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Thread: Circuit Breaker teardown and defective Siemens latching mechanism

  1. #21
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    Quote Originally Posted by tersh View Post
    Ok. Thanks for the info. Need to convince the neighbors. Lol.

    Well. I'm presently studying about arc flash. How many current in a wire before it can become explosive enough to injure the electrician?

    https://www.youtube.com/watch?v=6hpE5LYj-CY

    Once I saw an electrician trying to connect a breaker live. Although there is no direct connection between two terminals. There are carbon sooths, and this created a small arc flash enough to injure him. After that. I won't even go near an electrician when he fixed stuff. And also staying from the electronic or electrical engineering field as it's very dangerous field.

    In the Philippines where electricians don't have to worry about neutral and grounding, but just able to connect the red and black wires without even polarity. Many of them are doing it live (only skill they can boost that cut them above ordinary folks). I know this is very dangerous. Many of them don't even know what is arc flash.

    I want to share them this so they be more careful. In a basic home panel. What usually is the current before the arc flash can occur similar or even half the video (above) intensity?

    And if AFCI are installed. Can it totally prevent it or just diminish the intensity (by how many percentage)?
    "Incident energy" is what determines how dangerous the arc flash is. Not every incident will be the same.

    Safety policies will calculate a maximum expected incident energy level to determine what PPE is necessary to work on a particular piece of equipment. A lot of times you aren't permitted to work live but must still don protection to take voltage readings to ensure it is dead before working on it.

    Said incident energy level calculations take the available fault current as well as the trip curve of overcurrent devices into consideration, but it is still a little more complex than just those two items, high current for short time can still release less overall energy than a lower current for longer time.
    I live for today, I'm just a day behind.

  2. #22
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    Quote Originally Posted by mbrooke View Post
    Oh, this is easy! UL did a residential aging report, and the majority of the breakers that failed to trip where outdoors (in a rain proof enclosure)- I can only imagine here where they are actually being rained on.


    I do not know the internals, but it would not shock me if they have all seized up considering the above is a code violation. Breakers must be protected from water.
    If the rain can get inside the breakers. Then if the springs are rusted. There is the possibility when you turn it to off position, it won't return to on because the springs and rusty latches would no longer work, isn't it?

  3. #23
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    Quote Originally Posted by tersh View Post
    I've never seen anything this ridiculously bad.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  4. #24
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    Quote Originally Posted by LarryFine View Post
    I've never seen anything this ridiculously bad.
    It's typical Philippines service entrance. This is outside our townhouse when we bought it second hand.




    The panel cover gave way after it was rusted. The 4 neighbors refuse to cooperate to have it repaired. This is because inside each house there is a separate one like it before the main panel. So it can be treated as just a conductor with the internal parts like springs and thermal and magnetic strips no longer working.

    I need to master computations of arc flash so in case it rains and the terminals shorted. I want to estimate if it can create self sustaining plasma that can grow large in size as it engulf the panels or area.


    What is the best book or reference about arc flash and example of actual computations?

  5. #25
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    Quote Originally Posted by tersh View Post
    It's typical Philippines service entrance. This is outside our townhouse when we bought it second hand.




    The panel cover gave way after it was rusted. The 4 neighbors refuse to cooperate to have it repaired. This is because inside each house there is a separate one like it before the main panel. So it can be treated as just a conductor with the internal parts like springs and thermal and magnetic strips no longer working.

    I need to master computations of arc flash so in case it rains and the terminals shorted. I want to estimate if it can create self sustaining plasma that can grow large in size as it engulf the panels or area.


    What is the best book or reference about arc flash and example of actual computations?
    How spectacular of a flash can occur is probably mostly dependent on what contaminants can accumulate that won't burn until something sets them off, most the time a little moisture presence will begin to conduct and vaporize itself until it can't conduct, and cycle gets repeated. component failure resulting in lost power through the device is more likely to happen first - at which point user will have an interest in doing something to restore power again, though it may be just to replace failed breaker unfortunately in your case with one that will be subjected to same conditions and probably will eventually fail again. I have bigger concern over potential shock hazards with this installation than with potential arc flash being on any severe level - unless maybe the source transformer is only 5 feet of supply conductor away, but from other posts you have made sounds like it is probably at the top of a pole.
    I live for today, I'm just a day behind.

  6. #26
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    Quote Originally Posted by tersh View Post
    What is the best book or reference about arc flash and example of actual computations?
    IMO this is one of the best books on the subject

    https://brainfiller.com/product/comp...ation-studies/

  7. #27
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    Quote Originally Posted by tersh View Post
    If the rain can get inside the breakers. Then if the springs are rusted. There is the possibility when you turn it to off position, it won't return to on because the springs and rusty latches would no longer work, isn't it?
    Its possible.

  8. #28
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    Can't speak for the breakers in your image, but most will have openings for pressure relief should the device have to open under high current conditions. Those openings will let not only moisture but insects, dirt, etc. inside and those things also cause trouble with operation of internal parts.
    I live for today, I'm just a day behind.

  9. #29
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    Quote Originally Posted by mbrooke View Post
    Its possible.
    mbrooke. Why are some breakers so big and some so small (like the European breakers) yet they have same rating say 125A. For example, the following GE is so big.




    Compared it to other very small compact breakers 1/3 its size. Do you think the thermal strip is same size for both since you have seen the internal components of so many breakers? Which do you prefer, big or small and why?

  10. #30
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    Quote Originally Posted by tersh View Post
    mbrooke. Why are some breakers so big and some so small (like the European breakers) yet they have same rating say 125A. For example, the following GE is so big.




    Compared it to other very small compact breakers 1/3 its size. Do you think the thermal strip is same size for both since you have seen the internal components of so many breakers? Which do you prefer, big or small and why?


    Look into "amp frame"


    Every amp trip has a maximum frame size, for example the highest you can can get for a 1 inch style 2 pole plug in breaker is 125 amps, that is unless you want to take up 4 spaces and a bit of gutter space its 200amps.










    Higher current ratings will have larger sizes, but you can also get smaller ratings in the same package to fit the same space.


    Ie, many years ago the number of spaces in load centers was limited, and a 125 amps 42 space panel was not available to my knowledge- but if you needed the space and 125amps was your service size, you could take a 200amp 42 space panel and swap the 200amp main with the exact 125 amp you pictured. It would fit will meeting code. Another common example is in switch-gear and panel boards where you have a location for a 400 amp frame, but need say a 20 amp lighting circuit.

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