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Thread: Motor hums and trips breaker - not sure if the capacitor is the problem

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    Join Date
    May 2012
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    Houston, TX
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    37

    Motor hums and trips breaker - not sure if the capacitor is the problem

    I have a Century Electric B855 2hp motor running my Pentair pump. After a big storm 2 weeks ago, I found that the motor wasn't running. It hums and trips the breaker.

    I figured the capacitor may have died, but the capacitor looks fine - not bulging at the bottom as it has in the past when it's blown. Ordered the wrong one by mistake (50 mfd instead of 30 mfd) but the motor did the same thing when I connected the 50 mfd capacitor to try it.

    I disconnected the motor from the wet end and both the impeller and shaft turn freely. I ordered a new 30 mfd capacitor to see if that will fix it.

    Not sure what to do if the new capacitor doesn't fix the problem. I just installed the motor a year ago, and will be bummed if the motor is fried.

    Any recommendations would be much appreciated. Some algae has started growing on the sides, so I brushed and added 4 bottles of bleach to my 18K gallon pool. I would really like to solve this before the pool turns all green!

    Thanks in advance for any help.
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    Re: Motor hums and trips breaker - not sure if the capacitor is the problem

    I've seen an issue that might be what you have but then again maybe not. Key phrase being "after big storm". If the area where the pump sits is prone to flooding, you might've flooded the motor and caused internal damage. You'll know when you replace the capacitor (smoke/sparks).

    Remember if replacing the capacitor you need to discharge it by placing a screwdriver between the two contact banks.

    GL!

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    In the Industry

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    Re: Motor hums and trips breaker - not sure if the capacitor is the problem

    On the back of the B855 motor there should be a big plastic nut looking piece. Grab a wrench give it a quarter turn and pull it off. You'll see a metal nub, that is the shaft. Take your wrench and see if it turns. If it's hard to turn keep turning it back and forth til it gets easier. Once it turns easy then try to turn on the pump. If it doesn't turn at all then your shaft is locked and you need a new motor.
    40k Gallon Grecian true L Gunite Pool/Spa. Clean clear plus 520 cartridge. IntelliFlow VS-3050. Polaris booster pump w/ Polaris 360 cleaner. Silencer 1 1/2 hp Blower. Aqualink RS8 w/ Iaqualink 2.0 upgrade kit.

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    May 2012
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    37

    Re: Motor hums and trips breaker - not sure if the capacitor is the problem

    Quote Originally Posted by JoelFitz View Post
    I've seen an issue that might be what you have but then again maybe not. Key phrase being "after big storm". If the area where the pump sits is prone to flooding, you might've flooded the motor and caused internal damage. You'll know when you replace the capacitor (smoke/sparks).

    Remember if replacing the capacitor you need to discharge it by placing a screwdriver between the two contact banks.

    GL!
    Thanks for the reminder about discharging the capacitor. I always do that before touching it. The pump sits on higher ground than the lawn, so I'm pretty sure it did not get flooded. There was a lot of lightning during the storm, so I'm wondering if that fried something in the motor. The motor was likely off during the storm though.

    I replaced the capacitor with a new 30mfd and the motor still just hums, followed by a ping sound, then it stops. After a few seconds there is another small ping. The breaker is not being tripped anymore, but it seems that the thermal cutoff switch (or whatever its called) inside the motor trips and cuts power to the motor for a few minutes.

    I guess I need a new motor? I may replace the motor and have the current one repaired as a back-up.

    - - - Updated - - -

    Quote Originally Posted by RedBluePool View Post
    On the back of the B855 motor there should be a big plastic nut looking piece. Grab a wrench give it a quarter turn and pull it off. You'll see a metal nub, that is the shaft. Take your wrench and see if it turns. If it's hard to turn keep turning it back and forth til it gets easier. Once it turns easy then try to turn on the pump. If it doesn't turn at all then your shaft is locked and you need a new motor.
    Tried that already. The shaft turns freely. The motor had been running fine all this time, until the storm happened.
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