Bunnings EV charger displays, photo posted November 19th 2024
It seems you can buy just about anything at Bunnings these days, with EV charging systems the latest addition to the ever-growing hardware store, despite most definitely not being a DIY project.
The big green shed has caused a stir in EV enthusiast circles by launching yet another potentially dangerous line of merchandise, complete with warning labels on their displays telling customers they will need qualified installation — so SolarQuotes decided to investigate.
After crawling through Binno’s websites, pursuing web chats, and even enquiring in-store, we found that, unsurprisingly, the people selling paint and pot plants don’t know what the pointy end of an EV charger looks like.
What Could Possibly Go Wrong?
The installation service Bunnings offers to sublet isn’t up to standard, and this is not a project you should risk undertaking yourself: we’ve covered the perils of unqualified electrical work a few times in the past, from electric shocks that can knock you off your ladder to the dangers of pests chewing through exposed wiring.
This isn’t the first time the supposed DIY store has moved into products which require a professional. You might technically need a license to install a new tap from Bunnings, but the risks posed by a water leak are pretty low (I could make a joke here about a plumber’s licence to make sh!t flow downhill).
I would never recommend people do their own gas plumbing with the fittings available at Bunnings. If that goes pear-shaped, it can level your house and kill all the occupants in an instant. That’s a good reason to get off gas, in any case.
EV Chargers Require Permission
After checking out a point-of-sale display with Deta (home brand) DeWalt and Tesla EVSE equipment, we found that only the Tesla QR code worked when scanned in-store, while the others had broken links. It seems the Tesla and DeWalt units were the only Open Charge Point Protocol (OCPP) compliant options, which are legally required to install in South Australia, the state where the display was located.
There are 17 different network companies in Australia and they all have differing requirements for EV charging equipment to be connected, through your retail meter, to their poles and wires. Not all of them mandate OCPP connectivity right now, but they will soon enough.
Permission Comes Via Your Electrician
The green shed retailers can’t actually organise your installation, as they don’t have the licence or the login to use the appropriate Distributed Network Service Provider (DNSP) portal. Rather, they offer to get a subcontracted electrician to do the preparation, installation and compliance (for a rock-bottom price of course).
Bunnings has clarified that warranty works on a defective unit will be paid for, as they should under consumer law.
However, the “home brand” DETA wall connector at Bunnings’ flagship store at Mile End has now disappeared, presumably because it is non-compliant and can’t be installed in SA.
Bunnings Offers Inadequate Protection
The installation Bunnings specified is $699 and includes 10 metres of 6mm² cable and 32a circuit breaker. This simply isn’t enough.
It’s a bit like an airline offering “free transfers” and supplying a bicycle for you to pedal to your hotel.
On the surface, a 7000-watt load divided by 230 volts equals a current of 30.43 amps, which equates to 5% headroom before you’ll theoretically trip a 32-amp circuit breaker.
However, the circuit breaker isn’t a perfect device. Its role is to protect both the cable and the device at the end, but there’s two ways it works:
- Where somebody drives a screw through the appliance and creates a dead short circuit, there could be 1000 amps in an instant. This is a violent failure, where a circuit breaker uses the magic of magnetism to throw the contacts open in a fraction of a second.
- Where there is a long-term overload, heat is created by continual heavy current. This sort of slow burn is managed by the thermal side of a circuit breaker. Heat causes a bi-metal strip to open the contacts, but this mode is less precise and more easily influenced by external heat sources.
When you consider variations in supply voltage and standard deviation in mass-produced circuit breakers, a larger margin must be built into the circuit design to manage the variables.
The same principle applies to protecting a standard 10 amp power point with a 16 amp circuit breaker.
Heat Is The Killer
EV charging is unlike any other common domestic load. It’s not only the largest but also the longest.
Where a stove may have high demand to boil pasta for ten minutes, the simmerstat (temperature control) means the consumption is moderate while you make jam. Stoves have a specific carve-out in regulations to reflect this diversity.
The same is true for air conditioning. Once switched on, it may work hard for an hour, pulling the temperature down in summer, but then it will throttle back, either by cycling or dynamic speed control.
EV chargers, in contrast, come on at a full 7kW, and they can run for 6 or 16 hours flat out.
This means the whole system must be able to cope with full-rated capacity, when everything is soaked with internal electrical heat and external environmental heat.
Bunnings EV Charger Cable Is Undersized
While 6mm² twin sheathed cable (single phase) is rated for 46 amps under ideal conditions, it must sit on a hard surface or ladder-style cable tray. The cable must be able to radiate heat into a space with an ambient temperature of less than 40°C.
The exact same cable can carry less than half that current if it’s “completely surrounded by thermal insulation”.
A Basic Failure
You’ll commonly find cables are thrown into a low portion of the roof, simply laying across the top of bulk insulation, meaning they are defined as “partially surrounded with thermal insulation.”
- So, at this first hurdle, the bargain install fails, with the 6mm² cable only rated for 31 amps in this situation.
- It gets hot in your roof space, and even at a fairly modest 50°C, the cable loses another 18% capacity.
- Realistically, a 60ºC figure means 31 amps x 0.6 or a safe rating of 18.6 amps.
- If the cable is bunched together, touching others, it may suffer a further 0.85 rating.
In other words, this nominal 46 amp cable can only safely carry 15.8 amps once you’ve applied some conservative but not unrealistic conditions. It’s all about how the cable is installed.
Manufacturer Instructions > Standards > Bunnings
AS3000 specifies the minimum standard and often defers to manufacturer instructions as best practice.
Schneider Electric (the company that bought Clipsal) has specific considerations for circuit rating and protection in switchboards:
- A 40A circuit is required for each charging outlet.
- This is necessary because the continuous output current from the charging station can be as high as 30A.
Increasing EV charging cables from 6mm² to 16mm² will mean the job costs a little more, but doing it right will be a lot cheaper than doing it twice.
Electrical goods manufacturer Hager recommends a 40A protective device for a typical 7 kW domestic charger, based on testing conducted in their accredited laboratory.
In fact, Hager goes further. If your switchboard is full, it’s liable to be heat-soaked after hours of EV charging, so they recommend you double the circuit breaker rating to counter the thermal derating on a crowded DIN rail. This means the cable sizes must be increased to match the circuit breaker.
The silver lining for this oversized cable is greater efficiency. More of the energy you pay for will end up in the battery instead of being burnt off as waste heat.
Be aware – Bunnings will not honour the warranty on an item bought through their “marketplace” online portal that is labelled with the red “marketplace” tag.
Some Electricians Recommend Bunnings EV Chargers
Tesla, amongst others, offers mail-order EV charging equipment, so customer-supplied hardware isn’t highly unusual. While your local sparky might lose some margin, it saves them on wholesaler handling and warranty obligations.
But if you want an EV charger with good technical integration, appropriate permissions, properly-sized supply and one-stop warranty, it is best to look elsewhere. For a broader overview on Bunnings’ EV chargers, take a look at our dedicated page on what they are offering. Dive into this guide if you’d like to do your own research on EV chargers, or click here for quotes from a reputable expert in the field.
Remember: when lowest prices are just the beginning, lower install standards will apply in the end.
About Anthony Bennett
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