National Grid incoming supply house fuse upgrade questions

Petriix

I ripped out an 8kW electric shower before getting my EVSE fitted so didn't even think about the fuse. I found out later that it's 60A. I gather that my installer should have checked it, which they may have done when pulling it out but it wasn't mentioned.

As I understand it a 60A fuse won't pop immediately if you briefly go over its limit but I have set a hard limit of 60A in the Zappi so it should automatically throttle charging if it would ever exceed that. However, even when running the oven along with the washing machine and tumble dryer at the same time as charging the car, import peaks at ~ 13kW which is around 52A at 240v. It's pretty rare to run this much load so I'm happy to stick with it.

The Zappi itself was installed on a separate CU, split with a Henley block before the main CU. 

cm4ever

Petriix said:

The Zappi itself was installed on a separate CU, split with a Henley block before the main CU. 

That's how our solar & battery storage was installed.

Interesting comments about your max house load experience, definitely food for thought and we use GCH for the shower, so no additional load there.

cm4ever

Reed_Richards said:

I take it you will be driving long distances each day so will need to add a lot of charge to the car each night?  Or you are signing up to a tariff that only gives you a short time to charge your car?  

Daily long distances - no not really, we only have the one car and our standard car use now isn't that much use really as I'm fortunate to have access to a hire car scheme at work for during the day work car use, after using public transport to commute to and from work. My wife mainly works from home, apart from 1/2 days per week where I'd take her in and she'd use public transport to return home.

So generally apart from holidays (which are only within the UK as far as our car use is concerned) the move to an EV wouldn't be a massive shift really apart from the initial cost of course, another factor in the planning / research. 

Tariff wise, I hadn't got that far with my thinking yet - maybe I've lined my ducks up in the wrong order so to speak with my EV charging research so far.

The potential incoming supply existing fuse rating was a potential red flag I'd come across so far, in isolation really to everything else I'd need to look at. From everything I've read, it seems to be a common potential requirement to change, if you see where I'm coming from.

I'll be honest in not being familiar with how long the different EV battery capacities would take to fully / part recharge normally from a plugin or granny charger, compared to a dedicated wall changer - but don't think my wife would be so favourable to that sort of setup compared to a dedicated EV charger, the more I could make it easier to recharge the better, so it can't be classed as 'a right faff to charge' otherwise the whole idea would be less appealing to her.

As ever, everything is a compromise to a certain degree in the end though.

silvercar

"I'll be honest in not being familiar with how long the different EV battery capacities would take to fully / part recharge normally from a plugin or granny charger, compared to a dedicated wall changer - but don't think my wife would be so favourable to that sort of setup compared to a dedicated EV charger, the more I could make it easier to recharge the better, so it can't be classed as 'a right faff to charge' otherwise the whole idea would be less appealing to her"

Household dedicated chargers are going to charge at up to 7KW depending on the car (my Leaf will take 6.6KW). A "granny charger" as they are known is basically a lead with a 3 pin plug at one end. That should deliver about 3KW. So to charge using a 3 pin plug is going to take a bit more than twice as long as a dedicated charger.

If you don't need that much charge (each kwh will give 2.5-4 miles, depending on outside weather driving speed etc so my 39KWH leaf gives about 120 miles in Winter, 160 miles in Summer) then you could charge overnight every night and have enough for daily use.
Questions about cheap rate tariffs are to determine if you could get all your charging needs during your tariff's cheap rate. So if you only have 4 hours of cheap rate, you will be more restricted than if you have 8 hours. If you don't have a time of use tariff it's irrelevant and the only question is whether you have sufficient time at home to charge your car on the granny charger, to give you enough kwH for your needs. 

You could make your charging "dedicated" with a granny charger, by having an outdoor socket fitted in a convenient location. That would hardly be any different to using a proper EV wall charger!

If we hadn't have had a free installation offer, we would not have needed a dedicated charger and we run 2 EVs and OH has a 50 mile round trip commute most days.  

MultiFuelBurner

We need to replace "granny charger" with "slow charge(r)) my granny isn't slow she is just considerate, unhurried but deliberate.

matelodave

As far as I know a granny charger is limited to 2kw, so you can expect to recharge at a rate of around 6miles per hour (assuming a rough estimate of 3mile/kwh, although some cars do better many do less in the winter) so an overnight charge of eight hours should give you around 48-60 miles.

A 7kw charger should manage that in around two and a half hours which allows you to take advantage of overnight EV tariffs which usually only give you 4-5 hours.

Netexporter

> As far as I know a granny charger is limited to 2kw

Mine runs at 2.3kW, so a third of the rate of a 7kW charger. I don't really need a 7kW charger for the speed, per se, but it would enable me to make maximum income when the Agile price goes negative.

MeteredOut

> As far as I know a granny charger is limited to 2kw

Mines runs at 3kW, as measured by both the energy monitor it is plugged into, and what the car states it is being received. Car also states 8-10 miles per hour, depending on temperature and recent driving metrics.

cm4ever

Thanks all for the variety of and information in your posts.

I've definitely got more food for thought on a possible move to an EV as our only vehicle, I can see now that I've got to initially look at it more "as a whole", then depending on the ideal outcome from our perspective, work out how this would be implemented in practice, some of my initial red flags may not really be issues after all.

Some really thought provoking questions and ideas, thanks.

dunstonh

With a view that in the future we may be looking at getting an EV. What are peoples experiences with the process of and the ins & outs of getting an incoming supply fuse upgrade?

We did it earlier in the year and it took about 3 months.

Although we're fortunate in being able to live in a fairly low usage household, our existing supply fuse is only 60A. I'm expecting that this would need to be updated to probably 80A to accommodate a future EV charger - maybe even 100A depending on specific EV charging requirements...

60amp to 80amp can be done easily and would be quicker.   We moved to 100amp and that required some extra work but it was better in the long run.  100amp because of a second high use device and that we wanted faster charging and room for future upgrades.  i.e. may as well go to 100amp if you are going to have to change it.

The car charger required upgrades to our consumer unit (time delay relay).   These were done by our electrician.   The meter tails needed upgrading.  They were done by EDF.   We were very lucky here as we didn't have a smart meter.  So, EDF arranged the smart meter and that involved adding an isolator switch and the meter tails.   The UK Power Networks (our DNO) did a site visit and arranged a second visit where they replaced the fuse case, the fuse and the wiring from the house to the power cable.

I'll be honest in not being familiar with how long the different EV battery capacities would take to fully / part recharge normally from a plugin or granny charger, compared to a dedicated wall changer - but don't think my wife would be so favourable to that sort of setup compared to a dedicated EV charger, the more I could make it easier to recharge the better, so it can't be classed as 'a right faff to charge' otherwise the whole idea would be less appealing to her.

PHEVs pretty much need overnight charging every night.  EVs need charging less frequently unless you are pushing high mileage daily.     Granny chargers will give you about 35 miles (late Spring/summer) or 24 miles Autumn/winter on a 7 hour charge (to match economy 7).

So, going full EV really does make a charger necessary unless you do very low mileage.  In that case, you would question whether EV is viable for that low mileage.

There are many reports of granny chargers melting sockets.  Often because the feed the garage is not sufficient or extension leads not up to the job are being used.

Another consideration you need with many chargers (all possibly?) is a wifi connection.  We have a pod point and the charging times are loaded by an app. Not the charger itself.  The charging times are on pod points server.   If the pod point loses internet connection, it goes to its default of charge on.     So, you can find it charging out of hours which can be expensive if its peak hours.     We have a mesh network that covers a couple of acres of our site and the the charger gets the signal it needs.      You may need to consider something similar if your charging point is not in wifi range of the house.