When the power goes out, a generator keeps the lights on, the refrigerator running, and medical devices working. Portable models are cheaper and more flexible, while permanently installed standby units start automatically the moment the grid drops. The buying decision comes down to three numbers: the wattage of the essentials you must run, the fuel you can store or pipe to the unit, and the budget for installation. There is also a sound factor that gets ignored until the first overnight outage, and the noise attenuation for construction generators techniques used on job sites, from enclosures to mufflers to placement, apply at home almost unchanged.
Work through the decisions in order: choose the type, size the unit, pick the fuel, plan the installation, and set up a maintenance routine. Each step changes the others, so a spreadsheet and a pad of paper beat impulse buying. A generator that runs for six hours and then stalls for lack of fuel or maintenance is worse than no generator at all, because the outage outlasts the machine.
Portable, Standby, and Inverter Generators
Three product families cover nearly every home. Portable generators run 3,500 to 12,000 watts and cost from about $400 to $4,000. Standby generators run 7 to 24 kilowatts or more, mount on a concrete pad outside, and cost $3,000 to $12,000 installed. Inverter generators, usually 2,000 to 4,000 watts, produce cleaner power for electronics and run quieter than conventional portables.
Portable generators
A portable unit wheels out of the garage, gets connected with extension cords or a manual transfer switch, and runs until the fuel runs out. They dominate the market because they are cheap and simple. The trade-offs are manual setup, gasoline handling, and noise.
Standby generators
A standby unit connects to the gas line or a large propane tank, sits on a pad, and starts itself within seconds of an outage. An automatic transfer switch separates house circuits from the grid so the generator never feeds power back into the line. Installation requires a licensed electrician and often a building permit, which is why the installed price runs two to three times the equipment price.
Inverter generators
The electronics-safe choice
Inverter generators use a more complex alternator to produce stable power with total harmonic distortion under 3 percent, safe for laptops, televisions, and medical devices. They also throttle the engine to match the load, which cuts noise and fuel use at partial load. Two small inverters can be paralleled with a cable to double the output.
The full comparison across the categories, including how these machines are used on construction sites, is covered in the guide to types of generators for construction and home use.
Sizing: Running Watts and Starting Watts
Size the generator for the loads you actually need during an outage, not the whole house. The standard method: list the essentials, add their running watts, add the largest starting surge, then multiply by 1.2 to build in the 20 percent buffer that manufacturers recommend.
Running watts versus starting watts
Motors draw two to three times their running wattage for the first second or two. A refrigerator that hums along at 700 watts can demand 2,200 watts at startup, and a 1-horsepower well pump jumps from 1,500 to 3,000. Add up the starting surges, not just the running loads, or the generator will stall when the fridge kicks on.
| Appliance | Running watts | Starting watts |
|---|---|---|
| Refrigerator | 600 to 800 | 1,800 to 2,200 |
| Chest freezer | 500 to 700 | 1,500 to 2,100 |
| Sump pump, 1/2 hp | 800 | 2,000 |
| Well pump, 1 hp | 1,500 | 3,000 |
| Furnace fan | 800 | 1,200 |
| Microwave oven | 1,000 | 1,000 |
| LED lights, whole house | 60 to 300 | 60 to 300 |
Essentials package versus whole house
A 5,000 to 7,500-watt portable covers the essentials package: fridge, furnace fan, sump pump, lights, and a few outlets for phone chargers and a router. A 12,000 to 24,000-watt unit handles most of the house including a well pump, electric water heater, and window air conditioners. Shoppers on a budget can find workable models in roundups like the best cheap home generators, but price per watt is only one variable; check the starting-watt rating against your surge list.
Fuel Options and Runtime
The fuel choice decides how long the generator runs, what it costs per hour, and how much maintenance it needs. Gasoline is easy to find but degrades in storage. Propane stores indefinitely and burns clean. Natural gas gives unlimited runtime but requires a licensed hookup. Diesel suits large portable and industrial units.
| Fuel | Storage | Shelf life | Runtime at 50% load | Notes |
|---|---|---|---|---|
| Gasoline | 5-gallon cans | 3 to 6 months with stabilizer | 10 to 14 hours per tank | Most portable, gumming risk |
| Propane | 20-lb tank or larger | Indefinite | 8 to 12 hours per 20-lb tank | Clean burn, cold-weather friendly |
| Natural gas | Pipeline | Unlimited | Continuous | Needs licensed hookup, no storage |
| Diesel | Cans or tank | 6 to 12 months | 12 to 18 hours per tank | Fuel for large portables |
Dual-fuel flexibility
Dual-fuel models burn gasoline or propane and let you switch without stopping the engine. Propane is the better storage fuel because it does not gum the carburetor, while gasoline offers more energy per gallon and easier refueling. The trade-offs between the two are laid out in the comparison of dual fuel generators and how gas versus propane changes backup power economics.
Safe Operation and Installation
Generators kill people every year with carbon monoxide, not electricity. The exhaust contains CO, and running a unit in a garage, basement, or attached shed pushes the gas into living space even with the door open. Code and common sense agree on the basics: operate outside, far from doors and windows, with the exhaust pointed away.
Transfer switches and backfeeding
Connecting a generator to house wiring requires a transfer switch under the National Electrical Code. The switch isolates the house from the grid so the generator cannot backfeed the utility line, a condition that can electrocute a lineworker and start fires. Plugging a generator into a dryer outlet with a modified cord bypasses that protection and is illegal for good reason.
Carbon monoxide rules
- Run the generator at least 20 feet from the house with the exhaust facing away from doors, windows, and air intakes
- Never operate one indoors, in a garage, or in a crawlspace, even with ventilation open
- Install battery-operated CO alarms on every level and test them before the first outage
- Keep the unit dry and use a generator canopy rated for the exhaust heat
Sizing, fuel selection, and safe operation get a full treatment in the guide to backup generators for home power outages, including the load calculations and the checklist for first use.
Siting, Noise, and Jobsite Lessons
Placement and clearances
Set the generator on a level surface at least 5 feet from combustible walls and keep exhaust away from windows, doors, and fresh-air intakes. Standby units need a concrete pad and clearance for service access, and local codes may require a specific distance from property lines because of noise.
Sound management
Bringing the decibels down
A generator at 70 decibels at 23 feet is loud enough to interrupt sleep and annoy neighbors. Distance is the cheapest silencer, followed by sound-attenuating enclosures, and the same techniques used on job sites work at home. The backup generators for home and jobsite guide covers sizing, fuel, and safe installation in both settings, and its placement rules apply no matter which side of the fence the machine sits on.
Maintenance and Long-Term Care
Monthly exercise and oil changes
An idle generator fails exactly when it is needed. Run the unit 20 to 30 minutes every month under a real load, change the oil every 50 to 100 hours or annually, and replace the air filter and spark plug on schedule. Log the hours after each run so the intervals stay honest.
Seasonal storage checklist
- Add fuel stabilizer and run the engine for 10 minutes so treated fuel reaches the carburetor
- Drain the carburetor or run it dry to prevent gumming during long storage
- Connect a battery maintainer on electric-start models
- Cover the unit and store it in a dry, ventilated space
- Run a full-load test before the storm season starts
Generator sizing, installation, and maintenance for construction and standby power applications ties the whole lifecycle together, from the load study to the annual service visit, and the same discipline keeps a home unit ready for the next blackout.