What the best portable generators have
- Reliable performance. Above all else, your generator has to run when you need it to run. The bitterest complaints about generators come from people whose units wouldn't start up when the power went out. Once it's up and running, the generator should deliver smooth, consistent voltage.
- Easy starting. Ideally, the generator should fire up on the first or second pull of the starter cord. Some portable generators include a push-button starter, which is easier to use than a cord. These run off a battery that's often sold separately.
- Adequate run time. Some generators can run for over 16 hours on a full tank of gas, while others conk out after as little as 4 hours.
- Low emissions. Portable generator engines that meet CARB (California Air Resources Board) requirements, sometimes called 50-state compliant models, pollute the least.
- Economy mode. In economy mode, or "eco" mode, the engine speed drops to meet the electrical load. This further reduces emissions and fuel use when you don't need the generator's full power.
- Basic safety features. Low-oil shut-off protects your generator's engine from damage if it runs too low on oil. Outlet covers protect plug-ins from the elements. GFCI outlets protect you from electrical shocks in wet conditions.
- Maintenance gauges. A fuel gauge shows you how much gas is left in the tank, so you know when to top it up. An hour meter tracks how long the unit has run, so you know when it's due for an oil change or other maintenance.
- Low noise. All generators make noise when you're standing right next to them, but the best ones aren't obtrusively loud when you're indoors with the generator running outside.
- Wheels. It isn't really possible to move a 200-pound generator without wheels – yet not every model comes with them. When wheels are sold separately, they can add as much as $150 to the price of the generator.
- A two- or three-year warranty. This is typical for all but the least expensive generators. Familiarize yourself with the terms of the warranty so that you understand what it and isn't covered.
Know before you go
What's your peak-wattage load? Check the owner's manual to determine an appliance's peak wattage. This is how much power it takes to run at its highest level of power consumption, usually when appliances are first starting up. To determine whether your portable generator has the juice it needs to power up your appliances simultaneously, add the peak wattage of all the appliances you want to run. The sum is the peak output your portable generator needs to be able to start everything up at once. (If your generator can't meet this load, you can get around it by plugging in appliances one at a time.)
What are your running-wattage needs? You may not need to start your appliances all at once, but your portable generator definitely needs to provide a steady stream of electricity to keep everything on. To calculate your continuous or running wattage needs, check your owner's manuals again. This time, add up the running wattages of all the appliances you need to run. If you don't have the manuals for all your appliances, you can estimate your needs with an online calculator like this one from Northern Tool.
How will you hook everything up? If you want a generator to power your whole home, it's best to get one with at least four electrical outlets to distribute the load. For camping or emergency use, you can connect your appliances to the generator with heavy-duty extension cords. However, if you have a portable generator of 5,000 watts or more, and you expect to be using it on a regular basis, experts recommend having an electrician install a transfer switch. This allows you to connect the generator to your circuit board with a single cable, safely. When you want to run the generator, you just connect this cable and then flip a few switches to route power from the generator instead of the grid. A transfer switch is also necessary to run anything that's hard-wired into your home, such as a well pump, furnace, or electric water heater.
Will you need to power sensitive electronics? Ordinary generators can create power surges that will fry delicate electronics like computers and flat-screen TVs. For these, it's best to choose an inverter generator; these are usually smaller and more expensive, but they provide smooth, continuous power.
Where will you have your generator serviced? Most generator manufacturers require you to use approved service centers for warranty repairs, and they won't pay for the cost of transporting a generator to and from the service center. In other words, you'll either have to pay the repairman to come to you, pay for the service company to pick up your generator and then return it, or set aside the time to make the trip(s) yourself. So before you buy a portable generator, check to see where you can get service for that brand.
Portable generators pose three main safety risks: carbon monoxide (CO) poisoning, electric shock, and fire. The American Red Cross offers these tips for using one safely:
- Never run a portable generator indoors. This includes garages, sheds, basements, attics, and crawl spaces, as well as living areas. Even in a well-ventilated area, CO from the exhaust can build up. To avoid letting CO into your home, don't place the generator near any windows that might be opened to let in fresh air.
- Keep portable generators high and dry. Like any electrical appliance, portable generators pose a potential electrocution hazard if they're exposed to water. Keep your generator and cords dry and sheltered from the elements, and never handle them with wet hands. You can protect your generator from rain by installing an open, canopy-like structure over it, such as a tarp suspended on poles.
- Handle fuel safely. Keep the fuel for your generator in an approved safety can. Store it outside your home's living areas, in a locked shed or other protected area. Check with your local fire department to see how much fuel you're allowed to store on your property. Never store fuel near any fuel-burning appliance, such as a natural gas water heater.
- Use the right cords. If you don't have a transfer switch, it's safest to plug appliances directly into the generator. If you can't do that, use a heavy-duty extension cord rated for outdoor use. Make sure the cord is rated to handle the total wattage or amperage of the appliances you're connecting with it. Extension cords should always be grounded (with three prongs) and free of cuts or tears.
- Let it cool. Make sure to let the generator cool down before adding more fuel. Spilling gasoline onto a hot engine is a recipe for a fire.
- Don't backfeed. Never plug the generator into one of your home's wall outlets. This practice, known as backfeeding, creates an electrocution risk for utility workers and neighbors who use the same utility transformer. It also puts your own home at risk by bypassing built-in safety devices. If you want to use the generator to power your home's outlets, install a manual transfer switch instead, but hire for a licensed electrician to do the job. This Old House has more information.