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  1. #1
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    How are ground fault mini-breakers wired ? Are they even mini-breakers at all?

    This breaker is single-pole-sized and appears to only snap onto one buss bar in the panel. It had one full-sized single pole breaker looking 'switching handle' on it.

    But . . . it has two screw terminals - and so in that regard looks like the output end of a mini-breaker.

    Under the twin screw load side terminals there is a white wire coming out. This lone white wire goes to the neutral/ground connection terminal buss.

    There is a freezer drain line heater wired to this breaker. Both sides of the drain line circuit are wired to the two terminals on the breaker. This seems like it cannot possibly work as the potential would be the same on both sides of the circuit.

    Ahhhhh . . . . but it Does work - apparently because only one of the breaker's screw terminals have power. <g>

    So anyway: wth am I looking at here? Is there supposed to be the same power from each of the output screw terminals? That is: 120 VAC to neutral? Mini breaker fashion?

    Or . . . . is the second terminal actually a common connection - being made through that white wire going to the neutral/ground bar?

    So? How do it work? <g>
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  2. #2
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    I cant comment on the science of it poodle but that white wire is how the gfci will sense the voltage to ground and trip.

  3. #3
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    What you are looking at is a typical gfci breaker. It compares the current flow in the white wire to the curremt flow in the grounding conductor, and if over 0.006 amps flows in the grounding conductor, this device will open the circuit power.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  4. #4
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    So the common is also switched ?

    So both the 120VAC leg and the Common leg are switched by the breaker?

    And the common wire IS supposed to be connected to the breaker?

    PHM
    ------
    '




    Quote Originally Posted by timebuilder View Post
    What you are looking at is a typical gfci breaker. It compares the current flow in the white wire to the curremt flow in the grounding conductor, and if over 0.006 amps flows in the grounding conductor, this device will open the circuit power.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  5. #5
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    Yes.

    The common goes to the breaker just like the feed.

    Then, the common comes OUT of the breaker (it's another white wire, usually coiled like a pig's tail) and then THAT common goes to the neutral buss.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  6. #6
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    Didn't think the common is switched. I thought the white wire went through a currant transformer thinge.

    Quote Originally Posted by timebuilder View Post
    Yes.

    The common goes to the breaker just like the feed.

    Then, the common comes OUT of the breaker (it's another white wire, usually coiled like a pig's tail) and then THAT common goes to the neutral buss.

  7. #7
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    Correct.

    I didn't say common is switched. It is attached to the breaker in the same manner as the feed wire.

    Internally, the common current is measured, and it continues to the neutral terminal block via the coiled white wire coming out of the breaker.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  8. #8
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    I am not a fan of ground fault breaker or receptacles. They always seem like far more trouble than they are worth.

    Thanks for your help. I guess the easy repair is out now - I'll have to crawl around in the ceiling and figure out what the electricians did wrong. They installed new door lights on all the display wall doors - and the next day all the door heaters weren't working.

    A mere coincidence the electricians say - as they didn't work on anything which could have caused that problem.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  9. #9
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    I'm told the gfci receptacles have a 10% failure rate out of the box.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  10. #10
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    In my entire lifetime I have only very rarely been shocked by a 120V circuit and not even in a single instance have I died as a result. And I don't know anyone, or even of anyone, who Has been killed either. GFI seems like a solution in search of a problem to me.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  11. #11
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    Quote Originally Posted by Poodle Head Mikey View Post
    In my entire lifetime I have only very rarely been shocked by a 120V circuit and not even in a single instance have I died as a result. And I don't know anyone, or even of anyone, who Has been killed either. GFI seems like a solution in search of a problem to me.
    What about the hair dryer in bathtub and extension cord in swimming pool urban legends?

  12. #12
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    No one who lives anywhere near me can afford hairdryers, let alone bathtubs or swimming pools. Those legends are probably just the way the universe weeds out the stupid-rich.

    PHM
    ------




    Quote Originally Posted by SBKold View Post
    What about the hair dryer in bathtub and extension cord in swimming pool urban legends?
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  13. #13
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    Hundreds of people die every year from 120 volt shocks.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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