How to Use a Portable Generator Safely

The number one rule: outdoors only

Portable generators produce carbon monoxide (CO), a colorless, odorless gas. In an enclosed or partly enclosed space it can reach deadly levels within minutes. Many deaths occur when people run a generator in a garage with the door open, in a basement or in a shed during an outage.

• Never run a generator inside a home, garage, basement, crawlspace, carport, shed or tent, even with doors and windows open or a fan running.
• Place it outdoors at least 20 ft (6 m) from the house, the distance in US public health guidance, with the exhaust pointing away from doors, windows and vents.
• Keep it away from your neighbors' windows and air intakes as well.

CO alarms and warning signs

Install CO alarms on every level of the home and outside sleeping areas. During an outage they must run on batteries or have battery backup. Test them before storm season.

Early symptoms of CO poisoning include headache, dizziness, weakness, nausea, confusion and chest pain. People who are asleep or have been drinking can die before they notice anything. If an alarm sounds or anyone feels ill, get everyone out into fresh air immediately and call emergency services from outside.

Connecting power safely

There are only two safe ways to use generator power:

1. Extension cords run from the generator to individual appliances. Use outdoor-rated, heavy-duty cords with a ground pin, sized for the load and length. Check them for damage, and do not run them under rugs or through doorways where they can be pinched.
2. A transfer switch or interlock installed by a licensed electrician, with a proper inlet box outside. This lets you power hard-wired equipment such as a furnace or well pump without feeding power back to the grid. Most places require a permit.

Never plug a generator into a wall outlet or a dryer outlet. This "backfeeding" sends power back through your meter onto utility lines, where it can kill line workers and neighbors, and it can start a fire in your home when the grid power returns.

Plan your loads

A generator that is too small will trip its breaker or stall when a motor starts. List what you truly need: refrigerator, furnace blower, sump pump, a few lights, phone charging. Then add up running watts and find the peak starting load.

Example: a rural home on a private well wants to keep a refrigerator (700 W running, 2,200 W starting), a chest freezer (500 W, 1,500 W), a ½ hp well pump (1,000 W, 2,100 W), eight LED bulbs (80 W) and a TV with router (200 W). That is 2,480 W running. The largest starting jump is the refrigerator's 1,500 W, so the peak is 3,980 W. With a 25 percent margin, that points to a 3,500 W generator running at about 71 percent of its rating. Plugging in a 1,000 W microwave as well raises the running total to 3,480 W, the peak to 4,980 W and the recommended size to 4,500 W.

The generator wattage calculator does this for your list. To make a smaller generator go further, run heavy loads one at a time and start the largest motor first.

Fuel and refueling

• Turn the generator off and let it cool before refueling. Gasoline spilled on a hot engine can ignite.
• Store fuel in approved containers, outside the living area and away from fuel-burning appliances and their pilot lights.
• Add stabilizer to stored gasoline, or rotate it into your car before it gets old.
• Run the generator for a short test every few months so it starts when you need it.

Weather and electrical hazards

• Keep the generator dry. Run it on a dry, level surface under an open, canopy-style cover designed for generators, not in an enclosed box or under a porch roof next to the house.
• Touch the generator only with dry hands. Make sure it is grounded as the manual requires.
• Do not overload it. Watch for flickering lights or a tripped breaker, and shed loads if it struggles.

Other winter outage hazards

Never use a gas oven, charcoal or propane grill, camp stove or outdoor heater to warm the home. They produce CO too. If you lose heat in freezing weather, close off unused rooms, gather in one room and dress in layers, and go to a warming center if the home gets dangerously cold.

Frequently asked questions