Xantrex. The company's line of backup power systems offers seamless transfer to 120/240 VAC that is converted from batteries. The units will operate small to medium electrical equipment and appliances for outages from six to 12 hours. (800) 670-0707. www.xantrex.com.

Kohler. Automatic backup generator systems feature a generator set, an automatic transfer switch, and a battery and charger. Available for existing homes or new construction, the systems are about the size of an air conditioner. They are available in 8.5- to 100-kw models and are enclosed in a tamper-resistant, sound-deadening, weatherproof housing. (800) 456-4537. www.kohler.com.

Generac. Permanently installed outside of the home, Guardian generators supply electrical power to pre-selected emergency circuits. The line includes factory pre-wired air-cooled units. The units, which range from 7,000 to 40,000 watts, include sound-dampening, weather-resistant enclosures and an automatic transfer switch. (800) 333-1322. www.generac.com.

Coleman Powermate. The company has introduced 10 new PowerStation emergency backup power systems for high-end residential and light commercial applications. The diesel-fueled systems range from 20 to 200 kw with 100- to 350-gallon double-walled fuel tanks. Tanks run for at least 24 hours before sounding a low-fuel alarm. (800) 445-1805. www.colemanpowermate.com.