Frequently Asked Questions About Generators
Q. What size generator do I need for my house ?The generator size will depend on the total load or "wattage" you demand from the generator. This of course will depend on what electrical devices you will need to run while supplying your house with generator power. See the chart below of common household devices and their power requirements. To get a rough idea of the capacity of the generator you need simply add up the power requirements for all of the devices you anticipate operating while on generator power. Q. I have a generator. How do I determine what combination of devices I can run at one time without exceeding the capacity of my generator?Refer to the chart of common household devices. Like in the above example you can add up the power of each device. The total should not exceed the capacity of your generator. It may be necessary to temporarily turn off one or more devices in order to run another. For example you may have to turn off the air conditioner in order to operate the clothes dryer.
Q. How does the generator connect to the electrical system ?Typically a generator will connect to the electrical system with a transfer switch which will allow either generator power or utility company power to supply electricity to the building. The switch allows only one source of electric current at any one time. There are two types of transfer switches. The first is a manual switch. With this type of switch a person must physically throw the switch to the generator position in the event of a power outage and then physically switch it back when utility company power is restored. The second type of transfer switch is automatic. This type is generally not used with PTO generators but with diesel, prpane or gasoline powered generators although a manual transfer switch can be used with this type generator also. The Automatic Transfer switch monitors the power line coming from the electric utility company. In the event of a power failure, the switch will automatically start the generator and switch the generator output to the building(s) electrical system. When the Automatic switch again detects the proper power coming from the electric utility company, it switches the building electric system back to the utility company and shuts down the generator. |
Wattage Requirement Chart
Device |
Run Watts |
Starting Watts |
Air Cleaner |
45 |
75 |
Air Conditioner - room |
670 |
2000 |
Blender |
300 |
600 |
Broiler (countertop) |
1200 |
1200 |
Clock |
2 |
2 |
Clothes Dryer |
5000 |
5000 |
Coffee Maker |
1000 |
1000 |
Dehumidifier |
600 |
1400 |
Dishwasher |
1000 |
2000 |
Electric Blanket |
90 |
90 |
Fan (attic) |
370 |
700 |
Fan (ceiling) |
90 |
150 |
Fan (window) |
200 |
450 |
Freezer 20cu.ft. |
900 |
1900 |
Furnace - Gas |
1500 |
2500 |
Furnace - oil |
800 |
1800 |
Garbage Disposal |
914 |
2000 |
Hair Dryer |
1200 |
1400 |
Heat Lamp |
250 |
250 |
Heat Pump (3 ton) - AC |
3500 |
8500 |
Heat Pump (3 ton) - Heat |
3500 |
8500 |
Heat Pump - Electric Backup Heat |
8000 |
8000 |
Heater (portable) |
1000 |
1200 |
Heating Pad |
70 |
70 |
Humidifier |
175 |
250 |
Iron |
1100 |
1100 |
Microwave |
1500 |
1750 |
Oven |
3600 |
3600 |
Personal Computer |
150 |
150 |
Radio |
75 |
75 |
Range (2 burners or oven) |
3000 |
3000 |
| Range (all burners and oven) | 7000 | 7000 |
Refrigerator/Freezer |
850 |
2000 |
Sewing machine |
75 |
200 |
Shaver |
15 |
15 |
Stereo System |
90 |
100 |
Sun Lamp |
800 |
800 |
Television - Color |
100 |
275 |
Toaster |
1200 |
1200 |
Toothbrush |
10 |
10 |
Vacuum Cleaner |
1300 |
1800 |
VCR |
30 |
50 |
Waffle Iron |
650 |
650 |
Washing Machine |
500 |
1200 |
Water Heater - Quick Recovery |
5000 |
5000 |
Water Heater - Regular |
3800 |
3800 |
Well Pump (1/2 HP) |
1000 |
2200 |
| Well Pump (3/4 HP) | 1500 | 3300 |
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