voltage drop

Discussion in 'Pumps and Tanks Well Forum & Blog' started by ugabulldog, Jan 20, 2011.

  1. ugabulldog

    ugabulldog Member

    Joined:
    Nov 27, 2007
    Location:
    Northeast GA
    Voltage drop was calculated for #10 wire and I am very close (right at) to the max run so I think I will need to size down to #8 wire running 390 ft. to well,....wire in well is 240' of #10 wire, is this ok to mix 8 & 10 to compensate for volt drop?
     
    Last edited: Jan 20, 2011
  2. valveman

    valveman Moderator Staff Member

    Joined:
    Mar 15, 2006
    Occupation:
    Pump Controls Technician
    Location:
    Lubbock, Texas
    Actually having the maximum recommended cable length is a good thing. It makes a natural soft starter. #10 wire will go 630' with a 1 HP motor. It doesn't hurt anything to start with #8, except that it won't give you the soft start like 630' of #10 will do.

    "Reduced-voltage starters may not be required if the maximum recommended cable length is used. With maximum recommended cable length there is a 5% voltage drop in the cable at running amps, resulting in about 20% reduction in starting current and about 36% reduction in starting torque compared to having rated voltage at the motor. This may be enough reduction in starting current so that reduced-voltage starters are not required."

    Heres the link;
    http://www.franklin-electric.com/aim-manual/page-36.aspx
     
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  4. ballvalve

    ballvalve General Engineering Contractor

    Joined:
    Dec 28, 2009
    Occupation:
    "retired" and still building and troubleshooting
    Location:
    northfork, california
    I have almost the exact same setup and pump is happy for several years and runs on 239 volts after start up. I may even have a 1.5hp motor on it.

    But where is the control box? at the beginning of the run, or at the well head?
     
  5. valveman

    valveman Moderator Staff Member

    Joined:
    Mar 15, 2006
    Occupation:
    Pump Controls Technician
    Location:
    Lubbock, Texas
    I don't think it will make much difference where the control box is. But I think the starting torque would be less the further away the control box is.
     
  6. ugabulldog

    ugabulldog Member

    Joined:
    Nov 27, 2007
    Location:
    Northeast GA
    That is my problem,...I am a little over 630', by a few feet, so I should go with #8, in fear of burning pump up faster, correct?
     
    Last edited: Jan 22, 2011
  7. ballvalve

    ballvalve General Engineering Contractor

    Joined:
    Dec 28, 2009
    Occupation:
    "retired" and still building and troubleshooting
    Location:
    northfork, california
    You can mix wire sizes. But the charts have much leeway in them. Dont sweat a few feet.
     
  8. ugabulldog

    ugabulldog Member

    Joined:
    Nov 27, 2007
    Location:
    Northeast GA
    control box is at the well head, does this make a differnce ballvalve or anyone??
     
  9. justwater

    justwater Well Drilling/Service

    Joined:
    May 13, 2010
    Location:
    FL/GA
    it's fine, no worries.
     
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