Shelter · Fire & Utility Safety
A portable generator can keep the lights on during a power outage. It can also kill your family in minutes if you put it in the wrong place. This page covers the placement rules, the fuel handling, and the electrical connection that keep a useful tool from becoming a lethal one.
The placement ruleThe risk
The U.S. Consumer Product Safety Commission estimates that approximately 100 people die each year from carbon monoxide poisoning caused by portable generators.[1] Between 2004 and 2021, more than 1,300 people died this way.[2] One in four fatal incidents involves multiple deaths at once, sometimes entire families.
These are not equipment failures. In 77 percent of fatal cases, the generator was placed inside the living area of the home. In two out of three cases where information was available, there was no attempt at ventilation.[3] The generator worked exactly as designed. The placement killed people.
Carbon monoxide is colorless and odorless. You cannot see it, smell it, or taste it. A single portable generator produces as much carbon monoxide as hundreds of cars.[4] In an enclosed space, CO levels can reach lethal concentrations within minutes. Symptoms of CO poisoning (headache, dizziness, nausea, confusion) mimic flu and fatigue, and exposed people often become unconscious before they recognize what is happening.
Most of these deaths happen during weather-related power outages, exactly when people are most likely to use a generator for the first time. The top scenarios are storms, winter weather, and hurricanes.[3] Everything on this page exists to prevent your household from joining that count.
The most important rule
The CPSC, CDC, FEMA, and NFPA all converge on the same placement standard for portable generators: at least 20 feet from any door, window, or vent, with the exhaust pointed away from the house.[5] This is not a suggestion. It is the minimum distance that reduces the risk of CO drifting into your home.
Where a generator must never run
Inside your home. Not in the living room, not in the hallway, not in the kitchen. Not even with windows open.
In the garage. An open garage door does not create enough airflow to clear exhaust. CO pools inside and seeps into the house through the connecting door and shared walls. This is one of the most common fatal scenarios.[5]
In the basement or crawlspace. CO is slightly lighter than air but mixes readily with room air and accumulates in enclosed spaces. A basement with a running generator becomes lethal within minutes.
On a porch, in a carport, or under a deck. These feel "outside" but behave like funnels. The roofline traps exhaust and the nearest path for fumes is the closest door or window.
In a shed or outbuilding. Any enclosed or partially enclosed space traps CO. The only acceptable location is fully outdoors, on open ground, 20 feet from the building.
Twenty feet is a real distance. It means the generator is well into the yard, not against the house. Bridge the gap with heavy-gauge outdoor-rated extension cords. The correct solution to a cord problem is a longer cord or a heavier cord, never a shorter distance between the generator and the house.
Set the generator on a level, dry, non-combustible surface. Concrete, gravel, or bare ground are fine. Not a wooden deck, not on dry leaves, and not on grass if the exhaust faces downward. Generator exhaust temperatures can reach 1,300°F, enough to ignite nearby materials.
If rain is the reason you are tempted to move the generator closer to the house or under cover, use a purpose-made generator canopy or open-sided cover that keeps water off the outlets while leaving airflow on all sides. Never drape a tarp over a running unit. Never pull it into the garage when the weather turns. That decision, made in a moment of convenience, is the decision that kills people every storm season.
Fuel handling
Never refuel a running generator. Shut it down and let it cool before adding gasoline. A hot engine, a hot exhaust, and gasoline vapors are a combination that causes fires. Gasoline vapors are heavier than air and pool at ground level, which means spilled fuel and invisible vapor can travel to the hot exhaust pipe even if the spill seems far away.
Store gasoline only in approved, UL-listed portable fuel containers. As of 2023, federal law requires all portable fuel containers sold in the U.S. to include flame mitigation devices.[6] Never store gasoline in glass containers or repurposed plastic containers like milk jugs. Never store fuel containers inside your home. A detached shed, a well-ventilated garage (away from water heaters, furnaces, or any appliance with a pilot light), or an outdoor storage cabinet is acceptable.
A typical portable generator burns 0.5 to 1.5 gallons of gasoline per hour depending on size and load. For a 72-hour power outage running 8 to 12 hours a day (enough to cycle the refrigerator, charge devices, and run essential lights), plan for 10 to 20 gallons of stored fuel. This is 2 to 4 five-gallon containers. Gasoline degrades over time; add fuel stabilizer if you plan to store it longer than 30 days, and rotate it through your vehicles or lawn equipment to keep the supply fresh.
Some generators run on propane (LP gas) instead of or in addition to gasoline. Propane does not degrade in storage the way gasoline does, and the CO output from propane generators is somewhat lower, though still dangerous in enclosed spaces. All placement and ventilation rules apply equally to propane generators. The only difference is the fuel source. If your household already uses propane for heating or cooking, a propane-capable generator simplifies the fuel supply. Our Energy section covers generator selection, sizing, and capacity planning in depth.
Electrical connection
The simplest and safest way to use a portable generator is to run extension cords directly from the generator to individual appliances. No wiring changes are needed. No risk of backfeed. If this approach meets your needs, it is the right approach.
If you want to power circuits in your home's electrical panel (lights, the well pump, hardwired appliances), you need a transfer switch. A transfer switch is a device that connects your generator to your panel while physically disconnecting the panel from the utility grid. It ensures only one power source feeds the panel at any time.
Never plug a generator into a wall outlet
Plugging a generator into a standard household outlet, sometimes called "backfeeding" or using a "suicide cord," sends electricity backward through your panel and out onto the utility power lines. This energizes lines that utility workers believe are dead. Workers have been electrocuted by backfed lines while restoring power after storms.[7]
Backfeeding is illegal. The National Electrical Code (NEC Article 702.6) requires transfer equipment for any generator connected to building wiring. Beyond the legal requirement, it is one of the most dangerous things a homeowner can do with a generator. The risk is not theoretical. It has killed people.
Manual transfer switch: You flip a switch or handle to move selected circuits from utility power to generator power. Costs $200 to $500 installed. Works with portable generators. Requires you to start the generator and flip the switch manually during an outage. This is the most common residential option.
Automatic transfer switch (ATS): Detects a utility power loss, starts the generator automatically, transfers the load, and reverses the process when utility power returns. Standard with permanently installed standby generators. Costs $500 to $2,000+ installed depending on capacity.
Both types must be installed by a licensed electrician. Both require a permit and inspection in most jurisdictions. This is not a project for a YouTube tutorial and an afternoon. The consequences of a wiring mistake include electrocution, fire, and damage to your generator and appliances when utility power returns.
Your last line of defense
Correct placement is the primary defense against generator CO poisoning. A carbon monoxide detector is the backup. If CO enters your home despite correct placement (a wind shift, an unusual air current, a neighbor's generator), the detector is what wakes you up before you stop waking up.
Install battery-powered or battery-backup CO detectors on every level of your home and near every sleeping area. Test them monthly. Replace batteries at least annually. Replace the detector units themselves every 5 to 7 years per the manufacturer's instructions; the sensors degrade over time.[5]
If a CO detector alarms while a generator is running, get everyone out of the house immediately. Do not try to find the source. Do not open windows and wait to see if the alarm stops. Leave, call 911 from outside, and do not re-enter until emergency responders have cleared the home.
Our Smoke Alarms and CO Detectors guide covers placement standards, detector types, and maintenance in detail.
What goes wrong
Mistake
"I'll just run it in the garage with the door open"
This is the single most common scenario in generator CO fatalities. An open garage door does not create enough airflow. CO accumulates under the ceiling, moves through the connecting door to the house, and seeps through shared walls. A family sleeping on the other side of that wall may never wake up. The generator goes outside. Twenty feet from the house. Every time.
Mistake
Refueling while the generator is running
Gasoline spilled on a hot engine or exhaust pipe can ignite instantly. Shut the generator down. Wait at least two minutes for it to cool. Then refuel. The inconvenience of restarting is trivial compared to a gasoline fire.
Mistake
Using a "suicide cord" to backfeed through a wall outlet
A male-to-male extension cord plugged from the generator into a wall outlet is called a suicide cord for a reason. It energizes your entire panel and every wire connected to it, including the lines running to the utility pole. It is illegal, it is uninsured, and it has killed utility workers restoring power for your neighbors. Use extension cords to individual appliances, or have an electrician install a transfer switch.
Mistake
Overloading the generator
Every generator has a rated wattage. Exceeding it does not just trip a breaker; it can damage the generator, damage connected appliances, and create a fire risk. Know your generator's rated (continuous) wattage. Add up the wattage of everything you plan to connect. Stay under the rated number, not the peak or surge number printed on the label. Our Energy section covers load calculation.
Mistake
No CO detectors in the house
Even with perfect 20-foot placement, wind shifts happen. If you own a generator and do not have working CO detectors on every level of your home, fix that before the next outage. A $30 detector is the cheapest life insurance your household will ever buy.
During extended outages
During a short outage, a running generator is unremarkable. During an extended one, it sends a clear signal to every house within earshot: your household has fuel, stored food, and the planning to use both. Most neighbors will simply be glad someone nearby is prepared. But in a prolonged event, generator noise and visible light from powered windows can draw attention your household is not prepared to manage.
This is not about distrusting your neighbors. It is about recognizing that a generator is loud and a lit house in a dark neighborhood is visible from a distance. Run the generator during daylight hours when ambient noise is higher. Cycle it rather than running it continuously. Close curtains over lit windows at night. These are simple adjustments that reduce your household's visibility without reducing its capability.
For a full timeline of what changes during an outage that lasts beyond 72 hours, see When the Power Stays Off.
What this page does not cover
This page covers the safety rules that keep a generator from harming your household. It does not cover which generator to buy, how to calculate your household load, how to size a generator for a well pump or HVAC system, or how portable generators compare to battery systems and standby units. That information lives in the Energy section, which covers the full range of backup power options in depth.
Sources
Related
Smoke Alarms and CO Detectors
Placement standards, detector types, and the maintenance schedule that keeps them working.
Utility Shutoffs
How to locate and operate your gas, water, and electrical shutoffs before an emergency.
Energy
Generator selection, battery systems, solar, and the full range of backup power options for your household.
Home Fire Preparedness
Escape planning, prevention habits, and what to do in the first moments of a fire.