6 Generator Safety Mistakes That Kill People Every Year

TL;DR: Portable generators kill about 80 people a year in the U.S., and the leading cause is carbon monoxide poisoning from running a generator inside a garage or too close to windows and doors. The other big killers are backfeeding power into house wiring without a transfer switch, overloading extension cords, and refueling a hot engine. Keep the generator at least 20 feet from your home, use a listed transfer switch, and never run it indoors or in a garage — even with the door open.

_Last reviewed: July 2026 · 7 min read_

A storm knocks out the power, you drag the generator out of the garage, and thirty minutes later you're not thinking about carbon monoxide — you're thinking about keeping the fridge cold. That's exactly how people die. Six specific mistakes account for almost every generator-related death and injury reported to the Consumer Product Safety Commission, and every one of them is avoidable if you know what to watch for.

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What's the single most common way people die running a generator?

Carbon monoxide poisoning kills more people from portable generators than any other cause, accounting for the large majority of the roughly 80 generator-related deaths reported annually. CO is odorless and colorless, and a generator engine produces it in concentrations high enough to be fatal in minutes inside an enclosed or semi-enclosed space.

The mistake isn't usually running it in a sealed room — it's running it in a garage with the door open, on a covered porch, or near an open window during rain. CO builds up faster than most people expect, and it doesn't stay outside just because the generator is technically "outdoors." CPSC guidance says to keep portable generators at least 20 feet from any door, window, or vent, with the exhaust pointed away from the house. A battery-powered CO alarm on every level of the home, especially near sleeping areas, is the backup for when someone forgets the 20-foot rule at 2 a.m. during a blackout.

Why does backfeeding your generator into house wiring risk killing linemen?

Backfeeding sends generator power out through your home's wiring and onto the utility line, which can electrocute a lineman working to restore power miles away who assumes the line is dead. This happens when someone plugs a generator directly into a wall outlet using a "suicide cord" — a cable with male plugs on both ends — instead of using a proper transfer switch.

The fix is a manual or automatic transfer switch, typically costing $500 to $900 installed, wired by a licensed electrician so the generator circuit is fully isolated from the utility feed. If your panel is older or you're unsure it can handle a transfer switch and the loads you want to run, it's worth checking whether your service has enough power before adding equipment. Backfeeding is illegal in most jurisdictions for exactly this reason, and it's one of the few generator mistakes that can kill someone who isn't even on your property.

What happens when you overload a generator with too many extension cords?

Overloading a generator or running too many devices off undersized extension cords causes cords to overheat, which is a leading cause of generator-related house fires. A generator rated for 5,000 watts running a refrigerator, sump pump, space heater, and window AC unit simultaneously can pull well past its safe capacity, and a 16-gauge cord meant for a lamp will get hot fast under a 15-amp load.

| Cord gauge | Safe amperage | Typical use | |---|---|---| | 16-gauge | up to 10 amps | small lamps, phone chargers | | 14-gauge | up to 15 amps | space heater, TV | | 12-gauge | up to 20 amps | sump pump, window AC |

Use heavy-duty, outdoor-rated cords no longer than 100 feet, and add up your wattage before you plug anything in. If your home still has older wiring, mismatched loads are riskier than they'd be on a modern system — the same reasoning behind flagging homes with knob-and-tube wiring for extra caution.

Is it safe to refuel a generator while it's running?

No — refueling a running or recently shut-off generator is a top cause of generator fires and burn injuries. Engines run at 150 to 200°F and gasoline vapor ignites easily on contact with a hot muffler or exhaust manifold. Spilled fuel on a hot engine block has caused fires within seconds in documented CPSC incident reports.

Shut the unit off and let it cool for at least 15 minutes before adding fuel. Store gasoline in an approved container away from the house, garage, and any ignition source, and never store more than local fire code allows — usually 25 gallons for residential properties, though this varies by state. Keep a fire extinguisher rated for fuel fires within reach of wherever the generator runs.

What about running a generator in the rain or on wet ground?

Running an unprotected generator in the rain or setting it on wet ground creates a serious electrocution risk, since water intrusion into the outlets or control panel can energize the frame. A generator isn't like an outdoor AC condenser built for weather exposure — most portable units need a dry, ventilated cover or a purpose-built generator tent, never a tarp draped directly over the running unit, which traps CO and heat.

Set the generator on a dry, level surface, plug it in with your hands dry, and confirm it's properly grounded per the manufacturer's manual before storm season starts. If your outlets at home are still two-prong, that's worth resolving separately — see how to upgrade 2-prong outlets safely — since ungrounded household wiring compounds the risk when you're running extension cords from a generator into the house.

FAQ

How far should a generator be from the house?

At least 20 feet from any door, window, or vent, with the exhaust facing away from the home, per CPSC guidance.

Can I run a generator in an open garage?

No. Even with the garage door fully open, CO can accumulate to lethal levels inside and drift into the house within minutes.

Do I need a transfer switch for a portable generator?

Yes, if you want to power hardwired circuits or avoid backfeeding the utility line; a licensed electrician typically installs one for $500 to $900.

How long can gasoline sit in a generator before it goes bad?

Untreated gasoline degrades in about 30 days; use a fuel stabilizer if you're storing it longer, and drain the tank before extended storage.

What size generator do I actually need for a power outage?

Add up the running watts of essentials like the fridge, sump pump, and a few lights — most households get by on a 5,000 to 7,500-watt unit, but confirm your panel's transfer switch is rated to match.

This is educational information, not electrical or safety advice. Call a licensed electrician for transfer switch installation and consult your local fire code before storing fuel on your property.