I have equipment, an MCC, where the the available fault current is less than 42 kA and the upstream OCPD has a cycle clearing time of less than 2 cycles. Can I then refer to row 1 since the OCPD cycle clearing is less than the 2 cycles?
As long as you are referring to a 600 volt class MCC and the minimum “working distance” of 18" between the potential arc source and the worker’s torso, face and head is maintained, then yes.
Also pay particular attention to the Note contained in NFPA 70E Table130.7(C)(15)(a) which if applicable may allow you to reduce the arc flash PPE category by 1.
Thanks Steve for the response. I see the note but can I go down to Cat 2?
Where the available fault current is less than 42 kA and the upstream OCPD has a cycle clearing time of less than 2 cycles, can I then refer to row 1 where it states a maximum of 65kA? For example if the available fault current is calculated to be 40,000 amps. Technically it would fall under both 42kA and 65kA but the 65kA row specifies less than 2 cycles.
Ruben, As you describe your system the maximum values are not exceeded and Arc Flash PPE Category 2 would be allowed.
That's what I was thinking and I just needed reassurance.
Thanks so much for your time.
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