2009 NFPA 70E Table 130.7(C)(9) Notes
2009 NFPA 70E Table 130.7(C)(9) Notes
(OP)
The notes setting the boundaries for table use list a maximum short circuit amps available and a maximum fault clearing time.
Is this "maximum fault clearing time" determined by the "maximum short circuit amps"?
Thanks
Is this "maximum fault clearing time" determined by the "maximum short circuit amps"?
Thanks






RE: 2009 NFPA 70E Table 130.7(C)(9) Notes
However, it should be noted that the maximum fault current does not always create the largest arc flash hazard, IMO this is a problem with the tables. I would rather see a limit in maximum amp-cycles but that was viewed by the commitee to be too complicated (Basically requires a full analysis)
RE: 2009 NFPA 70E Table 130.7(C)(9) Notes
RE: 2009 NFPA 70E Table 130.7(C)(9) Notes
The problem with the table is that for a system of any size, by the time you've gotten enough data to determine if the table note limits are met, you are more than halfway to a full incident energy analysis.
RE: 2009 NFPA 70E Table 130.7(C)(9) Notes
RE: 2009 NFPA 70E Table 130.7(C)(9) Notes
RE: 2009 NFPA 70E Table 130.7(C)(9) Notes
While I agree the highest arc flash hazard may very well not be at maximum availabel fault current the notes of the tables are refering to the clearing time at the maximum avilable fault current not to exceed the fault current listed in the tables, right or wrong, that is clearly the intent of the notes.
RE: 2009 NFPA 70E Table 130.7(C)(9) Notes