Generator Safety Tips: How to Avoid Carbon Monoxide Poisoning and Other Hazards

Carbon Monoxide: The Silent Killer

Carbon monoxide (CO) is odourless, colourless, and tasteless. You cannot detect it without an alarm. It is the leading cause of non-fire-related accidental poisoning death in North America — and during power outages, generators are the primary source.

The numbers are stark. According to the U.S. Consumer Product Safety Commission (CPSC):

• Portable generators cause more CO poisoning deaths than any other consumer product
• More than 900 people die annually in the U.S. from CO poisoning related to non-vehicular consumer products — generators account for the majority
• Most deaths occur within the first hour of generator operation
• Deaths spike dramatically during and after major storms and outages, when people are most likely to use generators without following safety protocols

In Canada, Health Canada reports that carbon monoxide poisoning sends hundreds of Canadians to hospital each year and kills dozens — with generator misuse cited as a major contributor, particularly following ice storms and winter outages like those Ontario experiences regularly.

CO is deadly because it binds to haemoglobin in red blood cells with 200× the affinity of oxygen. Even at relatively low concentrations (35 ppm), it causes headache and dizziness. At 150 ppm, it becomes dangerous within hours. At 1,600 ppm — which a single generator running nearby can easily produce — death can occur within 2 hours. Victims often lose consciousness before recognizing the symptoms.

The 20-Foot Rule: Placement and Exhaust Direction

The CPSC requires a minimum of 20 feet (approximately 6 metres) of clearance between a generator's exhaust and any door, window, vent, or opening to the home. This is not a suggestion — it is a hard safety minimum.

Additionally:

• Point the exhaust away from the home. Even at 20 feet, if exhaust is directed toward the house, CO can concentrate near windows and enter through small gaps. Orient the generator so exhaust points away from all structures.
• Consider wind direction. Wind can carry CO back toward the house even if your initial placement looks correct. Check wind direction before starting and reposition if necessary.
• Never place near HVAC intakes. Air conditioner and heat pump compressors have air intakes. CO drawn into an HVAC system gets distributed through the entire home. Map your HVAC intake locations before you need to run a generator.
• Avoid low-lying areas near the home. CO is slightly heavier than air and can pool in basements and crawl spaces if generated nearby. Keep the generator on a higher, open surface where exhaust disperses freely.

Many homeowners install a dedicated generator pad — a poured concrete or paver pad in a pre-surveyed location that is the correct distance from all home openings. This eliminates guesswork every time you need to deploy the generator in an emergency situation.

Never Run Indoors — Including Garages

This cannot be overstated: a generator must never be operated indoors, in an attached garage, on a screened porch, in a basement, in a shed with doors closed, or in any partially enclosed space.

The garage misconception kills people every year. A common belief is that running a generator in the garage with the door open is safe. It is not. CO is produced in quantities that a partially open garage cannot ventilate. The gas accumulates, seeps through the door connecting the garage to the living area, and reaches lethal concentrations in occupied rooms — often while occupants are asleep.

Similarly, a covered porch or carport is not acceptable. Even with open sides, architectural features, landscaping, and wind patterns can trap CO against the home.

The only acceptable location for generator operation is fully outdoors in open air, at the required clearance distance from the home.

CO Detector Requirements

Every home with a generator needs battery-operated CO detectors. Battery operation is critical — in a power outage, plug-in detectors are useless.

Where to install CO detectors:

• At least one on every floor of the home, including the basement
• Within 10 feet of each bedroom door
• Near the garage door entry to the home (if attached garage)
• Not in kitchens (cooking appliances can cause nuisance alarms) or within 5 feet of fuel-burning appliances

Standards to look for:

• UL 2034 (U.S./Canada standard for CO alarms)
• CSA 6.19 (Canadian standard, equivalent level of protection)

If the CO alarm sounds: Evacuate immediately. Do not stop to investigate. Call 911 from outside. Do not re-enter until emergency services give clearance.

CO detectors should be replaced every 5–7 years — check the manufacture date on the back. Many homeowners discover during emergencies that their detectors are expired.

Shop battery-operated CO detectors on Amazon →

Proper Grounding

Portable generators must be properly grounded to prevent electrocution. Most modern portable generators are "separately derived systems" and in many cases, the generator frame itself can serve as the ground — but this varies by model and configuration.

Key grounding rules:

• If the generator has a metal frame and you're using extension cords directly, the frame ground is generally sufficient per the National Electrical Code
• If you're connecting via a transfer switch to your home's panel, the electrician performing the installation handles grounding as part of the work — do not attempt to ground a panel-connected generator yourself
• Never modify the grounding prong on generator outlets or extension cords
• Do not operate a generator on a wet surface — place it on a dry, stable platform if necessary

Consult your generator's manual and a licensed electrician if you're unsure about grounding for your specific setup.

Extension Cord Safety

When powering appliances via extension cord from a generator, the wrong cord can cause fires, equipment damage, and overloads. Use this table as a guide:

Additional extension cord rules:

• Use outdoor-rated (SJOW, SJTOW, or SOW jacket) extension cords only — indoor cords are not rated for moisture or generator use
• Keep cords fully unrolled — coiled heavy-load cords can overheat
• Never run cords under rugs, through walls, or in areas where they can be pinched or abraded
• Use the shortest cord adequate for the job — every extra foot adds resistance and voltage drop
• Do not daisy-chain extension cords — connect appliances directly to the generator or via a single cord
• Check cords for damage before each use — cracked insulation on a high-load cord is a fire hazard

Transfer Switch: Never Back-Feed the Grid

One of the most dangerous and unfortunately common generator mistakes is "back-feeding" — plugging a generator into a household outlet (often via a "suicide cord" or "backfeed plug") to power circuits through the panel. This is:

• Illegal — prohibited under the Ontario Electrical Safety Code and the Canadian Electrical Code
• Deadly to utility workers — back-fed electricity travels back through the meter and onto the utility lines. Lineworkers restoring power assume lines are dead. They are not. Multiple lineworkers have been killed this way across North America
• Dangerous to you — when grid power is restored, the voltage surge can destroy your generator and potentially start a fire

The correct solution is a manual transfer switch or interlock kit installed by a licensed electrician. A manual transfer switch isolates your home from the grid before connecting the generator, making back-feeding electrically impossible. An interlock kit is a mechanical device that prevents the main breaker and generator breaker from being on simultaneously.

In Ontario, this work requires an ESA permit. Installation typically costs $800–$1,500 including parts and labour. It is a one-time cost that permanently solves the safety problem and makes every future outage safer and more convenient to manage. See our generator sizing guide for sizing recommendations before booking the electrical work.

Wet Weather Operation

Operating a generator in rain or wet conditions creates shock and short-circuit hazards. Follow these rules:

• Use a commercial generator cover or "generator tent" designed for use while operating — these allow exhaust ventilation while protecting from rain
• Never operate under a tarp that traps exhaust — CO buildup can occur even with partial enclosure
• If no generator tent is available, position the generator under a wide roof overhang — but only if clearance distances from windows and doors can still be maintained
• Never touch the generator, outlets, or cords with wet hands
• Place the generator on a dry surface — a plywood sheet or generator mat works if the ground is wet
• After rain exposure, allow the generator to dry before storing — moisture in fuel can cause starting issues next time

Safe Fueling Practices

Generator fires are frequently caused by improper fueling. Gasoline spilled on a hot engine ignites immediately. Follow these rules absolutely:

• Never refuel a running generator. Shut down the generator and allow it to cool for at least 2 minutes before adding fuel
• Never refuel near an open flame — including other equipment running nearby, pilot lights, or smoking materials
• Use an approved fuel container (CSA or UL listed) for gasoline storage and transport
• Don't overfill the tank — leave a small air gap for fuel expansion
• Wipe up any spilled fuel before restarting — a single teaspoon of gasoline can flash-ignite on a hot engine
• For propane-fuelled or dual-fuel units, check hose connections for leaks with soapy water before each use; never check with an open flame

Fuel and Generator Storage

Improper storage creates both safety risks and maintenance headaches:

• Gasoline storage: Store in approved containers in a detached, ventilated structure — not attached garages. Use fuel stabilizer for any gas stored more than 30 days. Rotate stock: use old fuel in your vehicle and refill with fresh for generator storage
• Propane storage: Store tanks outdoors or in a well-ventilated non-living-space structure. Never store propane inside the home, basement, or attached garage. Propane stores indefinitely — no additives needed
• Generator storage: Before long-term storage (end of season), run the carburetor dry by shutting off the fuel valve and running until it stops, or add fuel stabilizer to the tank. Store in a dry location with the fuel valve in the off position
• Monthly maintenance: Run the generator under load for 30 minutes monthly to keep oil circulating, check starting systems, and verify operation before you need it in an emergency

Best Generators With Built-In Safety Features

Modern generators increasingly include CO shut-off technology — a sensor that automatically shuts down the unit if CO accumulates to dangerous levels. The CPSC has pushed strongly for this feature following fatal incidents. Look for generators with:

• CO-GUARD or similar automatic CO shutdown (Honda, Generac, Westinghouse, and Champion all offer this on newer models)
• Covered outlets for wet weather protection
• Low-oil shutdown to protect the engine and prevent fires from oil leaks onto hot surfaces
• Fuel gauge to prevent running dry and surge-damaging connected equipment

See our complete best portable generators guide for detailed picks including models with CO safety technology. If you want to eliminate generator risks entirely, a home battery backup system like those covered in our whole-house battery backup guide produces zero CO and can safely operate indoors.

For standby generator safety requirements specific to Ontario, the Ontario Electrical Safety Authority (ESA) generator safety page has jurisdiction-specific requirements including permit obligations and inspection procedures.