Determining Your Needs
How much power do you need? What other factors should be considered when choosing a portable generator?
How will your generator be used?
Generators are used to perform a wide variety of tasks, and we offer a variety of models to suit almost all potential users. Cummins Onan portable generators provide a high quality power source that is tough, reliable and convenient View our product selection.
How quiet does your generator need to be?
Cummins Onan generators are known for quiet operation. While a camping application may require a smaller "neighbor-friendly" inverter generator, construction or fire/rescue applications may require more power that a commercial generator provides.
Is electric start required?
Cummins Onan generators are easy starting, even when only equipped with a manual recoil starter. We offer many models with the convenience of electric start or duel manual/electric start for applications where the ease of electric start is preferred.
How "portable" do you need your generator to be?
While all of these generators are portable by definition, most models include standard or optional wheel kits for easy movement of the generator from storage to the wherever it is needed. The P1700i Inverter model is only 45 pounds and easy to handle without wheels while the powerful Commercial PX12000 comes standard with 4 wheels for easy transportation. Consider the wheel kit options when selecting the right model for your application.
How much power do you need?
Generators produce AC voltage, very similar to the voltage available in your home, however while your electric utility company produces sufficient power for all your electric powered devices, a portable generator is limited in power output directly related to the engine horsepower. The amount of power that a generator can produce is rated in watts. Rated power is less than peak power as certain components lose efficiency as they are heated from use.
To determine wattage requirements you should determine which devices need to be powered simultaneously and what are the starting requirements. The wattage chart is provided below to assist you. Remember that with simple "power management" techniques, a small generator can provide adequate power for home or recreational applications.
The wattages listed below are based on estimated wattage requirements. For exact wattages, check the data plate or operator's manual of the item you wish to power.
| Tool or Appliance | Running Watts |
Starting Watts |
| Ceiling Fan | 800 | 1200 |
| Central AC - 10,000 BTU* | 500 | 3000 |
| Central AC - 24,000 BTU* | 3800 | 4950 |
| Circular Saw - 7 1/4" | 1400 | 2300 |
| Clock Radio | 100 | - |
| Clothes Dryer - Gas | 700 | 1200 |
| Coffee Maker | 1500 | - |
| Computer - 17" Monitor | 800 | - |
| Deep Freezer | 700 | 1000 |
| Dishwasher - Hot Dry | 1500 | 1500 |
| Electric Water Heater - 40 Gallon* | 4000 | - |
| Fax Machine | 65 | - |
| Furnace Fan | 800 | 1300 |
| Garage Door Opener | 750 | 1200 |
| Hair Dryer | 1250 | - |
| Hot Plate | 2100 | - |
| Inject Printer | 80 | - |
| Iron | 1200 | - |
| Laser Printer | 950 | - |
| Microwave Oven-1000 Watt | 1000 | - |
| Miter Saw - 10" | 1650 | 2400 |
| Oscillating Fan | 200 | 400 |
| Quartz Halogen Work Light | 1000 | - |
| Reciprocating Saw | 1200 | 2000 |
| Refrigerator/Freezer | 700 | 1500 |
| Security System* | 500 | - |
| Space heater | 1800 | - |
| Stereo Receiver | 450 | - |
| Sump Pump | 800 | 1200 |
| Table Fan - 14" | 200 | 400 |
| Television - 27" | 500 | - |
| Water Well Pump - 1/3 HP (220V)* | 1000 | 2000 |
| Window AC - 10,000 BTU | 1200 | 2200 |
* These unit are usually hard-wired and require a professionally installed transfer switch.
Additional Power Considerations
Some appliances need a "surge" of energy when starting. This means that the amount of electrical power needed to start the appliance may exceed the amount needed to maintain its use. Electrical appliances and tools normally come with a label indicating voltage, cycles/Hz, amperage (amps) and electrical power needed to run the appliance or tool. Check with your nearest dealer or service center with questions regarding power surge of certain appliances or power tools.
Electrical loads such as incandescent lamps and hot plates require the same wattage to start as is needed to maintain use.
Loads such as fluorescent lamps require 2 to 2 times the indicated wattage during start-up. Loads for mercury lamps require 2 to 3 times the indicated wattage during start-up.
Electrical motors require a large starting current. Power requirements depend on the type of motor and its use. Once enough "surge" is attained to start the motor, the appliance will require only 50% to 30% of the wattage to continue running.
Most electrical tools require 2 to 3 times their wattage for running under load during use. (For example, a 9,000 watt generator can power a 3,200 to 7,000 watt electrical tool.)
Loads such as submersible pumps, air conditioners and air compressors require a very large force to start. They need 3 to 5 times the normal running wattage in order to start. (For example, a 5,000 watt generator would only be able to drive a 1,800 to 3,100 watt pump.)
If the power consumption of electrical appliances exceeds the operating range or if there is short circuit or other problems in the appliances, the AC breaker could trip "OFF" or the rotation of the generator could be abnormally reduced. In this case, stop the generator to see if the power consumption of the appliances is too large and if there is a problem in the appliances.
