Using generators safely

In a generator, a combustion engine drives an electricity generator. Because combustion in the engine is never quite complete, the exhaust contains a lot of carbon monoxide. When breathed in, CO enters the blood and binds to the red blood pigment much more tightly than oxygen does. The blood can then carry less oxygen, and the brain and heart get too little of it.

The treacherous thing is that you cannot perceive CO. It has no smell, you cannot see it, and the first signs – headache, dizziness, nausea, tiredness – seem harmless and are often mistaken for flu or exhaustion. During sleep you do not notice them at all. An open window or door is not enough to safely carry away the exhaust of a running engine.

The second danger is electrical. If a generator feeds the household wiring through a socket, the current also flows into the line to the street. There it energises lines that are supposed to be dead – deadly for utility workers and neighbours. Fires and damage can also happen when grid power returns.

The location decides how safe it is. The generator belongs outdoors on firm, dry ground, well away from windows, doors, vents and neighbouring houses, with the exhaust pointing away from the house. How far away it must be is stated in the manufacturer's manual and your authorities' guidance – stick to it, even when it is inconvenient.

Devices are connected one by one to the generator using undamaged extension cords rated for outdoor use. Watch the power limit: the generator can only deliver a certain amount of power, and too many devices at once overload it. Read the manual before first use and practise starting it in daylight – not for the first time in the dark during an outage.

Anyone who wants to supply the house with backup power permanently needs a transfer switch installed by a qualified electrician. It disconnects the house from the public grid before the generator feeds in. This is not a DIY job, and the rules for it differ from country to country.

Battery-powered carbon monoxide alarms in the house, especially near bedrooms, are an important second layer of protection. They beep before the amount of CO becomes dangerous – even while you are asleep. Check them before you start the generator.

If the alarm sounds or someone gets a headache, dizziness, nausea, weakness or drowsiness: everyone into fresh air immediately, call the local emergency number (112 in the EU) and do not go back into the house to fetch something “just quickly”.

When refuelling: switch the engine off and let it cool, only then top up. Remove spilled fuel before restarting. Fuel belongs in approved containers outside living areas and away from ignition sources; check local storage rules. Keep the generator dry, do not handle it with wet hands and protect it from rain only as the manufacturer allows – never enclose it.

A generator can supply a fridge, lamps or chargers during long outages. But it brings noise, exhaust in the neighbourhood, fuel storage and a theft risk. For many households it is enough to run only a few truly important devices.

An alternative is a battery power station. It produces no exhaust and may be used indoors, but has only limited capacity and must be charged beforehand. For life-sustaining medical devices, neither is a solution to improvise on your own: this needs a plan agreed with the doctor and the device supplier.

The US health agency CDC and Ready.gov explicitly warn against running generators in homes, garages, basements or near windows. After storms and floods, carbon monoxide poisonings from incorrectly placed generators happen again and again – often because people wanted to protect the generator from rain or theft.

A common misconception is: “It's safe with the garage door open.” It is not. Exhaust can still build up and drift into the house through doors and gaps. The only reliable solution is a place outdoors with enough distance.