charger help - what happened?

[Yellowelise]

Hi all

Any one else had their granny charger moulded plug melt down?

Have had our ZS LR since April
Almost exclusively granny charger charged (1, 20 min rapid chrge in July).
Never used an extension, have socket in porch direct out to car.
Got stuck in a motorway jam on Thursday and ended up getting home with 7% battery left.
plugged in as bormal left plugged in all night and day, went to take off plug around midday but it wouldn't come out of socket.
hubby couldn't get it out either so off goes electric and socket faceplate.
photos show the plug overheated a pin and melted!!

did not short the fuse
car fully charged and giving 313 miles range.


Anyone else had this?
Ideas as to what happened?
also can I cut the cable and put a non moulded 3 pin plug on

 

[Gadget Geek]

Most domestic sockets are not rated to take 10 Amps over that prolunged period of time.

You need something like this;

Sync EV Masterplug EV Mode 2 Charger with a Type DP RCBO - EVH132S1SPA

Electrical2Go Sell Discount Sync EV For use with Mode 2 EV charging cables (UK 3 pin to Type 1 or Type 2). for Both Trade & Home Use. Big Name Brands, Free Delivery.

www.electrical2go.co.uk

 

[Yellowelise]

thanks @Gadget Geek

I am assuming I can't use the charger like that?
can I just put a new plug on?

 

[Gadget Geek]

Yes, just make sure it's a good quality one. There's a british standard, I'm sure an electrician on this forum would know.

 

[MG steve]

Is your wiring red and black throughout your property as it’s quite old and probably due for a rewire.

You can get a granny charger where you can reduce the current but of course it’ll take even longer to charge. I have a Vonhaus one where it measures the temperature and I have set charge current to be 6A.

 

[Jomarkh]

thanks @Gadget Geek

I am assuming I can't use the charger like that?
can I just put a new plug on?

No, as the moulded plug has a thermal sensor built-in.
Was the socket used a new installation with protection to the lastest regs?

 

[Gadget Geek]

If it has a thermal sensor built in, it ain't working.

 

[Alb]

You can certainly fit a new plug but make sure it's a good quality one and research how to make good connections if you don't already know how to do this.
Your installation isn't unsafe just because it has old colour conductors but it wouldn't be a bad idea to have an EICR done.

 

[Rolfe]

There is damage there to both the socket and the plug. The socket is relatively easily replaced, but has the damage to the plug buggered his granny charger entirely? Some say yes, some say that the plug can be replaced?

But what was the primary cause of the fault? The plug or the socket?

 

[Lovemyev]

But what was the primary cause of the fault? The plug or the socket?

I am going to speculate that the problem started at the outlet switch plate myself and not the moulded three pin plug myself.
The heat generated at termination of the conductor is likely the cause of the damage to the three pin plug.
That outlet would ideally be wired on its own dedicated circuit in the CU and a high quality socket outlet installed with trip built in maybe, as I have a feeling that the CU maybe the older type CU that is not fitted with any RCD’s etc.
As the OP states that it did not blow the fuse.
The problem installing a new three pin plug, is that making off the conductors is difficult because of the size outer cable protection.
The problem I have with use of Granny cables, is that because they are fitted with a three pin plug, everybody assumes that these things are fair game to be used on any socket outlet installed everywhere !.
Without having the outlet checked for suitability first.
A socket outlet that was installed twenty years ago to power a table light or a lawnmower for twenty minutes, is not ideal for prolonged use on a high demand item like a Granny unit, without having it checked first.
The cause of the excessive heat needs to be investigated and resolved.
It’s normal for the plug top to get warm, but NOT to a level where the conductor has failed to this level.
A potential fire was averted here thank goodness !.

 

[Alb]

I'd also say that a socket fault was much more likely than a plug one.

 

[Grriff]

'A socket outlet that was installed twenty years ago to power a table light or a lawnmower for twenty minutes, is not ideal for prolonged use on a high demand item like a Granny unit'.
Any socket that was installed 20 years ago (and I rewired two houses before then - both then checked by a professional and certificates issued), should be on a ring main with sockets capable of delivering 13 amps without overheating.
The only problem I have had with overheating occurred due to loose connections into the main switch in the consumer unit (my fault). I called a professional electrician in, who installed a new mains switch but reversed neutral and live! Luckily I discovered this very quickly but it finished off the washing machine.
I would suggest a loose connection - possibly the 13A fuse in the plug.

 

[gazza487]

'A socket outlet that was installed twenty years ago to power a table light or a lawnmower for twenty minutes, is not ideal for prolonged use on a high demand item like a Granny unit'.
Any socket that was installed 20 years ago (and I rewired two houses before then - both then checked by a professional and certificates issued), should be on a ring main with sockets capable of delivering 13 amps without overheating.
The only problem I have had with overheating occurred due to loose connections into the main switch in the consumer unit (my fault). I called a professional electrician in, who installed a new mains switch but reversed neutral and live! Luckily I discovered this very quickly but it finished off the washing machine.
I would suggest a loose connection - possibly the 13A fuse in the plug.

Delivering 13a yes but not for a sustained period, this is why “official” granny leads are 10a which is what a socket should be able to sustain. Lots available will ignore and pull 13a - some really bad ones seem to be even worse and will try 16a which is more suited to other countries despite them sticking our plug on. This is one area our ring finals lets us down on, the fuses tend to heat up at sustained high load and conduct down the pins a la a melted mess.

There is another issue or 2 that can arise - the spring contacts in a socket can relax / become oxidised leading to heat generation at the contact. I have also had wiring when over the years cycling temperatures the terminating screws slacken off - again a poorer contact.

OP looks like the neural got too hot so agree probably bad connections. I’d contact a sparky for assessment of the home wiring if unsure and replace the sockets/whatever is necessary. Some granny chargers have sensing in the plug so there will be extra wires in the lead not just positive, neutral and earth - there would be smaller conductors to go to a thermistor in the plug. If it is just standard 3 core you could replace with a good quality plug, if there are more you are out of luck without some serious fiddling.

 

[Lovemyev]

I have taken another look at the photo supplied by the OP and it does not include the negative ( black - old colours ) single line conductor in the shot ?.
I imagine it’s totally fried though !.
The red live conductor appears to have had the red outer isolation sleeve pinched slightly by the termination screw.
This condition can produce a bad connection at the outlet, heat slowly builds up over a longer period of time.
A poor connection / termination is likely to be the main cause, maybe combined with a lower quality accessory / outlet plate.
The supply cable should be rated at 2.5 mm and no lower, it will have been affected by the over heating.
The heat damaged cable will require cutting hard back and checking for transmitted heat damage.
This may cause an issue when it comes to terminating the new socket outlet.
Unless it can be relocated to gain more cable length ??.

 

[Yellowelise]

Yes, just make sure it's a good quality one. There's a british standard, I'm sure an electrician on this forum would know.

Thanks again @Gadget Geek, I have already replaced the socket faceplate and will get a good quality plug for the charger which appears to be absolutely fine.

There is damage there to both the socket and the plug. The socket is relatively easily replaced, but has the damage to the plug buggered his granny charger entirely? Some say yes, some say that the plug can be replaced?

But what was the primary cause of the fault? The plug or the socket?

hi @Rolfe , the charger itself appears to be fine. car fully charged with no detriment we can see. Have replaced socket faceplate already as had a spare.

I am going to speculate that the problem started at the outlet switch plate myself and not the moulded three pin plug myself.
The heat generated at termination of the conductor is likely the cause of the damage to the three pin plug.
That outlet would ideally be wired on its own dedicated circuit in the CU and a high quality socket outlet installed with trip built in maybe, as I have a feeling that the CU maybe the older type CU that is not fitted with any RCD’s etc.
As the OP states that it did not blow the fuse.
The problem installing a new three pin plug, is that making off the conductors is difficult because of the size outer cable protection.
The problem I have with use of Granny cables, is that because they are fitted with a three pin plug, everybody assumes that these things are fair game to be used on any socket outlet installed everywhere !.
Without having the outlet checked for suitability first.
A socket outlet that was installed twenty years ago to power a table light or a lawnmower for twenty minutes, is not ideal for prolonged use on a high demand item like a Granny unit, without having it checked first.
The cause of the excessive heat needs to be investigated and resolved.
It’s normal for the plug top to get warm, but NOT to a level where the conductor has failed to this level.
A potential fire was averted here thank goodness !.

thanks @Lovemyev clear and sensible once you think about it. We do have a new CU though with RCD's for each element, this socket is a single spur off the downstairs socket ring main. The socket itself was an external box in an unheated porch and quite an old one > 10 years to my knowledge. As we have been charging the car using this since new (>6 months) with the advice given here I am gauging that time is the element as we have never charged for 24hrs from 7% before.
we will only normally charge for short periods in future and keep an eye on the socket until we can change to an ev charging socket. Will investigate these next week.

I have taken another look at the photo supplied by the OP and it does not include the negative ( black - old colours ) single line conductor in the shot ?.
I imagine it’s totally fried though !.
The red live conductor appears to have had the red outer isolation sleeve pinched slightly by the termination screw.
This condition can produce a bad connection at the outlet, heat slowly builds up over a longer period of time.
A poor connection / termination is likely to be the main cause, maybe combined with a lower quality accessory / outlet plate.
The supply cable should be rated at 2.5 mm and no lower, it will have been affected by the over heating.
The heat damaged cable will require cutting hard back and checking for transmitted heat damage.
This may cause an issue when it comes to terminating the new socket outlet.
Unless it can be relocated to gain more cable length ??.

I have taken another look at the photo supplied by the OP and it does not include the negative ( black - old colours ) single line conductor in the shot ?.
I imagine it’s totally fried though !.
The red live conductor appears to have had the red outer isolation sleeve pinched slightly by the termination screw.
This condition can produce a bad connection at the outlet, heat slowly builds up over a longer period of time.
A poor connection / termination is likely to be the main cause, maybe combined with a lower quality accessory / outlet plate.
The supply cable should be rated at 2.5 mm and no lower, it will have been affected by the over heating.
The heat damaged cable will require cutting hard back and checking for transmitted heat damage.
This may cause an issue when it comes to terminating the new socket outlet.
Unless it can be relocated to gain more cable length ??.

hi @Lovemyev , none of the socket wires have any heat damage. The melted part of the faceplate in photo is where the melted plug pin sits.

The only heat damage is to the insulation on the three pin plug which has completly melted off and the corresponding area on the rear inside faceplate.

All wiring (E/N/L) and it's insulation shows no damage at all, they were not loose but still securly connected to the faceplate when I went to change the faceplate.

No, as the moulded plug has a thermal sensor built-in.
Was the socket used a new installation with protection to the lastest regs?

Hi @Jomarkh
Do you know if the MG granny charger has this thermal cut out or not?

it was an existing installation, yes to all the relevant regs.
Although as below it is a spur off the downstairs socket ringmain.

 

[Lovemyev]

hi @Lovemyev , none of the socket wires have any heat damage. The melted part of the faceplate in photo is where the melted plug pin sits.

The only heat damage is to the insulation on the three pin plug which has completly melted off and the corresponding area on the rear inside faceplate.

All wiring (E/N/L) and it's insulation shows no damage at all, they were not loose but still securly connected to the faceplate when I went to change the faceplate.

When you removed the three conductors from the old burnt outlet, was there any evidence / witness marks on the plastic insolation of the individual conductors, where the termination screw had pinched the plastic sleeving ?.
In this situation, the termination screws are tight, but they are biting on the plastic isolator and NOT directly onto the copper cores with sufficient pressure.
Resistance then causes heat to develop.
If the individual conductors were made off correctly and the termination screws tightened to the correct torque, then the quality of the outlet has to be the questionable cause.
I tend to favour MK products or another quality brand of accessories myself.
Given the spur is taken from a ring main, I am a little surprised it did not trip the breaker ?.
A good reason to have the outlet on its own dedicated circuit I guess.
A wall box is the best solution as it places less restriction on length of charging required and it offers a second means of charging, in cases like this !.
Install a wall box and then retire the Granny unit is more ideal for long term usage .

 

[tsedge]

Don't forget you can limit the current that an AC granny charger will draw in the car via the charging screen, to keep loads down I'd recommend chosing the 6A setting for any installation that does not have a dedicated socket connected directly to the consumer unit and checked by an electrician.

The problem is granny chargers were initially intended for occasional use, partly because so many houses have sub- standard wiring. There's no problem with good wiring and a quality granny charger but there's a lot of people out there without both.

 

[Rolfe]

Is it possible to spot a problem like this before it actually occurs? Every time I have felt my granny charger plug after many hours of charging it has been cold. I showed the setup to my electrician while he was here about another matter, and without looking at it in detail he said it was fine. The power points in my garage are metal-jacketed (which he said would help dissipate any heat) and on a dedicated ring main. He also said the garage being dark and cool was a good thing.

If one checks for heat in the plug periodically, and there is none evident, how likely is it that something will blow up with no warning?

 

[Yellowelise]

Don't forget you can limit the current that an AC granny charger will draw in the car via the charging screen, to keep loads down I'd recommend chosing the 6A setting for any installation that does not have a dedicated socket connected directly to the consumer unit and checked by an electrician.

The problem is granny chargers were initially intended for occasional use, partly because so many houses have sub- standard wiring. There's no problem with good wiring and a quality granny charger but there's a lot of people out there without both.

@tsedge thanks thats really useful, how do we limit the current to 6A?
Apologies if we should already know how to do this.

 

[Rolfe]

I think you do it on the charging screen in the car.