Portable Generator Wattage Calculation

santim_paSeptember 6, 2011

I would have a basement aquarium if not for my sump pump. Recent years, the power has been going out a lot more often... and I'd feel better with a port. gen. for the sump pump and for two side by side refrigerators.

The sump pump is a 1/3 hp pedestal style. The tag on it shows 3.5amp 115volts. Am I correct in calculating it to need approx. 1200 watts surge to start it and approx. 400 to run it? Add in two full size side by side refrigerator/freezers and a few 60 watt light bulbs.

I'm looking at the Honda EU6500is inverter generator. Variable automatic throttle, 5500 watts with 6500 max. Is that big enough to handle the above?

I know it is expensive, but if it has to run a long time and last a long time I think it is a good investment. The next step down for the Honda inverter generator is a 3000 watt... I think that is too small??

A transfer switch will be needed. Is that a crazy expensive item to have an electrician install, and is there one style better than another?

Thanks for any help. I know there is alot of info available on the web, but it is sort of "general" info. I was trying to get an answer using the numbers I'll be dealing with.

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Based on your post, the 5500 watts will be completely adequate and will also allow for operation of your computer, television and ordinary lighting in the house.

    Bookmark   September 6, 2011 at 7:47AM
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The Honda unit is a good one with one small caveat. If you do not use the ecomomy throttle feature, it will respond better to the starting of your pump. The engine speed will still slow with lighter loading, just not as much.

I have several in service, they work well as long as you use fresh, clean gasoline and run it dry before extended storage. FYI-there was a recall on some earlier units for a fuel leak issue.

    Bookmark   September 6, 2011 at 8:12AM
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