KA SCCA IN THE NOTES

[jimbo123]

What do you do if you use the task tables in 70e and you have to use say note 4, 35 ka short circuit current available ; 0.5.sec. Your circuit breaker is rated for 65ka does this mean I am out of the parameters for using the notes. IF it does how would i use the tables for the ppe ?
A study has not beeb done as of yet and i don't know about getting clearing times and afc. Is the ka rating on the cb have any use with the notes ?

 

[don_resqcapt19]

Even to use the tables you have to know the available fault current and clearing time. If those values as less than what is in the table you can use the table, if not you can't use the table.
The rating of the breaker itself does not have anything to do with using the table.

 

[zog]

What do you do if you use the task tables in 70e and you have to use say note 4, 35 ka short circuit current available ; 0.5.sec. Your circuit breaker is rated for 65ka does this mean I am out of the parameters for using the notes. IF it does how would i use the tables for the ppe ?
A study has not beeb done as of yet and i don't know about getting clearing times and afc. Is the ka rating on the cb have any use with the notes ?

What Don said is correct, however until the real study is done there are some assumptions that you can make. A 65kAIC rated breaker was likely an extra cost to whoever designed the syystem over a lower rated breaker, so chances are good you have >35kA available, so until the study is done I would not assume you meet the criteria of the tables so I would not use them. Until the analysis I would avoid working on the system energized and if you must overprotect yourself PPE wise.