Wire size for a submersible lake irrigation pump

Discussion in 'Electrical Forum discussion & Blog' started by WD40, May 22, 2020 at 2:07 PM.

  1. WD40

    WD40 New Member

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    I'm installing a new 2 wire 2HP 230V submersible pump in a lake for lawn irrigation, replacing an old above ground unit. Total run from the breaker panel to the pump is 420ft (200' breaker to shore and 220' shore to pump) pump mfg wire chart shown 10 awg is good to 411'. pump draw is 10 amps. there will be no control box, but some type of a junction box near the shore. I plan to run conduit from breaker box to shore junction, and thinking about conduit to pump just for wire protection not waterproofing, concerned about fishing lures snagging the wire. I dont know anything about the flat wire I've seen on the internet, So am I safe with all 10 awg? or 8 awg from breaker to junction box and 10 to pump? Would appreciate your thoughts. Thanks
     
  2. Reach4

    Reach4 Well-Known Member

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    Did you buy the pump yet? If not, note that a submersible pumps a lot more per HP. A suitable 1 HP pump may do as well as your old 2 hp suction pump.

    Put the pump into a 4 inch pipe. That will serve as a flow inducer sleeve.

    Use a 2-pole GFCI breaker.
     
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    The data sheet on that pump would normally tell you what size circuit you needed...but, if you make the assumption that it can literally develop 2 HP, that's a bit over 6A at 240 vac or a bit under 7A at 220. Given the length of the run and the desire to keep the voltage drop within reason, you really need to know what the actual power draw on the pump is to decide what gauge wire to use. Voltage drop in the wire will make the pump work harder and will waste energy as the wire itself heats up.

    Take the amps, then multiply it by the indicated resistance from the calculator on this page https://www.cirris.com/learning-center/calculators/133-wire-resistance-calculator-table to get the voltage drop through that wire.
     
    Last edited: May 22, 2020 at 4:27 PM
  5. WD40

    WD40 New Member

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    The pump mfg website shows 2hp 220v at 9.5amp draw & 20amp breaker. I have 240v at my breaker box, using the calculator I get 3.99 so I can assume my voltage at the pump will be 236v? Does that mean 10awg wire will work the entire run? The wire size chart I looked at didn't specify whether it is solid or stranded wire, how much difference is there between the two? Have you used the flat well wire? And how resistant is it to cuts & such?
     
  6. WD40

    WD40 New Member

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    I have ordered the new pump, I sized it by TDH which I need (tdh 200 @ 20gpm), I will be installing it in a flow sleeve with an inlet strainer. Will there be any issues using a GFCI breaker without a neutral wire coming back? Its a 2 wire pump. Thanks
     
  7. Reach4

    Reach4 Well-Known Member

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    No neutral needed.

    Most 2 HP pumps are 3-wire.

    Instead of conduit under water, you could run 4 inch from shore. How far out will the pump be?

    Instead of a 4 inch screen, you may want a bigger cage of mesh with more surface area. Keep a few leaves from blocking you.
     
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    A GFCI monitors the current between the hot and neutral on a 120vac circuit, and the L1 and L2 hot lines on 240vac. If those aren't equal, that means that some of the current is leaking, and if it exceeds the limit (about 5ma), it trips to open the circuit up.
     
  9. WorthFlorida

    WorthFlorida The wife is still training me.

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    What is your exact model pump you ordered? 240 volt two wire pump will have three wires. Two black, one green.
     
  10. fitter30

    fitter30 Active Member

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  11. WD40

    WD40 New Member

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    Munro MXS206s22, Its a high head, high pressure low gpm pump, bottom suction, 5" pump. Will be placed inside 6" pvc flow sleeve with a 6" suction screen. draws 9.5 amp, recommended 20 amp breaker, no control box needed, cooled by intake water, sometimes used as a cistern pump. pump info attached. I cant find where I read it is a 2 wire, I'll know when it arrives, It won't affect the wire size, 2 hots, 1 neutral, 1ground. I will run 4 wires in my conduit, just incase my next pump is a 3 wire. Going to run 210' in conduit of #8, then 220' #10 to the pump. Thanks everyone for your help.
     

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