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480V Main Disconnects - CB Operation

Discussion in 'Electrical Safety Practices' started by WJMan, Sep 30, 2009.

  1. WJMan New Member

    An arc flash analysis has been performed at one of our multiple-story facilities. As a result, many of the 480V disconnects on each floor were labeled with the 'DANGER - ENERGIZED WORK PROHIBITED' labels in accordance with NFPA 70E for components determined to be greater than 40cal.

    The maintenance employees responsible for the electrical facilities within the building are now questioning whether they can safely operate the CB disconnect which is located outside the disconnect enclosure. They believe operating a disconnect with doors closed is not considered energized work since no electrical conductors or circuit parts are exposed.

    The debate continues to whether operation of the disconnects can still be accomplished without deenergizing the entire building. Does anyone have any thoughts or clear guidance on what should be done in this particular scenario?
    WJMan, Sep 30, 2009
    #1

  2. Zog Well-Known Member

    They are wrong, unless you have arc rated switchgear operation and/or racking of breakers with the doors closed is considered energized work per the 70E, they use the phrase "interaction with equipment" in the definition and cite the task tables as examples.

    They can use remote operators to operate them from outside the arc flash boundary. That what most facilities are starting to do.
    Zog, Sep 30, 2009
    #2

  3. Canuck01 Member

    Hazards over 40 cal

    Hello Zog
    Remote racking is a great way to remove the risk when racking but I am struggling with the Test portion of lockout. Testing will require the electrician to interact with the gear and be exposed to the potential arc hazard. any thoughts on how to deal with a +100 cal hazard when testing? Am I thinking about this all wrong??
    Canuck01, Oct 1, 2009
    #3

  4. Zog Well-Known Member

    Good discussion on the testing part here. http://www.arcflashforum.com/showthread.php?t=673
    Zog, Oct 1, 2009
    #4

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