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Thread: Ceiling fan tripping earth leakage.

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    Ceiling fan tripping earth leakage.

    Hi All

    Maybe someone can explain theoretically why the following occurs.

    First time I've experienced the following:

    A ceiling fan is tripping the earth leakage relay only the moment it is switched off.
    It can run for hours on end without a problem, but the moment you switch it off, the earth leakage trips.

    Maybe someone can explain what is happening here.

    Regards ... Derek

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    Diamond Member adrianh's Avatar
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    I would think that when the circuit is broken a couple of things might happen:
    1. There would be a spark in the switch causing a transient into the motor coil.
    2. That transient may be high enough to to cause a short in a moist or already compromised environment.

    Maybe one of your motor coils has failed.

    I had a similar thing with one of my CNC machines. It would run happily for hours on end and only trip when I turn the main power off. After much stuffing about and replacing many components did it come to light that the coolant pump had failed and I suppose the excessive magnetic field built up in the motor coil with the addition of the switch opening transient field was enough to short the pump to ground.

    Dunno - may be I am talking rubbish but it seems to be the only thing that makes sense.
    “Why, sometimes I've believed as many as six impossible things before breakfast.”
    ― Lewis Carroll, Alice in Wonderland

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    Diamond Member AndyD's Avatar
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    There may be high standing leakage from other circuits and the arc caused when you switch the ceiling fan off is enough to cause tripping.
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    Bit of feedback.

    Definately a fault with the fan.

    There are another 5 fans on the same circuit and it's only this one causing the earth leakage to trip.

    Have megger tested it ok. infinity .

    Have removed the fan and replaced it with another ( same make and model ) ..... problem solved, but it still remains a mystery why.

    Will start playing around with it in the workshop when time permits.

    Regards ... Derek

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    IF you have done an insulation resistance test and it is clear ...my guess would be one of the capacitors are faulty... (without actually checking the fan it would be just that ...a wild guess) or a pinched wire...this is why i have a current leakage tester.

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    Earth leakage breakers can be a bit skittish. I had issues with one that used to trip every evening when the council street lights switched on. They can be a bit sensitive to phase angle fluctuations upstream as well as downstream especially with switching of highly capacitive or highly inductive loads. Usually a different brand of earth leakage breaker sorts it out but in your case it was probably just easier to replace the fan.
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    Diamond Member adrianh's Avatar
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    Quote Originally Posted by AndyD View Post
    Earth leakage breakers can be a bit skittish. I had issues with one that used to trip every evening when the council street lights switched on. They can be a bit sensitive to phase angle fluctuations upstream as well as downstream especially with switching of highly capacitive or highly inductive loads. Usually a different brand of earth leakage breaker sorts it out but in your case it was probably just easier to replace the fan.
    Next time I will ask you first before speaking a lot of $h1T :-)
    “Why, sometimes I've believed as many as six impossible things before breakfast.”
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    Quote Originally Posted by adrianh View Post
    Next time I will ask you first before speaking a lot of $h1T :-)
    Actually your statement is not total bullshyte...nobody really knows the real answer unless a variety of tests are done using the correct equipment.

    Comments made on a social media platform are merely suggestions.

    Andy is also correct in what he stated... i wouldnt total agree with his statement ...but as i mentioned they merely suggestions.

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    Quote Originally Posted by ians View Post
    Actually your statement is not total bullshyte...nobody really knows the real answer unless a variety of tests are done using the correct equipment.

    Comments made on a social media platform are merely suggestions.

    Andy is also correct in what he stated... i wouldnt total agree with his statement ...but as i mentioned they merely suggestions.
    Well I can tell you, sometimes the answer that solves a problem is really odd. I did a roughing toolpath on a cnc job last week and it was perfect. So I saved the file to a new revision today and made some alterations to the part. (made it a bit longer and added some elements) The CAM sotfware refused point blank to create the roughing path correctly. It would simply ignore large parts of the geometry. I spent many hours faffing with it - making al the parts nurbs, then nubs and meshes, then just a big mesh and and and.... I compared to the old revision and everything is correct (stock, bounding geometry etc). Then I turned the entire thing 90 degrees....Now the damn thing works perfectly. I have absolutely no idea why the stupid thing likes the drawing better landscape than portrait. It doesn't matter because I will place the stock accordingly. The point that I am trying to make is that the solution to the problem is totally irrational though it seems to be the only thing that works.
    “Why, sometimes I've believed as many as six impossible things before breakfast.”
    ― Lewis Carroll, Alice in Wonderland

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    Hi All

    A bit of feedback.

    Meggered the motor. Result infinity.

    Connected the fan in my workshop and tested.

    Turned it on and off a couple of times ..... no problem.
    Left it running for an hour. When I turned it off, the earth leakage tripped.

    While the motor was still warm, I meggered it again and found the reading to be lower than when the motor was cold. 1,5 megs.

    The insulation resistance is reducing with an increase in temperature.

    I am aware that the earth leakage should only start tripping when the insulation resistance is approx 8k or lower, but I suppose the reduction in insulation resistance combined with the arc from the switch does something that causes enough current to earth to trip the earth leakage.

    I still don't fully understand the theory behind it, but I now know that it's the fan that's faulty.

    Derek

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