Mid-Size Portable Generators

4,000- to 8,000-watt portable generators

Midsize generators are most often used to power essential appliances during emergencies, as well as on job sites. Generators in the 4,000- to 8,000-watt class will provide enough power to keep a refrigerator, home lighting, and at the higher end, a small, window air-conditioning unit running simultaneously.

The 5,500-watt Generac GP5500 (*Est. $720) , is recommended by the in-house product experts at ElectricGeneratorsDirect.com as the best generator in its size range. It surges to 6,875 watts and features automatic voltage regulation, a fuel gauge, and an hour meter that helps you keep track of when it's due for an oil change. A tubular steel frame adds sturdiness and comes with a portability kit with rubber wheels and a fold-down handle. The Generac GP5500 has a two-year warranty and a Good Housekeeping two-year, refund-or-replace guarantee. Owners give it high ratings at ElectricGeneratorsDirect.com, NorthernTool.com and HomeDepot.com. A few complain about its noise level, but the majority have good things to report.

Generac now manufactures and sells portable generators under the Honeywell brand, and a couple of Honeywell models also score recommendations from ElectricGeneratorsDirect.com. The 5,500-watt Honeywell 6036 (*Est. $800) surges to 6,875 watts and has the same features as the Generac GP5500, with the addition of an easily accessible, all-in-one control panel. An electric-start model, the 6037 (Est. $900) is also offered. The 7,500-watt Honeywell 6039 (*Est. $1,100) , surges to 9,375 watts and otherwise has features identical to the 6037. All of these Honeywell generators have Generac OHV engines, but their three-year warranties Offer an additional year of coverage over the Generac generators. Since the Honeywell generators are new on the market, user reviews are scarce as of this writing.

Reviewers also recommend a couple of midsize Briggs & Stratton models: the 7,000-watt Briggs & Stratton 30470 (*Est. $950) , which surges to 8,750 watts, and the 8,000-watt Briggs & Stratton 30471 (*Est. $1250) , with 10,000 surge watts. Both have similar features, including  an electric start with recoil back-up, automatic voltage regulation to protect appliances from power surges, an hour meter and a fuel gauge.  Both come with batteries; the 30471 also includes a float charger so the battery never runs down. The 30470 gets high ratings from owners at ElectricGeneratorsDirect.com, while the 30471 gets both high owner ratings and a recommendation from a product expert on the site.

Popular Mechanics singles out the CARB-compliant, 8,000-watt Generac XG8000E (*Est. $1,350) for its power bar, which indicates the amount of power being used and lets users know when the generator is approaching capacity. The XG8000E also has covered GFCI outlets, an electric starter and a 410 cc OHVI engine. A number of owners rate and review the Generac XG8000E at ElectricGeneratorsDirect.com; they rave about it, with several mentioning how easy it is to start and others expressing disbelief at how much power it has on tap. Popular Mechanics named the entire Generac XG series an Editor's Choice following its introduction at the 2009 National Hardware Show.

Whole-house generators, 10,000 to 17,500 watts

You can get portable generators in larger sizes, but these might be overkill if you just want a backup generator to keep your fridge and a few lights on during occasional power outages.

For wattages capable of powering an all-electric home, for example, we saw some support for Generac generators, though it's difficult to find reviews on models in this size range. The Generac 5734 and 5735 GP Series generators provide enough power to run most household lights and appliances plus a central heating or air-conditioning system, but you'll need to purchase and install a transfer switch to provide power to systems and devices that are not plugged in but connect directly to your breaker box.

The 15,000-watt Generac 5734 (*Est. $2,320) surges to 22,500 watts, while the 17,500-watt Generac 5735 (*Est. $2,600) provides up to 26,250 surge watts. Each features an electric starter, full-pressure lubrication and automatic low-oil shutoff. A 16-gallon gas tank provides about 10 hours of runtime at half load. With the auto-idle feature activated, the generator's engine adjusts to one-fourth, one-half, three-fourths or full-load wattage. Both big Generac models are powered by the manufacturer's overhead valve industrial (OHVI) engine, which meets California emissions standards. Because they're part of the GP Series, these whole-house Generac generators come with two-year factory warranty coverage, plus the Good Housekeeping warranty under which Good Housekeeping will replace the unit or refund the full purchase price for two years following its purchase.