What Is the 20-20-20 Rule for Generators?
The 20-20-20 rule for generators is a US memory aid, not an Australian rule. Keep the generator 20 feet from your house, let it cool 20 minutes before refuelling, and the third 20 varies. Here's the Aussie version.
Where the 20-20-20 Rule Comes From
The rule turns up on US city, county and fire district pages, usually when a hurricane or ice storm has knocked the power out. The City of New Orleans runs one of the tidier versions on its NOLA Ready power outage page.
None of the Australian regulators we checked use it. Energy Safe Victoria, Queensland's Electrical Safety Office, Energex and Ausgrid all give generator safety advice without it. It's a memory aid, not a standard, which is why the versions don't line up.
20 Feet From the House
NOLA Ready says keep generators 20 feet away from the house, doors and windows. That's about 6 metres. The US Centers for Disease Control and Prevention says much the same: use generators outside, more than 20 feet from your home, doors and windows.
The point is carbon monoxide. Exhaust that drifts to an open window or vent ends up inside.
20 Minutes to Cool Before Refuelling
The second 20 is a cool-down. NOLA Ready says power off and allow a 20-minute cool-down before refuelling. Petrol spilt on a hot engine can catch.
The Third 20
This is where it falls apart. NOLA Ready's third 20 is a $20 battery-operated carbon monoxide alarm. OUPES, a US power station brand, makes it 20 inches of clearance around the generator, or 20 feet depending on local code.
Same name, different rule.
The Maintenance Version
Search the phrase and you'll also find a maintenance rule that has nothing to do with safety. DIYPower, a generator set supplier based in Hong Kong, says run the generator for at least 20 minutes, every 20 days, at 20% of its rated load.
That's about keeping a standby set exercised. The service schedule in your own owner's manual beats it.
What Australian Guidance Says Instead
Our regulators cover the same ground as the US rule, just without the catchy numbers.
Distance From Your House
No Australian regulator we checked gives a distance. Ausgrid says operate it outside only, in a well-ventilated area, away from doors, windows and vents, and never in a garage or enclosed space. Energex adds your neighbours' open windows to that list.
The manuals give you a minimum. Westinghouse's Australian iGen instruction manual says at least 1.8 m from any building, other equipment or combustible material, and not near windows, doors or vents. Treat that as a floor, not a target. We compare the brands in how close a generator can be to your house.
Carbon Monoxide Alarms
This is the part of the US rule that holds up here. Queensland's Electrical Safety Office says install a battery-operated carbon monoxide alarm. Energex says use one with the generator, so it alerts you if levels become dangerously high.
Victoria's health department says carbon monoxide is invisible and you can't smell it. If it builds up in your home, garage or caravan, it can cause sudden illness, loss of consciousness and death. The warning signs are in can a generator cause carbon monoxide poisoning.
Some generators add their own protection. The Briggs & Stratton P2500 has CO Guard, which monitors the air around the machine and shuts the engine down before carbon monoxide gets dangerous. It's a backstop. It doesn't change where the generator goes.
Refuelling a Hot Generator
Australian advice doesn't put a clock on it. The Electrical Safety Office says turn the generator off and let it cool down before refuelling, because fuel spilt on hot engine parts could ignite. Energex says never refuel a hot generator or one that's running.
The manuals vary. Westinghouse says wait until the muffler access cover is cool to the touch. Briggs & Stratton's Australian operator's manual for its P2200 inverter says turn the engine off and let it cool at least 2 minutes before removing the fuel cap. If 20 minutes helps you remember, it errs on the safe side of both.
Running It Overnight
The US rule leaves this one out. Energex says turn the generator off at night and when you're away from home. Run it while you're up and about, then shut it down.
20-20-20 Rule Compared With Australian Guidance
| US 20-20-20 rule | Australian guidance | Who says it |
|---|---|---|
| 20 feet (about 6 m) from the house | No set distance. Outside only, away from doors, windows and vents. Manual minimum 1.8 m from buildings | Ausgrid, Energex, Westinghouse iGen manual |
| 20-minute cool-down before refuelling | Turn it off and let it cool. Never refuel it hot or running | Electrical Safety Office (QLD), Energex |
| $20 carbon monoxide alarm | Battery-operated carbon monoxide alarm | Electrical Safety Office (QLD), Energex |
| Not covered | Turn it off at night and when you're away | Energex |
So the 20-20-20 rule isn't wrong, it's just American and incomplete. Here, run the generator outside, well clear of windows, doors and vents, put a battery CO alarm inside, let it cool before refuelling and switch it off at night.
If you're choosing a generator for blackouts or camp, the generator finder narrows it down. Or talk it through with us on 03 7056 6732, or SMS 0476 330 590.
