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Electric Motors/Boat Lift Motor Trips GFCI

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Question
I have a 1HP AO Smith motor that is being used to run my boat lift. After working fine for several years, it now works fine when lowering the boat but when attempting to lift the boat the motor trips the GFCI immediately.  At first this was an every once in a while problem, but now is happening pretty regularly.  If I plug the motor into a non GFCI protected circuit it works fine in both directions.

I had a similar problem with the motor on my other lift.  I got a new motor and it seems to be working fine without tripping the GFCI.

Do I need to replace the second motor also, or is there possibly something else I can do to fix the problem?

Answer
Mike  

First motor may be just fine also,  here is why,


Motor 1 fail in lift direction only      on GFCI NOT BREAKER

Replace motor and it works fine    lift direction,  

Because a GFCI  is a comparative type device it just wants to see the same thing on both hot and nuetral,

The boat motor is likely not to be bad in one direction    

Even though the new motor works,  it almost sounds like the terminal board in the old motor, or the reversing [probably drum switch] or the wiring in and out of any device is bleeding through  and when you changed the motor it may have jiggled some weak point so it is now not as sensitive,        


It could also be a weak GFCI they do go bad,    just guessing the load is more on the up than down,   

I would take a close look at the terminal board, the reverse switch, and the wiring     you may find a carbon track or darkened area  and that may be carbon causing this trip,    but I would not trash the old motor yet as it is really unlikely it is bad   maybe on the internal reversing switch of the old motor depending on the type of setup you have some motors have a reverse switch internally others are reversed with a drum switch or double pole double throw center off switch that swaps the start winding ends,      then again that GFCI might be weak and seeing just enough current on the old motor,  a little wear to the bearings so on adds up with some rusted connections here and there

I would start with the GFCI even though it is not tripping with the new motor because it is critical around a boat launch      for safety reasons and they are not that expensive, and then look for good tight connections and or corrossion anywhere,    clean any corroded connections up,   inspect the wire visually    look for pin holes damage to the exterior etc,         

I am pretty sure you will find something external to the motor or in the terminal board of the old motor because it is the same winding in both directions,       and if you do find a problem that would trip the GFCI or the GFCI got weak then you have a spare motor,        any questions if you find something let me know and we will go into detail about anything suspect  

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Will

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Three phase/ AC DC single phase motors, controls, any problems or failures, motor installation, performance issues, connections. All other electric motors/gearboxes/apparatus. Specialty repair concerns, obsolete motors and solutions. Other mechanical or specialty equipment. See my profile under Home/electrical at this site

Experience

30 plus years in the electrical motor and apparatus repair industry. VP level management of repair facilities, current owner of my own specialty repair and consulting firm.

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EASA, IBEW [retired], other specialty organizations, Lubrication, Vibration EDI, Tribo-electric Councils

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Currently fielding concerns at this site under "Home Electrical"

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4 year technical, College level specific courses, EASA repair courses, vibration analysis electronic and electrical trade school.

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