Generator safety basics for homes with backup power
Keep a generator at least 20 feet from the home, guard against carbon monoxide, store fuel safely, match loads to its rating, shut it down safely and never connect it to a household outlet.
A generator can keep a refrigerator, a furnace blower, and a few lights running through a long outage, but it also produces carbon monoxide, a gas that can kill quickly and without warning. Nearly all generator safety comes down to three things: where it runs, how its fuel is handled, and how it connects to the house. Get those right, and the rest is routine.
Read the owner's manual before the first use, and follow it closely. The manufacturer sets limits on load, placement, fuel, and maintenance for your specific unit. Where this guide gives general figures, such as distances, the manual takes priority if it sets a stricter one.
Keep it outside and well away from openings
Run a generator outdoors only, at least 20 feet from the house, with the exhaust pointed away from doors, windows, and vents. The 20-foot figure is a widely cited minimum in public safety guidance, not a safe margin in every wind. Many manuals and warning labels only say to keep the unit far from windows, doors, and vents, so follow whichever instruction is stricter. Set the unit on dry, level ground, and keep it clear of shrubs, deck railings, and any spot where snow or leaves could build up around it. Keep it dry and do not run it in rain or snow unless a cover or open canopy designed for generator use shelters it without trapping exhaust; never touch it with wet hands. Never run one in a garage, even with the door open, or in a basement, crawlspace, or shed. The same applies to a carport or porch that has walls or a roof trapping exhaust around the unit.
Carbon monoxide is the main hazard
Carbon monoxide is colorless and odorless, and it spreads through a house quickly. Exhaust can drift through open windows, doors, and vents even when the generator is well outside, which is why the placement rules matter. Install battery-backup carbon monoxide alarms on every level of the home and outside each sleeping area, and test them when you test the generator. Replace alarms on the schedule the manufacturer gives.
Watch for symptoms of carbon monoxide exposure, which include:
- headache, dizziness, or weakness
- nausea or vomiting
- confusion or drowsiness
- chest pain or shortness of breath
These symptoms can resemble the flu, so do not try to decide whether they are serious. If anyone in the home has them, or if an alarm sounds, get everyone outside into fresh air and call emergency services. Do not go back inside to shut the generator off. Pets can be affected as well, so bring them outside with the people.
Store and handle fuel carefully
Gasoline and other generator fuels are flammable, and their vapors can ignite from a spark or a hot engine. Store fuel only in containers approved for it, in a cool, ventilated area outdoors or in a detached shed, away from living space, heat sources, and any appliance with a pilot light. Keep the amount modest, and label each container with the date it was filled. Gasoline breaks down over months, so add a fuel stabilizer when the manufacturer recommends it, and use or replace old fuel before it goes stale.
Refuel only after the generator is switched off and has cooled. A hot engine or exhaust can ignite spilled fuel, so wipe up any spill before restarting. Do not smoke near the generator or the fuel. Keep fuel out of reach of children, and never store it inside the house or the garage.
Never connect it to a household outlet
Plugging a generator into a wall outlet, or into a dryer outlet, is dangerous. Electricity can flow backward into utility lines, where it can injure line workers who believe the line is dead. It can also damage the generator and the appliances in the house. The safe way to connect a generator to home wiring is a transfer switch or an interlock kit installed by a licensed electrician, who can also tell you whether your area requires a permit.
Extension cords are a separate matter. Use only cords rated for outdoor use and sized for the load, with a lower gauge number for longer or heavier runs. Run cords directly from the generator to each appliance rather than chaining cords together, and keep them dry and off the ground where water collects. Check each cord for damage before use, since a damaged cord can overheat or shock someone.
Match the load to the generator's rating
Every generator has a rated running wattage and often a higher starting wattage. The labels on your appliances list how much power each one needs. Motors, such as those in refrigerators, well pumps, and furnace blowers, draw more power to start than to run, so the starting load matters as much as the running load. Add appliances one at a time, watch the generator, and avoid running it near its maximum for long periods. An overloaded generator can stall, overheat, or stop supplying the devices you care about most.
Prioritize the essentials, such as the refrigerator, a few lights, a router, and phone charging. Electric dryers, electric ranges, and space heaters draw large amounts of power and are rarely practical on a portable unit for long periods.
Start, check, and shut down safely
Before starting, check the oil and fuel levels and inspect the air filter. Make sure the unit sits on firm, level ground in the spot you chose. Once it is running, listen for changes in sound, check the exhaust area from a safe distance, and inspect cords and connections at intervals. Keep a fire extinguisher rated for flammable liquid fires, known as Class B, within reach, and make sure everyone knows where it is in the dark.
To shut down, turn off the loads first, then switch off the generator and let it cool before refueling or moving it. Then store it in a dry place, with its fuel drained or stabilized as the manual directs, and keep it clean between uses. A unit stored in an attached garage or other enclosed space should have its fuel drained unless the manual says otherwise, because fuel vapors can build up in a closed space. Never run it where it is stored, because a garage, shed, or porch can trap exhaust. Schedule maintenance as the manual describes, and if the manufacturer recommends running the unit periodically, do it outdoors under the placement rules above, so you know it starts when you need it.
Write the rules that apply to your unit on a card kept with it, so anyone in the household can follow them during a storm, when the house is dark and everyone is tired. Review that card whenever you service the unit, so it matches the current owner's manual.