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  1. #71
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    Sep 2008
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    8

    Default Re: Can someone explain the difference between phases and poles??

    Quote Originally Posted by JLMCDANIEL View Post
    The 128.7 vac is close to the no load voltage of the system
    The 123.4 vac is the voltage drop across the measured points
    The 5.3 vac is the voltage drop across the rest of the wiring
    The 9.1 ohms is the total impedance of the phase wiring and the ground wiring. The find the impedance of the ground wire alone you would have to know the impedance of the phase wiring from the source and subtract that from the 9.1 ohms. Because this a ac the resistance of the wiring is only a contributing factor to the impedance of the circuit so it makes it very difficult to estimate accurately with only the length or ga. of the wiring.
    Jack
    ***... you guys respond pretty fast. Ok.. first I need to apologize. I rechecked my test setup and determined the lightbulb I was using was 7 watt and not 40. So the 0.058 (58mA) holds. This means that the impedance remains 91 ohms and not 9.

    I guess from JLMCDANIEL´s explanation above it does indeed make it difficult to know what part of this impedance is in fact the ground since the phase wiring is included. My house is in fact spread out over 2 buildings so there are some larger than usual distances involved.

    I was just trying to get an estimate because lightning hit near the house the other day and 3 of my breakers went off. Also some damage to some minor electronics. Luckily computer was isolated.

    Excelent and informative discussion here.

  2. #72
    Join Date
    Aug 2007
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    The Great White North
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    4,045

    Default Re: Can someone explain the difference between phases and poles??

    Lightning induced surges are something that's difficult .... in cases impossible .... to control..... especially when they come in through the service entrance.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  3. #73
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
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    5,557

    Default Re: Can someone explain the difference between phases and poles??

    It should also be noted that lightening does not follow normal electrical rules. Lightening can even come into the household wiring through the ground, roll around on the floor and jump out a window.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  4. #74
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    Aug 2007
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    Default Re: Can someone explain the difference between phases and poles??

    ..... stay for dinner .....
    "" an ounce of perception -- a pound of obscure "
    - Rush

  5. #75
    Join Date
    Dec 2007
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    MN
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    455

    Default Re: Can someone explain the difference between phases and poles??

    Holy mackeral guys interesting stuff.
    You even have a plumber kicking in.

  6. #76
    Join Date
    Sep 2008
    Posts
    8

    Thumbs up Re: Can someone explain the difference between phases and poles??

    If anyone else is game to try the test in my message number 64 (on this thread), I would be interested in hearing the results for comparison purposes.

    Although it is not an exact measurement of your house´s ground impedance it does give you a general feeling without having to use special test equipment.

  7. #77
    Join Date
    Aug 2007
    Location
    Denver, CO
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    666

    Default Re: Can someone explain the difference between phases and poles??

    Quote Originally Posted by Sabio View Post
    If anyone else is game to try the test in my message number 64 (on this thread), I would be interested in hearing the results for comparison purposes.

    Although it is not an exact measurement of your house´s ground impedance it does give you a general feeling without having to use special test equipment.
    Sabio,

    I suggest that you go back and re-read my first link in post #55. Your test does not measure the impedance of “ground” or, earth. It is not a “ground” test.

    Although, it has been interesting.

  8. #78
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    Jun 2007
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    Fayette County, Ohio
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    Default Re: Can someone explain the difference between phases and poles??

    I have to agree with Kent. An interesting experiment but little relationship to ground testing. If you changed your connection from ground to common on this circuit you would get nearly the same results. The only difference would be the effect of the resistance if the ground wire and the common wire are of different gauges because they run nearly the identical path and would be affected by nearly the same length, counter EMF, forward EMF, etc. This set up would be more useful in showing the differances in power loss if you re-routed the cable or changed the wire gauge used.
    Jack
    Last edited by JLMCDANIEL; 10-09-2008 at 10:13 AM.
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  9. #79
    Join Date
    Aug 2007
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    The deep South
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    459

    Default Re: Can someone explain the difference between phases and poles??

    Quote Originally Posted by kentvw View Post
    Sabio,

    I suggest that you go back and re-read my first link in post #55. Your test does not measure the impedance of “ground” or, earth. It is not a “ground” test.

    Although, it has been interesting.
    That pretty much sums it up .

  10. #80
    Join Date
    May 2008
    Location
    Pacific Northwet
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    1,356

    Default Re: Can someone explain the difference between phases and poles??

    It can be difficult to measure the resistance/impedance to ground, at least in the US. Standard grounding practices here connect the ground to the neutral at the panel, the neutral goes back to the utility transformer where it's connected to the utility mains neutral (and and a ground rod at that location as well) which is connected to all your neighbors' ground rods and countless dozens at each stop on the way back to the substation. So the "ground" in your house may be connected to every other ground rod in your neighborhood, which may total in the hundreds! The only place the ground/grounded neutral system does NOT go is back to the generating plant from the substation along the high-voltage trunk lines.

    Of course, considering that there is some inherent resistance/impedance in the wires, it's not a 100% foolproof ground. But you get the point.

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