Quick answer
A portable generator is a small engine-driven power plant, usually on wheels or a frame, that burns gasoline, propane or diesel to make electricity you can use away from the grid or during an outage.
You start it by hand, run it outdoors, and connect loads with cords or through a transfer switch. It is not wired into the home, which is why exhaust and backfeed are the two big hazards.
Quick facts
The key facts about Portable Generator, with sources:
- Main hazards named by OSHA
- Shock and electrocution, carbon monoxide, fire from fuel, noise and vibration 1
- Deaths from generator CO
- About 85 a year in the U.S. (2017–2019 average, CPSC report covering 2011–2021) 2
- Where deaths happen
- 81% in homes and other residential locations 2
- Connecting to house wiring
- Only through a transfer switch installed by a qualified electrician 1
- Safety standards with CO shutoff
- PGMA G300-2018 and UL 2201 2
Key takeaways
- A portable generator is a movable engine and alternator that you run outside and connect to loads yourself, unlike a standby unit that is wired in.
- Carbon monoxide from the exhaust is the leading killer. CPSC puts the toll at about 85 deaths a year, mostly at home.
- Run it at least 20 feet from the house, never in a garage, porch or carport, and never with doors or windows open as a fix.
- Plugging a generator into a wall outlet sends power back onto the utility lines. Only a transfer switch or a listed interlock, put in by an electrician, makes a house hookup safe.
- Size it to the few loads you truly need, then let an electrician plan the inlet and switch.
What a portable generator is, in plain terms
A portable generator joins two machines on one frame. A small engine burns fuel and spins a shaft. The shaft turns an alternator, which makes alternating current, the same kind of power your outlets carry. Outlets on the generator panel let you plug loads straight in.
The word “portable” is the key part of the name. Nobody wires it into your home. You roll it out, fuel it, start it, and plug things in.
That freedom is why it is cheap and handy. It is also why it is risky: the user, not an installer, decides where it runs and how it connects.
OSHA describes portable generators as engines used when temporary or remote power is needed, often after hurricanes and other storms 1. For a house, that usually means keeping a refrigerator, a few lights, a phone charger and maybe a furnace blower going until the grid comes back.
How a portable generator makes and delivers power
- Fuel (gasoline, propane or diesel) → engine turns a shaft
- Shaft → alternator → 120-volt or 120/240-volt AC at the generator outlets
- Outlets → heavy-duty cords → appliances placed directly on the cord
- Or: outlet → power inlet box → transfer switch → selected house circuits
- Exhaust → carbon monoxide that must stay far from doors, windows and vents
Backfeed can kill line workers
Never plug a generator into a wall outlet or dryer receptacle. OSHA warns that connecting a generator to building wiring without a properly installed transfer switch can energize wiring for great distances and electrocute utility workers and neighbors 1. Only an electrician should connect a generator to house wiring.
Running watts, starting watts and fuel
Generators carry two power ratings. Running watts is what the unit can supply hour after hour. Starting watts, also called surge watts, is the short burst it can give when a motor kicks on. A refrigerator or well pump draws far more for a second or two at start-up than it does once running.
Most portable units run on gasoline. Dual-fuel models also burn propane, which stores longer without going stale. Larger units may offer a 240-volt outlet so an electrician can feed a switch for 240-volt loads like a well pump.
The generator sizing tool adds up the running and starting watts of the loads you pick. That is a better guide than the number printed on the box.
Types of portable generators
| Type | How it differs | Typical home use |
|---|---|---|
| Conventional (open frame) | Engine runs at a fixed speed to hold 60 Hz | Outage backup through cords or a transfer switch |
| Inverter generator | Makes DC, then an inverter shapes clean AC; engine speed can drop at light load | Electronics, camping, quieter use |
| Dual-fuel or tri-fuel | Runs on gasoline and propane (some add natural gas) | Owners who want fuel that stores longer |
| Models with CO shutoff | Senses CO build-up and stops the engine; certified to PGMA G300-2018 or UL 2201 2 | Any home use; CPSC urges choosing one |
Example: reading an outage plan against real fuel prices
Public outage numbers make the case that a portable generator is a short-term tool, not a whole-home plan. EIA reports U.S. customers averaged 11 hours without power in 2024, with nearly 9 of those hours from major events 5.
| Step | What to check | Result |
|---|---|---|
| Average outage exposure | EIA 2024 national average | 11 hours per customer 5 |
| Worst state in 2024 | EIA state figure | South Carolina, nearly 53 hours 5 |
| Loads that matter | Refrigerator, lights, phone charging, furnace blower | A short list you plug in or route through a switch |
| Runtime per tank | Owner’s manual figure for your model at your load | Varies by model; never refuel while hot 4 |
| Where it sits | Outdoors, 20 ft or more from the home | Fixed by safety guidance 2 |
A one-day outage fits a portable unit well. A multi-day storm means many refuels, often at night. That is where a standby generator or a home battery starts to earn its keep.
Where portable generators show up in a home plan
On an electrician’s quote, a portable generator usually appears as the reason for three line items: a power inlet box on the outside wall, a cord rated for the generator outlet, and a transfer switch or panel interlock. The generator itself is often the owner’s purchase.
On a permit, the inlet and the switching device are what the inspector checks. The generator is outside the building wiring. Our guide to electrical permits covers when that work needs one.
In a storm plan, the generator sits next to fuel storage, CO alarms and a list of loads. Ready.gov pairs generator advice with CO detectors on every level of the home 4.
What a portable generator does well, and where it falls short
Benefits
- Low entry price compared with a wired-in standby unit.
- Works anywhere: home, job site, camping, a neighbor’s house.
- Keeps food cold and phones charged through a typical short outage.
- With a transfer switch, it can feed a well pump or furnace safely.
Limits you should plan around
- Weather. OSHA says keep it dry and do not use it in rain without a canopy; never touch it with wet hands 1.
- Overloading. Too many loads can overheat the unit and start a fire 1.
- Cords. Only grounded, three-prong cords rated for the load; damaged cords are a shock risk 1.
- Noise. OSHA lists noise and vibration among the hazards, which matters for neighbors at night.
- Power quality. Conventional units can produce rougher power than an inverter model; check device manuals before running sensitive electronics.
What drives the cost of a portable generator setup
We do not publish dollar prices here. These factors move the total. The project cost estimator shows how the electrical side adds up.
- Output size. More running watts means a larger engine and frame.
- Inverter vs conventional. Inverter models usually cost more per watt but run quieter.
- Fuel type. Dual-fuel adds hardware; propane needs tanks and safe storage.
- CO shutoff. Models certified to PGMA G300-2018 or UL 2201 add a sensor that CPSC links to fewer deaths 2.
- Connection hardware. An inlet box, cord and transfer switch or interlock add electrician labor and a permit.
- Life and upkeep. Engine life depends on hours and maintenance; follow the maker’s service schedule and warranty terms.
How a safe house hookup gets installed
Generator hookup is work for a licensed electrician, not a weekend project. Here is what the job looks like so you know what to expect.
- You list the loads you need and the electrician checks your panel and the generator’s outlets.
- The electrician picks a transfer switch or a listed panel interlock that suits your panel.
- A permit is pulled where your town requires one.
- The electrician mounts an outdoor power inlet, wires the switching device, and labels it.
- An inspector checks the work. The electrician shows you the switch-over steps.
Our generator installation service page covers what an electrician quotes for this work.
Keeping a portable generator ready
- Follow the labels and owner’s manual, and keep up the maker’s maintenance schedule.
- Store fuel only in approved containers and never indoors 1.
- Let the engine cool before refueling; fuel on hot parts can ignite 4.
- Check cords for cuts and frayed jackets before every use 1.
- Test CO and smoke alarms monthly 2.
Warning signs and when to call for help
Carbon monoxide has no color and no smell. Ready.gov calls it a gas that can kill you 4. Headache, dizziness, nausea or confusion in more than one person during an outage is a reason to get everyone outside and call 911.
Open doors and windows do not make indoor use safe. CPSC says never run a generator inside a home, garage, basement, crawlspace, shed or other enclosed space 3. Not on a porch or in a carport either.
Call an electrician if cords get hot, a breaker on the generator keeps tripping, or lights flicker when the generator runs through a switch. Call the utility if you see downed lines. See emergency electrician help for urgent faults.
CO is the leading generator killer
CPSC estimates about 85 people die each year from carbon monoxide from gasoline portable generators, and 81% of those deaths happen at home 2. Run it 20 feet out, point the exhaust away, and keep battery CO alarms on every level.
Rules and standards that apply
| Authority | Rule or standard | What it says |
|---|---|---|
| OSHA | Fact sheet, Using Portable Generators Safely | Connect to a building only through a transfer switch installed by a qualified electrician; use GFCIs in wet areas 1 |
| CPSC | CO fatality report, 2011–2021 (released 2022) | About 85 deaths a year; 20-foot distance; choose a CO shutoff model 2 |
| NFPA 70 (NEC) | Section 702.5, 2017 edition as cited by UL | Transfer equipment must prevent the normal and alternate sources from connecting by accident 6 |
| UL / PGMA | UL 2201; PGMA G300-2018 | Voluntary standards with CO safety features 2 |
Portable generator vs other backup options
| Option | Starts how | Fuel or storage | Connection |
|---|---|---|---|
| Portable generator | By hand | Gasoline, propane, diesel | Cords, or inlet + interlock / transfer switch |
| Standby (wired-in) unit | Automatically | Natural gas or propane line | Automatic transfer switch |
| Battery storage system | Automatically | Stored electricity | Gateway or critical loads panel |
| UPS | Instantly | Small battery | Plug-in, one device |
Common myths about portable generators
- Myth An open garage door gives enough air.
- Reality CPSC says open doors and windows do not provide enough ventilation 3.
- Myth A “suicide cord” to a wall outlet is fine if the main is off.
- Reality Any direct connection without a transfer switch can backfeed the grid; OSHA says never attach a generator to a building unless a qualified electrician has installed a transfer switch 1.
- Myth Bigger is always better.
- Reality An oversized unit burns more fuel at light load. Size it to real loads.
- Myth If I don’t smell exhaust, I am safe.
- Reality CO has no smell 4.
How your state changes the picture
Outage exposure is the state variable that matters most. EIA found South Carolina customers averaged nearly 53 hours without power in 2024, far above the 11-hour national average 5. The connection rules also vary: states adopt different NEC editions on their own schedules, and electrician licensing differs by state.
Is a portable generator right for you?
A portable generator suits homes with short, rare outages and an owner who is home to run it. It fits a tight budget and can serve double duty on jobs or trips.
If you travel, have medical equipment, or face multi-day storms, compare a standby generator or a home battery. Start with the sizing tool, then ask an electrician about the safest hookup for your panel.
- If Outages are short and rare
- Then A portable unit with cords may be enough
- If You need the furnace or well pump
- Then Add an inlet and transfer switch, installed by an electrician
- If You are often away or need hands-free backup
- Then Look at a standby generator or battery
- If Anyone in the home uses medical equipment
- Then Plan automatic backup and talk to the utility
Next step
Write down the five loads you cannot lose, then run them through the sizing tool before you buy.
Questions about Portable Generator
How far from the house should a portable generator be?
Keep it at least 20 feet from the house, with the exhaust pointed away from doors, windows and vents. CPSC and Ready.gov both use the 20-foot figure.
Do not run it on a porch or in a carport, and do not count on open windows for air. Closer placement lets carbon monoxide drift inside, where it builds up without any smell.
Can I plug a portable generator into a wall outlet?
No. Plugging a generator into a wall or dryer outlet is called backfeeding, and it can send power back onto utility lines and shock line workers or neighbors.
OSHA says a generator should connect to a building only through a transfer switch installed by a qualified electrician. Use cords straight to appliances until that switch is in place.
Can I run a portable generator in my garage with the door open?
No. CPSC says never run a portable generator in a home, garage, basement, crawlspace or shed, even with doors or windows open. Opening the door does not move enough air to clear carbon monoxide. Keep the generator outdoors, 20 feet away, and keep battery-powered CO alarms on every level of the home.
How many people die from portable generator carbon monoxide?
CPSC estimates about 85 people die each year in the U.S. from carbon monoxide from gasoline portable generators. That figure is the 2017–2019 average in a report covering 2011 to 2021. The same report found 81% of those deaths happened in residential settings, which is why the agency focuses on placement and CO alarms.
What size portable generator do I need for a house?
It depends on which loads you run at the same time. Add the running watts of each load, then allow for the largest starting surge, which motors like refrigerators and well pumps draw for a moment at start-up.
Our generator sizing tool does this math. Most portable units cover must-run circuits, not central air or a whole home.
What is the difference between an inverter generator and a regular one?
An inverter generator makes direct current and then shapes it into clean alternating current, so its engine can slow down at light load. A conventional generator spins at a fixed speed to hold 60 hertz. Inverter models tend to be quieter and gentler on electronics, while conventional models often give more watts for the money.
Do I need a permit to hook a generator to my house?
Often, yes. Adding a power inlet and a transfer switch or panel interlock is permanent wiring, and many towns require a permit and inspection for it. The rules depend on your local electrical code and the NEC edition your state adopted. A licensed electrician will know whether your town requires one and will pull it.
Is it safe to run a portable generator in the rain?
Not without protection. OSHA says keep a generator dry and protect it with a canopy if needed, and never handle its controls with wet hands or while standing in water. Ready.gov adds that touching a wet generator or connected devices can cause shock. Use GFCI-protected cords in damp areas.
What does a CO shutoff feature do on a generator?
A CO shutoff senses carbon monoxide building up around the generator and stops the engine. CPSC estimates that models certified to PGMA G300-2018 would cut generator CO deaths by 87%, and those certified to UL 2201 by 100%. The feature does not make indoor use safe; it is a backup for mistakes.
How should I store fuel for a portable generator?
Store fuel in approved containers away from the home’s living space, and never indoors, as OSHA advises. Let the engine cool before refueling, because spilled fuel on hot parts can catch fire. Gasoline goes stale over months, so many owners use fuel stabilizer or choose a dual-fuel model that also runs on propane.
Sources
- OSHA, Fact Sheet: Using Portable Generators Safely (FS-3286, September 2005), retrieved .
- CPSC, CPSC Releases New Report on Carbon Monoxide (CO) Fatalities, Urges Generator Safety (2022), retrieved .
- CPSC, As Winter Storms Continue, CPSC Urges Families to Take Steps to Prevent CO Poisoning and Fires (2024), retrieved .
- Ready.gov, Power Outages, retrieved .
- U.S. EIA, Today in Energy: hurricanes in 2024 led to the most hours without power in 10 years (Dec 2025), retrieved .
- IAEI Magazine, UL Question Corner: panelboard interlock kits as transfer equipment (NEC 702.5), 2017 NEC, May/June 2017, retrieved .
Expert review
Written by the HyreElectrical Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Safety facts checked against OSHA, CPSC and Ready.gov guidance and EIA outage data on 2026-10-10. Held for review by a qualified electrician before indexing.
Suggest a correction. We fix errors and say what changed.