' it took the electrician and me a few days to sort it out so that the new board didn't keep tripping.

I would highly recommend getting a proper electrician in to sort this out. It sounds to me like you have some dodgy wiring or connection somewhere. Not wort taking the risk with the UMC pulling the load over an extended period.

Just my 2p :) (after inflation)
 
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JS77

Member
Nov 24, 2019
141
88
England
Thanks, everyone. I've attached a picture of the fuse board and highlighted the RCD that is tripping. Fingers crossed I have an electrician scheduled to visit end of this week (but he's cancelled before so...)

IMG_9150.jpg
 

Jason71

Active Member
May 8, 2019
2,985
2,934
Shropshire
Thanks, everyone. I've attached a picture of the fuse board and highlighted the RCD that is tripping. Fingers crossed I have an electrician scheduled to visit end of this week (but he's cancelled before so...)

View attachment 682209
OK so its def the RCD tripping not the MCB's so its not a high current issue but a current leakage issue. I would have called it out as an UMC fault if you had not used it successfully at the neighbours ( I assume they have a fully functional RCD?)
Could be that your RDC is faulty or over sensitive but if so very odd that nothing else trips it.
Definitely sounds like one for an electrician though. Don't think you are going to find a magic bullet on the forum sadly.
 
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Durzel

Active Member
Jul 17, 2019
3,468
2,427
Bath, UK
I’m probably being an idiot but why is it that you’ve got a bunch of circuits that don’t appear to be protected by an RCD at all?

Typically you see sockets and lights distributed between two RCDs, the logic being that if you lose lights or sockets downstairs that you’ll still have them upstairs, and vice versa, etc.

Are those Hager breakers MCBs or RCBOs? Circuit #3 is a RCBO for sure.
 

MrT3

Member
Jun 26, 2021
171
98
UK
Thanks, everyone. I've attached a picture of the fuse board and highlighted the RCD that is tripping. Fingers crossed I have an electrician scheduled to visit end of this week (but he's cancelled before so...)
All you can do is unplug everything (physically remove plugs from the sockets) and switch off any appliances that are hardwired via the isolator switch (e.g. cooker, immersion), then plug in your UMC and then start to plug other things back in and see what trips.

You could have a number of items that have small amounts of leakage and in combination you go over the 30mA limit.

Otherwise you need to get an electrician in. They can test the RCD is tripping at the correct current and it could be damp within a wall socket for example which they can help you find.
 
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