Fusing - Positive vs 2-pole


Solar Enthusiast
Feb 22, 2022
I'm trying to understand why conventional wisdom is to just fuse on the positive for a fairly large (>600Ah) ungrounded 48V battery bank. I get that it is fine to do that on smaller systems (say <100Ah), or if it is negatively grounded, or if you have an insulated busbar and short run to the fuse, but I don't understand why fairly large systems are only fused on the positive.

Is this how the server rack batteries are operating as well?

My current plan has about 18" of wire between the busbars and the circuit breaker. Do I need 2-pole fusing/circuit breakers, or is single pole code compliant?