Generator Changeover Switch for Business: How to Connect a Backup Generator Safely

Byron Knight, Licensed Electrical Contractor

QLD Lic. 1511406 · 20+ years’ experience · Gold Coast & SEQ · Updated October 2026

Every storm season on the Gold Coast, the power drops for a few hours and businesses that rely on it lose stock, sales and staff hours. Some buy a generator from a hardware store, and it sits in the storeroom until the next outage. That’s when they find there’s no safe way to connect it to the things that matter.

This guide is for owners and managers of shops, cafes, clinics, offices and small warehouses who want backup power that works when it’s needed. It covers how a generator changeover switch works, what Queensland’s safety regulators say, which circuits to back up first, and what to settle before the next storm. If you’re thinking about a generator for your home, start with our power outage guide for Gold Coast homes instead.

What is a generator changeover switch?

A changeover switch is fitted at your switchboard and selects where the building’s power comes from: the grid (Energex) or your generator. It has an off position between the two, so both sources can never be connected at the same time.

Energex says the only way to safely connect a generator to your home or business’ wiring is to have an isolating switch installed by a licensed electrical contractor, and notes this is also known as a changeover switch. Queensland’s Electrical Safety Office says the same about permanently connected generators: a licensed electrician must make the connection and install a permanently wired changeover switch, so power is fed “from only one source” at a time.

For a portable generator, the changeover switch is usually paired with a generator inlet. That’s a weatherproof socket on the outside of the building that the generator plugs into with a proper lead. When the power goes, you run the generator outside, plug it into the inlet and move the changeover switch across. The generator then supplies only the circuits wired to it.

Why plugging a generator into a power point is so dangerous

Backfeeding usually happens when someone uses a double-ended lead (Energex calls them “suicide leads”) to push generator power into a power point, or connects a generator directly to the switchboard. Energex lists who that can kill: you, your staff, your neighbours, anyone near fallen powerlines, and the crews working to restore supply.

For a business there’s a legal side too. Every business in Queensland has a duty under the Electrical Safety Act 2002 to be conducted in a way that is electrically safe, and a makeshift generator connection is unlicensed electrical work. The Electrical Safety Office says unlicensed electrical work is illegal, with penalties of up to $40,000 for individuals and much higher maximums where someone is exposed to a risk of death or serious injury. For where the legal line sits, see what you can legally do yourself in QLD.

Portable generator with an inlet, or a permanent generator?

Most small Gold Coast businesses choose between two set-ups.

Energex notes that large generators can keep businesses running and are essential for some, but “they’re expensive and they’re not portable.” For most small businesses, a well-chosen portable unit and a properly wired inlet is the practical answer. The ESO says permanent installations must meet AS/NZS 3000 (the Wiring Rules) and AS/NZS 3010, the standard for generating sets, along with Energex requirements.

What should a business back up first?

Trying to run everything is the most common mistake. A generator big enough for the whole building is a much larger job, and most businesses don’t need it. Start with what has to stay on for you to keep trading safely, or to avoid losing stock.

1. Refrigeration. Fridges, freezers and coolrooms hold the most money at risk in food and medical businesses. For the food-safety side of an outage, see our commercial kitchen guide.
2. Payments and communications. EFTPOS terminals, the internet modem and router, phone systems and the till. They draw very little power but stop trade completely if they go down.
3. Safety and security. Some lighting, alarm panels, cameras and access control. If staff are still on site, they need to be able to see and get out.
4. Critical equipment. A server, a medical fridge, a sump pump or anything else your business can’t do without.
5. Everything else, only if the budget allows. Air-conditioning, ovens, hot water and large motors are what push a generator from a portable unit to a much bigger install.

We then wire those circuits so the generator feeds them, usually through a dedicated section of the switchboard. It’s also the time to look at the board’s condition. If it’s old, corroded or full, it may need a switchboard upgrade before it can take a changeover switch, and a switchboard inspection tells you that before you buy anything.

Sizing: why motors matter more than the label

Motors in fridges, compressors and pumps draw a surge of current when they start, well above their running load. A generator that looks big enough on paper can stall when two compressors start at once. Size the generator from what’s actually on the backed-up circuits, including start-up loads. If your business runs on three-phase power, the generator and changeover arrangement have to match it. Our three-phase vs single-phase guide explains the difference.

Solar and batteries change the design

If the building has solar panels or a battery, tell your electrician before anything is designed. A grid-connected system shuts down in an outage for safety reasons, and the way the generator, inverter and changeover switch interact has to be planned. Our battery storage and switchboard guide covers some of the same ground for homes.

Running a generator safely on the day

Even with the right switch, the generator itself needs care. The ESO’s generator do’s and don’ts and Energex’s guidance cover these points:

• Run it outside only. Energex warns that fuel-burning generators produce carbon monoxide, which is colourless and odourless. Keep it away from doors, windows and air intakes, including your neighbours’.
• Fit a battery-operated carbon monoxide alarm, as the ESO recommends.
• If there’s no inlet, plug individual appliances straight into the generator using heavy-duty, outdoor-rated leads with an earth pin. Never try to power the building’s wiring through a power point.
• Check the site first. Energex says not to turn on the isolating switch if your premises have been damaged.

Before storm season: a business backup-power checklist

1. List what must stay on, and roughly how long you’d need it.
2. Get a licensed electrician to check the switchboard and quote an inlet and changeover switch for those circuits.
3. Choose a generator sized for those circuits, including motor start-up loads.
4. Keep the certificate of testing for the installation. Licensed contractors must give you one, and our compliance certificate guide explains why it matters.
5. Write a one-page procedure and keep it near the switchboard, so whoever is on shift knows how to switch over and back.
6. Run the generator and practise the changeover now and then, so the first time isn’t in the dark during a storm. Add it to your preventative maintenance plan if you have one.

For the wider list of storm jobs, see our Gold Coast storm season prep guide.

Backup power for businesses on the southern Gold Coast

We see two patterns locally. Strip shops and cafes along the coast from Burleigh Heads to Currumbin and Tugun mostly need a portable set-up for refrigeration and payments, and their switchboards have often been extended by several tenants and need checking first. Light industrial and medical tenancies around Burleigh Waters, Varsity Lakes and the Molendinar industrial area are more likely to have three-phase equipment, which changes the generator and switch design.

The work is the same in principle either way: a licensed connection, a changeover switch, and a clear plan for what runs during an outage. If the power’s already out and something isn’t right, our 24/7 commercial emergency electrician service covers the southern Gold Coast, and our general wiring and installations team handles the inlet and switch.