I understand that a DC fuse's voltage rating is determined by the possibility of a connection-sustaining plasma arc. However, unlike the current rating, which is based on the very well understood principles of resistive heating, the voltage rating is based on the likelihood of plasma creation, and this seems to be much more stochastic. I expect that as a result, the current rating is very precise, but in contrast the voltage rating is very conservative.
I'm interested in how much excess voltage is actually required in typical circumstances to see plasma arcing. I'd also like to know what factors affect the likelihood of plasma creation, and how do they play into the fuse's real-world behavior.
UPDATE: Another way to phrase this is that I'm looking for an understanding of DC fuses' design safety factor and how environmental factors affect the real-world safety margin.