Replacing an old fuse box

[Silly Car]

Her in doors doesn't want a thick black cable clipped to the outside of the house.

Have it mounted low and go buy some plants to, erm , plant in front of it, our garage feed run is clipped to the front of the house, in summer you can't see it for the flowers and in winter it's dark anyway.

Or get busy with a spit shovel and trenching spade…

[.....]

I thought I'd try my granny charger today, had the car two months and had never had it out the bag.

Got an alert from the app that charging had stopped after 10mins.

Checked the charger and a red thermometer was flashing.

Good job these chargers have temp sensor in the three pin plug part ...

PXL_20251004_155348854.jpg

Fitted a different face plate I had laying around and it's done the same (this is a socket in the garage near the main door).

Assume I really just need a brand new decent quality socket and it's nothing to do with the wiring?

Looks like you're doing mate's rates nowadays!

[KungFooBob]

This thread seems to have split into two topics, the original wiring query and then my granny charger issue...

So the charger...

I put a nice new MK metal clad socket up.

Chopped back the cable a bit and spotted a badly kinked live, stripped back it, was only the insulation holding the cores together. I guess that was a potential source of extra resistance.

Anyway new socket up and working, the charger plug started to get very hot again. I pulled the plug and popped the fuse cover off, it was all black and charred with half the carrier melted into the fuse holder. I cleaned it all up, scrapped all the melted crap out, rubbed the fuse contacts clean, tried again. Charred the fuse again in five mins.

Another clean and a new fuse, plugged into a different socket, same result. So i'm going with a fucked charger (tho' the original socket might have be the root cause)

I'd like to just chop the three pin glug off and put a new one on, but it contains two thermistors and there's three additional cables over the L/N/E.

I have discovered that the charger is used in a dozen different BMW markets, so the mains end is removable from the charger body. Hopefully a new part will get it working again.

[mangocrazy]

I'm more than a little confused as to why the fuse doesn't blow. It seems to have more than enough provocation. Did you dial the car's charging request down from 13A to !0A, as you said you were going to? Certainly something in the circuit is operating at or beyond it's intended limit. I wouldn't be remotely comfortable using that charger until you've definitely established what the issue is and fixed it.

[KungFooBob]

I'm more than a little confused as to why the fuse doesn't blow. It seems to have more than enough provocation. Did you dial the car's charging request down from 13A to !0A, as you said you were going to? Certainly something in the circuit is operating at or beyond it's intended limit. I wouldn't be remotely comfortable using that charger until you've definitely established what the issue is and fixed it.

I did dial the amps back, no difference.

This is the first time I've ever tried to use the granny charger, after the first time it stopped of its own accord it's never been unattended or left on for more than a couple of mins for testing.

[mangocrazy]

I just Googled 'EV 13A charger overheating' and this was the first hit on the list:


https://www.speakev.com/threads/corsa-e ... re.166682/

Sounds like a carbon (no pun intended) copy of your issue. Basically 13A sockets are only rated at 10A max in continuous running, and less is preferable. A lot of responses suggest running at 8A or even 6A. Some 13A chargers when tested are pulling 15A, apparently.

[KungFooBob]

Yeah, I think the first time I used the granny (13a) charger the socket overheated (albeit only took about 20mins rather than several hours).

This then permanently damaged the three pin plug on the charger, so now it gets too hot to touch after about 5 mins regardless of where you plug it in.

I was only trying the granny charger for the first time because I got an email saying I had two hour of free leccy on Saturday. I guess it's better its failed when I don't need it rather than getting home at some point on minimal SOC and not being able to to charge it.

[mangocrazy]

Sounds about right. At least you can get hold of a new charger in advance of needing it, so something good has come out of it.

[KungFooBob]

I still need a proper 7kwh charger, the 2kwh granny charger is supposedly only a last resort.

For the last two months I've been charging at work for free, but it might not last forever.

[mangocrazy]

I'd call a decent home-charging point an essential if you're running an EV, which is one of the reasons I don't see an EV in my short to medium term future. No off road parking and a terraced house.

[KungFooBob]

I kind of agree, but only because public chargers are as expensive as buying petrol.

I've an InstaVolt charging station 0.7 miles from my house in the Tesco Local carpark. It'll charge my car from 10% to 80% in 30mins while I buy my booze and scratch cards, but it costs 87p a KWH!!!

[Taff]

I did some quick sums a little while ago, and figured that about 47p /kwh is about the equivalent of running our diesel ovlov.

The only chargers around here that are cheaper than that are the tesco ones at 44p, all the rest are 56p +.

£1800 to get the charge point fitted is a lot of diesel.

[KungFooBob]

£1800 is a lot for a charger, I thought they were typically around a grand?

All new builds with parking have to have a charger. As I see it, as EV's start to become the norm an EV charger will be something that house buyers will be looking for, so it's adding value to your house.

[Taff]

It is a lot, but it's the cheapest quote (and most sensible) by quite a margin.

The charger is nearly 70m from the house fuse board by the time it goes around the garden by the simplest route that doesn't involve a long trench.

[Couchy]

6mm 'should' be ok for the EV charger, if there's not a lot of load on the other circuits, most can be tuned, so rather than pulling the full 7kw, they can be tweaked to 5 or 6 if it trips.

I had read about the RCD selectivity, which was why I haven't been to Screwfix yet

If the CU has a 6mm feed and you are running another 6mm to the car charger the main feed may not be big enough. Also you shouldn’t be connecting a car charger to a normal RCD that you have in the house as the car charger can blind an RCD making it useless. The car charger should be connected directly to the incoming supply in the house and not through an RCD that the house uses. The car charger should,d have an inbuilt RCD or a type B RCD feeding it which can’t be blinded. It should also not be connected directly to the house earth and PME earthing unless it has an open neutral device built in which a lot do have.
Changing the garage CU is easy but the car charger comes with its own set of regs and you don’t want to get it wrong, if you do and the local transformer loses its neutral the whole load of that transformer could in theory go through your metal car body, only releasing when you touch the car grounding it. Message me if needed

[KungFooBob]

6mm 'should' be ok for the EV charger, if there's not a lot of load on the other circuits, most can be tuned, so rather than pulling the full 7kw, they can be tweaked to 5 or 6 if it trips.

I had read about the RCD selectivity, which was why I haven't been to Screwfix yet

If the CU has a 6mm feed and you are running another 6mm to the car charger the main feed may not be big enough. Also you shouldn’t be connecting a car charger to a normal RCD that you have in the house as the car charger can blind an RCD making it useless. The car charger should be connected directly to the incoming supply in the house and not through an RCD that the house uses. The car charger should,d have an inbuilt RCD or a type B RCD feeding it which can’t be blinded. It should also not be connected directly to the house earth and PME earthing unless it has an open neutral device built in which a lot do have.
Changing the garage CU is easy but the car charger comes with its own set of regs and you don’t want to get it wrong, if you do and the local transformer loses its neutral the whole load of that transformer could in theory go through your metal car body, only releasing when you touch the car grounding it. Message me if needed

Cheers Couchie, I've just got off the blower with a local installer, they're gonna do me a quote for it all.

There were on about taking the feed from the meter and going under the floor rather than clipping it to the house, which might make her in doors happier

[crust]

....useful stuff....

Changing the garage CU is easy but the car charger comes with its own set of regs and you don’t want to get it wrong, if you do and the local transformer loses its neutral the whole load of that transformer could in theory go through your metal car body, only releasing when you touch the car grounding it. Don't forget to get someone to video this, it will be worth a fortune on youtube

Fixed that for you

[KungFooBob]

So rightly or wrongly I've had my charger/fuse box done today.

The bloke was lovely, a proper nice fella, all the work looks neat and I'm very happy.

The car charges at the full 7kwh fine and nothing seems to be on fire.

I'm not going to use the charger much as it's free at work, but it's a nice to have just in case.

[Couchy]

You did say the feed to the consumer unit is on a 32A mcb from the house and on the RCD side too ? The car charger is on a 40A so that’s against the regs as there’s no discrimination, if the car charger overloads it won’t trip the 40A first it’ll trip the 32A in the house. There’s also the issue of the house RCD which will be a type AC and these can be blinded by a car charger in fault so aren’t recommended to feed them.
If the car charger is on drawing 32A and you plug anything of load into the socket you’ll also run the risk of overloading the 32A and the cable feeding the CU.

I’d def be asking questions of the installer here mate.