The disruption of power for substantial lengths of time can occur at any time due to hurricanes, earthquakes, fires, snowfall and other natural calamities. Having emergency backup power in such situations is not only essential for hospitals and commercial establishments but also in homes to run critical appliances like lights, refrigerators, heaters and medical equipment.

There are basically two types of generators that can be used in an emergency: portable and permanent standby generators. The main difference between the two is their output power and price.

In times of emergencies, portable generators provide the most economical way of supplying back up power. Appliances are directly plugged into the generator using the recommended extension cord or alternatively are connected to the home wiring system using a transfer switch. The generators come with an electric start or a pull start and loaded with many other features including the GFCI receptacles.

Portable and permanent generators come in varying sizes and types. There are some generators that supply 120 volts while others come with a 120 to 240 volts supply. Determining the right size and type of generator is important. This depends on the individual house owners need for power in emergencies. A portable generator can provide power to run some basic electrical appliances like lighting, furnaces, televisions, refrigerators and water well pumps. Normally, for most homeowners a portable generator of the capacity of 5000 to 6000 watts may be sufficient. Portable generators may cost $600 or more depending upon the quality and type of generator.

Gasoline powered generators are the most familiar among portable generators. There are models that are powered by diesel, while some models available have multi fuel capabilities that run on gasoline, propane or natural gas. Gasoline powered generators are the least expensive but have a relatively shorter life span and require frequent maintenance.

Diesel generators are expensive. They are fuel-efficient, require less maintenance and have a longer life. However, diesel generators are hard to start in the cold season. Using propane or natural gas powered generator is the best alternative if the fuels are readily available. These generators are expensive but require less maintenance and burn cleaner.

A permanently installed generator can power up critical systems in homes automatically within 10 to 20 seconds of loss of power -- even in the absence of the house owner, Permanent generators are connected to the home wiring system through the transfer switch. The transfer switch automatically starts the generator in case there is disruption of power. As soon as normal electricity is restored, the transfer switch automatically shuts down the generator. Most of these generators run on natural gas or LP. The same gas used for home appliances can be utilized to fuel the generator. The size of the generator will depend upon the number of systems the house owner wants to power up during emergency. A generator in the range of 8000 to 17,000 watts will be sufficient for a homeowner seeking to install permanent generators. Permanent generators cost $5000 to $10000. Whatever the type of generator, every generator should provide 60 hertz power for proper performance of any electronic equipment.