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05112011, 12:24 AM  #1 
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submersible water pump
how much would it cost to run a 5 HP submersible water pump that is 210' in the well, & running with 18amps at 230volts for 6 hrs with 11 cents / kw charge .
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05112011, 03:03 AM  #2 
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18 amps X 230 volts = 4140 watts, or 4.14kW. 11 cents/kWh X 4.14kW = 45.54c/hour. 6 hours X 45.14c/hour = 273.24c, or $2.73.
Now, it's actually going to cost less than that. The 5HP / 18A rating for the pump is the absolute maximum amount of power it can draw in operation. Depending on the flow rate and pressure, the pump may use considerably less power than that. You'd have to measure the actual current in operation to know for sure. Also, the calculation above doesn't consider "power factor". The watts = volts X amps calculation is always off by a bit in AC circuits with certain types of loads, motors included. It will actually use about 20% less power than the volts X amps calculation would indicate. So to get a better idea of how much it will really cost to run, measure the current and the voltage in operation. Multiply them, and multiply by 0.8. That will give you a much more accurate value for power consumption. Advertisement 
05112011, 03:51 AM  #3 
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thanks, im trying to figure out how much its going to cost to do some supplementel irragation at my hay farm in beevill tx . was thinking about one of those water wheels that irragate a football field in one path, w/ about 1/2 inch of water + 

05112011, 04:10 AM  #4 
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That pump seems very small for irrigation purposes. When I was in Nebraska, the typical electric well pumps were at least 60HP, and often 100HP. They each had their own dedicated 480V 3phase service. A 5HP well pump will not move much water.

05112011, 07:52 PM  #5 
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yea, i knw the 5hp motor only puts out 78 gpm . i just want to supplement irrigate 3 (three) 15 ac grids. i don't have the paper work here at wok, but if i remember its going to cost about $22 per 6hrs of use. & im thinking 3 pulls per grid, so 20x3=$60. am i figuring right ? ( ex. 16amp x 230v = 3680 / 1000 = 3.68 x 6 = $22 ? hopefully the pastures will get 1/4 inch of water. i can regulate the speed of the water wheel . i still have reservations w/ the water wheel. $180 ? im still exploring other possibilties of supplemental irrigation. in the mean time we'll prey for rain here in south texas . thanks & don't sweat the small stuff

05112011, 09:03 PM  #6 
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? My calculation I already posted is correct (based on 18A load, not 16A). Your calculation above is missing some steps. Where are you getting dollars from? You calculated the load as 3.68kW, then multiplied by 6 hours. That gives you 22kWh, not $22. Multiply by the cost per kWh (11 cents) to get the cost of operation per pump, per 6 hour period: $2.42.

05112011, 09:41 PM  #7 
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yea, i did miss a step on the calculation. thanks for your help
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