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Thread: HVAC TEACHER AT UEI SHOULDNT BE TEACHING ELECTRICAL

  1. #11
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    simmer down

    for very elementary diagrams the source and load are shown as grounded at times
    also done for not so elementary work
    simplifies things

    it's better to listen
    you know technically the return path is not ground but to illustrate some basics it is useful
    but by focusing on that you may have missed a relevant point he was trying to make

    this is from a grad level course on power system analysis
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    Last edited by Ingenieur; 01-08-18 at 08:26 PM.

  2. #12
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    Quote Originally Posted by Ingenieur View Post
    simmer down

    ...

    it's better to listen
    you know technically the return path is not ground ...
    Exactly.

    The return path is not people, either, but electricity will use it if they put themselves between the ungrounded conductor and any kind of grounded path, be it a grounded conductor, EGC, bonded frame, etc.

    Sounds like the teacher didn't get a chance to really make whatever point was coming.

  3. #13
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    Quote Originally Posted by Ingenieur View Post
    simmer down

    for very elementary diagrams the source and load are shown as grounded at times
    also done for not so elementary work
    simplifies things

    it's better to listen
    you know technically the return path is not ground but to illustrate some basics it is useful
    but by focusing on that you may have missed a relevant point he was trying to make

    this is from a grad level course on power system analysis
    Not quite the same thing. Kinda like talking about a circuit board ground trace in this context. Just not the same discussion.
    BB+/BB=?

  4. #14
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    Quote Originally Posted by MAC702 View Post
    The return path is not people, either, but electricity will use it if they put themselves between the ungrounded conductor and any kind of grounded path, be it a grounded conductor, EGC, bonded frame, etc.
    But who would say electricity is trying to get to people?
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  5. #15
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    Quote Originally Posted by mivey View Post
    But who would say electricity is trying to get to people?
    No one I can see here, and doesn't really address the point.

    Fact is, we don't know what the teacher was trying to say.

    Saying "electricity wants to go to [electrical] ground" is a likely precursor to saying 'so don't be the part that lets it' or 'so that's why we sometimes have two conductors for it to do so: a purposeful one for some voltages, but always one for safety.'
    Last edited by MAC702; 01-08-18 at 09:10 PM.

  6. #16
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    Quote Originally Posted by mivey View Post
    Not quite the same thing. Kinda like talking about a circuit board ground trace in this context. Just not the same discussion.
    True, however, it does illustrate that [electrical] ground can be a "common" termination point. And that we don't mean each of those ground symbols is a rod in the dirt.

  7. #17
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    Quote Originally Posted by mivey View Post
    Not quite the same thing. Kinda like talking about a circuit board ground trace in this context. Just not the same discussion.

    pretty much exactly the same
    in this case a 1 ph-g equivalent

    without seeing his material we don't the context
    could be static electricity or lightning

  8. #18
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    Quote Originally Posted by Ingenieur View Post
    simmer down

    for very elementary diagrams the source and load are shown as grounded at times
    also done for not so elementary work
    simplifies things

    it's better to listen
    you know technically the return path is not ground but to illustrate some basics it is useful
    but by focusing on that you may have missed a relevant point he was trying to make

    this is from a grad level course on power system analysis
    Thats a transmission line which in many cases does indeed factor in the earth in terms of fault clearing and relay settings (ie k0 factor)


    http://www.relaytech.com/files/34789992.htm
    Last edited by mbrooke; 01-08-18 at 09:54 PM.
    I'm in over my head...

  9. #19
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    Quote Originally Posted by Ingenieur View Post
    pretty much exactly the same
    in this case a 1 ph-g equivalent

    without seeing his material we don't the context
    could be static electricity or lightning
    If you want to lean to that understanding then that is fine. I disagree.
    BB+/BB=?

  10. #20
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    Quote Originally Posted by Ingenieur View Post
    pretty much exactly the same
    in this case a 1 ph-g equivalent

    without seeing his material we don't the context
    could be static electricity or lightning


    No its not.

    2x 3/8HS steel, a metal tower going a dozen feet into the earth, 69,000 volts L-G and a vastly different OCPD system is at play vs 600 volts and under.

    No matter what that diagram is not relevant to the NEC.
    I'm in over my head...

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