How to Select a Home Standby Generator
Blizzards, Ice Storms, Tornadoes, Hurricanes, a careless driver striking a power pole -- there is no end to the natural and man-made disasters that can shut the power down at your home. In the past people would light some candles, fire up the gas stove, and tough it out. But now, with most homes being nearly 100% electric, losing power can be more than an inconvenience; it can be life-threatening.
Fortunately standby power generators, once exclusively used by factories and large companies, are within the financial reach of any home owner. They're safe, quiet, and efficient. In fact, the only issue is: Which generator is right for you?
What's the Watt?
Generators are sold by wattage rating. If you were absent from school on that day, you might not know that wattage is sort of the electrical equivalent to horsepower. Remember Ohm's law? Don't worry, I didn't either. Anyway, Watts = Volts x Amps and Amps = Watts/Volts. While theoretical knowledge is a wonderful thing, here's some more practical information to help you select the right home standby generator for you.
Power Consumption Calculations
Most every electrical appliance has a tag somewhere that will tell you at least two of the numbers that you need to calculate the right size emergency generator for you. If you have volts and amps, you can use Ohm's law to calculate the watts.
Of course, if they list the watts, then you're all set -- almost. Electrical motors require up to four times as much wattage to start up than they do to keep running. It's got something to do with inertia and friction, but I was absent on that day as well. So, a good rule of thumb is to multiply the wattage on the label (or the wattage that you calculated) by 4 if you're dealing with any electrical appliance that has a motor.
When it comes to calculating the wattage required to run electrical lighting, you could have been absent from school for the entire year and still get this one right. It's printed right there on top of the bulb. That means, if you want to power a 60 watt light bulb, then you'll consume... yep, 60 watts of power.
The following chart lists the average wattage for the average household appliances. Use these figures only as a guideline as your appliances may be extraordinarily un-average.
Typical Home Appliances Wattage Requirement Appliance
(multiply Watts x 4 to determine startup requirements for appliences with motors)
Coffee Maker 1750
0 Dishwasher (no heat) 700 (2800)
1400 Electric Fry Pan 1300
Electric Range 8-inch element 2100
Microwave Oven 625 watts
Refrigerator or Freezer 700 (2800)
Clothes Washer 1150 (4600)
Electric Clothes Dryer 5750 (23,000)
Furnace (gas or fuel oil) 1/8 Horsepower 300 (1200)
1/6 Horsepower 500 (2000)
1/4 Horsepower 600 (2400)
1/3 Horsepower 700 (2800)
1/2 Horsepower 875 (3500)
Lights as printed on bulb
Radio 50 to 200 0
Color Television 300
10,000 BTU Central Air Conditioner 1500
If you were planning to power everything listed above then, at first glance, you might think that you're going to need a 30,000 watt generator. Maybe buying a small nuclear reactor would make more sense. But wait! Look what happens when you apply a little power management logic to the formula.
Power Management 101
The first thing to remember is that the maximum wattage for anything motor-driven is only used when the motor first starts up. Moments later it drops down to the normal running wattage. So, you need to select a generator that outputs enough wattage to handle the appliance with the highest startup rating. Then, simply make sure no two appliances are started at the same moment and you can dramatically cut down your calculation.
The second thing to remember is that the total of the running wattage column is only an issue if you plan to run every appliance, all at the same time, and all day and night. So you see, by simply mapping out a reasonable power management schedule you can cut way back on the size of your power requirements. For most people a 2500 watt generator will do the trick.
Fuel Requirements
Although diesel-powered generators exist, they are typically used in commercial and industrial environments. For us homeowners there is a choice between gasoline and liquid propane gas (LPG). As a rule of thumb, the LPG models run quieter than the gasoline models. Fuel consumption varies depending upon the horsepower rating of the generator's engine. An 8 HP model will run about 10 hours +-, at full load, while an equivalent LPG model runs 1 hour for every 5 lbs of fuel that it burns.
Start Your Engines
There are 3 basic ways to fire up a generator. Some models come with a recoil starter, just like a lawn mower's starter, other come with an electric (battery) push-button starter, and other comes with an auto start switch, also called a transfer switch, that must be wired directly to your home's existing electrical system.
If you lose power frequently, or there is some device in your home that must remain powered on at all times for health or security reasons, then a transfer switch-equipped standby generator will virtually ensure that you have power even if you are not home when the outage occurs.
In Summary
Now that you have the basic facts, go ahead and make your own wattage consumption chart. Then devise your personal power management program, decide if you need a transfer switch or not, and go shopping for the peace of mind that an emergency generator will bring in times of trouble.
