Estimating Your Power Needs

Estimating Your Power Needs

To select the right generator set for the job, determine what equipment you will run individually and simultaneously. Check the wattage requirements on each item (volts x amps = watts). Total the wattages of all equipment to be run simultaneously. Bear in mind that electric motor starting may require up to three times the running power.

Once you determine your wattage needs, go back to the Generator Selector tool and tell us a few additional facts about your power needs and Maybin’s Emergency Power Systems will recommend the Cummins Onan Commercial generators that are best suited for the job.

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.


Equipment – Fire/Rescue Average Required Wattage
Quartz lights 500-1500(each)
Blower fans 1500-2500
Extraction equipment 1500-2500
Rooftop AC(12,000 BTU) 1500-1700(each)
Equipment Utility Average Required Wattage
Fiber optic line purging compressor 1500-2500
HEPA filter ventilator 1000
Manhole heater ventilator 1500-2000
Bucket heater 1500
Skill saw 1500
Drill 400
Electric impact 500
De-watering pump 1500-2000
Battery charging backup (location) 2000 – 3000
Hydraulic power (bucket) 2500 – 3000
Equipment – Specialty Average Required Wattage
Ventilator fans 1000-1500
Rooftop AC (12,000 BTU) 1500-1700 (each)
Exterior lighting 50-1500 (light specific)
Interior lighting 500-1000 (light specific)
Equipment – Mobile Service Average Required Wattage
Refrigeration 500-1500
Computers 250-300 (each)
Service tools 100-2000 (depends on tool)
Battery charging 1000-3000
Equipment – TV-Radio-Broadcast Average Required Wattage
Air compressor 1000
Rooftop AC (12,000 BTU) 1500-1700 (each)
TV/monitors 100 (each)
Microwave amplifier 200-2000
Rack equipment 500 (per rack)
Exterior lighting 500 – 1000
Battery charging 1000


Additional Power Considerations

Some tools and appliances need a “surge” of energy when starting. This means that the amount of electrical power needed to start the tool or 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.

Help Determining Your Commercial Power Requirements

For assistance in estimating your power needs and determining the right generator for the application contact a Cummins Onan Dealer. Our sales and service locator will direct you to your nearest qualified Cummins Onan dealer or distributorship.