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Thread: Circuit Breaker teardown and defective Siemens latching mechanism

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    Circuit Breaker teardown and defective Siemens latching mechanism

    Even after having meeting with other local engineers. We still couldn't fathom the cause of this strange Siemens main panel latching anomaly.

    First. I just made teardown of a Westinghouse breaker and became so familiar with all the mechanisms I can take all things apart and assemble the inside.

    Click image for larger version. 

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    In this video. If I don't lock the on position by pushing it down, it won't lock.

    https://www.youtube.com/watch?v=fTo2acI93XM

    Here I locked it in position and it stays on. In the third attempt. I didn't push it in so it returned.

    https://www.youtube.com/watch?v=tCqGNRzIMO0

    Has anyone tried any Siemens main panel breaker used the PL series? Could it somehow be normal (or just tolerance issue)? Using the Westinghouse breaker teardown. I couldn't extrapolate what is wrong with the Siemens.

    I couldn't return the item. It costs $45. And a new one cost $85 shipped. So I need to know if what could possibly be wrong with the Siemens. Doesn't it use a standard latching mechanism? Any illustration of what mechanism it could be using?

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    Methinks it's a simple case of mechanical wear.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

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    Quote Originally Posted by LarryFine View Post
    Methinks it's a simple case of mechanical wear.

    But it's brand new. Never been used. I couldn't return it because it has to be exchanged at a US address.

    For normal circuit breaker. When it trips. You have to put it to OFF first to re-engage the lever next to the bi-metal or thermal magnetic strip. Then you turn it ON to engage the contacts. I have played with the teardown Westinghouse breaker and so familiar with it.

    In the case of the brand new Siemens breaker. One has to press gently after it is in ON position before it stays ON.

    Anyone has actually handled one of these? Isn't it normal?

    Click image for larger version. 

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    Sounds like a defective unit.

    We have discover that many CH 200 amp main breakers will not either turn off the power or the handle will just flip back up without engaging the mechanism. We installs many of these in the 90's and now I have gone back to about 5 different jobs where we had to work on the service and discovered they were defective. CH started to cover the cost of the breaker but now has refused to do so. I think they have had a defective batch that never got caught because no one usually turns the main on and off again on install.
    They say I shot a man named Gray and took his wife to Italy
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    After teardown of the Westinghouse Breaker and handling it for a day at office during break removing the parts and putting them back again and again. It gave me courage to finally initiate teardown of the Siemens Load Center main circuit breaker (especially when no one can offer any clue what could be wrong with it and no teardown of it anywhere in the net).


    I spent more than an hour in the evening removing the 4 mini-bolts manually so it won't damage the unit if drill is used. I found out the problem. First youtube video of the internal parts and illustrations:







    It's just a typical circuit breaker internal components. Nothing unique. The source of the problem why you need to push it a bit more for the latching to be made is due to housing dimension tolerance. Compared to other breakers where the latching is made 75%. In the Siemens. It is 90% before the spring hatches it to make full contact. So slight housing misalignment need you to push it a bit more (and it is only in one of the breaker (remember it is two pole so has 2 separate unit). No problems with the bi-metallic strips or catch mechanism.
    Last edited by tersh; 02-02-19 at 07:35 PM.

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    Fascinating. Even if you cannot officially return for warranty replacement, I am sure there are engineers in the company who would love to take a look at that breaker.

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    Quote Originally Posted by GoldDigger View Post
    Fascinating. Even if you cannot officially return for warranty replacement, I am sure there are engineers in the company who would love to take a look at that breaker.
    They did that with a GFCI of mine, though it was Leviton.

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    Quote Originally Posted by tersh View Post
    After teardown of the Westinghouse Breaker and handling it for a day at office during break removing the parts and putting them back again and again. It gave me courage to finally initiate teardown of the Siemens Load Center main circuit breaker (especially when no one can offer any clue what could be wrong with it and no teardown of it anywhere in the net).


    I spent more than an hour in the evening removing the 4 mini-bolts manually so it won't damage the unit if drill is used. I found out the problem. First youtube video of the internal parts and illustrations:







    It's just a typical circuit breaker internal components. Nothing unique. The source of the problem why you need to push it a bit more for the latching to be made is due to housing dimension tolerance. Compared to other breakers where the latching is made 75%. In the Siemens. It is 90% before the spring hatches it to make full contact. So slight housing misalignment need you to push it a bit more (and it is only in one of the breaker (remember it is two pole so has 2 separate unit). No problems with the bi-metallic strips or catch mechanism.
    You are smarter then I am, that is for sure. I think you've figured it out, and better then I could have despite tearing down many breakers...

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    Quote Originally Posted by mbrooke View Post
    You are smarter then I am, that is for sure. I think you've figured it out, and better then I could have despite tearing down many breakers...
    You provided me all the references. And i dont come actual defects. If there is actual mechanical defects. Then i dont know either also there seems to be other designs with solenoids. I havent seen them and hope i wont as breakers are critical components and better left to the factories But in case you have seen teardown of GFCI breakers. Pls let me know. I dont want to be tempted to teardown a new one just to see how the compnents are put together or layout. Lol

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    Quote Originally Posted by tersh View Post
    You provided me all the references. And i dont come actual defects. If there is actual mechanical defects. Then i dont know either also there seems to be other designs with solenoids. I havent seen them and hope i wont as breakers are critical components and better left to the factories But in case you have seen teardown of GFCI breakers. Pls let me know. I dont want to be tempted to teardown a new one just to see how the compnents are put together or layout. Lol


    Regular US breaker:












    Old (trash) FPE breakers:





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