There are two main types of generators: permanent standby generators and portable generators. A permanent standby generator can be an expensive investment but offers consistent power to keep most of your appliances running simultaneously, including a central air conditioner. Standby generators are quieter than portable generators and automatically turn on in the event of a power loss.

Portable generators are a smaller, more affordable option that can power a few electrical devices and are used more for temporary outages. Portable generators run off gasoline and need to be run at least 10 feet from your home to protect against dangerous carbon monoxide buildup, cautions FEMA. This means you'll need to run long, heavy-duty extension cords from the generator to your appliances. Another option is to have an electrician install a manual transfer switch subpanel off your main circuit panel. In the event of a power outage, the backup generator can directly power the subpanel using a single extension cord.

Once you have selected a generator, basic maintenance will help keep it ready for use at any time:

1. Protect your generator. Both portable and standby generators need to be operated outside, which can leave your generator susceptible to weather, storm and animal damage. Consider investing in a cover or enclosure to protect your generator from the elements while still providing adequate ventilation.

2. Have backup parts on hand. Keep a small supply of new oil and a backup filter on hand should the generator require an emergency change. Manufacturers recommend running your generator for 30 minutes every three months to keep it ready for use.

3. Schedule preventive maintenance for a permanent generator. Dirt, heat, and moisture buildup along the alternator or other parts can interfere with operations. Start with a monthly, visual inspection, and check the oil and fuel levels and confirm there are no loose wires or clamps. Every six months, inspect accessory belts and check the coolant-thermal-protection level. Check with your generator's manufacturer for additional recommended maintenance.

4. Keep portable generators full while in use. Portable generators that run on gas need to be kept full while in use. Should the generator run out of gas, the generator won't be able to produce power, and the electric load in your home may suck the magnetic field from the generator, causing permanent damage. Monitor gas levels and refill as needed.

5. Don't overload your generator. When selecting a generator, consider which appliances are essential for day-to-day use during an extended power outage. Make a list of your "must use" appliances and note the wattage they require to run. Add up the wattage requirements to determine the right generator to meet your needs. Consider keeping this list in your emergency kit so you'll know exactly how much power each appliance requires and can moderate your power usage to prevent system strain. For example, if your basement is flooded and you need to run the sump pump off your emergency generator, you may need to refrain from using other appliances at the same time.