EV charger installation and fuse upgrade questions

Ectophile

If it's a wire from the incoming neutral to earth, then I wouldn't expect to see more than a few milliamps flowing through it. It's there for safely earthing the system, not carrying current in normal operation. It would be a slightly unconventional style of PME.

Without knowing what the cable is, it's hard to tell. Given that it's thinner, maybe it's a low power loop through to a small building somewhere. If that's the case, then clamping around the whole cable would reveal nothing, as you'd be clamping both the live and neutral, and they cancel out.

lohr500

https://forums.moneysavingexpert.com/discussion/comment/82102370#Comment_82102370

Thanks for the input.

I can't see it being a loop through to another building unless it was for a building that was demolished prior to us moving into the property in the early 1990's, and there are no other houses/buildings within a 500 yard + radius. If it is a loop through then goodness only knows how/where it terminates.

I followed @QrizB suggestion to see if there were any markings on the cable to identify if it was multi core or not, but drew a blank as there were no meaningful markings on the cable.

To compound matters, the email/webhosting service I use has been down today for over 10 hours so I can't access any emails to see if the DNO has responded. Might be time to change my hosting provider as I don't consider 10 hours acceptable for disaster recovery!!!

FreeBear

https://forums.moneysavingexpert.com/discussion/6679617/ev-charger-installation-and-fuse-upgrade-questions

Going back to the opening post… I have a 60A fuse with 16mm² tails. Had an Ohme Pro charger installed a couple of years back without any problem. Didn't get a fuse upgrade either. If you think your total current draw is getting close to 60A, I wouldn't worry about blowing the main fuse. Those things will quite happily let around 85-90A pass without blowing. You could even pull higher currents for short periods without blowing the fuse. See graph below for the current/time characteristics of your main fuse.

lohr500

https://forums.moneysavingexpert.com/discussion/comment/82101063#Comment_82101063

@QrizB I found the data for our specific transformer in the substation database section of the Northern Powergrid website. The map tool shows the exact location of it and it is named with our property name. Amazing what other info is buried in their free to access database section.

It indicates that the transformer is rated at 25kVA.. I've gone back to Northern Powergrid suggesting we have a phone call to discuss so we can resolve the maximum load question and the issue over the mysterious return cable from the incommer before the Pod Point engineer carries out the installation on the 26th August.

Heedtheadvice

As posted above 100A fuse holder is it's max capacity not the rating of the fuse contained. Often it is a 60A fuse.

Unless you need a big charge to an EV on the better chargers ( like the Zappi mentioned) the built in functionality is designed to be used to limit grid current draw when charging I conjunction with other 'appliances'/ storage.

I you charge at 7 kW for 4 hours and a bit more at a reduced rate that will be over 30kWh which is nearly half the capacity of many vehicles. That could be over 100miles charge a day even for winter driving or getting on for 250 miles over a couple of days all at a cheap TOU tarrif. A couple of hours at a higher cost rate (if needed) can then give another 50miles for a fiver. So unless you need more than 150 miles a day range ( which some will) then it is surely not an issue. Summer time with PV storage is then ( owing to lower general demand ) ok.

The high power domestic appliances ( dish/washing machine ) only draw kW for short periods a d can also be used outside of cheap periods with battery storage.

Qyburn

https://forums.moneysavingexpert.com/discussion/comment/82102773#Comment_82102773

Is there a rating plate on the actual transformer? I'm suspicious of that 25kVA rating. Maybe needlessly but our transformer is physically larger and rated 16kVA and 64A.

lohr500

https://forums.moneysavingexpert.com/discussion/comment/82103206#Comment_82103206

No rating plate on the transformer. I've looked closely with a decent pair of binoculars but nothing to be seen.

The main fuse is definitely 100 Amp (I saw the physical fuse last year when the Tesla battery installer checked it).
Prior to the battery install, the seal and label were intact so I'm guessing it must have been fitted by Northern Powergrid, or even the YEB before them.

No word back yet from then DNO. If I haven't heard anything from them by the middle of next week I will call them to discuss.

Qyburn

The main fuse is definitely 100 Amp

We have a 100A fuse, confirmed by the guy fitting our meter.

lohr500

https://forums.moneysavingexpert.com/discussion/comment/82103586#Comment_82103586

I wonder if your fuse had been upgraded at some point. Would it be normal to fit a main fuse with a rating much higher than your 64 Amp transformer? You would think the DNO would prefer your house fuse to blow before the transformer or any pole mounted fuse.

lohr500

Well after much communication to and from the DNO and Pod Point it seems as though the EV charger will have to be configured to a whole house load of 60 amps (as per the DNO EV charger approval letter) until I can get the 100 amp main fuse "upgraded" to 80 amps!!

DNO are saying the largest fuse they will now allow for a single phase supplies is 80 amps.

They won't accept my information that the current fuse is 100 amp and in the absence of any information of their own, they had assumed it was a 60 amp fuse, hence the 60 amp whole house limit they set.

So now I've had to submit an upgrade request to upgrade the main fuse to 80 amps. Even though there is a 100 amp fuse in place!!!

Without sorting the fuse, Pod Point are saying they have no option but to follow the previously granted 60 amp whole house load.

Nothing is simple!!!!