grounding devices that are not plugged into a wall outlet

Discussion in 'The Projects Forum' started by sportsfan27, Jan 30, 2009.

  1. sportsfan27

    Thread Starter Active Member

    Jan 29, 2009
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    How do I ground various components (such as a voltage regulator) inside a device that won't be plugged into a grounded wall outlet?
     
  2. mik3

    Senior Member

    Feb 4, 2008
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    They don't need ground!
     
  3. thingmaker3

    Retired Moderator

    May 16, 2005
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    The "ground" in such circuits is only a common reference point. It is a "chassis ground" instead of an "earth ground."
     
  4. DickCappels

    Moderator

    Aug 21, 2008
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    Or, if you are worried about safety when your device connects to AC operated equipment, shielding the circuit from ESD, or establishing a ground for your AM crystal radio, connect to the ground pin on a three pronged power plug, connect to a ground rod or other grounded metal structure such as a water pipe (if you live in a place old enough to have metal pipes that go into ground or concrete).
     
  5. sportsfan27

    Thread Starter Active Member

    Jan 29, 2009
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    So I would just not connect the "ground" pin to anything?
     
  6. thingmaker3

    Retired Moderator

    May 16, 2005
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    You would connect the "ground" pin to "circuit ground." It's a just name, like "Peter," or "Madalyn." But though "Peter" means "rock," Peter is not actually made from stone. And many Madalyns have never even been to Magdala, even though their name means "from Magdala."

    So the "circuit ground" need not be connected to "earth ground." It is simply a common point of reference for all the other voltages and signals.
     
  7. sportsfan27

    Thread Starter Active Member

    Jan 29, 2009
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    OK thanks, that clears up a lot of confusion. One question that just popped up due to curiosity is, in a generator, how are the 120VAC outlets grounded, or are they?
     
  8. Wendy

    Moderator

    Mar 24, 2008
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    They use the classic 3 prong system. Ground on the connector is a looong wire that goes to where ever your power tap off the grid is, and is usually about 3-6' of wire (or spike) going into the earth.

    This article touches lightly on the subject, from a different point of view. I wrote it for the AAC book.

    http://www.allaboutcircuits.com/vol_3/chpt_9/1.html
     
  9. sportsfan27

    Thread Starter Active Member

    Jan 29, 2009
    43
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    I don't think I was clear enough-I'm talking about portable generators such as those you might have during an emergency that provide power to cell phones, radios, flashlights, etc.
     
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