A potential customer called into our engineering department one day from the middle of Iowa. “I was just told by a fuse salesman that if I buy his arc flash fuses that I don’t have to worry about arc flash in my facility”. (The idea is that “arc flash fuses” are fast acting and can clear a fault before the flash has time to reach out and injure employees or equipment). We then learned that the fuse salesman’s plan was to replace all the fuses in three bus bars for a low low rate of $20,000, then he could “guarantee” that all the equipment these buses fed to, would be at an arc flash hazard which would require minimal arc flash PPE. This facility has well over 30 buses total, so just the fuse price could run several hundred thousand dollars if the fuse salesman got his way!
First of all, you can’t “guarantee” arc flash values without conducting an incident energy analysis. We made that clear to our customer then, offered an option: “let us calculate the available incident energy at those three buses and see where you are now”
That’s what we did. In this case, the calculations showed that it didn’t matter what fuse was used in the overhead bus, there was no real arc flash hazard to equipment or personnel. Their existing configuration was already at the lowest arc flash hazard. In other words, the “arc flash fuses” would not increase safety at all.
Just the cost avoidance paid for a full evaluation of their facility. The Rozel team also provided device coordination and were able to eliminate nuisance tripping which had been a problem for years prior. This situation was unique, sometimes a different fuse can help, other times they do not. Mersen sells an impressive line of equipment which when used appropriately, can help tremendously: http://ep-us.mersen.com/ Of course, we recommend a device coordination study to ensure proper tripping.
Always be sure by completing a proper evaluation before spending the money.