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Thread: Arc Flash - Electrically Safe

  1. #11
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    Mar 2013
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    Rutland, VT, USA
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    Quote Originally Posted by petersonra View Post
    however, you can add these to make it possible to test for voltage w/o needing anything other than PPE for electrocution hazards.

    http://www.graceport.com/safeside/p-s10s21-m3rx
    I am not sure that would be acceptable based on NFPA 70E Article 120.1. I would not want some intervening test device between the subject conductors and my test instrument. How do I know that the device is working properly. With a multimeter, you are supposed to test it on known live circuit (such as an outlet) to verify test device working including lead integrity, test the specimen, then test the multimeter again on the known source to verify it is still operating.

    I think that graceport device all you can comfirm is that the device is de-energized not the conductors or bus that you are working on.

  2. #12
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    Quote Originally Posted by wbdvt View Post
    I am not sure that would be acceptable based on NFPA 70E Article 120.1. I would not want some intervening test device between the subject conductors and my test instrument. How do I know that the device is working properly. With a multimeter, you are supposed to test it on known live circuit (such as an outlet) to verify test device working including lead integrity, test the specimen, then test the multimeter again on the known source to verify it is still operating.

    I think that graceport device all you can comfirm is that the device is de-energized not the conductors or bus that you are working on.
    There is nothing between the test port except a wire and a resistor.
    Bob

  3. #13
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    wbdvt
    Can you really use the utility disconnection of service....How does this work with the lock-out tag-out protocol ?
    In other words, if something goes wrong. Can you claim the utility said it was OK ?
    Would you not still have to suit-up for verification of no voltage on the main ?

    Petersonra
    Only allowed to do live work for testing and debugging ?
    Are there not scenarios such as hospital's where CBers are replaced live ?

    Golddigger
    Is there industry standard language for say a multi-section switchboard with main in compartment one, that would allow work in the other sections and a SC would not be able to cross into the main compartment ?
    Arc-Shield...Arc-resistant ??

  4. #14
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    Anyone....before subject falls off the page.

  5. #15
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    Quote Originally Posted by MyCleveland View Post

    Golddigger
    Is there industry standard language for say a multi-section switchboard with main in compartment one, that would allow work in the other sections and a SC would not be able to cross into the main compartment ?
    Arc-Shield...Arc-resistant ??
    Not that I am aware of.

  6. #16
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    Just me.

    It seems to me that if you were to do a rigorous risk assessment, you might be able to convince yourself that something is safe, and it might well be safe.

    But you not only have to protect yourself against real hazards but imaginary ones that OSHA might come up with.

    I don't see how working inside of a MCC bucket where the main four sections away has been opened presents any opportunity for a hazard. But you will potentially have to be able to defend this decision to OSHA. And if an incident happens, you are truly screwed.

    The problem is that OSHA does not really care if you are safe or not. When they come into look at your facility they want to issue fines. That is all they really care about. Just like traffic cops or the IRS.
    Bob

  7. #17
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    Thank you

  8. #18
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    Rutland, VT, USA
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    Quote Originally Posted by MyCleveland View Post
    wbdvt
    Can you really use the utility disconnection of service....How does this work with the lock-out tag-out protocol ?
    In other words, if something goes wrong. Can you claim the utility said it was OK ?
    Would you not still have to suit-up for verification of no voltage on the main ?
    I have seen some utilities will at the request of the customer install grounds on the rise cables after the cutouts are open. So if the utility is your only source, then you have a visible disconnect and a set of grounds at the source connection. This would have to written into the LOTO procedure for de-energizing the main transformer and system.

    If it sounded like I was saying the utility said it was ok, that was not my intention. The utility is doing the work at your request as it is their equipment except the riser cable may be customer owned and you may have to pay the utility for this work.

    If there is only one source of electrical energy in the system and that is grounded, I would say that the source has been removed and the utility would have tested for de-energized prior to installing grounds.

  9. #19
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    Cleveland, Ohio
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    Thanks wbdvt
    I am not an EC, was not trying to be argumentative....just trying to understand the difficulties of what EC's are up against.

  10. #20
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    Quote Originally Posted by Sahib View Post
    "Arcshield" equipment from Allen Bradly has arc flash resistance design even with cover opened for maintenance.
    Depending on what voltage level you are talking about, that's either untrue or partially true. MV ArcShield MCCs and Starters can have the LOW VOLTAGE control compartment opened while the MV is energized and still be safe from arc flash in the MV section. This is called "Class 2B" design per IEEE /ANSI C37.20. Nothing can be opened in LV ArcShield MCCs without being exposed to the arc flash danger, it is Class 2, but the "B" can't apply because it's ALL low voltage (600V and below).

    Even if you get the SecureConnect option on a unit that removes the stabs from the MCC bus before opening the door, you still need to put on the bunny suit to open the door and remove the bucket. SecureConnect (and Cutler Hammer's Flash Guard) makes it electrically safe to open the doors, but that's different from arc flash protection. Whenever a door is open and power is energized in the same air space, you are at risk from blast pressure, plasma burns and shrapnel.

    So bringing this back to the OP, there is no scenario in which you can avoid needing to preform a study of the risks. Even if an owner farms out the "hot work" to someone else, the study still must be done for THEM to know the proper PPE, and farming it out does NOT relieve the owner of that responsibility. So, if they DO choose to farm it out, the first contractor hired to do the hot work will STILL need to have the study data to be able to proceed, so that will take time and if it's a breakdown situation with loss of revenue involved, that extra time will cost them a LOT more than just having the study preformed ahead of time, because the study can be done without de-energizing anything (in most cases).
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