Get quotes from vetted installers

Ready to get up to 3 quotes to compare?

Tricks and traps when charging from a standard powerpoint. 

Spent all your spare cash on an electric car and don’t want to incur the expense of a hard-wired home EV charger? Then this is the post for you.

For five years, my two EVs have only ever been plugged into a powerpoint.

My Australian-delivered 2015 Outlander PHEV doesn’t have a fast DC charging port and Irene the iMiev has never needed a fast charge, so they’ve only ever had a diet of general purpose electrons from general purpose outlets or GPOs, as we’ll refer to them.

And as for extension cords, my lived experience as a licensed electrician is that it can be done despite what the manufacturer’s instructions say. But like anything electrical, you need to be observant and try not to push your luck because I’ve been doing that for you, dear reader.

If you only travel a modest mileage or have a small battery, then no – you don’t need a hard-wired EV charger.

All electric vehicles (except recent Teslas) and PHEVs come with what is variously described as an EVSE, mobile connector, slow charger, brick or granny charger. Think of it as part of the tool kit in the boot, but more useful than the dodgy pliers, jack and wheel brace for the spare wheel they probably didn’t give you anyway.

In Australia, they come in two flavours. One has a nominal 10 amp plug that like any other appliance plugs into any general power outlet. The other has a 15 amp plug, which you’ll be familiar with if you have a decent-sized welder, air compressor, urn, bain marie or caravan. The 15A plug has a wider earth pin that won’t fit in a 10A socket.

The 10A and 15A ‘tails’ from a Tesla mobile connector. The Tesla mobile connector is unique, as far as I know, in that you can buy a 32A tail, to charge at up to 7 kW from an industrial-style 32A socket.

The difference between a 10 amp and 15 amp outlet has little to do with the earth pin. The real distinction is that an electrician must design the wiring and circuit protection behind the wall for the rated load. The cable must be big enough to handle the heat and deliver enough energy to do the job.

Checking the current draw, seems 8.8 amps is as much as it will pull.

My own PHEV came with 10 and 15 amp chargers, and I have measured them draw around 8 amps and 12 amps, which is 80% of the rated current available from the respective GPOs.

This thing is that they draw 80% of the rated load for hours on end.

Your kettle might draw a similar amount of power, but it doesn’t run for more than a couple of minutes. A bain marie or a compressor might draw a similar load, but cycle in and out.

Standard EV chargers just run full-time at full whack.

For example, when you plug into a standard indoor type GPO that’s spent 40 years in a carport, there’s some chance it’s got some corrosion on the contacts. 20 minutes to vacuum the car will be no issue, but 8 amps for 6 hours, otherwise expressed as 2kW to charge 16kWh into a PHEV battery, will likely melt the plug and socket. It’s a torture test that will soon find the weak links.

Notice the browning of the wall plate around the left-hand active pin, and the “puddle” of melted plastic around the opposite neutral pin on the plug. This is exactly why you must be vigilant when charging an EV.

The same thing applies to the extension cord you inherited from Dad; the one he might have naughtily made up to plug the 15 amp caravan into a standard 10 amp GPO. It doesn’t have to be dripping in verdigris, but if it isn’t perfectly bright and shiny there’s a good chance you’ll generate some heat that will damage the plug and socket.

At the very least, this pre-2004 plug must have the pins scuffed, sanded or polished until you have 10mm of shiny bright brass. It will likely cause trouble otherwise.

Whenever you use a plug-in car charger, you should turn the switch off at the wall before unplugging the cord. No, really; this isn’t nanny-state hyperbole this time. If the plug or socket has been damaged, the pins may be welded together. Whether it’s still hot or not, the plastic could be melted enough that the plug comes apart in your hand, exposing live metal parts.

So far, I’ve had to replace one plug top, two cord extension sockets and 2 GPO wall plates over five years of charging a car with a standard EVSE. None of them has been what I would call a dangerous situation. I’ve just noticed the plugs were hot to the touch, the plastic was soft and, as a result, discoloured or slightly deformed.

Thermal images show a plug & socket assembly in the middle of this experiment is running comparatively warm.

This experiment involves a supply from the top and human foot for temperature reference. The random recycled white appliance lead connects to a breakout box with a kilowatt-hour counter and loop for measuring current. Then the Mitsubishi supplied EVSE at the bottom is connected to the car itself.

Be aware that things like powered sites in caravan parks are normally held in contempt by electricians. They’re often poorly maintained and can offer marginal capacity. I have seen first-hand examples that meet the stereotype. They’re old, cruddy and not well-designed in the first place. With the rise of all-electric camping, there will have to be improvements made.

Ironically, PHEVs are quite popular in towing caravans across the UK, and I must relate an amusing story.

In England, etiquette, like queuing, is a finely developed art. So it seems the poms have decided it’s bad form to “pump fuel” out of the caravan park into your car, so they plug the van into the mains riser with a cord, then run a second cord out of the van to charge the car. Apparently, the physics of adding a dozen connections, potential points of failure, or maybe an electrical fire isn’t as important as saving face in a budget holiday park. People are ludicrous.

If you intend to use your standard plug-in EV charger regularly, then it’s worthwhile having a proper circuit run from your switchboard with an industrial-style IP-rated plug and GPO. These are weatherproof, so they can be installed outdoors, but I still wouldn’t recommend anything electrical be installed in the driving rain or blazing sun.

Not only is this plug sealed with an “O” ring to make it weatherproof to IP66, the screw collar means it can’t be withdrawn inadvertently.

If you install a screwed connector to your EVSE/brick, it will still mate with a standard GPO or cord extension socket like this 15 amp one.

This is the matching 15 amp socket outlet for a screwed connector. They will still accept garden variety appliance leads but probably not a plug pack for your Christmas lights.

This socket is how extension cords are done right.

Running a Cat6 data cable or two alongside the new supply is also highly recommended. This allows a reliable hard-wired internet connection for a charger. As we progress there may be a call for DNSP control of EV charging, just like they already do with solar generation and air conditioning demand response to help maintain stability on stinking hot afternoons and mild spring days alike. An internet connected charger also opens up the possibility of charging coordinated with dynamic tariffs like Amber.

If you are installing a dedicated circuit, you could get some basic solar-smart automation done at the same time. Using a solar diverter such as a CatchPower relay, it’s easy to control the EV circuit so it only uses excess solar energy generation or off-peak rates if you have TOU metering.

Bear in mind the cost of cable is negligible compared to the labour involved with crawling through the roof, so specify at least a 6mm² cable (in single or 3 phase if you have it).  That allows a nominal 7 or 22kW charger to be added easily if the need arises.

If you only charge Tesla EVs and have a solar inverter on this list, you can do solar-smart charging with a dumb charger without paying for any extra hardware or wiring, via the ChargeHQ app. This is possible because the app can control charging by talking to the car, not the charger. I’m not aware of any other electric car brands that offer this.

At the end of the day, EVs will push the rated capacity of the wiring in your house, the connection to the street and the grid more broadly. That’s not to say we will overload everything and there will be mass blackouts and a war on the weekend. That would be useless dumb hyperbole, when in actual fact, EVs will help with the transition away from fossil fuels.

We need to remember that when you plug in a car, it will pull a significant amount of power from the wall. Until now, few commonly available appliances pull power as hard and fast as an EV. So, make sure everything is up to snuff or, if you don’t want to worry about it, bite the bullet and get a dedicated circuit and wall box charger.

Learn more about electric vehicle chargers in SQ’s EV Charging 101 guide.

Sign up for our weekly newsletter!

As a child, Anthony marvelled at his Solarex toy helicopter made with shards of smashed solar cells. With some education, he became a jack of all trades & master of several, qualified contractor, builder, roofer, auto and licenced electrician, veteran car restorer & Dad. After 14+ years of lugging, lifting, plumbing and fixing, wiring, dialling and evangelising for everything solar power-related, on-grid and off, he's got a few yarns to share.

I think a genuine tightarse would include instructions on how to re-charge your EV using the neighbour’s supply.

Funnily enough this was the original header image – until the post became all about home charging…

Anthony, you did not mention loops in cables. I always ensure the cable is free of loops (to reduce Inductive heating). Like you, I plugged in for years. I also replaced a few plugs & sockets.

I have a genuine 2.5 mm sq lead I bought from Masters some time ago. This definitely needs to be stretched out to use.

My economical wall charger is a ZJ Beny OCPP charger (wifi linked) that has a single phase 32A plug & socket. The main thing is any connections must be tight, & I like using ferrules to contain the wires. My OCPP charger runs from Home Assistant, using the OCPP software module.

With a dumb charger, it would be possible to control the 240v with a wifi switch (Tasmoto or similar) controlling a min 25A contactor. This could easily be controlled by Home Assistant.

One other issue I see is really slow charging: Charging an EV at less than about 8A (ie 2Kw) is where the efficiency reduces. Unless the power is free, always charge at a rate where the efficiency is better than 90%+.

On the subject of Charging I am wondering how the approved wall box bi-directional charger works from a protection and earthing point of view. I am told that for anything that is connected to a household you must have a M.E.N in place. Is that the case for the bi-directional EV charger. I have an EV with VTL ability and have has an REC install a designated generator circuit with a Manuel change over switch and a CB of 15Amps. When I connect a small generator this works fine as a limited supply for my house. But not when I try to discharge from the car. From testing we believe the issue is the M.E.N and the fact the EV has a sensitive 15milliamp RCD that sees this MEN. Given the change over switch only disconnects the active and is not double pole (Disconnected active and neutral) we believe this is the issue. But a double pole is not allowed. How does the bi-directional charger get around this issue?

I’m still curious how (logistically) service stations for petrol and diesel aren’t constantly queued around the block, with an average of 2900 vehicles at last count for every station in the country. And with no regulated re-fuelling procedure, everybody just turns up when they need to. Something in the way that was figured out should be applicable for new fast-charging stations for EVs. We should need fewer of them (there are 7000 traditional service stations), as most daily use can be charged at home, whereas everybody needs to go to a servo to get petrol or diesel. And I read there are already 3000 fast-charging stations in Australia.

Funnily enough, in the WHS meeting I was just in, we were looking at a photo of a car parked outside of one of the work buildings, connected via a long extension lead running through an open second floor window…. :-/

Hypothetically, if one had an inverter/battery capable of drawing 15amps and a CABLE rated for 15Amps but with a 10amp PLUG, what would be the likely outcome, assuming it didn’t blow a fuse in the switchboard?

For 3-phase I would say go even heavier on the wire – 6mm2 on 3phase partially surrounded in insulation is only good for 30A, and that’s right at the thermal limits too. Even 6mm2 on single phase is only good for 35A, but that’s assuming the roof space is 40 deg C, it can get way hotter than that if there’s no anticon.

Please keep the SolarQuotes blog constructive and useful with these 5 rules:

1. Real names are preferred - you should be happy to put your name to your comments. 2. Put down your weapons. 3. Assume positive intention. 4. If you are in the solar industry - try to get to the truth, not the sale. 5. Please stay on topic.

Notify me of follow-up comments by email.

Notify me of new posts by email.

Read The Good Solar Guide Free Online!

Get quotes from vetted installers

© 2009 to 2023 Peacock Media Group

Ready to get solar quotes?

Get up to 3 free quotes

Download the first chapter of The Good Solar Guide, authored by SolarQuotes founder Finn Peacock, FREE! You’ll also start receiving the SolarQuotes weekly newsletter, keeping you up to date on all the latest developments on Australia’s solar scene.

We respect your privacy and you can opt out from the newsletter at any time.