A generator used incorrectly during an outage isn’t just less effective — it can be genuinely dangerous, to you, your household, and in one specific case, to utility workers you’ll never meet. This isn’t scare-tactic content: the U.S. Consumer Product Safety Commission estimates roughly 100 deaths a year from portable generator carbon monoxide poisoning alone.

Here’s how to actually use a generator safely and correctly, from before the outage hits to shutdown.

Before the Outage: Prepare While You Still Have Power

Don’t wait for the storm to find out your generator doesn’t work.

  • Inspect the generator and any extension cords for damage before severe weather arrives.
  • Check the oil level — starting a generator with insufficient oil can damage the engine within minutes.
  • Do a real test run — connect a few devices and let the generator run for several minutes to confirm everything works, rather than discovering a problem mid-outage.
  • Confirm you have an approved, manufacturer-rated rain cover if you may need to run the unit during active weather. Running a portable generator in rain or snow without one is a real electrical hazard, not just a durability concern.

Rule 1: Never Run a Portable Generator Inside or Too Close to Your Home

This is the single most important rule. Never run a portable generator inside a home, garage, basement, crawlspace, shed, or any other enclosed space — and don’t run one on a porch or in a carport either. Opening doors and windows does not provide enough ventilation to prevent a lethal buildup of carbon monoxide (CO), which is odorless and invisible.

Per CPSC guidance, operate a portable generator outside only, at least 20 feet away from your home, with the exhaust pointed away from your house and any other structure someone could enter. In still air, or when wind pushes fumes toward your home, anything closer can allow CO to drift back inside.

Install battery-operated (or battery-backup) carbon monoxide alarms on every level of your home and outside sleeping areas. If you’re shopping for a portable generator, look for one with a built-in CO shutoff sensor that automatically stops the engine if CO levels rise dangerously.

This risk is specific to fuel-burning portable and inverter generators. A properly installed whole-home standby generator is permanently sited outside at a safe, code-compliant distance as part of installation — one of several reasons standby systems carry a meaningfully different risk profile than portable units.

Rule 2: Starting and Shutting Down the Right Way

How you start and stop a portable generator matters more than most people assume.

Starting: Check the oil level first. Place the generator in its operating location — outside, 20+ feet from the house, exhaust pointed away — before starting it. Start the generator with nothing plugged in, then add devices one at a time once it’s running. Let the engine stabilize at operating temperature before adding load where possible.

Shutting down: Turn off and unplug every device before shutting the generator down — not after. Stopping a generator abruptly while it’s still under load can cause a voltage spike that damages the unit’s voltage regulator and alternator, and in some setups can contribute to backfeeding risk. Let it cool down before refueling.

Rule 3: Never Plug a Generator Directly Into a Wall Outlet

This is called “backfeeding,” and it’s dangerous for a reason most people don’t expect: it’s not primarily about your own home’s wiring. When a generator is plugged into a wall outlet, its power can travel backward through your home’s electrical panel, through your meter, and out onto the utility’s power lines — where neighborhood transformers can step up that voltage to thousands of volts. That’s enough to electrocute a utility lineworker working on what they believe is a dead line, potentially miles from your home. It also forces utility crews to stop and search for the hazard, delaying power restoration for your entire neighborhood.

Never plug a portable generator into a wall outlet or your home’s electrical system. After starting the generator, plug appliances directly into it, or into properly rated extension cords connected to it, instead.

If you want your generator to power your home’s existing circuits rather than running individual appliances off cords, the safe way to do that is a properly installed transfer switch, which physically prevents backfeeding by design. This is standard on every whole-home standby installation, and it’s also available as an add-on for portable generator setups when installed by a licensed electrician — not something to wire yourself.

Rule 4: Use the Right Extension Cords, and Ground the Generator Properly

Extension cords for generator use aren’t a “whatever’s in the garage” choice:

  • Use only outdoor-rated cords (look for SJTW or STW jacket ratings) — they’re built to resist moisture, temperature extremes, and UV exposure that indoor-rated cords aren’t designed for.
  • For most household loads up to about 50 feet, a 12-gauge (12/3) cord is standard; for runs of 50–100 feet or heavier loads, step up to 10-gauge to avoid dangerous voltage drop.
  • Use a three-prong, properly grounded cord — the ground wire is a real safety component, not a formality.
  • Keep cord connections elevated and dry during wet weather; never let a connection point sit in a puddle.

Grounding: most portable generators have a grounding terminal. Check your specific generator’s manual for how to ground it correctly — this varies by model and setup, and is worth confirming rather than assuming your unit doesn’t need it.

Rule 5: Respect the Generator’s Actual Capacity

Overloading a generator can damage both the generator and anything plugged into it. Add up what you’re actually running, keeping in mind that motor-driven appliances (a refrigerator, a window AC unit) draw significantly more power for a few seconds at startup than while running continuously. If you’re not sure what your total load adds up to, that’s worth figuring out before an outage, not during one — our Best Generator for a Power Outage guide breaks down what different wattage classes can actually handle.

Rule 6: Handle Fuel Safely

Let a generator cool down completely before refueling — fuel spilled on a hot engine is a real fire risk. Store gasoline or propane in approved containers, away from the house, and never refuel a generator while it’s running.

For Whole-Home Standby Owners: What You Actually Need to Do

If you have a properly installed automatic standby generator, most of the above is handled by the system itself — that’s the point. Your generator starts automatically, the transfer switch prevents backfeeding, and it’s sited at a safe distance as part of installation. What’s still worth doing:

  • Keep the area around the unit clear of debris, leaves, and snow.
  • Don’t ignore a yellow maintenance-reminder light (see our Generac error code guide for what the light colors mean).
  • Know your fuel type and have a general sense of run-time expectations if your outage is extended.

Frequently Asked Questions

How far does a portable generator really need to be from my house?
At least 20 feet, per CPSC guidance, with the exhaust pointed away from your home and any structure someone could enter — closer than that risks carbon monoxide drifting back inside, especially depending on wind direction.

Can I run my generator in the rain?
Only with a manufacturer-approved rain cover designed for use while the unit is running — not a generic tarp, which can trap heat and create its own hazards. Without proper weather protection, don’t run a portable generator in active rain or snow.

Do I really need to ground a portable generator?
Check your specific generator’s manual — most units have a grounding terminal, and grounding requirements vary by model and how you’re using it. It’s worth confirming rather than assuming it doesn’t apply to your setup.

What extension cord should I use with my generator?
An outdoor-rated (SJTW or STW), three-prong grounded cord — 12-gauge for runs up to about 50 feet, 10-gauge for longer runs or heavier loads.

Have Questions About Generator Safety or Sizing? Talk to a Specialist

Whether you’re running a portable unit or considering a whole-home standby system, we’re happy to help you do it safely and size it right.

Get a free quote in 30 seconds, or call (817) 439-9009.