Home charging cable plug melt down

[uncleman]

I have a nearly 3 year old MG4 bought from new. I do very low mileage and have only charged the car from home with the cable lead that came with the car. Yesterday when I noticed my car stopped charging at 94%, we could smell smoke in our living room. I then noticed the 3 pin plug that goes into the socket had melted down. This is only the 3rd time in the 3 years that I tried to charge my car 100% as I was going on a 300 mile return journey trip. I normally charge my car 20/80. Like I said I do low mileage and charge my car roughly every 6 weeks, on average. I'm wondering has anyone else had a similar incident, if not please be aware and not leave the car charging over night from inside your home socket. Maybe it's something that happens over time, I don't know but I never had charging issues before.

 

[Jomarkh]

Hi, it is not uncommon for the fuse holder in the plug to fail which looks like the cause in your case. How often do you charge up and is the granny EVSE left plugged in?

 

[Tight Git]

Yikes - that could have gone very badly and shows why granny chargers are only meant for emergency use.

It looks like the fuse hasn't been making a good contact in its holder and has caused the overheating. However I'm surprised that the thermal cutout didn't trip it.

Just be aware that you cannot just chop the plug off and connect a new one as there are thermistors in the plug (or at least there should be!)

 

[Everest]

I'm wondering has anyone else had a similar incident, if not please be aware and not leave the car charging over night from inside your home socket. Maybe it's something that happens over time, I don't know but I never had charging issues before.

Yes - happened to a few already and posted on here (for example with @Yorkshire Hillbilly)

Thanks for sharing the detail - out of interest what rate were you charging at? Regular (i.e. non BS1363-2 EV rated) plugs and sockets are not recommended for continual charging over 8A.

The connection of a BS1363 plug's fuse is a particular weak point, due to limited contact area, as I mentioned in my posting of just 2 weeks ago...

Post in thread 'MG4 - charging from a 13A socket'

Nov 13, 2025

re comments from @tsedge and @Fogey.

The main concern with using a regular (rather than EV-rated) 13A plug+socket is that they are not designed for or tested against continual high loads or disconnection of inductive circuits under load.

The weak points are:-

a) the contact of the live and neutral pins which, being square, rely on a small surface area of contact. The resistance of which will increase due to tarnishing on the brass pins and weakness over time of the spring of the socket's connection and

b) the limited contact area and quality of the connection of where...

• Everest

• 
• 

 

[Yorkshire Hillbilly]

As @Everest said, I had an issue with charging from a granny charger but, it was the extension cable plug and Tapo socket that were melted together.

I've since changed the plug socket and extension cable to EV rated ones. And I'm using a CT clamp and Fingerbot to automate the socket switch-off should someone in the street happen to plug something into my extension cable whilst I'm not at home.
*the 30m extension ends in a bush next to my private parking space in a public carpark.

please be aware and not leave the car charging over night from inside your home socket

Fortunately my cable's plugged into my garage with its own consumer unit (fuse board). I'd never plug it into my house or any other house unattended.

Contact MG and ask for a new one? Tell them you were using it as an emergency charger as described in the manual

 

[Everest]

Contact MG and ask for a new one? Tell them you were using it as an emergency charger as described in the manual

. I'd certainly do that.

Personally, I'd also be inclined to raise the issue with Trading Standards as your charger was presumably a genuine MG one - it is clearly not up to the job, unless you were charging at a greater rate than the MG was designed to do... Which itself, should not be possible with a properly designed product.

And... don't let them fob you off with "you weren't using it in a BS1363-2 EV rated socket either. Whilst overheating problems are commonly triggered by faulty sockets, in your case, it was clear a sub-standard plug, specifically overheating at the fuse connection point.

Spoiler: Don't try this at home!

And as a total aside.... = don't try this at home! IMHO, the weakest point of a BS1363 plug is the fuse contact (as in these two examples above). A safer solution, if one were forced to use a 13A plug would be to wire a socket on a dedicated circuit via a 10A MCB. Then 'hack' the plug to bypass the fuse by repurposing a 'neutral' pin from another plug. Having said that, it would be preferable still to use a commando plug and socket, which are designed for 16A or 32A loads.

 

[EvTek23]

The part that has got hot in the plug is the connection/ interface of the fuse to the plug internals, and not the connection to the 13A socket. This looks like the Granny charger plug, or at least the fuseholder moulded into the plug is at fault as @Everest points out.

 

[Lovemyev]

Given the state of that 3 pin plug, then I would strongly suggest that you consider replacing the socket outlet front that it was plugged into.
Surprised it never tripped the breaker tbh ?.
Assuming your consumer board ( fuse box ) has them installed of course.
If not, then consider replacing the front with a socket accessory that does includes a built in RCD trip at the very least.
Regular charging via a granny unit is better supplied by its own dedicated circuit supplied direct from the consumer unit, not off the domestic ring.
A suitable rated weather outside IP socket, is a safer option.
The subject of using Granny units to safety carry out lengthy regular charging sessions, has been completely done to death on this forum already tbh.
There are simplytoo many factors involved in different user cases and individual ages of home electrical wiring and supply that is a not suitable for the safe load term use of Granny units.
Yes of course, these units are designed to be used safely from any 13 Amp socket outlet in principle, this makes them appealing and simple for charging your EV or PHEV’s.
However remember the constant high sustained load generates unwanted heat at the weakest point in the circuit.
This is likely to be the holding pins of the 13 Amp in line fuse holder inside the plug.
Add in the mitigating factor of the length of time spent supplying this high load on a full charge cycle and there is the problem in a nut shell.
Some other appliances do pull similar loads in the home, but rarely over long time scales and frequently like in these cases.

 

[Everest]

Given the state of that 3 pin plug, then I would strongly suggest that you consider replacing the socket outlet front that it was plugged into.

good point.

Totally agree on the issue of BS1363 not being designed for sustained usage at high current. And that problem has got worse in the last 5 years or so when most EV's have at least 50kWh batteries compared to the "first generation" ones that were often in the 20-30kWh range, resulting in extended charging durations.

With regard to your other points... my 2p worth is:-

Surprised it never tripped the breaker tbh ?.

An MCB will only trip when significantly too much current is drawn and nothing to do with the lack of dissipation of heat on any part of a circuit. It was likely just 8 or 10A passing though the plug, with a poor fuse connection that has caused the overheat issue. I doubt the granny charger started pulling 40A+ that would be needed to trip a 32A ring final MCB.

Assuming your consumer board ( fuse box ) has them installed of course.
If not, then consider replacing the front with a socket accessory that does includes a built in RCD trip at the very least.

All CU's should have old fashioned fuses, if not MCBs.

With regard to RCD's; they were mandatory for all new builds after mid 1970, (edited out) commonly installed for any CU upgrade since the 16th Edition Wiring regs. (=1992). RCDs then became mandatory for any new ring final upgrades after 2008.

So, it's technically possible the house was pre-1970's and never had update that added RCD protection to the ring circuits. If that is the case, I'd suggest the OP gets a sparky into upgrade the electrics to current standards, rather than having a workaround of an individual RCD protected socket.

 

[Lovemyev]

Our current house was built in1982 and it had re-wirable fuse box.

 

[Everest]

My mistake - was only for sockets that may be used outside before 16th Ed.