What is the NEC article that shows the back-up fuse req's for Motor Protection applications?

This is what I understand:

The back-up fuses are necessary only if the short circuit current is higher than the breaking capacity of the Motor starter/protector. This is also in addition to the branch protection fuses.

Or is the only reference in IEC 947-2?

Can someone elaborate on this?

Carl Lee Tolbert
Technical Support
AC Drives
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