Does anyone have insight on where the fuse industry is going in regards to Class L fuses and arc flash? Specifically larger Class L type fuses acting as mains as well as large time delay fuses for motors or transformers/drives? This type of design is great for coordination but typically not as good as static trip breakers for reducing arc flash levels which can get very pricey.

I don’t know of anything new in the works. Someone else may have something. However, you point out a valid recurring concern. Just because a current limiting fuse is used, does not mean that it is the “magic bullet�. It must be properly sized and a fuse that is too large may not operate in its current limiting region. However, if a fuse is properly selected, it can go a long way towards reducing the incident energy.

A concern that I have is the original IEEE 1584 tests were performed with fuses from one manufacturer. U.L series rated tests use “Umbrella Value� current limiting fuses when testing combinations of devices. The “Umbrella Value� test fuses have the maximum let thru characteristics of that particular fuse size and class and are not manufacturer specific. That way if the test passes with umbrella values (worst case) then any manufacturer’s fuses can be used of a particular class and size.

The IEEE 1584 Standard is a fantastic document and took arc flash calculations way beyond where we were before. I am sure in time, other issues like this one will be sorted out as well.