clearing times

[jimbo123]

This is about clearing times and bolted fault currents that exceed 100ka cycles when defauting to table to use a arc flash analylsis of 4'. If i were to use the tables in 130.7[c][9] and were to look at 600volt class switch gear- it says to look at note 4. that the maximun of 42ka scc and maximun of 20cycles fault clearing time. [ 42x 20 ]
Maybe i have something mixed up but i was thinking all calculations had to be under 100ka to use the table ? How would i apply note 4 ?

 

[zog]

This is about clearing times and bolted fault currents that exceed 100ka cycles when defauting to table to use a arc flash analylsis of 4'. If i were to use the tables in 130.7[c][9] and were to look at 600volt class switch gear- it says to look at note 4. that the maximun of 42ka scc and maximun of 20cycles fault clearing time. [ 42x 20 ]
Maybe i have something mixed up but i was thinking all calculations had to be under 100ka to use the table ? How would i apply note 4 ?

The 100ka-cycles you refer to are for using the 4 foot arc flash boundary for LV systems. Each equipment type has it's own limits to use the PPE HRC's from the tables.