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N1 or N11 Description When Running Arc Flash Using NFPA 70E Method

The NFPA equations shown below are applicable for systems with voltages <= 1kV.



For bus voltages above 1kV, Lee Equation is used.



When the system voltage is outside the NFPA range, the Arc Flash module will show the notes (*N1) or (*N11) in the displayed Protective Clothing Category. The following description shows how the AF module implements the specified notes:

N1 - Out of NFPA 70E ranges. Lee equation is used and applicable for "Open Air" equipment types.

N11 - Out of NFPA 70E ranges. Lee equation is used and applicable for "In Box" equipment types.

The Lee equation is only applicable for "Open Air" equipments. However, we applied the equation for "In Box" conditions for there is no other recommended method available. Having a separate note N11 provides distinction between the "Open Air" and "In Box" conditions.