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130.3 Exception No. 1

Discussion in 'General Discussion' started by soulmandcc, Apr 14, 2010.

  1. soulmandcc New Member

    If a system meets all conditions listed in Exception No. 1, an arc flash hazard analysis is not required.

    Say the system is at 120 volts and meets all conditions in Exception No. 1, does the arc flash boundary move to the 4ft default boundary? Or is there no arc flash boundary?
    soulmandcc, Apr 14, 2010
    #1

  2. arcflash71 Member

    A strict interpretation of the standard seems to require the 4 foot boundary for this case.

    However, 130.3(B)(2) implies that you can use the task table to select PPE inside the 4 foot boundary. If the table recommends HRC0 for the task you want to do inside the 4 foot boundary then the impact seems negligible.
    arcflash71, Apr 20, 2010
    #2

  3. seriouswatts New Member

    Can you use the exceptions?

    If you meet all of the criteria for Exception No. 1, but determine that your incident energy is over 100kA cycles, are you now required to perform the calculations? 130.3 (A)(1)?
    seriouswatts, Jun 22, 2010
    #3

  4. cbauer Well-Known Member

    Yes, you would then be required to calculate the FP boundary.
    cbauer, Jun 22, 2010
    #4

  5. seriouswatts New Member

    If you are required to calculate the FPB if over 100kA cycles, whats the point of the exception? Either way you are going to have run calculations to determine whether or not you meet the 100kAC. Thus negating the exception to not have to.
    seriouswatts, Jun 22, 2010
    #5

  6. cbauer Well-Known Member

    I did not say that the exception made any logical sense, just that the exception exists.
    cbauer, Jun 22, 2010
    #6

  7. JBD Well-Known Member

    Technically, determing the 'kA cycles' is a short circuit and coordination analysis not an 'arc flash analysis'.:D:rolleyes:
    JBD, Jun 22, 2010
    #7

  8. seriouswatts New Member

    A SSC/PDC study would give you your interrupting current to size your equipment (kAIC). The kA cycles is more for arc flash becasue you are concerned with the opening time of the device relative to the amount of fault current available.
    My point is really, that you can meet all of the criteria for exception one to not have to do an arc flash analysis, but if you have low fault current your OCPD opening time could be long, and thus over the 100kA cycles. So either way you have run calculations, you can't just blindly take the exception.

    Does that sound right?
    seriouswatts, Jun 24, 2010
    #8

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