How to Buy the Right Backup Generator

October 10th, 2011

When extreme weather conditions across the U.S. created widespread power failures this year, many people considered buying a backup generator. But that’s no easy task, since it takes quite a bit of research to figure out what kind to buy, and how much power you need. It’s also a purchase best made in the off season, because generators were either very expensive or in short supply during those power outages.

Selecting the right generator

• Decide whether you want a portable generator that you can also use for camping, or a permanently installed generator that will come on automatically in the event of a power outage.
• Make a list of the items you need to power. The outage may last for an extended period, and saving the contents of your refrigerator and freezer can save you a lot of money. Do you need only small appliances and lights? If you have medical equipment or extra freezers, be sure to add them to the list.
• Add up the wattage to calculate your total power needs. You’ll need to find both the running wattage and the startup wattage, these are usually in the product manuals or on the products themselves. Estimated values for common appliances can be found on websites like Consumer Reports or Home Depot. The Consumer Reports link also helps you match the generator and its wattage to the appliances you plan to power.
• The amount of power required to start an appliance can be 3-5 times the power necessary to keep it running, so you’ll have to add these values together to make sure you have enough total power.  Lowe’s, Generac, and Kohler all  provide handy online calculators to help you estimate the power you’ll need.

Kinds and cost of generators

• Portable generators – The most common type are the portable, gasoline-driven generators that are designed to be used with appliances plugged into them with cords. They can also be handy to use in remote locations, such as camping sites. Lights and small appliances can be plugged into the outlets on these portable generators.  Prices range from $400-$800 for small 3,000-4,000 watt portables to several thousand dollars for a large 10,000 watt generator.  All of these models are noisy.
• Fixed generators – These larger generators are connected directly to building wiring, automatically providing standby power during emergencies and power outages. This wiring needs to be properly installed by a qualified electrical contractor, and is not a “do it yourself” job. They can produce 10,000-20,000 watts and cost $5,000-$10,000 or more plus an extra $1,000 for installation. These generators are programmed to switch your power over and turn on automatically in the event of a power outage, and to shut down when the power returns.  With one of these, your home will be protected even if you are not present at the time of the outage. Fixed generators can be powered with any fuel, but natural gas is the preferred choice if you have it available for your home.  Natural gas can provide virtually indefinite operation in the event of a truly long-term power outage.  A 20,000 watt system will typically provide enough power to operate your home normally.

Safety concerns

• Electric shock – The portable generators cannot be connected directly to your electrical wiring. This could produce “back feed,” a dangerous current that could electrocute or critically injure someone. Use heavy-duty exterior extension cords to plug appliances directly into the generator, or use a single cord and connect the generator to a power-transfer switch at a cost of $500-$1,000. The transfer switch option will enable you to power built-in appliances that cannot be connected with an extension cord. The generator must also be properly grounded and placed above water level. Obviously, a portable generator cannot be used in a flooded basement. Always properly disconnect from your utility service before starting your backup generator.
• Carbon monoxide – A portable generator produces a poisonous carbon monoxide gas exhaust and must be placed outside, at least 15 feet away from the house, with adequate ventilation and air flow around it. Carbon monoxide monitors should be placed in the house.
• Fuel storage – Fuel is usually in short supply during widespread power outages, because stations have no power to pump. You’ll need extra gasoline that should only be stored in ANSI-approved containers in a cool well-ventilated area, and out of the reach of children. Flames or cigarettes should be extinguished when handling gasoline. Keep a fully charged, approved fire extinguisher near the generator, and always turn off and allow the generator to cool off before adding fuel.  To be sure it works properly when you need it, you’ll have to test run the generator on a regular basis, and use gasoline stabilizer to prevent the fuel from deteriorating. This works out nicely if you already use your generator regularly on outings like camping trips, picnics, or tailgating at sporting events.

Other considerations

• For portable generators, choose a wheeled model that can be moved easily. When choosing the size, in addition to wattage you should also consider the weight and how many people may be available to help you move it.
• Remember that manufacturers often overstate run time for gasoline models by basing it on 50 percent load. Take that into account when calculating your needs and selecting the size. Most home-sized models use 12 to 18 gallons of gasoline per day.
• Choose a model with a weather-protected control panel, larger fuel tank, and a muffler to reduce engine noise (absolutely critical at night).
• Use surge protectors to prevent damage if you connect computers or other electronics to your generator.
• Cell phones and other small electronics can be charged in the car if you have the right adapters on hand.

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