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Unusual MCB

Sparkymania
Here's an interesting one.

Federal Electric 20A MCB. Had no type on it and was taking a long time to trip. Opened one up and discovered why it didn't have a type.

Others with it were ECC but virtually the same design. Only thermal. Both are plug in types called stab-lok and are bakerlite.


No instantaneous trip mechanism. Only a thermal one.



34200b5e07a12e120f5fc679b8b1b9aa-huge-mcb-with-no-instantanious-trip-mechanism-4.jpg
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    Don't think so. The MCBs don't have electronics anyway, so same situation. The one I opened was a 10mA and would think there would be a risk of false tripping if a method like that was used.

    No way the thermal trip manages to be within 0.1. These DBs had to be replaced in an installation because they were taking far too long to trip on a direct fault.

    I think it is as it looks. No instantaneous trip in MCB and RCBO. Hard to understand the thinking of a manufacturer in making these for use in a DB.

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    Don't think so. The MCBs don't have electronics anyway, so same situation. The one I opened was a 10mA and would think there would be a risk of false tripping if a method like that was used.

    No way the thermal trip manages to be within 0.1. These DBs had to be replaced in an installation because they were taking far too long to trip on a direct fault.

    I think it is as it looks. No instantaneous trip in MCB and RCBO. Hard to understand the thinking of a manufacturer in making these for use in a DB.

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