Car is shorting my house out when it attempts to charge

[JonB]

Well merry effing Xmas to me.

Tried to put the car on charge today and it tripped the RCD in my fuse box. Tesla Service lady said it’s probably the UMC or cable. Now I’m worried because I have treated the unit and its cable like new born babies and it’s less than a month old, yet already it’s shorting between either live and earth or neutral and earth (hence, tripping the RCD). I do hope it is capable of more durability than that.

We’ll see what the service centre bods have to say on Thursday (50 mile round trip for me, harumph).

Bah, humbug etc.

 

[Forty_Two]

What charger do you have? Why are you sure it's not the charger or the installation or the load rating?

 

[Tony Hoyle]

Take your car to a public charger and try it. If it works, it's lkely your house wiring, so you need to get a sparky in... Tesla can't do much at that point.

 

[Irata]

Does indeed sound like a faulty UMC, that's the most likely leak to earth.

I presume anything else plugged into the same socket works, like a fan heater? Just on the remote chance the socket has an internal fault.

 

[Durzel]

Have you done any update recently? If so any chance it might have reset the charging amps to something your supply can’t handle?

 

[GeorgeSymonds]

Do you have one RCD covering a bunch if circuits? RCD trips when the total leakage exceeds a threshold and the car charger could just tip it over the edge. It happened to me, turned out the real fault was an outside light but only when the car was charging would it trip the house, and worse in the rain which also made me think it was the car. Sparky found it and problem solved.

 

[qwickshot]

Have you tried it on a different circuit? Most houses have two RCD’s these days, half the sockets will be on one and the other half will be on the other.

As other have said, there could be existing earth leakage in the circuit already and the car trips or over the edge.

The cable is very robust, I can’t see how you’d break it without standing there bending it constantly for days or just straight up cutting or piecing it. A UMC or car problem isn’t out of the question though.

 

[Irata]

Have you done any update recently? If so any chance it might have reset the charging amps to something your supply can’t handle?

It's their RCD tripping, not MCB.

 

[MovingSouth]

... shorting between either live and earth or neutral and earth ...

As implied by others above, but to be explicit, the RCD tripping indicates an imbalance between neutral and live / a leakage to earth, which is usually 30mA, so very small. A short would cause a far larger current that would usually be caught my a circuit breaker, with one on each circuit. As @GeorgeSymonds says, it's quite possible that an existing leakage is already close to the edge and the UMC just adds enough to push the RCD through the limit.

 

[NewbieT]

An SC visit will be a waste of your time if it’s your house causing the problem and not the car.

There is an easy test. Try turning off all MCBs in the consumer unit other than the one for the socket you’re using to charge. (Keep the RCD on too). Now try charging. If the car charges ok cancel the SC visit and book an electrician to fit a dedicated circuit or charging point.

For the technical reason…Earth leakage all adds up. Earth leakage

 

[Jason71]

My UMC trips one of my 2 RCDs.presume i have high leakage on that circuit already and UMC pushed it over the edge. UMC does have a significant residual current spike when plugged in but will not trip without help.
As others have said its probably your house. Try a different circuit or house to be sure.

 

[Sparkeur]

Plug in to your friendly neighbour and see what happens. If it works, it's your house. If it doesn't, it's the UMC. If your neighbour's house catches fire and burns down...take photo's and post them here.

 

[SpareHeadOne]

Plug in to your friendly neighbour and see what happens. If it works, it's your house. If it doesn't, it's the UMC. If your neighbour's house catches fire and burns down...take photo's and post them here.

And say, "Sorry".

 

[MrBadger]

The RCD is tripped by small amounts of current leaking away from the circuit not via the direct designed path. It is normally a very low nominal 30mA, although RCD's may trip at slightly different currents depending on age and condition, hence the reason to test every 6 months.

Is this current leakage a problem? Well, most often than not, no. It may well be absolutely normal and expected. It only becomes a problem if it is not expected or the current accumulates above the trip level and trips the RCD.

Many devices will leak current under normal safe operation. It may even be quite significant. The Tesla UMC will 'leak' around 2-3mA during normal use and several times that for a brief transient as the point that the car starts to charge.

The long and short of it is that it does not take many devices on a single RCD to get within striking distance of the RCD being tripped by an additional load, especially the UMC at start of charge. There is a big definitive article here Earth leakage that explains the problems along with the tripping current limits for different devices. Dishwashers, hobs, fridges, underfloor heating, heat pumps will all quickly lead to pushing the 30mA limit.

Its obviously up to you to get a electrician in to test the house for a fault. However if you turn off a couple of circuits served by the RCD at the current limiting circuit breakers (MCB's) (you could try unplugging a few individual appliances but you may end up chasing your own tail) then plug the UMC into a different live circuit and try and start a charge, if the RCD still trips, then you have a problem either with the UMC or the house that definitely needs further investigation. No need to inconvenience a neighbour and risk tripping their house electrics.

Unfortunately, if it is cumulative leakage, the only way to avoid the issue is to reduce the leak on the RCD. This may be as simple as using a different circuit, or may require a new RCD or even splitting circuits over more RCD's.

 

[JonB]

OK, some good replies here, thanks. I will visit the Service Centre to get the UMC checked out on Thursday. I've been using it to charge quite successfully for the last three weeks and now, suddenly, it has stopped working. And it's not as if it has just started raining... Earth leakage threshold going over the rated 30ma of my RCD is a credible possibility but I can't get an electrician out on a bank holiday (or at short notice). So, I'll see if the UMC is failing first. I did wonder about water ingress at the plug end - it's been reported before - but I've not been worried yet as I know it is supposed to be waterproof. Can't test the circuits today as I have a house full of family all on their PCs doing work. Joys of Xmas and all that. But it's a good call and I will try it if I get a chance. As regards testing with a neighbour, well I don't think it very neighbourly to come round, plug an appliance in and fuse their house! I do have a pod point in the local Tesco so I will see if I can get access (they are normally fully occupied).

 

[JonB]

An update on this problem - Tesla Gatwick tested my UMC and declared it good, so I waited until everyone was out of the house and did some tests. The sort of "does it charge with just the garage power on / circuit 1 / curcuit 1 + 2 / etc". I think it is called "ramp testing". Anyway, I seem to have isolated the problem to the consumer unit that controls the pool filter & heat pump so I have disconnected that for now, pending an electrician visit. It is undoubtedly as suggested - cumulative leakage tripping the RCD. Car is now charging fine with all the household circuits connected, which is a great relief.

Thanks to all for the advice, especially @VanillaAir_UK!

 

[Jason71]

I seem to have isolated the problem to the consumer unit that controls the pool filter & heat pump

#firstWorldProblems.

 

[Dilly]

Don’t go into the water…

 

[JonB]

#firstWorldProblems.

Indeed...

But no one who owns a new Tesla is going to be short of a bob or two, are they? Otherwise they'd be tooling about in a 15 year old Fiesta.

 

[M3noob]

Indeed...

But no one who owns a new Tesla is going to be short of a bob or two, are they? Otherwise they'd be tooling about in a 15 year old Fiesta.

Dunno. Some are just penny pinchers

Ooooo I just discovered a 22kw municipal charger that's FREE