I don't know about the NBS, but on my OBS the wire length from the alternator to my battery is about three feet....if yours is similiar, there is really no reason for a fuse when adding 0g/2g to a vehicle with a stock alternator.
As an example, I have a HD Chevy alternator @ 140amps. 0 gauge can easily handle 300amps, no need for me to have a fuse. Also, Chevy uses 4 gauge w/o a fuse (on my OBS), and i added 0gauage...extreme overkill for me b/c I retained the stock alternator.
If added a really big time 250+ amp alternator, then I would have definitely fused my setup just for piece of mind.
However, if you do want to fuse it...I would recommend buying a fuse that is lower then the max amp rating of your wire. So if you wire is rated at 300amp, buy a fuse around 250 or 275.
Purrely to be illustrative...if you want to fuse your new big wire and you are keeping the original wires, then you should splice into your existing power wire and add a fuse as well.
I don't know your NBS setup, but unless you plan on upgrading to some really heavy duty alternator setups, there is really no reason to fuse 0g. But then again, unless you plan on upgrading to really heavy duty alternators, there is no reason for 0g either
I was in your shoes about a year ago, but once I started working with 0g and how expensive the terminals are and the PITA it is to crimp those huge wires...i truly wished I only added 4gauge to my existing setup.
I hope that helps!! If you have any more questions or want me to walk you through it, send me a PM and I'd be happy to get on the phone with you.
Or, just reply here and I'll add any insight i have to the forum.