ground/earth qns

Discussion in 'Physics' started by killerfish, Mar 27, 2009.

  1. killerfish

    Thread Starter Member

    Feb 27, 2009
    17
    4
    Hi guys,

    i want to ask some silly qns, does ground count as good conductor since whenever leakage current from e.g fautly home appliance is flowing to ground? And so does soil also count as good conductor?

    Second, what if a power station is somehow faulty, there is this enormous current is injected into the ground. So does everyone inside the station get electric shock?

    Third, what the use of neutral wiring when we have ground wired to earth all the time?

    sry my science grade is alway bad...
     
    Last edited: Mar 27, 2009
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    1. Many conditions affect the quality of conduction through earth. Soil moisture and available chloride ions have a big effect. That is why we use earth ground as a reference rather than a conductor.

    2. The condition is the same as the bird on a wire. No potential difference will exist to cause current flow through the workers. Gonna be hard on the alternators, though.

    3. The neutral wire is part of the power circuit. It is intended to carry all the current. The ground wire is not a current carrier, except in case of a fault. It protects us from contacting a hot chassis/appliance, and may be used to sense a fault and shut down a bad circuit.
     
  3. davebee

    Well-Known Member

    Oct 22, 2008
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  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    In geographically limited areas. It may have some problems in areas like Arizona, California, and just about all the Middle East. Deserts don't conduct well.

    I^2R losses are dead losses to the utility. If any fraction of the power just heats the ground, it is a total loss to the utility. It also affects the distribution transformers, as the ground leg may be working into a significant voltage. That will cause the current through the primary to drop. That causes the loads to pull more current, which makes the loss in the ground leg get larger. It's only going to be applied under special circumstances.
     
  5. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    I wouldn't want to be standing on the ground near the return path for that one.
     
  6. killerfish

    Thread Starter Member

    Feb 27, 2009
    17
    4
    so we do get electric shock when we touch the ground wire when discharging of current is on going?
     
  7. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    If current is sufficient to cause a difference of potential between where we touch it and where we touch ground, then yes we do get shocked.
     
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