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Thread: What am I doing? Reopened

  1. #1
    Join Date
    Nov 2010
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    What am I doing? Reopened

    The original thread:
    What am I doing?
    I got into an argument with a QC. The craftsman was running the wire from an explosion proof disconnect to building structural steel. I say he was grounding the case. The QC said I was bonding the case. What do you think?

    The thread did not get a definitive answer. I came across this.

    Mike Holt wrote:


    For EC&M Magazine

    By Mike Holt, NEC Consultant

    Grounding and Bonding - Article 250, based on the 2017 NEC - Part 1



    Do you understand how to ground and bond your system?

    It’s important to understand the difference between grounding and bonding so you correctly apply the provisions of Article 250.

    We earth ground systems to the earth to reduce overvoltage (from lightning induced energy and other events) on the conductors and electrical components (such as transformer and motor windings) of the installation. Grounding metal parts helps drain off static electricity charges before flashover potential is reached. Static grounding is often used in areas where the discharge (arcing) of the voltage buildup (static) can cause dangerous or undesirable conditions.
    We bond so that metal parts of electrical raceways, cables, enclosures, and equipment are connected to the supply source via an effective ground-fault current path. To quickly remove dangerous voltage on metal parts from a ground fault, the effective ground-fault current path must have sufficiently low impedance to the source so fault current will quickly rise to a level that will open the circuit overcurrent protection device.

  2. #2
    Join Date
    Nov 2010
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    In conclusion, since the system was effectively grounded with the installed conductors, I still think the additional wire to steel is for grounding since this will bleed off any static or residual currents and does not facilitate the operation of the overcurrent device. Opinions?

  3. #3
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    Yes.

  4. #4
    Join Date
    Dec 2012
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    Placerville, CA, USA
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    It will do no more to bleed off static than the EGC would.
    But it would not hurt anything.
    It could be considered as both a bond and a ground. That often happens. It is not a code required bond or ground though.

    mobile

  5. #5
    Join Date
    Jan 2009
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    Quote Originally Posted by GoldDigger View Post
    It could be considered as both a bond and a ground. T


    The case is being grounded by the steel, assuming the steel qualifies as an electrode and the steel is being bonded by the case, assuming the case is bonded.
    "Electricity is really just organized lightning." George Carlin


    Derek

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