5 hp control box on a 3 hp pump ok?

Discussion in 'Pumps and Tanks Well Forum & Blog. Water is life.' started by Dale Newnham, May 14, 2018.

  1. Dale Newnham

    Dale Newnham New Member

    Joined:
    May 14, 2018
    Location:
    Desert Hills, AZ
    I found that we have a 5 hp rated box when I did a capacitor check this weekend. The pump is an older 3 hp rated. This box was installed by a pump repairman last year replacing the original 3 hp control.

    Will this kill our pump way faster or is it ok?

    What I understand is the capacitors and overloads are rated to large for the pump.
     
  2. valveman

    valveman Cary Austin Staff Member

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    Mar 15, 2006
    Occupation:
    Pump Controls Technician
    Location:
    Lubbock, Texas
    Yes the capacitors and overloads are rated for 5HP. The over sized capacitors won't hurt anything. But the overloads won't trip until it gets higher than like 28 amps, and a 3HP has max amps of like 14. Even this probably won't make much difference as overloads are not made to protect the pump anyway. They are designed to protect the grid power from your shorted motor. Most of the time the damage has already been done to a motor long before the overloads trip anyway. A motor can run dry and at low amps for quite a while. But when it finally gets to a critical temperature it goes south in a heartbeat. A 3HP rated for 14 amps will run a while at about 6 amps after pumping the well dry. Then it will go from 6 amps to 60 amps before you can get to the breaker to turn it off.

    Real protection happens with under load and rapid cycle protection devices, as they will shut the pump off long before an overload is needed. Because by the time the overload trips, it is too little and too late.
     
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  4. Dale Newnham

    Dale Newnham New Member

    Joined:
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    Location:
    Desert Hills, AZ
     
  5. Dale Newnham

    Dale Newnham New Member

    Joined:
    May 14, 2018
    Location:
    Desert Hills, AZ
    Thank You for getting back to me.
    I won't have to put a 3 hp control back on it at that rate. We are using a pump saver on the system so we should be ok then.
     
  6. valveman

    valveman Cary Austin Staff Member

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    Occupation:
    Pump Controls Technician
    Location:
    Lubbock, Texas
    The overload in the pump saver won't do you anymore good than the one in the 5HP control box. But if the underload and rapid cycle protection in the pump saver works like it does with a Cycle Sensor, the overload should never be needed.
     
  7. Dale Newnham

    Dale Newnham New Member

    Joined:
    May 14, 2018
    Location:
    Desert Hills, AZ
    Would it be advisable to change out the overloads in the box or let it ride?
     
  8. valveman

    valveman Cary Austin Staff Member

    Joined:
    Mar 15, 2006
    Occupation:
    Pump Controls Technician
    Location:
    Lubbock, Texas
    The pump saver should have an overload. If if is adjustable make sure it is set correctly then no, you don't need to replace the other overloads.
     
  9. Dale Newnham

    Dale Newnham New Member

    Joined:
    May 14, 2018
    Location:
    Desert Hills, AZ
    Yes it is set correctly, I will leave everything as it is now. Thank you for your help.
     
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