This generator installation safety checklist covers the four things that kill people during generator operation: carbon monoxide poisoning from improper placement, electrocution from backfeeding the grid, fire from improper fuel storage or electrical connections, and generator damage from improper grounding. Every one of these deaths is preventable. Every one of them occurs because someone skipped a step on this checklist. The checklist is not complicated. It is not expensive. It is not optional. A generator that is running during a power outage is keeping your house warm and your refrigerator cold. A generator that is installed incorrectly is keeping your house warm and poisoning the people inside it. The difference is where the generator is placed and how it is connected. The checklist covers both.
Generator installation falls into two categories: portable generators connected with extension cords, and standby generators permanently installed with an automatic transfer switch. The portable generator is the most common and the most dangerous — most generator deaths involve portable generators operated too close to the house or in an attached garage. The standby generator is professionally installed and significantly safer. The checklist covers both. The portable generator checklist is for the homeowner who buys a generator at a hardware store before a storm. The standby generator checklist is for the homeowner who contracts a professional installation. Here is what to check.
Portable Generator Safety Checklist
These seven checks are mandatory for every portable generator installation. The 20-foot placement rule and the CO detector are the two that prevent death.
| Check | Requirement | Why It Matters |
| Placement | At least 20 feet from the house, doors, windows, and vents; never in an attached garage, even with the door open | Carbon monoxide is odorless and colorless; CO from a generator placed too close to the house enters through windows, vents, and soffits and kills occupants while they sleep |
| CO detector | Battery-operated CO detector on every level of the house, outside each sleeping area | The CO detector is the only warning; the generator is running outside; you cannot smell the CO entering the house; the detector can |
| Connection method | Extension cords rated for outdoor use, sized for the load, plugged directly into the generator; NEVER backfeed through a dryer outlet | Backfeeding energizes the utility lines and can electrocute utility workers; it also bypasses the circuit breakers and can overload the house wiring |
| Transfer switch | If connecting to the house wiring, a manual transfer switch installed by an electrician is required | The transfer switch isolates the house from the grid; it is the only code-compliant way to power the house from a portable generator |
| Grounding | Ground the generator per manufacturer’s instructions — typically a ground rod and copper wire connection | Proper grounding prevents electric shock from a fault in the generator or the connected appliances |
| Fuel storage | Gasoline stored in approved containers, in a detached shed or outdoors, away from the generator exhaust | Gasoline vapors near a running generator or a hot exhaust can ignite; fuel should never be added while the generator is running or hot |
| Wet conditions | Generator must be dry; operate under a canopy or generator tent rated for wet-weather use; never indoors | Water and electricity are incompatible; a wet generator can short-circuit and electrocute anyone touching it |
Standby Generator Installation Checklist
These six checks cover the professional installation of a permanently installed standby generator. All require a licensed electrician and a licensed gas fitter.
| Check | Requirement | Why It Matters |
| Location | At least 5 feet from doors, windows, and combustible walls; 18 inches from the house wall; not under a deck or overhang | Indoor-rated generators must be installed in a dedicated, ventilated room with fire-rated walls |
| Automatic transfer switch | Rated for the generator output and the service size; installed between the meter and the main panel | The ATS automatically disconnects the house from the grid when the generator starts; it prevents backfeeding and isolates the circuits |
| Natural gas or propane connection | Installed by a licensed gas fitter; line sized for the generator’s fuel consumption at full load; gas shutoff valve accessible | Undersized gas lines cause the generator to run lean, overheat, or shut down under load; a gas leak near a running generator is an explosion risk |
| Electrical connection | Wired by a licensed electrician; conductors sized for the generator output; disconnect switch accessible | Improperly sized conductors overheat; loose connections cause arcing; both are fire hazards |
| Permit and inspection | Electrical permit, gas permit, and building permit as required; inspected after installation | The inspection confirms the installation is code-compliant; unpermitted work voids insurance and can block a home sale |
| Load management | Load-shedding modules installed to prioritize essential circuits — furnace, refrigerator, sump pump, well pump | A standby generator that is overloaded will shut down, leaving the house without power; load management prevents overload |
Carbon Monoxide — the Silent Killer
Carbon monoxide from a portable generator kills roughly 70 people per year in the United States. The deaths follow a pattern: a storm knocks out the power, the homeowner places the generator in the garage — with the door open for ventilation, or on the porch, or just outside the back door, and the CO enters the house through windows, soffit vents, or cracks around doors. The occupants do not smell it. They go to sleep. They do not wake up. The generator that was keeping the house warm killed the people inside it. The distance between the generator and the house is the margin of safety. The margin is 20 feet. The margin is the minimum. The margin is not negotiable. The generator must be 20 feet from the house, from the doors, from the windows, and from any vent that draws air into the house. The 20 feet is the distance. The distance is the difference between a generator that keeps you warm and a generator that kills you.
A battery-operated carbon monoxide detector on every level of the house, outside each sleeping area, is mandatory whenever a generator is in use. The detector alarms at 70 parts per million of CO after 60 to 240 minutes, at 150 ppm after 10 to 50 minutes, and at 400 ppm after 4 to 15 minutes. The alarm is the warning. The warning is the only sign of CO poisoning, the symptoms are headache, dizziness, nausea, and confusion, which are easily mistaken for flu or fatigue. The detector distinguishes between flu and poisoning. The detector costs $20 to $50. The detector is the cheapest life insurance available. The generator is the threat. The detector is the defense. The defense must be in place before the threat is activated. Install the detector before you start the generator. The detector is the first step. The generator is the second step. The order is not reversible.
The U.S. Consumer Product Safety Commission (CPSC) has issued mandatory safety standards for portable generators to reduce the risk of CO poisoning. The standards require generators to shut down automatically when CO levels reach a dangerous threshold near the generator. New generators manufactured after the standards took effect include this feature. Older generators do not. If your generator does not have an automatic CO shutoff, the 20-foot distance and the CO detector are even more critical. The generator will not shut itself off. The detector is the only thing that will alert you. The detector is the alarm. The generator is silent. The silence is the danger. The alarm is the safety.
Backfeeding, the Electrocution Risk
Backfeeding is the practice of connecting a portable generator to the house wiring by plugging a generator cord into a dryer outlet or a welder outlet, a suicide cord with male plugs on both ends. The generator energizes the house wiring. The house wiring energizes the utility transformer. The transformer energizes the utility lines that the utility workers are repairing. The utility workers believe the lines are dead because the main breaker is off. The lines are live because the generator is backfeeding through the house. The utility worker touches the line. The utility worker dies. Backfeeding kills utility workers. It is also illegal and a felony in some jurisdictions. The transfer switch is the only legal way to connect a generator to the house wiring. The transfer switch costs $500 to $1,500 installed by an electrician. The transfer switch isolates the house from the grid. The suicide cord costs $30 and kills people. The transfer switch is the only choice. The suicide cord is not a choice. The suicide cord is a weapon. The weapon points at the utility worker. The weapon fires when the generator starts. Do not make the weapon. Do not use the weapon. The transfer switch is the only connection.
Frequently Asked Questions
Where should a portable generator be placed for safety?
A portable generator must be placed at least 20 feet from the house, from all doors, windows, and any vent that draws air into the house, soffit vents, crawl space vents, foundation vents. It must be in a dry location, under a canopy or generator tent rated for wet-weather use. It must never be placed in an attached garage, a basement, a crawl space, or on a porch, even with the door open. The 20-foot distance is the minimum. Further is better.
Do I need a transfer switch for a portable generator?
Yes, if you want to connect the generator to the house wiring to power hardwired appliances like the furnace, the well pump, or the lights. A manual transfer switch costs $500 to $1,500 installed and is the only code-compliant connection. If you are using extension cords to power individual appliances directly from the generator, a transfer switch is not needed. Never backfeed the house through a dryer outlet or a suicide cord. Backfeeding is illegal and can kill utility workers.
How much does a standby generator cost installed?
A permanently installed standby generator costs $5,000 to $15,000 installed including the generator, the automatic transfer switch, the gas connection, the electrical connection, and the permits. The cost depends on the generator size, typically 10 to 22 kilowatts, and the complexity of the gas and electrical connections. The installation requires a licensed electrician, a licensed gas fitter, and permits.
Can I run a generator in the rain or snow?
No, not without protection. A generator must be operated under a canopy, a generator tent, or a purpose-built enclosure that is rated for wet-weather use, ventilated, and does not trap exhaust. Never operate a generator indoors, in a garage, or under a deck or overhang. The exhaust must vent freely to the outside air. The generator must be dry. Water and electricity on a generator are fatal.
How often should a standby generator be tested?
A standby generator should be exercised weekly on its automatic cycle, most units run for 10 to 15 minutes once per week to keep the engine lubricated and the battery charged. The oil should be changed every 100 hours of run time or annually, whichever comes first. The battery should be replaced every 3 to 5 years. A professional maintenance visit costs $200 to $500 per year and covers the oil change, filter replacement, battery test, and transfer switch test.
What size generator do I need for my house?
A portable generator rated at 5,000 to 7,500 watts can power a refrigerator, a furnace fan, a sump pump, and a few lights, the essentials. A standby generator rated at 10 to 14 kilowatts can power essential circuits plus some convenience circuits. A 20 to 22 kilowatt standby generator can power the entire house including central air conditioning. An electrician can perform a load calculation to determine the required generator size. The load calculation is the answer.
The Generator That Keeps You Safe
For a portable generator: 20 feet from the house. CO detectors on every level. Extension cords, rated and sized. No backfeeding. Dry location. Fuel stored away from the generator. The checklist takes 15 minutes. The checklist costs a CO detector, $30, and the right extension cords, $50. The checklist prevents death. The death is real. The death is preventable. The checklist is the prevention.
For a standby generator: professional installation by a licensed electrician and a licensed gas fitter. Automatic transfer switch. Properly sized gas line. Permits and inspection. Load management. The installation costs $5,000 to $15,000. The installation is permanent. The installation is safe when the checklist is followed. The installation is dangerous when the checklist is skipped. The checklist is the difference between a generator that powers the house through a storm and a generator that powers the house while poisoning the occupants, electrocuting the utility workers, or exploding from a gas leak. The checklist prevents all three. The checklist is not expensive. The checklist is not complicated. The checklist is not optional. The checklist is the line between safety and catastrophe. The line is clear. The line is 20 feet. The line is the transfer switch. The line is the CO detector. The line is the permits and the inspection. Cross every item on the checklist. Do not cross the line. Ever walked out to the garage during a power outage, flashlight in hand, eyeing the generator and thinking “if I just crack the garage door a few inches, the exhaust will vent outside”? It will not. The exhaust will fill the garage. The CO will seep under the door into the house. The detector may alarm in time. It may not. The 20-foot rule is not a suggestion. The 20-foot rule is the distance that decades of autopsy reports have established as the minimum safe distance. The autopsies were performed on people who thought the garage door was open enough. The garage door was not open enough. The distance was not 20 feet. The distance was zero feet — the garage is part of the house. The 20-foot rule is written in those autopsies. The rule is the distance. The distance is the margin. The margin is the difference between waking up when the power comes back on and not waking up at all. Measure the 20 feet. Walk it off. Mark it with a stake. The generator goes beyond the stake. The stake is the line. The generator is beyond the line. The generator is 20 feet from the house. The 20 feet is the difference.
Last modified: July 19, 2026
