Now, do you use a Slow Blow fuse/Time Delay Fuse, or a FAST Blow fuse? I tend to select the Slo Blo variety on AC Mains fuses. On most fuse data sheets, at 200% fuse rating, they call for a 5 Second Max hold before blowing. When you look at the curves on the Fuse Value (Horizontal) vs Time (Vertical), the Slow Blow fuse can handle much higher short-term current overloads than the Fast Blow variety. Such as LIttelfuse 312 (FAST) vs 313 (Slow).
I'm sure R.G. has a more exacting procedure in the selection process.