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Thread: A smokin' hot motor

  1. #51
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    Quote Originally Posted by drktmplr12 View Post
    I can see that argument being made, except the calculator (slide card, right?) states that 80A thermal mag is for short circuit protection only and depends on an enclosed starter with overload heaters for thermal protection. Taken without this context, that argument can work. However, it would be cherry picking information.
    Yes, slide card calculator is what I was going off of. In general there needs to be separate motor overload protection. I also find it a little surprising the OP's motor started without tripping the 40 amp breaker

  2. #52
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    Oct 2017
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    NORWAY
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    start current

    Be aware that an el. motor will increase current up to 8 times in the start moment. So it is strange that the 40A breaker doesn't trip at once. But i assume the breaker are VERY slow type. You should increase the breaker amp from 40 A to 70 A . That should be sufficient, but be aware that sudden load also will affect the start current.

    But you must install a O.L. . This for save the motor if the load, pump or other external issues are working abnormal.

    O.L. will be setup after motor sign 31A

  3. #53
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    Quote Originally Posted by harmony View Post
    Be aware that an el. motor will increase current up to 8 times in the start moment. So it is strange that the 40A breaker doesn't trip at once. But i assume the breaker are VERY slow type. You should increase the breaker amp from 40 A to 70 A . That should be sufficient, but be aware that sudden load also will affect the start current.

    But you must install a O.L. . This for save the motor if the load, pump or other external issues are working abnormal.

    O.L. will be setup after motor sign 31A
    Long feeders/branch circuits will limit that starting surge, so can impedance of the source. Then it depends on the instantaneous trip level of the breaker as to whether it will start without tripping, though I am a little surprised it apparently has started on a 40 amp breaker.

  4. #54
    Join Date
    Feb 2012
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    Did anyone actually read the current, both peak starting, running and with the valve throttled (if there is one)? They may be satisfied with less flow due to a throttled valve rather than an up-sized supply. Just a thought. Being the cheapskate that I am, that's probably what I'd settle for. But you could have motor problems, so you need to measure the motor current with no load and voltage (at the motor itself) at full load to verify no wiring problems or motor problems. Sounds like you're assuming overload. Might not be. Please don't shoot arrows at me.....

  5. #55
    Join Date
    Mar 2014
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    Quote Originally Posted by meternerd View Post
    Did anyone actually read the current, both peak starting, running and with the valve throttled (if there is one)? They may be satisfied with less flow due to a throttled valve rather than an up-sized supply. Just a thought. Being the cheapskate that I am, that's probably what I'd settle for. But you could have motor problems, so you need to measure the motor current with no load and voltage (at the motor itself) at full load to verify no wiring problems or motor problems. Sounds like you're assuming overload. Might not be. Please don't shoot arrows at me.....
    There is not any overload protection although it is required by code. Properly sized bimetallic overloads will protect the motor from exactly what happened. If he wasn't there to shut off the motor it would have caught fire. Throttling the valve will achieve the desired affect, but whats to stop someone from coming back in 2 years and opening the valve again, only to start a fire?

  6. #56
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    Quote Originally Posted by drktmplr12 View Post
    There is not any overload protection although it is required by code. Properly sized bimetallic overloads will protect the motor from exactly what happened. If he wasn't there to shut off the motor it would have caught fire. Throttling the valve will achieve the desired affect, but whats to stop someone from coming back in 2 years and opening the valve again, only to start a fire?
    Honesty? I didn't read all of the posts, so my suggestion is STUPID....sorry!
    Last edited by meternerd; 10-07-17 at 11:41 PM.

  7. #57
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    Quote Originally Posted by meternerd View Post
    [/B]

    Honesty?
    You can be honest and still have no idea what you’re doing.
    Tom
    TBLO

  8. #58
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    Quote Originally Posted by ptonsparky View Post
    You can be honest and still have no idea what you’re doing.
    Which is what happens with most non electricians getting involved in electrical work.

    It does make anyone qualified for a career in politics though.

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