Changeover switches and generator inlets explained: what a licensed electrician installs

A changeover switch is a switch on your switchboard that picks where the house gets its power: the grid, or your generator or power station. It can only be in one position, so the two sources never meet. The generator inlet is the weatherproof socket on the outside wall that the backup plugs into. In Queensland both must be installed by a licensed electrician, and once they are, you can run chosen circuits like the fridge and lights without carrying plugs around.

The rules here come from Queensland's Electrical Safety Office, Ergon Energy and Energex. EcoFlow's Australian site supplied the station figures, and the runtimes are our sums, not measurements.

Why the switch exists

When the power's out, the street lines are dead and crews are working on them. If backup power gets into your house wiring with the main supply still connected, it can travel back out through your meter and energise the transformer that serves your street. The Electrical Safety Office calls this backfeeding and says it's an electrocution hazard for line crews and for your neighbours. It can also wreck the generator when the grid comes back on.

A changeover switch makes that impossible. The ESO describes it as allowing power from only one source at a time, either your generator or the Energex or Ergon supply. Ergon calls the same thing an isolating switch and says it's the only safe way to connect a generator to household wiring. You'll see both names on quotes.

The thing it replaces is the double-ended lead from a generator into a power point, which Ergon and Energex call a suicide lead. It feeds power back into the network and puts you, your family, neighbours and line crews at risk of a fatal shock. It also bypasses some of the protection built into your switchboard, according to the ESO. Never use one, and never let anyone talk you into it.

What the electrician actually fits

There are usually three parts. The changeover switch goes in or beside the switchboard. An inlet socket goes on an outside wall, so a generator can stay outdoors where its exhaust can't get inside. Then the electrician wires the circuits you've chosen to the backup side of the switch, so only those run in a blackout.

The work has to meet AS/NZS 3000, the wiring rules, plus Energex or Ergon requirements. A fixed generator also has to meet AS/NZS 3010. For a portable generator, the ESO says your electrician will check that the wiring and safety switch are compatible with it. Tell them if the backup will be a power station rather than a generator, because the same check applies. EcoFlow sells a grounding adapter for its stations in Australia. Whether your setup needs one is the electrician's call, not ours.

In a blackout the routine is simple. Start the generator outside, or switch the station on, plug it into the inlet with the lead your electrician specifies, then flip the changeover switch to the backup position. Ergon adds one rule worth remembering: don't turn on the switch if the house has been damaged. After a cyclone, get the wiring checked first.

Manual or automatic

Most home setups use a manual changeover switch, which you flip yourself. Automatic transfer switches flip on their own when the grid drops. EcoFlow's Australian store lists one for its larger stations with a transfer time of 1 to 2 seconds, and says only qualified professionals may install or maintain it. The same listing says it's certified by Canada's ISED and doesn't mention an Australian certification, so ask your electrician whether it suits your switchboard under the Australian wiring rules before buying it.

A 1 to 2 second gap is fine for a fridge and lights. It will drop a modem or a computer, which is why we'd still run the modem from a station's UPS outlet, as our renters' guide explains.

How far a power station goes on circuits

Circuits draw more than the one appliance you had in mind. Anything left plugged in on that circuit draws standby power too, and the station's inverter is on the whole time.

Take the EcoFlow DELTA 3 Plus, which EcoFlow lists at 1,024Wh with 1,800W of AC output. Allowing 15% for conversion losses, which is our assumption, you have 1,024 x 0.85 = 870Wh. Now say the electrician wires the fridge circuit, one lighting circuit and the circuit with the modem on it.

That's 1,636Wh for a full day, so 870Wh lasts about 870 / 1,636 x 24 = 13 hours, before you count any standby loads. The fridge figure comes from its Energy Rating label: 400,000Wh / 365 days is about 1,096Wh a day. Our fridge guide shows how running it in blocks stretches a battery much further.

Output limits matter more than with a generator. An 1,800W station draws at most 1,800 / 230 = about 7.8A, so a circuit that also has the kettle or the microwave on it will trip the station's overload protection. Pick circuits with the electrician, and leave the oven, air conditioner, pool pump and hot water off the backup side.

Is it worth it with a power station?

For a small station, usually not. If you've got around 1kWh, plugging the fridge, modem and a lamp straight into the station's own outlets does the same job with no wiring, no electrician and no permanent change to the house. Our cyclone season sizing guide works out what most homes need that way.

An inlet and changeover switch starts to make sense with a generator, because it has to stay outdoors anyway, or with a big expandable station where you want hard-wired lights and ceiling fans running. If you're weighing those two up, our power station vs generator guide has the fuel and watt-hour sums. Renters need the owner's written approval before any of this goes in.

Quick questions

Can I use a changeover switch with rooftop solar?

That depends on how your solar inverter and switchboard are set up, and it's a question for the licensed electrician quoting the job. Don't assume the panels will keep the backed-up circuits going in a blackout.