[Jetlagged]

I'm a total newbie to the EV scene and considering my first purchase and also I only have a basic knowledge of house electrical systems, so go gently please!

I was planning to ask a couple of charging questions. However, I have just read through the very interesting thread, "newbie advice on getting ready for an EV" and I think I'm sunk even before I start on my planned move into the world of EV ownership. Our house has a 30A main fuse and, from what I have been reading, I don't think that this will support a 7.4kw wall charger. The situation is that the meter is on an outside wall by the front gate, the distribution board is by the front door and the garage is underneath the house. Is it possible to run a supply to the wall charger im the garage directly from the meter thus bypassing the need to upgrade the fuse in the distribution board please?

 

[GOSPORT DAVE]

My knowledge is pretty limited in this area as well, but what I do know from having a Podpoint charger fitted, is that you property electric supply needs to be protected with a 100amp fuse, a lot of properties only have an 80amp fuse which make thing a bit tight, which could result in your charger being limited to 16amp (3.6Kws)

The fuse is located between the incoming electric supply and meter, your energy supplier should update this fuse free of charge on request. (it should state the current capacity on it)

When to charger is installed, it is connected up to the supply directly with a spur after the meter so that the supply to the consumer unit is not interfered with. I has it's own circuit breaker unit for protection and isolation.

hope this helps, I am happy to be corrected if I am off the mark with anything.

 

[cah197]

Our house has a 30A main fuse and, from what I have been reading, I don't think that this will support a 7.4kw wall charger.

Where exactly are you?

We have the same issue, but you can’t just run cable to the distribution fuse as that has a maximum limit as well.

In practice 30 Amp is probably manageable, if you limit your EVSE to 15 or 20 Amps. How far are you driving every day? Overnight charging at this rate may be fine for you.

Or speak to your Supplier about increasing your main fuse and supply Amps.

Most people don’t actually need a 7 kW charger.

 

[Carty]

Our house was built in 1982 and like a lot of people close buy, we are running on a 60Amp fuse fitted by the DNO when the house was first commissioned.
Our 32 Amp wall box is being supplied via a stand alone circuit breaker enclosure.
The meter tails where upgraded in size and split to provide a health feed to supply the stand alone unit.
6mm twin & earth flat cable is then run the very short distance from the stand alone breaker unit to the EV wall box.
Upgrading from the original 30 Amp DNO installed protection fuse to a 100 Amp appears to be a huge jump in size.
I guess it is 30 Amps for a good reason ?.
To make an upgrade that substantial I am sure the DNO who need to check if the incoming cable size capacity could carry a 100Amp protection fuse ?.
Do really know - just making an assumption.
Is the member resident in the U.K. as wiring regs are completely different elsewhere.

 

[GOSPORT DAVE]

Sorry, cock up on my part, I didn't realise that the poster wasn't based in the UK. Obviously local rules apply to EU country's, need an expert to comment, I am just an enthusiastic amateur, I am afraid.

The fuse that I speak of sits between the street cable and the property meter and is owned by the energy supplier as it their side of the meter.

Most new builds are fitted with a 100A fuse as standard, older properties have a 80A fitted

If the charger draws 32A then that leaves 60A to play with (an electric shower can be 40A) so anything less doesn't leave much to play with.

Podpoint wouldn't do my install without 100A fuse fitted or would have limited it to 16A

 

[Jetlagged]

Thank you all for your replies. Perhaps I should have mentioned I am based in Portugal but I'm not able to find a forum as comprehensive and helpful as this one.

Electricity supply here is charged according to the maximum power that you contract for which is measured as "potência". Ours is 6.9 kVa requiring a 30 amp fuse in the main board. I have absolutely no idea what kVa means or the relationship between that and kW or kWh.

I've had a lengthy phone call this afternoon with another forum member also based in Portugal and have more clarity on the situation now.

 

[mikeselectricstuff]

kVA is the same as kW for the purposes of this discussion.
You will probably need to limit your charge rate to maybe 20A, as well as use a load-balancing charger that limits the EV charge rate to control the maximum total load on the house. Unless you really need a full charge overnight this shouldn't be much of a problem in practice.

 

[HandyAndy]

Jetlagged, kW is a measure of power, so the motor of an Ev might be rated 100 kW for example. kWh is how much energy there is in a power of 1 kW lasting for one hour. In UK domestic electricity consumption is measured in Units, and one Unit is = 1 kWh. If you consume 2kW over 1/2 an hour, you multiply these two figures together and it's again 1 kWh. kW and kWh are frequently confused, not least by car dealers! So kW is the same kind of thing as Horsepower, and kWh is the same kind of thing as litres of petrol. Related, but different meanings.

Your Ev may come with what we call a "granny" charger, as it's often used when visiting granny far away and she hasn't got a proper EVSE wall-mounted unit. It's a low-power portable domestic plugin EVSE, and these can often be set to 6, 8 or 10A.
6A is the lowest an EV can be charged at, so on a 250V mains supply that would be Watts = Volts * Amps, so W = 250 * 6 = 1500W, or 1.5 kW. This should give around 5 miles range for each hour plugged in, so even this may be enough charging power if your mileage is low. It's not recommended to run these "granny" chargers at more than 10A, as domestic plugs & sockets aren't always that good, especially with things plugged in as long as EVs tend to be.

There are some EVSEs than support variable power charging; those with solar-panel sensors do, but it's also possible to get an EVSE controller unit like a Viridian Mainpine; I have one of these fitted into my dumb Rolec, and this one has a resistor to set the current allowed. So I could set mine to anywhere between 6A, and 32A (the maximum my wiring allows). If your supply is restricted, you might be able to use one of these, and maybe set it to 5 kW for example.

 

[Jetlagged]

kVA is the same as kW for the purposes of this discussion.
You will probably need to limit your charge rate to maybe 20A, as well as use a load-balancing charger that limits the EV charge rate to control the maximum total load on the house. Unless you really need a full charge overnight this shouldn't be much of a problem in practice.

Thanks for your explanation and advice. It's appreciated.

 

[Jetlagged]

Jetlagged, kW is a measure of power, so the motor of an Ev might be rated 100 kW for example. kWh is how much energy there is in a power of 1 kW lasting for one hour. In UK domestic electricity consumption is measured in Units, and one Unit is = 1 kWh. If you consume 2kW over 1/2 an hour, you multiply these two figures together and it's again 1 kWh. kW and kWh are frequently confused, not least by car dealers! So kW is the same kind of thing as Horsepower, and kWh is the same kind of thing as litres of petrol. Related, but different meanings.

Your Ev may come with what we call a "granny" charger, as it's often used when visiting granny far away and she hasn't got a proper EVSE wall-mounted unit. It's a low-power portable domestic plugin EVSE, and these can often be set to 6, 8 or 10A.
6A is the lowest an EV can be charged at, so on a 250V mains supply that would be Watts = Volts * Amps, so W = 250 * 6 = 1500W, or 1.5 kW. This should give around 5 miles range for each hour plugged in, so even this may be enough charging power if your mileage is low. It's not recommended to run these "granny" chargers at more than 10A, as domestic plugs & sockets aren't always that good, especially with things plugged in as long as EVs tend to be.

There are some EVSEs than support variable power charging; those with solar-panel sensors do, but it's also possible to get an EVSE controller unit like a Viridian Mainpine; I have one of these fitted into my dumb Rolec, and this one has a resistor to set the current allowed. So I could set mine to anywhere between 6A, and 32A (the maximum my wiring allows). If your supply is restricted, you might be able to use one of these, and maybe set it to 5 kW for example.

You are a star sir. Thank you so much for that. K