Wired for the Weekend

That EV Charger Could Trip the Whole House

The wall box is the easy bit. The real job is making sure the rest of the property doesn’t know it’s there.

By Mika

People usually ring after they’ve chosen the charger.

They’ve found a sleek 22 kW unit, picked the colour and worked out exactly where it’ll sit beside the car.

Then they ask, “Can you install it next week?”

Maybe.

But first, I need to look at the house.

A property like this can already have ducted air-conditioning, a heated pool, spa, induction cooktop, electric hot water, wine fridges, automated gates, security, solar, batteries and plenty of other equipment pulling power.

Then we add an EV charger that could run for eight hours straight.

That’s when the nice-looking wall box becomes the least interesting part of the job.

I start at the switchboard

Before recommending a charger, I want to know:

• Is the property single phase or three phase?
• What size supply does it have?
• What’s already running?
• How hard is the house working during peak times?
• Is there enough room in the switchboard?
• Is the existing protection up to scratch?
• How far is the garage from the board?
• Is there solar or battery storage?
• Which systems need to stay on if something trips?
• Who’ll be using the charger?

That last one matters.

An owner charging the same car every night is different from a property with new guests, hire vehicles, visiting family and staff all trying to use the system.

I’m not only checking whether the charger can turn on.

I’m checking whether it can run while the rest of the property carries on as normal.

Here’s where it goes wrong

Someone arrives with eight per cent battery.

They plug in the car, turn on several air-conditioners, heat the pool, start the oven and put a load through the dryer.

If nobody has looked at the combined demand, the main switch may trip.

Now the car isn’t charging, the house is dark and the property manager is getting a phone call at 10 pm.

That’s the problem we’re trying to avoid.

A proper installation considers what the house is likely to be doing at the same time as the car is charging.

The aim is simple: the car charges and nobody inside notices.

Bigger isn’t always better

The number printed on the charger tells you what the charger can deliver.

It doesn’t tell you what the house or vehicle can accept.

Actual charging speed is limited by:

• The property’s electricity supply
• The circuit and cable
• The charger settings
• Any load-management system
• The charging cable
• The vehicle’s onboard AC charger

You can install a 22 kW unit and still have a vehicle charging at 7 or 11 kW.

You’ve paid for a bigger number, but you’re not necessarily getting a better result.

*Based on adding 36 kWh, roughly equivalent to charging a 60 kWh battery from 20% to 80%. Actual times vary with the vehicle, battery conditions, charging losses and load management.

For a lot of properties, 7.4 kW is plenty.

Even 4.6 kW can put a useful amount of charge into a vehicle overnight.

The right setup is the one the property can support safely and reliably, not the biggest charger that will fit on the wall.

The Queensland rule people miss

A typical 7 or 7.4 kW single-phase charger draws about 32 amps.

In Queensland, dedicated single-phase EV charging above 20 amps generally needs an approved form of Active Device Management.

That may involve:

• An economy or controlled-load tariff
• Basic active management through a network device
• A dynamic connection

Dynamic load management is straightforward.

The system watches how much power the property is using. If the house is working hard, it turns the charger down. When demand drops, it lets the charger speed up again.

The owner doesn’t have to manage it.

The guest doesn’t need to understand it.

The system keeps the property within its available supply.

That’s problem avoidance.

You deal with the load before it becomes a blackout and a phone call.

Don’t assume the garage power point is fine

Some vehicles can charge from a normal 10 A or 15 A power point.

That doesn’t mean every garage outlet is ready to carry a heavy load all night.

The outlet may have loose contacts, tired wiring or other appliances sharing the circuit. It might have spent the last ten years running a vacuum cleaner for fifteen minutes at a time.

EV charging is a different job.

Before recommending regular power-point charging, I’d want to check:

• The outlet’s condition
• The circuit supplying it
• What else is connected
• The cable size
• Existing safety-switch protection
• Earthing
• Voltage drop
• How it performs under load

The portable charging cable also needs to plug directly into the approved outlet.

No power boards.

No double adaptors.

No extension lead running across the driveway or underneath the garage door.

And no cable hanging from an apartment balcony because the car park happens to be one level below.

The Australian Government also recommends connecting portable EV charging equipment directly to the power point rather than using a power board or extension lead.

The guest sees a charger. I see everything behind it.

The wall unit gets all the attention because that’s the part everyone can see.

I’m more interested in what is feeding and protecting it.

A proper installation may need:

• A dedicated circuit
• The correct circuit breaker
• Suitable RCD protection
• DC-fault protection
• Correctly sized cable
• Load management
• Isolation
• Weather protection
• Vehicle-impact protection
• Clear switchboard labelling
• Testing and compliance documentation

EV charging equipment can produce DC residual current.

If the charger can detect a DC fault above 6 mA and disconnect the supply, a Type A RCD may be suitable. If it can’t, a Type B RCD may be required.

That’s one reason a cheap charger bought online can become an expensive installation.

You save on the wall box, then spend the difference fixing what it doesn’t include.

Cable size isn’t a guess

People often ask whether a charger “just needs six-mill cable”.

Sometimes that may be suitable.

Sometimes it won’t be.

Cable selection depends on:

• Charger output
• Length of the run
• Voltage drop
• Temperature
• How the cable is installed
• Whether it passes through insulation
• Whether it’s grouped with other cables
• Mechanical protection
• Manufacturer requirements

A short run inside a cool garage is different from a long run through a roof, down an external wall and under a driveway.

That needs to be worked out properly.

I plan for the bad timing

Electrical problems never seem to happen at a convenient time.

So I want to know what happens if:

• The charger develops a fault
• The house reaches peak demand
• The internet goes down
• The owner’s app stops working
• A guest can’t start a charging session
• Someone drives over the cable
• A vehicle clips the wall unit
• Water gets near the equipment
• A protective device trips
• Another charger is added later

If the charger plays up, I don’t want it unnecessarily taking out the gate, security, refrigeration, internet or half the house.

Depending on the property, that may mean separating critical circuits, using load management, improving labelling, adding suitable surge protection or providing a clear way to isolate the charger.

The exact solution changes from property to property.

The thinking doesn’t.

Work out what can go wrong and deal with it while the job is still on paper.

The location matters

An outdoor charger needs to suit the weather conditions.

A charger installed near a parking bay also needs to survive living beside a moving vehicle.

The Electric Vehicle Council points to IP44 or higher as guidance for outdoor installations and a minimum IK07 impact rating in car parks or public locations.

IP relates to protection against water and solid objects.

IK relates to physical impact.

Neither rating fixes bad placement.

If the charger sits exactly where an unfamiliar driver is likely to reverse into it, it may need to be moved or protected with a bollard or wheel stop.

The same applies to the cable.

It shouldn’t sit in water, cross a walkway or land where a vehicle will drive over it.

Short stays need to be simple

The owner may understand the charger.

The next guest probably won’t.

They could arrive after dark, in the rain, with luggage, children and a hire car they’ve never charged before.

They need to know:

• Where to park
• Which connector they need
• Whether a cable is supplied
• How to start charging
• Whether they need an app, card or PIN
• What speed to expect
• Whether load management may slow it down
• What to do if a warning light appears
• Who to call if it doesn’t work

A tethered Type 2 charger is often easier because the cable is already attached.

An untethered unit can work perfectly well, but the guest needs to know they must bring the correct cable.

“EV charging available” isn’t enough information.

Tell them what they’re actually getting.

The people looking after the property are part of the system

The property manager and care team don’t need to become electricians.

They do need to know what normal looks like.

During a service or turnover, they can spot:

• A damaged plug
• A split or crushed cable
• Cracked casing
• Warning lights
• A loose wall mounting
• Water exposure
• Vehicle impact
• A cable that has been driven over
• A charger that isn’t operating normally

They report it and stop the next person discovering the problem with their car connected.

The property manager should also have:

• Basic operating instructions
• Isolation information
• Compliance records
• Network documents
• Access details
• Fault contacts
• A clear escalation process

Good systems don’t rely on the owner being nearby or one person remembering everything.

Strata needs a bigger conversation

In an apartment building, the wall beside the car space may be common property.

The job can involve:

• Body corporate approval
• Common-property cable routes
• Building electrical capacity
• Embedded-network requirements
• Fire-rated penetrations
• A dedicated EV distribution board
• Shared load management
• Electricity metering
• Access control
• Planning for future chargers

The question isn’t only whether one charger can be installed today.

It’s what happens when ten more owners ask for one next year.

Plan that properly at the beginning and the building avoids paying to redo the same work again and again.

What I need before I recommend anything

Before quoting the job properly, I want clear answers to these questions:

1. What supply does the property have?
2. What is it already running?
3. What charger output can it support?
4. Does Queensland’s 20 A requirement apply?
5. Is dynamic load management needed?
6. How will it work with the solar or battery?
7. Is the switchboard suitable?
8. What circuit and RCD protection is required?
9. Is the location exposed to weather or impact?
10. Who will use the charger?
11. What happens if the internet goes down?
12. What electrical upgrades are likely to come next?

Then I can recommend the charger.

Not the biggest one.

Not the most expensive one.

The one that works.

Keeping the house on is the real job

Installing the charger is the easy part.

The real work is making sure the car can charge while the air-conditioning, pool, kitchen, security and everything else carry on as normal.

The owner shouldn’t have to think about it.

The guest shouldn’t need an electrical lesson.

The property manager shouldn’t get the late-night call.

The car charges.

The house stays on.

That’s the job.