I’m an unrepentant supporter of the Government’s subsidy for EV take-up.

Likewise, a supporter of the urgings of the Climate Commission to do whatever is needed, as quickly as possible, to build the necessary public infrastructure (e.g., nationwide charging stations) to facilitate EV use.

I’ve even pleaded with PM Ardern to buy a Ford-150Lightening (EV ute) to silence the critics who would keep our farmers and tradies in petrol/diesel purgatory.

I’ve read heaps about the downsides of EV batteries, and still conclude that the energy efficiency, GHG advantages, other air pollution mitigation and cost advantages on a lifetime ownership basis easily recommend EVs over internal combustion engines.

Indeed, every vehicle manufacturer on the planet – whether they manufacture cars, utes, trucks, busses, even tractors – has come to the same conclusion and is phasing out their dinosaur ICE vehicles … some very quickly.

Carbon-fueled vehicles are dead.

So, wake up NZ vehicle owners, or our vehicle fleet will look like Havana, Cuba!

So, with that as a starting point, there is still room for a dose of reality around the pace with which the new EV transportation of the future can reach your garage.

I received such a dose this week from Brian Anderson, a self-described “old retired electrical engineer” from Havelock North. Here’s what he wrote me:

“With regard to EC charging …

“Building the required electricity infrastructure” is very easy statement to make. But is it understood that most houses in NZ are wired, single phase, to standards developed more than 60 years ago, and are incapable of supporting EV charging systems of even 7.4 kW. There is way too much marketing hype about how easy it is to charge an EV but one of the most important numbers to understand is the “Capacity” of your EV battery, specified in kilowatt hours [kWhr]. It is either barely mentioned, or hidden in the small print.

“At best, most houses will only support a maximum of about 4.6 kW, limited by the house wiring and a 20A circuit breaker. Even that would require a special charger wired into your garage. Costs? Perhaps around $5000. If your new EV has a battery capacity of say 85kWhr, that will take more than 20 hours to fully charge.

“For something like a “Fast Charger” rated at 7.4kW, additional house wiring with 32A circuit protection will undoubtedly be necessary. That, plus the charger would cost perhaps $5k-$8k. Even that is not sufficient to charge your Tesla overnight.

“If a number of houses in your street opt for “Fast Charger” installations the distribution network and distribution transformers for your street will require to be upgraded. 

“The costs of wiring additions, charger installations, and network infrastructure upgrades are going to be huge, but are presently glossed over.”

Chastening I agree, Brian, but still not reason enough to resist the inevitable. And what a business godsend for electricians!

Anyone want to take Brian on?

Join the Conversation


  1. Brian is totally correct !

    There is a real issue with the overall system cost of moving to an all EV fleet and should not be ignored.

    Our local distribution systems were simply never designed to have multiple EV’s fast charging in the same street.

  2. I bought my 30kw Nissan Leaf nearly 4 years ago and was offered a choice of a 3 pin plug lead or a Commando one that runs off a 16 Amp plug that are common place for anyone who needs an outdoor powerpoint for their RV or camping trailer and are the ones used in powered caravan parks. I chose the Commando lead and had the appropriate power point installed in my garage along with a circuit breaker in case I use my stove at the same time I was charging – which I don’t because I’ve programmed the car to run on off-peak power. It cost $250 for the coomando point and circuit breaker 4 years ago so probably a bit more now.

    If I had to charge from empty to full in would take 4 hours overnight but that doesn’t happen any more than ICE car owners run their fuel down to the last litre, so I just top up when I need to. I have just been on holiday in the Bay Of Plenty and used some rapid chargers on the way up and back but stayed in cabins in holiday parks and just charged up overnight at one of their powered points.

    I check up on my EV plan with my power company and with home and away charging I spend $300 pa on power for my car. It will cost a bit more when RUC come in on 1 April 2024. The will be no problem with several people in one street topping up their batteries every few days, especially on off peak power.

    1. Hi Rosie,
      Thanks for your observations. Unfortunately I have to disagree with some of your numbers, and it is hard to beat the laws of physics.

      If your circuit is protected with a 16 amp circuit breaker, then the maximum power output that can be expected from your charger is about 3.6kW. i.e. 16 amps x 230 volts.

      Then, assuming your Leaf battery has a “capacity” of 30kWh, to charge from empty to full will take at least 8 hours. Actually a little more than that because the last part of the charge, from say 80% to 100% is a deal slower and less efficient. Of course, you would never run your battery dead flat though.

      But, well done for taking the plunge early. Very brave.

  3. Brian is 100% correct. We are not equipped for an EV revolution. Let alone remote operators and Long haul large load operators.
    We would achieve a faster result by looking at city transport as well as waste and its disposal.

  4. As the police are changing their fleet are they about to go EV as well, what a saving that would be. As my car is doing under 1500km year I can’t justify spending $60,000 to buy an EV. Perhaps the Government could supple all pensioners with a free EV.

  5. While the uptake of evs is still very low it’s not a problem now, but the future looks bleak if ev uptake increases at the rate the government wants. Everything John Blundell wrote is correct.

  6. Rest assured Tom, Brian’s case is looking at an extreme situation and I’d venture to say borders on scare mongering; The case mentioned cites a car with a humungous 85kwh battery (this would be an Audi E-tron which has a range of about 400km) which presumably returns home after driving about 400km as it has an empty battery. And the owner expects to do another 400km the next day so wants a full charge from his home charger overnight!

    If we look at the more realistic situation, battery sizes of two mid sized EV’s available here for which the Government rebate is applicable are 50KwH for the Tesla model 3 std range+ and 64KwH for the Hyundai Kona, both of which have a range of about 400km. I only have the home charging data for Tesla; A Tesla home charger (NZ$870 plus a couple of hours by a sparky to install), on a single phase 16A supply, will provide a 3.7Kw charging rate which according to Tesla will provide approx. 25km of range per hour on charge. So an overnight charge at home will add 250km or more back in the “tank” which for most people would be more than enough. As I read Brian’s piece, this sort of electrical load is well within the “normal” range for a typical Kiwi house and would not dim the neighbourhood lights. And if you do need to do back-to-back 400km+ road trips, visiting a public fast DC charger along the way will be needed. The latest Chargenet ones going in are 300kw chargers which if your car can handle it will add up to 400km of range in just 15 minutes.

  7. More from Rosie Marriott:
    Hi Tom have just read your article on the Bay Buzz newsletter and the 2 inaccurate replies to it, so I have chipped in with my thoughts.

    But additionally to my reply I attended at Seniors group recently and the subject of EVs came up. During the discussion not one person said a single thing that was accurate about them. So I put my hand up and said that:
    Batteries last for at least 100,000 kms if being driven normally (not as racing cars)
    The batteries are easy and economical to replace (considering that the car has had little need for maintenance.
    The batteries do not go to landfill when no longer suitable for cars and can become power wall units for example
    ICE cars use less energy to manufacture and the rare elements needed for their manufacture are not that rare that there is any chance they’ll run out soon.
    The manufacturers of home power units seem to have a sweet deal going with the car dealers and make it sound like a necessity to have one but even a 3 pin plug lead will top up the car overnight. I have written to the AA motoring magazine several times about their constant misinformation about this and their refusal to mention 16 Amp commando points.
    I have had my EV for nearly 4 years now – I paid $22K for it new in 2017 – and will only need one more year of motoring for it to have paid for itself.
    They can be driven over fords, during thunderstorms, and do not explode all the time.
    You do not get electric shocks off them, not even static electricity.
    Honestly you would not believe the rubbish that is spoken and written about them in every case by non owners and non users.
    And now that the power grid won’t cope with them because, somehow, all the EVs will be charging in the same street at the same time using unnecessary and expensive wall units.

  8. Hi Peter,

    I have just found the specs for the Audi eTron. Nice car. The battery “capacity” [actually the energy content] is 95kWh. That’s big by today’s standards.

    No, I’m not scare mongering. Just using some numbers to illustrate an important issue . . “building the required electricity infrastructure”. Everyone’s experience with charging and the kM they obtain with their EV will vary and I am not arguing about that. What I am trying to point out is that typical house wiring may not support the charge rates that users expect, especially if they are swayed by some of the over-hyped marketing. If you have a 16amp circuit to your garage, that will support a charge rate of about 3.6kW. However, installing the wiring for a 32 amp circuit, which will provide a charge rate of about 7.4kW, is a different kettle of fish.

  9. Hi Brian, In terms of “electricity infrastructure”, I disagree that the potential problem concerns the limitations of house or indeed neighbourhood wiring. “Fast charging” can only be done via public charging stations which have the necessary power supply, or businesses which have 3-phase – this may be necessary for tradies Utes in the future – Ford America’s new F150 ute has a battery estimated to be at least 115kwh. Home charging will always be relatively slow, but provides an adequate rate of adding km of range overnight for the sort of vehicles which we will be seeing in the next few years, e.g VW’s ID3, Mazda’s MX30, MG’s models, not to mention current Tesla 3’s and Hyundai Kona’s. And as Rosie has pointed out, for the older original Nissan Leaf models, a regular wall socket works just fine. To put things into perspective, my understanding is that installing a charger at home with a 16amp supply cable back to the circuit breaker board is similar in terms of electrical load to installing a modest sized heat pump.

    However, coming back to “electricity infrastructure”, I do agree we have a potential problem in that our national power generation and distribution capability will need to keep pace with a growing feet of electric vehicles.

  10. I first drove an electric car in 2000, a production Honda Insight, snappy little vehicle. Out of my price range as I was a student at the time studying Renewable Energy in New Mexico. I pined for an electric vehicle of my own until almost five years ago, a Nissan Leaf came into my life. I live rural and charge my vehicle mostly at home (electricity connect in 1960) with the occasional fast charge (good for the battery to have variety). The technology has been around since the 70’s and the dinosaurs are still resisting, I know change is difficult for humans, but the best outcome of owning a fully electric vehicle is that it has raised my standard of living. Cleaner air, much more money in my pocket, less time standing in a polluted fuel station.
    Centralized electricity does not suit most of NZ, the power is produced at one end of the country and the highest use is at the other end of the country. Wind, solar and hydrogen produced on site solves a lot of that problem. Large vehicles (trucks and trains) are best suited for hydrogen, messing with smaller cars is a waste of the advantage of the technology. Our national grid is some of the infrastructure that needs updating and future proofing. Get solar on to every roof that faces north, build shelters over car parks that can receive solar and charge electric cars while people work.
    Resistance is futile. There will be no internal combustion propelled cars in production in five years.
    Lets apply some Kiwi can-do attitude and think outside the box. If our homes are not suitable for charging, put brand new purpose built chargers accessible in all areas where people gather.

  11. Thanks all for a spirited debate.
    As reported by NBR, Genesis has now put its first electric light truck on the streets of Auckland. Here are the charging specs on that:

    “An 81kWh lithium-ion, liquid-cooled battery pack powers the vehicle’s electric motor, providing a range of between 100km and 150km on a single charge, according to Fuso’s website, with zero on-road emissions, and free of road-user charges for those looking to adopt early.

    A standard CCS2 charging plug and direct current charging means the battery takes under an hour to recharge up to 80%, and 80 minutes to fully recharge. An alternating current charge cable also allows a full charge overnight using off-peak power. Fuso said maintenance costs were halved and a full recharge from 20% would cost $10, based on an off-peak residential rate of 15c a kWh.”

  12. I’m pleased about the debate too. We need more of it to balance out the over-hyped marketing.
    L Clem: I agree with many of your comments. Centralised generation and distribution is not the way of the future. Local generation is efficient, but very under-utilised in NZ. PV solar ought to ought to be incentivised, perhaps even mandatory, in many areas. [Just like double glazing].
    Tom: Please be careful about the marketing hype. DC charging at the rates being promoted are not possible in NZ houses today. The example you quote would have to be capable of at least 65kW, available from custom designed charging stations. Standard single phase wiring in NZ houses is capable of about 7.4kW. A 3 phase installation, which is quite unusual, is capable of about 21kW.
    And, please remember, the cheapest component of running a car is the cost of fuel [or electricity]. Some of the bigger costs are depreciation and insurance, for example.

  13. I charge my EV only using a portable EVSE which draws 8A, a trivial amount, and that will add about 80 km overnight. I keep the car at around 60% charge most of the time and so can jump in and drive 200 km at a moment’s notice. If I needed more charge quickly I can just hop over to the fast charger a block away and add about 40 km every 10 minutes.
    My flat has a 60A feed installed in 1932 and I could easily add a 16A EVSE on a dedicated 20A circuit for a one-time cost of perhaps $2,000. 16A would add about 160km overnight, and that’s on top of the 200km already present for a total of 360km. How often am I going to need 360km and not have some inkling of that the day before?

  14. Today I posted a poll on NZ’s largest FaceBook EV owners group regarding home charging and after only a few hours have obtained enough data from 76 owners of either 16A or 32A chargers to assure myself that:
    1. Homes with permanently-installed 32A charging make up 59% of homes with either a 16A or 32A permanently installed EV charger.
    2. Of the 43 homes with a 32A charger and that portion that have indicated they are on a 63A domestic supply, not a single recipient has said that they have had a problem with overloading the remaining capacity while charging. Of this group only one householder has indicated that they are aware of the supply limitations and make conscious efforts to avoid overloading the supply.
    I’m a retired engineer as well but recognise that easily obtained statistical facts can often overrule a single half-baked opinion.

    1. This!! I cant believe the misinformation in the original article. We have 63 A domestic supply, happily pull 7kw from our 32 A charger, while running 3 heatpumps cooking dinner and boiling the kettle (ok that’s a slight exaggeration – but we never have any concerns charging and using the rest of the supply). The charger cost us $1000 to purchase and wiring job (including the type 2 RCD) was $1000.

  15. As an EV owner, and electrician involved in the electricity industry for a few years, I consider the original comments from Brian and others about the cost of home charging and fragility of the distribution industry to be more than a bit misinformed.

    The media suggests that most EV’s are typically used for 40 – 60 km per day, so regardless of the battery size, most EV’s usually have a modest overnight charging requirement

    The battery in our BMW i3 is only 33kWh, so less than half the size of a Tesla, and the car is plugged into a three pin plug every night for an overnight recharge. I also have a 7kW charger, which I have not installed as they are required to have a special RCD protection device attached, which costs about $500 plus installation, and I found that do not need a 7kW charger at home. These “fast” chargers are fairly basic and consist of little more than a box with a socket, plus a contactor and control wiring. 7kW chargers can be purchased much cheaper than the thousands suggested by other commentators.

    Most residential homes are supplied from a single phase 63 amp (15kW) supply, and the 7kW charger draws about 28 Amps, which is much the same as a wall oven complete with electric hot plates. As an example, a 3kW hot water cylinder draws about 12 amps.

    In the industry we refer to “diversity of load”, and that means that not everyone in the street has their air conditioning, or hot water or oven or lights turned on, or electric car plugged in, at the same time, and the electrical load profile of every house in the street is also different, with some people on holiday, while others work night shift etc. The end result being that the electrical supply to our homes and neighbourhood can support a far greater electrical load than the sum of what is connected. The total load of 4*15kW homes may total only 25kW on the electricity network due to this diversity.

    The trick with electric cars and other non essential electrical load such as hot water cylinders, is to charge them at off peak periods, on off peak (cheaper) energy rates. Most retailers offer an off peak or night rate tariff, so turn your car charger on at 11pm or later, with smart technology, and reduce your motoring costs further due to lower night time energy rates. Shifting load to the night also reduces demand on the electricity network and minimises the (minimal) need for infrastructure enhancements.

    With off peak charging you may need to charge at a faster rate due to the limited (~8 hour) cheap priced charging window, and that is where the benefit of a 7kW charger is realised.

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