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My present understanding is that not just any fuse meets the paperwork qualifications of "branch circuit protection". In particular, I want to protect a variable frequency drive, so J-type fuses are my go-to. But no manufacturer I've seen makes J-type fuses above 600 amps. I need 700-amp fuses. What should I do in this situation? Use some other fuse not rated for BCP? Is there another class of fuses I should look at that is rated for BCP?

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  • \$\begingroup\$ Try database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/… if you really want fuses you need a different class ... just make sure your drive has been certified for the class of fuse if your in the US or Canada or as per local regulations. Look like class T might be suitable \$\endgroup\$ – Spoon Jan 22 '16 at 13:11
  • \$\begingroup\$ Forgive me, but have you done a short circuit study? Fuses are super fast - or rather they can be - but they also are pretty final after they blow. If it was my choice and there was money for it, I'd want a variety of trip times most easily afforded by fuses AND a circuit breaker, not either/or. Specifically, I'm interested in your professional opinion - I don't get to do much actual work with my degree, so I mooch vicarious learning experiences. \$\endgroup\$ – Sean Boddy Jan 31 '16 at 3:54
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I'd consider using a circuit breaker rated for branch circuits but you can also get fuses. See this from Cooper industries: -

Standard sizes for fuses and fixed trip circuit breakers, per 240.6, are 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300, 350, 400, 450, 500, 600, 700, 800, 1000, 1200, 1600, 2000, 2500, 3000, 4000 5000, and 6000 amps. Additional standard fuse sizes are 1, 3, 6, 10, and 601 amps.

This one goes up to 700A: -

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From this page.

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