The safe way to connect a generator to your house is a changeover switch at the switchboard plus a weatherproof generator inlet on an outside wall, both fitted by a licensed electrician. The switch connects the house to the grid or the generator, never both at once. Plugging a generator into a power point is dangerous and not permitted.
Can you plug a generator into a power point?
No. Feeding a generator into a power point, usually with a lead that has a plug on both ends, pushes power backwards into your house wiring and is not a legal or safe connection. Electricians call it back-feeding. While the generator runs, the spare plug on that lead has live, exposed pins.
The bigger risk is outside your house. If the main switch is still on, the generator can feed through your meter and onto the street supply. Line workers repairing the outage expect those cables to be dead. When the grid comes back, the mains supply can also hit the running generator, damaging it and the wiring and creating a fire risk. A changeover switch is designed so neither can happen.
What is a generator changeover switch?
A generator changeover switch is a switch at your switchboard that selects where the house gets its power: the grid, off, or the generator. It is built so the two supplies can never be connected together, which means your generator only ever feeds your own circuits.
A typical installation has three parts:
- The changeover switch, in or beside the switchboard, usually marked mains, off and generator.
- A generator inlet, which is a weatherproof male socket on an outside wall. The generator plugs into it with a single lead, so there are no live pins anywhere.
- The cable between the inlet and the switch, sized for the generator and the inlet rating, commonly 15 or 32 amps.
The switch is a cousin of the local off switch covered in our guide to isolator switches, but with a second supply wired in and a mechanism that stops both being on together.
What are the safe ways to run a house on a generator?
There are three legitimate set-ups, and the right one depends on how often you lose power and how much of the house you need running.
| Set-up | How it works | Suits |
|---|---|---|
| Appliances plugged into the generator | Heavy-duty outdoor leads run from the generator to a fridge or lamp, with no connection to the house wiring. | Short, rare outages and camping-style use |
| Manual changeover switch and inlet | The generator plugs into the inlet and the switch is turned to generator. Selected circuits or the whole house run from it. | Homes with occasional storm outages, home offices and full freezers |
| Automatic transfer switch | A fixed standby generator starts itself when the grid fails, then the switch swaps back when power returns. | Frequent outages, businesses and sites that cannot be without power |
For most Sydney homes, a manual changeover switch is the practical middle ground. It lets a portable generator safely run the lights, the fridge and the internet without the expense of a standby system.
How do you use a changeover switch in a blackout?
The order matters, and it is always the same: generator outside and running first, then switch over, and switch back before you stop it. A typical sequence looks like this:
- Set the generator up outdoors, well away from doors, windows and vents. Exhaust contains carbon monoxide, so never run one in a garage or under the house.
- Plug the lead into the wall inlet, then start the generator.
- Turn the changeover switch from mains to off, then to generator.
- Turn on the circuits you need one at a time, starting with the fridge and lights, so the generator is not hit with every load at once.
- When the grid comes back, turn the changeover switch back to mains, then stop the generator and unplug the lead.
Your electrician labels the switch and shows you the steps for your board. If you lose power and are not sure whether the fault is the grid or your own switchboard, our blackout action checklist helps you tell the difference first.
Want a generator ready for the next storm?
DM Electrical fits changeover switches and generator inlets so you can run the essentials safely through an outage. Based in Brookvale, Level 1 and Level 2 ASP accredited, working across the Northern Beaches and wider Sydney.
Which circuits can a generator run?
That depends on the size of the generator, so the first step is deciding what has to keep running. A portable generator is commonly rated at a few kilovolt-amps, which is enough for a fridge, a freezer, lights, the modem and a few power points. It will not comfortably run ducted air conditioning, electric hot water, an induction cooktop or a pool pump.
For that reason many homes wire the changeover switch to a small group of essential circuits rather than the whole board. Others have the whole house on the switch and rely on turning off the big loads by hand. Your electrician matches the layout to your circuits and the generator's rating. If your board has no room for the switch, or still uses old fuses, the job may sit alongside a switchboard upgrade.
What else does an electrician check?
A few details decide whether the generator supply is safe as well as working. The main ones are:
- Earthing and RCD protection. How the generator's neutral and earth are arranged affects whether your safety switches still work while the house runs on generator power. The connection is set up to suit your generator. Our guide to earth stakes covers why the earth matters.
- Solar. A grid-connected solar inverter is designed to shut down when the grid drops. The electrician keeps the solar system apart from the generator supply.
- Inlet and lead rating. The inlet, the lead and the generator outlet all need to match.
Who can install a changeover switch in NSW?
Fitting a changeover switch and generator inlet is electrical wiring work, so in NSW it must be done by a licensed electrician. The wiring rules and the Australian standard for generating sets, AS/NZS 3010, both require a changeover arrangement that stops a generator connecting in parallel with the grid. When the work is finished the electrician lodges a Certificate of Compliance for Electrical Work, which our guide to the CCEW certificate explains.
The Northern Beaches loses power to storms more often than most of Sydney, with trees across overhead lines a common cause. Our emergency electrician team handles the faults that follow, and spring is a good time to have a changeover switch fitted, before the summer storms arrive.
Frequently asked questions
Is it illegal to plug a generator into a power point?
Yes. Feeding a generator into a power point with a double-ended lead back-feeds the house wiring, which is not a compliant connection. It can put live pins within reach and send power out onto the street supply, putting line workers at risk.
Do I need an electrician to install a generator changeover switch?
Yes. In NSW, fitting a changeover switch and generator inlet is electrical wiring work for a licensed electrician, who lodges a Certificate of Compliance for Electrical Work when the job is done.
What is the difference between a changeover switch and a transfer switch?
They do the same job. A manual changeover switch is turned by hand when you start the generator. An automatic transfer switch works with a fixed standby generator and swaps the supply over by itself when the grid fails and again when it returns.
Can a changeover switch run my whole house?
It can, if the generator is large enough for everything that runs at once. Most portable generators are not, so many homes connect only essential circuits such as the fridge, lights and a few power points.
The bottom line
Never plug a generator into a power point. A changeover switch and generator inlet, fitted by a licensed electrician, lets you run the essentials through a blackout without back-feeding the grid or risking a shock. Decide what has to keep running, then get in touch and we will work out the right set-up for your board.