EV charge point 60A-100A or not?

[YorkshireMidge]

One of our neighbours/friends is looking to get an EV charge point installed and was asking me what might be needed, and I have to confess it's not a subject I've ever looked at. But what was obvious on both our house and theirs is the supply fuse is 60A, and when I look at articles regarding EV points, it often suggests taking that up to 100A which seems fairly beefy - and a potential bill from the DNO (Northern Powergrid in our case).

I don't know anything about the peak/ave load figures for their property at this point in time, but I have had a quick look around and both bathroom showers are mixers off a combi, so there is just an electric oven (hob is gas), washing machine and a tumble dryer as significant loads. So I'm kinda thinking that the EV charger is the equivalent of just adding an electric shower, and that doesn't feel excessive and maybe a 60A is still fine in this case. Obviously if there was an electric shower as well as the charger, then the need to go up from 60A is much clearer.

Does this feel about right based on the limited info I've provided?

Thanks.

 

[flameport]

60A OK in most cases, as almost all of them will monitor the total load on the installation and automatically reduce the charge current to avoid it going over a set threshold.

 

[ericmark]

It seems suppliers don't all read from the same song sheet, there is no reason why one should not charge an EV with a 60 amp supply, if a CT coil is used to reduce or stop the charge if the rest of the house is using too much.

However, we see some DNOs refuse to allow a charge point to be fitted because the supply is shared, in theory if you have a 60 amp fuse, you can draw 60 amps, in practice diversity is used, and the DNO does not expect every house to use the maximum at the same time, and this was true back in the last century, but the way we are using grid power, with solar panels and EV chargers has entirely changed what can be expected.

And it seems back in the 60s records were not always kept as to what has been done, so back in around 2010 my son wanted his supply moved, as building an extension, and he paid the money, and fitted a new meter cupboard ready, and then the workers arrived, and it seems he was bundled, but it was not on the records, and no way leave had been issued to allow cables to go around the side of his house to next doors.

His house was easy, supply cable would be shorter, and all in place, but next door was a problem, it would mean digging up next doors new drive. Also next door had the meters and fuses in a place where it was near impossible to get a cable to from front of house, lucky sons extension was stalled, lack of money, as it took over a year to sort out, lucky price was frozen, as it must have costed a fortune to get the new supply to next door.

But the DNO have been caught out a few too many times, so they are now more careful when giving permission etc.

The large problem is the neutral load, a supply to 150 homes back in the 60s would have very little load on the neutral, the three lines would have a large load, but this is the nature of a three phase supply. Today there are people like me, who use nothing in the day, but have a large load overnight in my case charging the solar batteries. So the load changes due to number of EVs or solar on that phase.

So today you simply don't know until you apply to the DNO. We as users have no idea how the power gets into out homes, we have a goverment saying do this and that, who have no idea what problems doing this or that will cause. Be it parking in front of a drop curb, parking on the walkway, cables on walkway, cables above the walkway, loss of PEN, and dangers as a result.

You must remember this where he clearly miss read advice, but sometimes it is not so clear, and goverments make errors. We were told drive diesel not petrol then the advice reversed. So ask the DNO not a forum, I have made many mistakes, and to make a mistake, so someone buys an EV then can't charge it at home, is serious, so ask the DNO.

 

[YorkshireMidge]

@ericmark Good points. I was just after a gut feel at this stage, as it will go for DNO check asssuming our friend takes the idea forward. Both yours and @flameport responses provided the gut feel and the point about CT clamps which I wasn't aware of, so thanks to both of you.

 

[ericmark]

I will say @flameport is a very clever guy, and I would say better than me. Yes hard to admit, but he is very much in the know, but he is advising like most of us, about what his own DNO does. As we move around the country, the results may vary.

 

[Murdochcat]

If you have gas central heating it’s unlikely to be an issue. If you have storage heaters it might be

 

[ebee]

Yes, as Eric has alluded to, we all give our opinions about the why and wherefore and though we might have specific knowledge we are not infallible so asking your DNO should be your first start and take it from there we are advising you the best we can . Run the question thru (so called) AI might give you additional info and opinions too

 

[ericmark]

If you have gas central heating it’s unlikely to be an issue. If you have storage heaters it might be

Very true, we tend to just consider our own homes, looking at my own I already use 4.4 kW overnight at cheap rate, add 7 kW to that and looking at 50 amps, so getting close to the mark, here I peaked to 6.4 kW so add 7 to that and at 58 amps, that's getting close to the mark. I call them the big three, washing machine, tumbler drier, and dishwasher, all three have a delay timer, so can set before going to bed to run when we have off-peak, summer we don't worry so much, but still we get 12p/kWh for export and pay 8.625p/kWh for off-peak import, so better exporting during the day and importing overnight. Winter we run out of battery, so can pay 32.277p/kWh using the items during the day.

The real point is what the charger can do? The same goes for what a solar inverter can do, I could not allow my supplier to control my inverter even if I wanted to, it has not got that option. The same goes for an EV charger, some you can allow the supplier to control, and as a result get an even lower tariff to my 8.625p/kWh overnight, son went with Octopus for whole package, as their charge rate is so low if you do, really unfair trading, as an independent electrician can't compete.

But this means Octopus control when your car is charged, which could result in a supply overload even if not in your own house, as it may charge your car during the day, as electricians we have no idea what the DNO infrastructure is like coming to our homes, only people who know are the DNO, and from YouTube videos it seems they have made errors, but if their error they put it right.

Personally I would follow sons example and let the billing agent do it all, i.e. Octopus. All we can do is guess.