Arc Energy Reduction Performance Testing

[Mchapman]

I have a new 1600A 277/480v switchgear with a fused main. Since it is rated 1200A or higher we are subject to the requirements of 240.67 for arch energy reduction. We do not have any of the methods to reduce clearing times listed in 240.67 (B) 1 thru 4. I will be relying on the fuse to clear in .07 seconds or less at the available fault current. If I get the proper documentation showing that the trip curve of the fuse will have a clearing time of .07 seconds or less at the available fault current, is 240.67 (C) performance testing still required? If it is required how would this testing be done since a fuse will be damaged with primary current injection?

 

[jim dungar]

I have a new 1600A 277/480v switchgear with a fused main. Since it is rated 1200A or higher we are subject to the requirements of 240.67 for arch energy reduction. We do not have any of the methods to reduce clearing times listed in 240.67 (B) 1 thru 4. I will be relying on the fuse to clear in .07 seconds or less at the available fault current. If I get the proper documentation showing that the trip curve of the fuse will have a clearing time of .07 seconds or less at the available fault current, is 240.67 (C) performance testing still required? If it is required how would this testing be done since a fuse will be damaged with primary current injection?

The fuse clearing needs to be based on the available arcing fault current, not the bolted fault current.
IMO you might want to show that a fuse does actually clears in time rather than just using the curves.